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  • 1.
    Alehojat, Mobin
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap.
    Jafari, Reza
    Tarbiat Modares University, Department of Material Science and Engineering, Tehran, 141 15, Iran (IRN).
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Electron beam-powder bed fusion of Alloy 718: Effect of hot isostatic pressing and thermal spraying on microstructural characteristics and oxidation performance2020Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 404, artikel-id 126626Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alloy 718 manufactured via electron beam-powder bed fusion (EB-PBF) was coated with a thermally- sprayed NiCoCrAlY coating for enhanced oxidation protection. A high-velocity air fuel technique was used to deposit the coating. The specimens were then subjected to hot isostatic pressing (HIP). Oxidation of the specimens was undertaken in an ambient air environment at 650 and 800 °C for 168 h. The oxidation performance of EB-PBF-built Alloy 718 was improved after the deposition of the coating, particularly at 800 °C. In this temperature, a thick Cr-rich oxide scale was found on the uncoated Alloy 718 specimen, whereas a thin and stable Al-rich oxide scale was formed on the surface of the coated specimen. HIPing enhanced the oxidation resistance of uncoated Alloy 718; however, the oxidation behavior of coated Alloy 718 was negatively affected by HIPing. © 2020 The Authors

  • 2.
    Clement, C.
    et al.
    National School of Engineers, University of Limoges, Limoges, 87280, France.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Lyphout, Christophe
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Corrosion behavior of HVAF- and HVOF-sprayed high-chromium Fe-based coatings2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fe-based coatings with three particular elemental compositions and two different powder particle size were prepared by high-velocity air fuel (HVAF) and high-velocity oxy fuel (HVOF) techniques. The corrosion behavior of which were comparatively studied in 3.5 wt.% NaCl solution. The results indicated that the coatings produced by HVAF process exhibited denser structure with lower porosity. Polarization and electrochemical impedance spectroscopy (EIS) tests indicated that the HVAF coatings provided better corrosion resistance than the HVOF coatings. The presence of defects was significant in HVOF coatings. The investigation illustrated that the corrosion paths initiated and grow through defects of the coating. Furthermore, adding Cr strongly improved the corrosion resistance of the coatings. The results confirmed that the cheap HVAF process could be a potential alternative to HVOF to fabricate Fe-based coatings for industrial applications.

  • 3.
    Eklund, Johan
    et al.
    Chalmers University of Technology, Energy and Materials, Department of Chemistry and Chemical Engineering, Göteborg, 412 96, Sweden.
    Phother, J.
    Chalmers University of Technology, Energy and Materials, Department of Chemistry and Chemical Engineering, Göteborg, 412 96, Sweden.
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Liske, Jesper
    Chalmers University of Technology, Energy and Materials, Department of Chemistry and Chemical Engineering, Göteborg, 412 96, Sweden.
    High-Temperature Corrosion of HVAF-Sprayed Ni-Based Coatings for Boiler Applications2019Ingår i: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 91, nr 5-6, s. 729-747Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The present study investigates the initial corrosion behaviour of HVAF-sprayed NiCr, NiAl and NiCrAlY coatings in two different environments, O 2 + H 2 O and O 2 + H 2 O + KCl at 600 °C for up to 168 h in order to evaluate the possibility of utilizing such coatings in biomass- and waste-fired boilers. SEM/EDX analysis showed that all coatings displayed a protective behaviour in O 2 + H 2 O. Upon addition of KCl (O 2 + H 2 O + KCl), the corrosion behaviour of the NiCr coating drastically changed as it formed a thick oxide layer and displayed major chlorine diffusion down to the substrate. The NiCrAlY coating displayed a significantly better corrosion resistance with only minor oxide formation. The NiAl coating exhibited a protective behaviour similar to when exposed in the absence of KCl indicating that a thin protective oxide has formed on the coating surface. The performance of the NiAl and NiCrAlY coatings is promising for future studies with long-term exposures in more corrosive environments such as in a biomass- and waste-fired boiler. © 2019, The Author(s).

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  • 4.
    Guerin, Elie
    et al.
    National School of Engineers, University of Limoges, Limoges, France.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Role of Chemistry on Corrosion Behavior of Various Ni-based HVAF-Sprayed Coatings in Simulated Boiler Environments2017Konferensbidrag (Övrigt vetenskapligt)
  • 5.
    Jafari, R.
    et al.
    Tarbiat Modares University, Department of Material Science and Engineering, Tehran, 14115, Iran.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Shahrabi Farahani, T.
    Tarbiat Modares University, Department of Material Science and Engineering, Tehran, 14115, Iran.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    KCI-induced corrosion behavior of HVAF-sprayed Ni-based coatings in ambient air2017Ingår i: Proceedings of the International Thermal Spray Conference & Exposition (ITSC 2017), Curran Associates, Inc. , 2017, Vol. 2, s. 946-950Konferensbidrag (Refereegranskat)
    Abstract [en]

    It is well known that the presence of KCl deposited on superheater tubes in biomass- and waste-fired boilers leads to a severe corrosion and premature damage. In order to protect such critical components which are routinely exposed to aggressive environments, thermal spray coatings are frequently proposed as a potential solution. By virtue of the techno-commercial benefits that provides as a direct outcome of its ability to cost-effectively deposit coatings virtually free of porosity and in situ formed oxides, the high velocity air-fuel (HVAF) process offers a particularly attractive approach. In the present work, the influence of KCl on the oxidation behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5AI, Ni21Cr7AI1Y, and Ni21Cr9Mo) has been investigated. The coatings were deposited onto specimens of 16Mo3 steel, a widely used boiler tube material. High temperature corrosion tests were carried out in ambient air at 600°C, with 0.1 mg/cm2 KCl being sprayed onto the samples prior to the exposure. Uncoated substrates and an identical test environment without KCl were used as reference. SEM/EDS and XRD techniques were utilized to characterize the as-sprayed and exposed samples. The results showed that the small addition of KCl significantly accelerated damage to the coatings. It was further revealed that the alumina-forming NiAl coating was capable of forming a more protective oxide scale compared to other chromia and mixed-oxide scale forming coatings. In general, the oxidation resistance of the coatings based on the kinetic studies had the following ranking (from the best to the worst): NiAl >NiCr> NiCrAlY> NiCrMo. © Copyright 2017 by DVS Media GmbH. All rights reserved.

  • 6.
    Jafari, R.
    et al.
    Department of Material Science and Engineering, Tarbiat Modares University, Tehran, Iran.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Shahrabi Farahani, T.
    Department of Material Science and Engineering, Tarbiat Modares University, Tehran, Iran .
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    KCl-induced corrosion behavior of HVAF-sprayed Ni-based coatings in ambient air2017Konferensbidrag (Övrigt vetenskapligt)
  • 7.
    Jafari, Reza
    et al.
    Tarbiat Modares University, Department of Material Science and Engineering, Tehran, 14 115, Iran.
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    High-temperature corrosion performance of HVAF-sprayed NiCr, NiAl, and NiCrAlY coatings with alkali sulfate/chloride exposed to ambient air2019Ingår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 160, artikel-id 108066Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The high-temperature corrosion of high velocity air-fuel (HVAF) thermal spray Ni21Cr, Ni5Al, and Ni21Cr7AlY coatings was investigated at 600 °C for 168 h in ambient air under KCl and 50-50 mol% KCl–K2SO4 salts. Chlorination-oxidation cycle and breakdown of the corrosion products layer were the dominant corrosion mechanism in the chromia-forming Ni21Cr and Ni21Cr7AlY coatings exposed to KCl. KCl–K2SO4 was less corrosive to the chromia-forming coatings as K2SO4 was less reactive to the protective Cr-rich oxide. The alumina-forming NiAl exhibited a better corrosion performance under KCl, though it partially suffered from selective sulfidation when exposed to the mixed salt. © 2019 Elsevier Ltd

  • 8.
    Jafari, Reza
    et al.
    Tarbiat Modares University, Department of Material Science and Engineering, Tehran, Iran.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Shahrabi Farahani, Taghi
    Tarbiat Modares University, Department of Material Science and Engineering, Tehran, Iran.
    Huhtakangas, Matti
    M. H. Engineering AB, Karlskoga, Sweden .
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    KCl-Induced High Temperature Corrosion Behavior of HVAF-Sprayed Ni-Based Coatings in Ambient Air2018Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 27, nr 3, s. 500-511Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    KCl-induced high temperature corrosion behavior of four HVAF-sprayed Ni-based coatings (Ni21Cr, Ni5Al, Ni21Cr7Al1Y, and Ni21Cr9Mo) under KCl deposit has been investigated in ambient air at 600°C up to 168h. The coatings were deposited onto 16Mo3 steel - a widely used boiler tube material.Uncoated substrate, 304L and Sanicro25 were used as reference materials in the test environment.SEM/EDS and XRD techniques were utilized to characterize the as-sprayed and exposed samples.The results showed that the small addition of KCl significantly accelerated degradation to the coatings. All coatings provided better corrosion resistance compared to the reference materials. The alumina-forming Ni5Al coating under KCl deposit was capable of forming a more protective oxide scale compared to the chromia-forming coatings as penetration of Cl through diffusion paths was hindered. Both active corrosion and chromate formation mechanisms were found to be responsible for Page 1 of 23ASM the corrosion damages. The corrosion resistance of the coatings based on the microstructure analysis and kinetics had the following ranking (from the best to worst): Ni5Al >Ni21Cr> Ni21Cr7Al1Y>Ni21Cr9Mo.

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  • 9.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Deng, Dunyong
    Linköping University, Division of Engineering Materials, Linköping, Sweden.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Olsson, Jonas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ålgårdh, Joakim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Swerea KIMAB AB, Kista, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Microstructure Development in Track-by-Track Melting of EBM-Manufactured Alloy 7182018Ingår i: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications / [ed] Ott, E., Liu, X., Andersson, J., Bi, Z., Bockenstedt, K., Dempster, I., Groh, J., Heck, K., Jablonski, P., Kaplan, M., Nagahama, D. and Sudbrack, C., Springer, 2018, s. 643-654Konferensbidrag (Refereegranskat)
    Abstract [en]

    Electron beam melting (EBM) is a powder-bed fusion process within the group of additive manufacturing (AM) technology that is used to fabricate high performance metallic parts. Nickel-Iron base superalloys, such as Alloy 718, are subjected to successive heating and cooling at temperatures in excess of 800 °C during the EBM process. Characterization of the dendritic structure, carbides, Laves and δ-phase were of particular interest in this study. These successive thermal cycles influence the microstructure of the material resulting in a heterogeneous structure, especially in the building direction. Hence, the aim of this study was to gain increased fundamental understanding of the relationship between the processing history and the microstructure formed within a single layer. Different numbers of tracks with equal heights were for this purpose produced, varying from one to ten tracks. All tracks used the same process parameters regardless of number and/or position. Microstructure characteristics (sub-grain structure, grain structure and phases) were analyzed by optical microscopy, scanning electron microscopy equipped with energy disperse spectroscopy and electron backscatter diffraction. The direction of dendrites changed in the overlap zones within the tracks due to re-melting of material in the overlap zone. The primary dendrite arm spacings slightly increased along multi-tracks owing to a slight decrease in cooling rate by addition of the next tracks. Epitaxial growth of grains were observed in all samples due to partial re-melting of grains in previous layers and surface nucleation was also found to occur in all tracks.

  • 10.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ålgårdh, Joakim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Powder Materials & Additive Manufacturing, Swerea KIMAB AB, Kista, 164 40, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    EBM-manufactured single tracks of Alloy 718: Influence of energy input and focus offset on geometrical and microstructural characteristics2019Ingår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 148, s. 88-99Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electron beam melting-powder bed fusion (EBM-PBF) is an additive manufacturing process, which is able to produce parts in layer-by-layer fashion from a 3D model data. Currently application of this technology in parts manufacturing with high geometrical complexity has acquired growing interest in industry. To recommend the EBM process into industry for manufacturing parts, improved mechanical properties of final part must be obtained. Such properties highly depend on individual single melted track and single layer. In EBM, interactions between the electron beam, powder, and solid underlying layer affect the geometrical (e.g., re-melt depth, track width, contact angle, and track height) and microstructural (e.g., grain structure, and primary dendrite arm spacing) characteristics of the melted tracks. The core of the present research was to explore the influence of linear energy input parameters in terms of beam scanning speed, beam current as well as focus offset and their interactions on the geometry and microstructure of EBM-manufactured single tracks of Alloy 718. Increased scanning speed led to lower linear energy input values (<0.9 J/mm) in an specific range of the focus offset (0–10 mA) which resulted in instability, and discontinuity of the single tracks as well as balling effect. Decreasing the scanning speed and increasing the beam current resulted in higher melt pool depth and width. By statistical evaluations, the most influencing parameters on the geometrical features were primarily the scanning speed, and secondly the beam current. Primary dendrite arm spacing (PDAS) slightly decreased by increasing the scanning speed using lower beam current values as the linear energy input decreased. By increasing the linear energy input, the chance of more equiaxed grain formation was high, however, at lower linear energy input, mainly columnar grains were observed. The lower focus offset values resulted in more uniform grains along the 〈001〉 crystallographic direction. © 2018 Elsevier Inc. 

  • 11.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ålgårdh, Joakim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). GE Additive | Arcam EBM, Designvägen 2, Mölnlycke, 435 33, Sweden.
    Harlin, P.
    Sandvik Additive Manufacturing, Sandviken, 811 81, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Effect of build location on microstructural characteristics and corrosion behavior of EB-PBF built Alloy 7182020Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 106, nr 7-8, s. 3597-3607Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Electron beam-powder bed fusion (EB-PBF), a high-temperature additive manufacturing (AM) technique, shows great promise in the production of high-quality metallic parts in different applications such as the aerospace industry. To achieve a higher build efficiency, it is ideal to build multiple parts together with as low spacing as possible between the respective parts. In the EB-PBF technique, there are many unknown variations in microstructural characteristics and functional performance that could be induced as a result of the location of the parts on the build plate, gaps between the parts and part geometry, etc. In the present study, the variations in the microstructure and corrosion performance as a function of the parts location on the build plate in the EB-PBF process were investigated. The microstructural features were correlated with the thermal history of the samples built in different locations on the build plate, including exterior (the outermost), middle (between the outermost and innermost), and interior (the innermost) regions. The cubic coupons located in the exterior regions showed increased level (~ 20 %) of defects (mainly in the form of shrinkage pores) and lower level (~ 30-35 %) of Nb-rich phase fraction due to their higher cooling rates compared to the interior and middle samples. Electrochemical investigations showed that the location indirectly had a substantial influence on the corrosion behavior, verified by a significant increase in polarization resistance (Rp) from the exterior (2.1 ± 0.3 kΩ.cm2) to interior regions (39.2 ± 4.1 kΩ.cm2). © 2020, The Author(s).

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  • 12.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ålgårdh, Joakim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). GE Additive | Arcam EBM, Mölnlycke (SWE).
    Keshavarzkermani, Ali
    Multi‑Scale Additive Manufacturing Lab, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (CAN).
    Esmaeilizadeh, Reza
    Multi‑Scale Additive Manufacturing Lab, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (CAN).
    Toyserkani, Ehsan
    Multi‑Scale Additive Manufacturing Lab, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo (CAN).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Columnar-to-equiaxed grain transition in powder bed fusion via mimicking casting solidification and promoting in situ recrystallization2021Ingår i: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 46, artikel-id 102086Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Columnar grain structure typically formed along the build direction in the electron beam-powder bed fusion (EBPBF) technique leads to anisotropic physical and mechanical properties. In this study, casting solidification condition was mimicked, and in situ recrystallization was promoted in EB-PBF to facilitate columnar-to-equiaxed grain structure transition in Alloy 718. This is achieved via a unique linear melting strategy coupled with a specific selection of process parameters in EB-PBF. It was found that site-specific melting using line order number (LON) function affected the cooling rate and temperature gradient, which controlled grain morphology and texture. A high LON resulted in a large equiaxed grain zone with a random texture, whereas a fixed LON with a high areal energy density led to a strong texture. The main driving force in the formation of cracks and shrinkage defects during the transition was investigated. A high LON at a fixed areal energy density reduced the average total shrinkage defects and crack length. The hardness was decreased through the transition, which was linked to the reduction in the size of the gamma ‘’ precipitates.

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    Additive Manufacturing
  • 13.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ålgårdh, Joakim
    Arcam-EBM (a GE Additive), 435 33, Mölnlycke (SWE).
    Olsson, Jonas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Hörnqvist Colliander, Magnus
    Department of Applied Physics, Chalmers University of Technology, Gothenburg (SWE).
    Harlin, Peter
    Sandvik Additive Manufacturing, Sandviken (SWE).
    Toyserkani, Ehsan
    Department of Mechanical and Mechatronic Engineering, Waterloo University, Waterloo (CAN).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Tailored grain morphology via a unique melting strategy in electron beam-powder bed fusion2021Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 824, artikel-id 141820Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study presents a unique melting strategy in electron beam-powder bed fusion of Alloy 718 to tailor the grain morphology from the typical columnar to equiaxed morphology. For this transition, a specific combination of certain process parameters, including low scanning speeds (400-800 mm/s), wide line offsets (300-500 mu m) and a high number of line order (#10) was selected to control local solidification conditions in each melt pool during the process. In addition, secondary melting of each layer with a 90. rotation with respect to primary melting induced more vigorous motions within the melt pools and extensive changes in thermal gradient direction, facilitating grain morphology tailoring. Four different types of microstructures were classified according to the produced grain morphology depending on the overlap zone between two adjacent melt pools, i.e., fully-columnar (overlap above 40 %), fully-equiaxed (overlap below 15 %), mixed columnar-equiaxed grains, and hemispherical melt pools containing mixed columnar-equiaxed grains (overlap similar to 20-25 %). The typical texture was <001>; however, the texture was reduced significantly through the transition from the columnar to equiaxed grain morphology. Along with all four different microstructures, shrinkage defects and cracks were also identified which amount of them reduced by a reduction in areal energy input. The hardness was increased through the transition, which was linked to the growth of the.” precipitates and high grain boundary density in the fully-equiaxed grain morphology.

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    Materials Science & Engineering A
  • 14.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Deng, D.
    Linköping University, Division of Engineering Materials, Department of Management and Engineering, Linköping, 581 83, Sweden.
    Gruber, H.
    University of Chalmers, Division of Materials and Manufacture, Industrial and Materials Science, Gothenburg, 412 96, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Nylen, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Influence of build layout and orientation on microstructural characteristics of electron beam melted Alloy 7182018Ingår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 99, nr S1, s. 2903-2913Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Effects of build layout and orientation consisting of (a) height from the build plate (Z-axis), (b) distance between samples, and (c) location in the build plate (X-Y plane) on porosity, NbC fraction, and hardness in electron beam melted (EBM) Alloy 718 were studied. The as-built samples predominantly showed columnar structure with strong ˂001˃ crystallographic orientation parallel to the build direction, as well as NbC and ÎŽ-phase in inter-dendrites and grain boundaries. These microstructural characteristics were correlated with the thermal history, specifically cooling rate, resulted from the build layout and orientation parameters. The hardness and NbC fraction of the samples increased around 6% and 116%, respectively, as the height increased from 2 to 45 mm. Moreover, by increasing the height, formation of ÎŽ-phase was also enhanced associated with lower cooling rate in the samples built with a greater distance from the build plate. However, the porosity fraction was unaffected. Increasing the sample gap from 2 to 10 mm did not change the NbC fraction and hardness; however, the porosity fraction increased by 94%. The sample location in the build chamber influenced the porosity fraction, particularly in interior and exterior areas of the build plate. The hardness and NbC fraction were not dependent on the sample location in the build chamber. © 2018, The Author(s).

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  • 15.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Åkerfeldt, Pia
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Luleå, 971 87, Sweden.
    Ålgårdh, Joakim
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Powder Materials & Additive Manufacturing, Swerea KIMAB AB, Kista, 164 40, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Influence of successive thermal cycling on microstructure evolution of EBM-manufactured alloy 718 in track-by-track and layer-by-layer design2018Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 160, s. 427-441Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Successive thermal cycling (STC) during multi-track and multi-layer manufacturing of Alloy 718 using electron beam melting (EBM) process leads to a microstructure with a high degree of complexity. In the present study, a detailed microstructural study of EBM-manufactured Alloy 718 was conducted by producing samples in shapes from one single track and single wall to 3D samples with maximum 10 longitudinal tracks and 50 vertical layers. The relationship between STC, solidification microstructure, interdendritic segregation, phase precipitation (MC, δ-phase), and hardness was investigated. Cooling rates (liquid-to-solid and solid-to-solid state) was estimated by measuring primary dendrite arm spacing (PDAS) and showed an increased cooling rate at the bottom compared to the top of the multi-layer samples. Thus, microstructure gradient was identified along the build direction. Moreover, extensive formation of solidification micro-constituents including MC-type carbides, induced by micro-segregation, was observed in all the samples. The electron backscatter diffraction (EBSD) technique showed a high textured structure in 〈001〉 direction with a few grains misoriented at the surface of all samples. Finer microstructure and possibility of more γ″ phase precipitation at the bottom of the samples resulted in slightly higher (~11%) hardness values compared to top of the samples. © 2018 Elsevier Ltd

  • 16.
    Karimi Neghlani, Paria
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Schnur, Christopher
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Contour design to improve topographical and microstructural characteristics of Alloy 718 manufactured by electron beam-powder bed fusion technique2020Ingår i: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 32, artikel-id 101014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Additive manufacturing (AM) processes are being frequently used in industry as they allow the manufacture ofcomplex parts with reduced lead times. Electron beam-powder bed fusion (EB-PBF) as an AM technology isknown for its near-net-shape production capacity with low residual stress. However, the surface quality andgeometrical accuracy of the manufactured parts are major obstacles for the wider industrial adoption of thistechnology, especially when enhanced mechanical performance is taken into consideration. Identifying theorigins of surface features such as satellite particles and sharp valleys on the parts manufactured by EB-PBF isimportant for a better understanding of the process and its capability. Moreover, understanding the influence ofthe contour melting strategy, by altering process parameters, on the surface roughness of the parts and thenumber of near-surface defects is highly critical. In this study, processing parameters of the EB-PBF techniquesuch as scanning speed, beam current, focus offset, and number of contours (one or two) with the linear meltingstrategy were investigated. A sample manufactured using Arcam-recommended process parameters (threecontours with the spot melting strategy) was used as a reference. For the samples with one contour, the scanningspeed had the greatest effect on the arithmetical mean height (Sa), and for the samples with two contours, thebeam current and focus offset had the greatest effect. For the samples with two contours, a lower focus offset andlower scan speed (at a higher beam current) resulted in a lower Sa; however, increasing the scan speed for thesamples with one contour decreased Sa. In general, the samples with two contours provided a lower Sa (∼22 %)but with slightly higher porosity (∼8 %) compared to the samples with one contour. Fewer defects were detected with a lower scanning speed and higher beam current. The number of defects and the Sa value for thesamples with two contours manufactured using the linear melting strategy were ∼85 % and 16 %, respectively,lower than those of the reference samples manufactured using the spot melting strategy.

  • 17.
    Kisielewicz, Agnieszka
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Sikström, Fredrik
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Christiansson, Anna-Karin
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS).
    Palumbo, Gianfranco
    CNR-IFN Institute for Photonics and Nanotechnologies, Physics Department, Bari, Italy (ITA).
    Ancona, Antonio
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för produktionssystem (PS). CNR-IFN Institute for Photonics and Nanotechnologies, Physics Department, Bari, Italy (ITA).
    In-process spectroscopic detection of chromium loss during Directed Energy Deposition of alloy 7182020Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 186, artikel-id 108317Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this work, a fast optical spectrometer was used to monitor the Directed Energy Deposition (DED) process, during the deposition of Alloy 718 samples with different laser power, thus different energy inputs into the material. Spectroscopic measurements revealed the presence of excited Cr I atoms in the plasma plume. The presence was more apparent for the samples characterized by higher energy input. The Cr depletion from these samples was confirmed by lower Cr content detected by Energy-Dispersive X-ray Spectroscopy (EDS) analysis. The samples were also characterized by higher oxidation and high-temperature corrosion rates in comparison to the samples produced with low energy input. These results prove the applicability of an optical emission spectroscopic system for monitoring DED to identify process conditions leading to compositional changes and variation in the quality of the built material.

  • 18.
    Mahade, Satyapal
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Baiamonte, Lidia
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Department of Chemical Engineering Materials Environment, Sapienza University of Rome, (ITA).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Marra, Francesco
    Department of Chemical Engineering Materials Environment, Sapienza University of Rome, (ITA).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Novel utilization of powder-suspension hybrid feedstock in HVAF spraying to deposit improved wear and corrosion resistant coatings2021Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 412, artikel-id 127015Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Deployment of a suspension feedstock has been known to alleviate problems associated with using sub-micron and nanosized powder feedstock for thermal spraying of monolithic as well as powder-suspension ‘hybrid’ composite coatings. However, a powder-suspension hybrid feedstock has never been previously used in high-velocity air-fuel (HVAF) spraying. In this work, for the very first time, a chromium carbide (Cr3C2) suspension has been co-sprayed along with an Inconel-625 (IN-625) powder by the HVAF process as an illustrative case study. Two variants of the IN-625 + Cr3C2 hybrid coatings were produced by varying relative powder-suspension feed rates. For comparison, pure IN-625 coating was also deposited utilizing identical spray parameters. Detailed microstructural characterization, porosity content, hardness measurement and phase analysis of the as-deposited coatings was performed. The suspension-derived carbides were retained in the bulk of the coating, resulting in higher hardness. In the dry sliding wear test, the hybrid coatings demonstrated lower wear rate and higher coefficient of friction (CoF) compared to the conventional, powder-derived IN-625 coatings. Furthermore, the wear rate improved slightly with an increase in Cr3C2 content in the hybrid coating. Post-wear analysis of the worn coating, worn alumina ball and the wear debris was performed to understand the wear mechanisms and material transfer in the investigated coatings. In the potentiodynamic polarization test, higher corrosion resistance for hybrid coatings than conventional IN-625 coatings was achieved, indicating that the incorporation of a secondary, carbide phase in the IN-625 matrix did not compromise its corrosion performance. This work demonstrates a novel approach to incorporate any finely distributed second phase in HVAF sprayed coatings to enhance their performance when exposed to harsh environments.

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  • 19.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Multi-Scale Additive Manufacturing Lab (MSAM), The University of Waterloo, Ontario (CAN).
    Asala, Gbenga
    Technology Access Centre for Aerospace & Manufacturing, Red River College, Manitoba (CAN).
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Multi-Scale Additive Manufacturing Lab (MSAM), The University of Waterloo, Ontario (CAN).
    Deng, Dunyong
    Division of Engineering Materials, Linköping University, Linköping (SWE).
    Moverare, Johan
    Division of Engineering Materials, Linköping University, Linköping (SWE).
    Hansson, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). GKN Aerospace Engine Systems, Trollhättan (SWE).
    Fatigue crack initiation and propagation in Alloy 718 with a bimodal grain morphology built via electron beam-powder bed fusion2021Ingår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 827, artikel-id 142051Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A unique melting strategy was implemented in electron beam-powder bed fusion (EB-PBF) of Alloy 718, resulting in the formation of a bimodal grain morphology consisting of fine equiaxed and columnar grains. The microstructure was preserved following various thermal post-treatments. The post-treated specimens were exposed to low cycle fatigue (LCF), and fatigue crack growth (FCG) tests in ambient air at 600 °C under pure and dwell-time (120 s) fatigue cycles. Clustered inclusions spanned a region of 100-600 µm in length acted as the crack initiation site, reducing the specimens' total fatigue life. When compared to pure fatigue cycles, dwell-time fatigue cycles reduced LCF life by approximately 35%, regardless of the thermal post-treatments. Due to a high fraction of grain boundary area in the as-built EB-PBF specimens, oxygen diffusion across the grain boundaries was enhanced. The intergranular fracture mode was favored in the plastic zone ahead of the crack tip, leading to rapid crack growth. No unbroken ligaments behind the crack front were found by high-resolution X-ray computed tomography, which was consistent with a large crack opening displacement linked to severe deformation around the crack tip. 

  • 20.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Chlorine-induced high-temperature corrosion and erosion-corrosion of HVAF and HVOF-sprayed amorphous Fe-based coatings2019Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 371, nr S1, s. 20-35Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Chlorine-induced high-temperature corrosion and erosion-corrosion behavior of amorphous Fe-based coatings sprayed by high velocity air-fuel (HVAF) and high velocity oxy-fuel (HVOF) techniques were investigated. The coated specimens were first exposed to isothermal high-temperature corrosion at 600 °C in ambient air with and without KCl. The exposed specimens were then subjected to alumina erodent. The as-sprayed HVAF coating showed a more compact and uniform microstructure with a higher hardness leading to higher corrosion and erosion-corrosion resistance. After erosion, all the coatings similarly exhibited a combined brittle/ductile damage to surface oxide scale that previously formed in the corrosive environment. The corrosion and erosion-corrosion behavior of the coatings primarily relied on the uniformity of coatings’ microstructure and distribution of alloying elements to form the protective oxide scale in the corrosive environment, which can resist against erodent in the erosive media. © 2019 Elsevier B.V.

  • 21.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Israelsson, Niklas
    GE Additive – Arcam EBM, Mölnlycke, Sweden.
    Shipley, James
    Quintus Technologies AB, Västerås, Sweden.
    Månsson, Tomas
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Hansson, Thomas
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). GKN Aerospace Engine Systems, Sweden.
    Inclusion-induced fatigue crack initiation in powder bed fusion of Alloy 7182020Ingår i: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 36, artikel-id 101670Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fatigue crack initiation of Alloy 718 additively manufactured via electron beam-powder bed fusion (EB-PBF) process was investigated. The melt parameters were chosen to achieve sufficient energy input and minimize process-induced defects. A line offset of 200 µm with enough line energy was used, leading to the formation of wide and deep melt pools. This strategy facilitated the formation of equiaxed grains at the melt pools bottom, and short columnar grains within the melt pools aligned parallel to the build direction. The mixed grain morphology and texture were retained after various thermal post-treatments, including heat treatment (HT), hot isostatic pressing (HIP), and HIP-HT. Micron-sized non-metallic inclusions in the feedstock powder, such as Al-rich oxide and titanium nitride clustered during the EB-PBF process, and remained intact during the post-treatments. Low cycle fatigue cracks mainly originated from the non-metallic inclusions found near the surface of the test specimens. HIPing was able to remove a portion of the internal defects, including round-shaped and shrinkage pores; therefore, a small fatigue life enhancement was observed in HIP-HT compared to HT.

  • 22.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Momeni, Soroush
    Friedrich-Alexander University Erlangen-Nurnberg, Department of Materials Science and Engineering, Erlangen, 91058, Germany.
    Seifi, Mohsen
    Case Western Reserves University, Department of Materials Science & Engineering, Cleveland, 44106,USA; ASTM International, Washington, DC 20036, United States .
    Eklund, Anders
    Quintus Technologies AB, Västerås, 721 66, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Influence of thermal post treatments on microstructure and oxidation behavior of EB-PBF manufactured Alloy 7182019Ingår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 150, s. 236-251Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The effect of thermal post treatments consisting of heat treatment (HT), hot isostatic pressing (HIP), and combined HIP-HT on microstructure and oxidation behavior of Alloy 718 manufactured by electron beam powder bed fusion (EB-PBF) technique was investigated. Oxidation of the as-built and post-treated specimens was performed in ambient air at 650, 750, and 850 °C for up to 168 h. Directional columnar-grained microstructure, pores and fine Nb-rich carbides were observed in the as-built specimen. The HT specimen presented the columnar microstructure, plate-like δ phase at grain boundaries, and pores. The dominant grain crystallographic orientation was changed from 〈001〉 in the as-built specimen to 〈101〉 after HT. No grain boundary δ phase was observed in the HIPed specimen, but recrystallization occurred in both the HIP and HIP-HT specimens due to a rapid cooling after HIPing motivating the nucleation of fine grains with limited time to grow. After oxidation exposure at 650 and 750 °C for 168 h, no big difference between weight changes of the as-built and post-treated specimens was noted, whereas at 850 °C, the combined HIP-HT specimen showed the most promising corrosion resistance with the least weight change. At 850 °C, a protective scale of Cr 2 O 3 rich in Cr, Ti, and Ni as well as an internal oxide (branched structure of alumina) developed in all the specimens, while, only a protective Cr 2 O 3 scale was found at 650 and 750 °C. The HIP-HT specimen at 850 °C developed an oxide scale, which was denser and more adherent in comparison to the oxide scales formed on the other three specimens, associated with its limited defect distribution and more homogenized microstructure. Moreover, the δ phase formed close to the surface of the exposed specimens during the oxidation exposure at 850 °C most probably led to nucleation and growth of the oxide scale. © 2019 Elsevier Inc.

  • 23.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants. Part I: Effect of Composition and Microstructure2019Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, nr 8, s. 1749-1788Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Power generation from renewable resources has attracted increasing attention in recent years owing to the global implementation of clean energy policies. However, such power plants suffer from severe high-temperature corrosion of critical components such as water walls and superheater tubes. The corrosion is mainly triggered by aggressive gases like HCl, H2O, etc., often in combination with alkali and metal chlorides that are produced during fuel combustion. Employment of a dense defect-free adherent coating through thermal spray techniques is a promising approach to improving the performances of components as well as their lifetimes and, thus, significantly increasing the thermal/electrical efficiency of power plants. Notwithstanding the already widespread deployment of thermal spray coatings, a few intrinsic limitations, including the presence of pores and relatively weak intersplat bonding that lead to increased corrosion susceptibility, have restricted the benefits that can be derived from these coatings. Nonetheless, the field of thermal spraying has been continuously evolving, and concomitant advances have led to progressive improvements in coating quality; hence, a periodic critical assessment of our understanding of the efficacy of coatings in mitigating corrosion damage can be highly educative. The present paper seeks to comprehensively document the current state of the art, elaborating on the recent progress in thermal spray coatings for high-temperature corrosion applications, including the alloying effects, and the role of microstructural characteristics for understanding the behavior of corrosion-resistant coatings. In particular, this review comprises a substantive discussion on high-temperature corrosion mechanisms, novel coating compositions, and a succinct comparison of the corrosion-resistant coatings produced by diverse thermal spray techniques.

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  • 24.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Advances in Corrosion-Resistant Thermal Spray Coatings for Renewable Energy Power Plants: Part II - Effect of Environment and Outlook2019Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 28, nr 8, s. 1789-1850Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-temperature corrosion of critical components such as water walls and superheater tubes in biomass/waste-fired boilers is a major challenge. A dense and defect-free thermal spray coating has been shown to be promising to achieve a high electrical/thermal efficiency in power plants. The field of thermal spraying and quality of coatings have been progressively evolving; therefore, a critical assessment of our understanding of the efficacy of coatings in increasingly aggressive operating environments of the power plants can be highly educative. The effects of composition and microstructure on high-temperature corrosion behavior of the coatings were discussed in the first part of the review. The present paper that is the second part of the review covers the emerging research field of performance assessment of thermal spray coatings in harsh corrosion-prone environments and provides a comprehensive overview of the underlying high-temperature corrosion mechanisms that lead to the damage of exposed coatings. The application of contemporary analytical methods for better understanding of the behavior of corrosion-resistant coatings is also discussed. A discussion based on an exhaustive review of the literature provides an unbiased commentary on the advanced accomplishments and some outstanding issues in the field that warrant further research. An assessment of the current status of the field, the gaps in the scientific understanding, and the research needs for the expansion of thermal spray coatings for high-temperature corrosion applications is also provided. © 2019, The Author(s).

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  • 25.
    Sadeghi, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Pant, Prabhat
    Department of Management and Engineering, Linköping University, Linköping, (SWE).
    Jafari, Reza
    Department of Material Science and Engineering, Tarbiat Moares University, Tehran (IRN).
    Peng, Ru Lin
    Department of Management and Engineering, Linköping University, 581 83 Linköping (SWE).
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Subsurface grain refinement in electron beam-powder bed fusion of Alloy 718: Surface texture and oxidation performance2020Ingår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Subsurface grains of Alloy 718 additively manufactured via electron beam-powder bed fusion technique were refined using shot peening to improve the surface texture and oxidation performance. Oxidation of the specimens was performed at 650 and 800 degrees C in ambient air. Due to plastic deformation upon shot peening, compressive residual stress and high microstrain were generated in the subsurface region within a depth of approximately 50 mu m. The shot-peened specimen exhibited lower surface roughness, finer subsurface grains, and higher hardness compared to the as-built specimen. Shot peening, coupled with hot isostatic pressing and heat treatment (HIP-HT), yielded superior oxidation performance with substantially low oxidation kinetics at 800 degrees C. The smooth surface, as well as dense and refined subsurface microstructure resulting from shot peening, facilitated the formation of a continuous, protective, and adherent Cr-rich oxide scale.

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  • 26.
    Sadeghi, M.
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Diaz, A.
    REM Surface Engineering, Brenham (USA).
    McFadden, P.
    REM Surface Engineering, Brenham (USA).
    Sadeghi, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Chemical and mechanical post-processing of Alloy 718 built via electron beam-powder bed fusion: Surface texture and corrosion behavior2022Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 214Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Alloy 718 specimens manufactured via electron beam-powder bed fusion (EB-PBF) were subjected to post-processing techniques, such as thermal post-treatment and surface finishing. Hot isostatic pressing followed by solution-aging heat treatment (HIP-HT) was used as the thermal post-treatment. Surface finishing techniques, such as turning (TU), shot peening (SP), chemically accelerated vibratory finishing (CAVF), and electro-polishing (EP), were applied on the as-built and HIP-HT specimens. The surface texture of all the specimens was characterized, with the HIP-HT specimen having the highest area arithmetical mean height (Sa) value of 52 ± 1.8 µm and the TU specimen having the lowest at 1.1 ± 0.1 µm. The corrosion performance, typically associated with surface texture, was not always tied to the overused Sa value. CAVF had the highest polarization resistance of 75.8 kΩ.cm2 among the studied methods, followed by TU with polarization resistance of 43.8 kΩ.cm2, showing that the two techniques have a great potential for improving the surface characteristics of the EB-PBF-built Alloy 718 parts. 

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    Materials & Design
  • 27.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Corrosion Behavior of HVAF-Sprayed Bi-Layer Coatings2016Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In a variety of engineering applications, components are subjected to corrosive environment. Protective coatings are essential to improve the functional performances and/or extend the lifetime of the components. Thermal sprayingas a cost-effective coating deposition technique offers high flexibility in coatings' chemistry/morphology/microstructure design. However, the inherent pores formed during spraying limit the use of coatings for corrosion protection. The recently developed supersonic spray method, High-Velocity-Air-Fuel (HVAF), brings significant advantages in terms of cost and coating properties. Although severely reduced, the pores are not completely eliminated even with the HVAF process. In view of the above gap to have a high quality coating, bi-layer coatings have been developed to improve the corrosion resistance of the coatings. In a bi-layer coating, an intermediate layer is deposited on the substrate before spraying the coating. The electrochemical behavior of each layer is important to ensure a good corrosion protection. The corrosion behavior of the layers strongly depends on coating composition and microstructure, which are affected by feedstock material and spraying process. Therefore, the objective of the researchis to explore the relationships between feedstock material, spraying process, microstructure and corrosion behavior of bi-layer coatings. A specific motivationis to understand the corrosion mechanisms of the intermediate layer which forms the basis for developing superior protective coatings. Cr3C2-NiCr top layer and intermediate layers (Fe-, Co- and Ni-based) were sprayed by different thermal spraying processes. Microstructure analysis, as well as various corrosion tests, e.g., electrochemical, salt spray and immersion tests were performed. The results showed a direct link between the corrosion potential (Ecorr) of the intermediate layer and the corrosion mechanisms. It was found that the higher corrosion resistance of Ni-based coatings than Fe- and Co-based coatings was due to higher Ecorr of the coating in the galvanic couple with top layers. Inter-lamellar boundaries and interconnected pores reduced the corrosion resistance of intermediate layers, however a sufficient reservoir of protective scale-forming elements (such as Cr or Al) improved the corrosion behavior.

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  • 28.
    Sadeghimeresht, Esmaeil
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Ni-based coatings for high temperature corrosion protection2018Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Biomass/waste-fired boilers severely suffer from high temperature corrosion of critical load-bearing components, e.g. water-wall and superheater tubes, due to presence of Cl-containing corrosive species. Deposition of a dense and adherent Ni-based coating by high velocity air-fuel (HVAF) thermal spray technique is a promising approach to extend the component's lifetime and, hence, increase the thermal/electrical efficiency of the boilers. In this research, high temperature corrosion of candidate Ni-based coatings –Ni21Cr, Ni21Cr7AlY, Ni5Al, Ni21Cr9Mo, Ni21Cr9Mo-SiO2 – sprayed by HVAF has been investigated through detailed laboratory studies in ambient air, moisture and HCl-laden environments. The exposures were conducted at 600 °C for up to 168 h with and without presence of KCl salt. All coatings were highly protective in all environments in the absence of KCl due to formation of corresponding protective scales of alumina or chromia on the coating surface. When KCl was introduced, chromia-forming coatings degraded through a two-stage mechanism; 1) formation of K2CrO4 and Cl- followed by diffusion of Cl- through oxide grain boundaries, leading to formation of Cl2, metal chlorides as well as a nonprotective oxide, and 2) inward diffusion of the formed Cl2 through defects in the non-protective oxide, leading to metal chloride evaporation and breakaway oxidation. The corrosion behavior of the chromia-forming Ni21Cr coating was improved by addition of alloying elements such as Al and Mo. It was also shown that adding dispersed SiO2 further increased the corrosion resistance of the coatings. The oxide scale formed in the presence of SiO2 effectively suppressed Cl- ingress and lowered the corrosion rate, since the formed oxide was continuous, adherent andrich in Cr. The performance of the coatings in the complex Cl-containing environment was ranked as (from highest to lowest corrosion resistance); Ni21Cr9Mo-SiO2 > Ni21Cr7AlY > Ni5Al > Ni21Cr9Mo > Ni21Cr, confirming the enhanced corrosion protection of chromia-forming coatings in the presence of alloying elements and dispersed SiO2.

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  • 29.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Eklund, J.
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, Gothenburg, 412 96, Sweden.
    Phother Simon, J.
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, Gothenburg, 412 96, Sweden.
    Lyske, J.
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, Gothenburg, 412 96, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Oxidation behaviour of HVAF-sprayed NiCr coating in moisture-laden environment2017Ingår i: Proceedings of the International Thermal Spray Conference & Exposition (ITSC 2017), New York: Curran Associates, Inc. , 2017, Vol. 2, s. 644-646Konferensbidrag (Refereegranskat)
    Abstract [en]

    Reducing CO2 emissions from power generation plants is intimately related to enhancing their thermal efficiency, which can be achieved by increasing the temperature/pressure of steam. However, any increase in steam temperature is inevitably accompanied by accelerated oxidation of boiler components. The use of renewable fuels such as biomass increases the problem by introducing a number of corrosive compounds into the boiler environment, resulting in more rapid degradation of components. Although thermal sprayed coatings are techno-commercially attractive solutions for augmenting the durability of degradation-prone boiler components and are already used, further improvements in their performance are continuously sought. High-velocity air fuel (HVAF) coatings are promising in this context. In the present work, isothermal oxidation behavior of a candidate HVAF-sprayed Ni21Cr was studied in N2 + 5% O2 + 20% H2O at 600°C for 168h. The oxide scale growth mechanisms were studied by BIB/SEM/EDX to evaluate the effectiveness of the coatings. It was found that the water vapor effect is insignificant due to the Cr reservoir in the Ni21Cr coating, which yielded enhanced oxidation protection by forming nano-scale Cr2O3

  • 30.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Eklund, Johan
    University of Chalmers, Gothenburg, Sweden.
    Phother Simon, Julien
    University of Chalmers, Gothenburg, Sweden.
    Liske, Jesper
    University of Chalmers, Gothenburg, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    HVAF spraying for biomass boiler applications:: Oxidation behavior of Ni-based coatings in moisture-laden environment2017Konferensbidrag (Övrigt vetenskapligt)
  • 31.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Eklund, Johan
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, 41296 Gothenburg, Sweden.
    Simon, Julien Phother
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, 41296 Gothenburg, Sweden.
    Liske, Jesper
    Chalmers University of Technology, Department of Environmental Inorganic Chemistry, 41296 Gothenburg, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Effect of water vapor on the oxidation behavior of HVAF-sprayed NiCr and NiCrAlY coatings2018Ingår i: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176, Vol. 69, nr 10, s. 1431-1440Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isothermal oxidation behavior of NiCr and NiCrAlY coatings deposited onto low alloy 16Mo3 steel by high-velocity air fuel (HVAF) process was investigated in 5% O-2+20% H2O+N-2 at 600 degrees C for 168h. Whereas NiCrAlY showed lower mass gain compared to NiCr, both coatings succeeded in maintaining the integrity with the substrate during the exposure without any breakaway oxidation. A thin Cr-rich oxide scale (Cr2O3) formed on NiCr, and a thin mixed oxide scale (Al2O3 with NiCr2O4) formed on NiCrAlY significantly increasing the oxidation protection in the presence of water vapor.

  • 32.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Hooshyar, H.
    Department of Environmental Inorganic Chemistry, Chalmers University of Technology, Gothenburg, Sweden.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Oxidation Behavior of HVAF-Sprayed NiCoCrAlY Coating in H2–H2O Environment2016Ingår i: Oxidation of Metals, ISSN 0030-770X, E-ISSN 1573-4889, Vol. 86, nr 3-4, s. 299-314Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isothermal oxidation behavior of an HVAF-sprayed NiCoCrAlY coating on AISI 304L was studied in an Ar–10 %H2–20 %H2O environment at 600 °C. Techniques such as BIB/SEM, EDS, and XRD were used to comprehensively characterize the coating and the coating/substrate interface to investigate the oxidation mechanisms. Results were also compared with those obtained from an uncoated AISI 304L substrate. The alumina-forming NiCoCrAlY coating was found to exhibit superior oxidation behavior due to the formation of a slow-growing and protective Al2O3 scale, while the chromia-forming bare 304L substrate lost its protective capability due to the formation of a duplex [Fe3O4 on (Fe,Cr)3O4 spinel oxide] corrosion product layer.

  • 33.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Jafari, Reza
    Dep. of Material Science and Engineering, Tarbiat Modares University, Tehran, Iran .
    Shahrabi Farahani, Taghi
    Dep. of Material Science and Engineering, Tarbiat Modares University, Tehran, Iran .
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    High Temperature Corrosion of HVAF-Sprayed NiCrAlY Coating Exposed to Various Corrosive Environments2017Konferensbidrag (Övrigt vetenskapligt)
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  • 34.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Karimi Neghlani, Paria
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Zhang, Pimin
    Linköping University,Department of Management and Engineering, Linköping, Sweden.
    Peng, Ru
    Linköping University,Department of Management and Engineering, Linköping, Sweden.
    Andersson, Joel
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för svetsteknologi (SV).
    Pejryd, Lars
    Örebro University, School of Science and Technology, Örebro, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Isothermal Oxidation Behavior of EBM-Additive Manufactured Alloy 7182018Ingår i: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications / [ed] Ott, E., Liu, X., Andersson, J., Bi, Z., Bockenstedt, K., Dempster, I., Groh, J., Heck, K., Jablonski, P., Kaplan, M., Nagahama, D. and Sudbrack, C., Springer, 2018, s. 219-240Konferensbidrag (Refereegranskat)
    Abstract [en]

    Oxidation of Alloy 718 manufactured by electron beam melting (EBM) process has been undertaken in ambient air at 650, 700, and 800 °C for up to 168 h. At 800 °C, a continuous external chromia oxide enriched in (Cr, Ti, Mn, Ni) and an internal oxide that was branched structure of alumina formed, whereas at 650 and 700 °C, a continuous, thin and protective chromia layer was detected. The oxidation kinetics of the exposed EBM Alloy 718 followed the parabolic rate law with an effective activation energy of ~248 ± 22 kJ/mol in good agreement with values in the literature for conventionally processed chromia-forming Ni-based superalloys. The oxide scale formed on the surface perpendicular to the build direction was slightly thicker, and more adherent compared to the scale formed on the surface along the build direction, attributed to the varied grain texture in the two directions of the EBM-manufactured specimens. The increased oxygen diffusion and high Cr depletion found on the surface along the build direction were attributed to the fine grains and formation of vacancies/voids along this grain orientation.

  • 35.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Electrochemical Behavior of Bilayer Thermal-Spray Coatings in Low-Temperature Corrosion Protection2017Ingår i: Coatings, ISSN 2079-6412, Vol. 7, nr 10, s. 1-13, artikel-id 162Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Cr3C2-NiCr coatings are greatly used to protect critical components in corrosive environments and to extend their lifetime and/or improve functional performance. However, the pores formed during spraying restrict the coating’s applicability area for many corrosion protection applications. To overcome this technical challenge, bilayer coatings have been developed, in which an additional layer (the so-called intermediate layer) is deposited on the substrate before spraying the Cr3C2-NiCr coating (the so-called top layer). The corrosion behavior of the bilayer coating depends on the composition and microstructure of each layer. In the present work, different single-layer coatings (i.e., Cr3C2-NiCr, Fe- and Ni-based coatings) were initially sprayed by a high-velocity air fuel (HVAF) process. Microstructure analysis, as well as electrochemical tests, for example, open-circuit potential (OCP) and polarization tests, were performed. The potential difference (Delta E) had a great influence on galvanic corrosion between the top and intermediate layers, and thus, the coatings were ranked based on the OCP values (from high to low) as follows: NiCoCrAlY > NiCr > Cr3C2-NiCr > NiAl > Fe-based coatings (alloyed with Cr) > pure Ni. The Ni-based coatings were chosen to be further used as intermediate layers with the Cr3C2-NiCr top layer due to their capabilities to show high OCP. The corrosion resistance (R-p) of the bilayer coatings was ranked (from high to low) as follows: NiCoCrAlY/Cr3C2-NiCr > NiCr/Cr3C2-NiCr > NiAl/Cr3C2-NiCr > Ni/Cr3C2-NiCr. It was shown that splat boundaries and interconnected pores are detrimental for corrosion resistance, however, a sufficient reservoir of protective scale-forming elements (such as Cr or/and Al) in the intermediate layer can significantly improve the corrosion resistance.

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  • 36.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Huhtakangas, M.b
    M. H. Engineering AB, 691 42 Karlskoga, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Isothermal oxidation of HVAF-sprayed Ni-based chromia, alumina and mixed-oxide scale forming coatings in ambient air2017Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 316, s. 10-21Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The power generation industry has been progressively shifting towards higher operating steam temperatures and pressures to increase efficiency and reduce CO2 emissions. However, higher operating temperatures lead to more aggressive oxidation of the boiler components. A promising route to improve the durability of degradation-prone components is through deployment of high-performance coatings. In the present work, four Ni-based coatings - Ni21Cr, Ni5Al, Ni21Cr9Mo, and Ni21Cr7Al1Y - thermally sprayed by the high-velocity air fuel (HVAF) technique on boiler steel (16Mo3) substrates were investigated. The isothermal oxidation behavior of the coatings was studied in ambient air environment at 600 °C for different time intervals i.e. 1, 5, 10, 24, 48, 96, and 168 h. The oxidation behavior of the as-sprayed and polished coatings was compared. The protective α-Al2O3 was not detected on the exposed alumina-forming NiAl coating. On the other hand, Cr2O3 along with a small amount of NiO were the main oxidation products on the surface of the NiCr and NiCrMo coatings, and were found to be relatively less protective. The mixed-oxide scale forming NiCrAlY coatings showed the best oxidation resistance due to the formation of a thin and slow-growing Al2O3 scale along with Ni(Al,Cr)2O4 and Cr2O3. The polished coatings were found to significantly reduce the oxidation rate in each case as the protective scale-forming elements were more uniformly supplied to the surface oxide scale by removing the surface asperities. © 2017 Elsevier B.V.

  • 37.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Hussain, Tanvir
    Univ Nottingham, Fac Engn, Nottingham NG7 2RD, England.
    Huhtakangas, Matti
    MH Engn AB, S-69142 Karlskoga, Sweden.
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Effect of SiO2 Dispersion on Chlorine-Induced High-Temperature Corrosion of High-Velocity Air-Fuel Sprayed NiCrMo Coating2018Ingår i: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 74, nr 9, s. 984-1000Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    NiCrMo coatings with and without dispersed SiO2 were deposited using high-velocity air-fuel technique. Thermogravimetric experiments were conducted in 5% O-2 + 500 vppm HCl + N-2 with and without a KCl deposit at 600 degrees C for up to 168 h. The SiO2-containing coating showed lower weight change as a result of formation of a protective and adherent Cr-rich oxide scale. SiO2 decelerated short-circuit diffusion of Cr3+ through scale's defects, e.g., vacancies, and promoted the selective oxidation of Cr to form the protective Cr-rich oxide scale. Furthermore, the presence of SiO2 led to less subsurface depletion of Cr in the coating, and accordingly less corrosion of the substrate. The formed corrosion product on the SiO2-free coating was highly porous, non-adherent, and thick.

  • 38.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion. Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW). Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Isothermal oxidation behavior of HVAF-sprayed Ni and NiCr coatings in H2-H2O environment2017Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 317, s. 17-25Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The formation of a protective chromia scale on stainless steels is known to be suppressed by the presence of water vapor in reducing conditions. Thermal spray coatings present a promising approach to improve the durability of steels by transferring the first line of oxidation attack from the bulk steel to the coating. In the present work, isothermal oxidation behavior of Ni and NiCr coatings deposited by High-Velocity Air Fuel (HVAF) process on 304L stainless steel was investigated at 600 degrees C for 168 h. Ar-10%H-2-20%H2O was selected as the oxidation environment to study the oxidation behavior of the coatings in a low pO(2) environment containing H2 and H2O. BIB/ SEM, EDS, and XRD techniques were used to characterize the as-sprayed coatings and to investigate the oxidation mechanisms in the coated samples. Results showed that both Ni and NiCr coatings imparted oxidation protection to the 304L substrate. The chromia-forming 304L steel presented a duplex but non-protective oxide scale comprising of an outer Fe3O4 layer on an inner (Fe, Cr)(3)O-4-spinel oxide. In contrast, the NiCr coating presented superior oxidation behavior due to the formation of a continuous, thin, and slow-growing Cr2O3 scale. The Ni coating, too, protected the substrate owing to limited nucleation and growth of the deleterious NiO scale in the low-oxygen -activity environment. (C) 2017 Elsevier B.V. All rights reserved.

  • 39.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylen, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Corrosion behavior of HVAF-sprayed Bi-layer coatings: Effect of intermediate layer's microstructure and chemical composition2017Ingår i: Proceedings of the International Thermal Spray Conference & Exposition (ITSC 201), New York: Curran Associates, Inc , 2017, Vol. 2, s. 941-945Konferensbidrag (Refereegranskat)
  • 40.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylen, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Microstructural characteristics and corrosion behavior of HVAF- and HVOF-sprayed Fe-based coatings2017Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 318, s. 365-373Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fe-based coatings have been shown to be viable alternatives to the more expensive and less environmentally friendly Co- and Ni-based coatings. In the present work, the microstructural characteristics and corrosion behavior of Fe-based coatings deposited by high-velocity air fuel (HVAF) and high-velocity oxy fuel (HVOF) processes were comparatively investigated. Different sets of powder composition and particle size were used to decrease the porosity and increase the corrosion resistance of the coatings. The corrosion behavior of the coatings was studied using electrochemical techniques, including open-circuit potential (OCP) and polarization tests in 3.5 wt% NaCl at 25 °C. Techniques such as scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), and X-ray diffractometry (XRD) were used to characterize the as-sprayed and corroded coatings. The results revealed that the HVAF coatings had lower porosity and oxide content than the HVOF coatings. The polarization tests confirmed that the HVAF coatings sprayed with finer particle size (− 36 + 20 μm) have higher polarization resistance (Rp) than the coatings produced by powders (− 53 + 20 μm). Based on SEM analysis, it was observed that corrosion initiated and grew through the surface defects of the coating and propagated through inter-lamellar boundaries.

    Keywords

  • 41.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT). Amirkabir University of Tehran, Tarbiat Modares University of Tehran.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    A Comparative Study of Corrosion Resistance for HVAF-Sprayed Fe- and Co-Based Coatings2016Ingår i: Coatings, ISSN 2079-6412, Vol. 6, nr 2, s. 1-15Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    There is an increasing demand to replace Co-based coatings with cheap and environmentally friendly Fe-based coatings in corrosive environments. The main objective of this work was to evaluate whether Fe-based coatings could present a better corrosion performance than Co-based coatings. Therefore, two types of Fe-based and one type of Co-based coatings with chemical compositions (in wt %) of Fe-28Cr-16Ni-1.85C (FeNiCrC), Fe-17Cr-12Ni (FeNiCr), andCo-28Cr-1C (CoCrC) were produced by High Velocity Air Fuel (HVAF) spraying. The corrosion behavior of the coatings was studied comparatively by electrochemical tests in 3.5 wt % NaCl solutionat 25 C. The polarization test results showed that the FeCrNiC coating protected the underlying substrate better than the CoCrC coating, while the FeCrNi coating failed to hinder the penetration of corrosive ions. Electrochemical impedance spectroscopy (EIS) measurements revealed that thesolution penetrated into the coating through defects, however the corrosion process slowed down due to clogging of the interconnected defects by corrosion products. Increasing the in-flight average particle temperature from 1400 C to 1500 C led to a denser coating with fewer defects which seemed to improve the corrosion resistance of the FeCrNiC coating. The high-alloyed Fe-based coatings had the best corrosion protection performance and can thus be recommended as a potential alternative toCo-based coatings.

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  • 42.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    A comparative study on Ni-based coatings prepared by HVAF, HVOF, and APS methods for corrosion protection applications2016Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 25, nr 8, s. 1604-1616Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Selection of the thermal spray process is the most important step towards a proper coating solution for a given application as important coating characteristics such as adhesion, and microstructure, etc. are highly dependent on it. In the present work, a process-microstructure-properties-performance correlation study was performed in order to figure out the main characteristics and corrosion performance of the coatings produced by different thermal spray techniques such as high-velocity airfuel (HVAF), high-velocity oxy fuel (HVOF), and atmospheric plasma spraying (APS). Previously optimized HVOF and APS process parameters were used to deposit Ni, NiCr, and NiAl coatings and compare with HVAF-sprayed coatings with randomly selected process parameters. As the HVAF process presented the best coating characteristics and corrosion behavior, various process parameters,e.g., feed rate and stand off distance (SoD) were investigated to systematically optimize the HVAF coatings in terms of high density and corrosion properties. The coatings with lower porosity and better corrosion behavior were obtained at an average SoD of 300 mm for the Ni and NiAl coatings and a SoDof 250 mm for the NiCr coating. Increasing the feed rate to 150 g/min in the Ni and NiAl coatings decreased the coating pores and accordingly increased the Rp.

  • 43.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Duplex thermal spray coatings: a critical approach to extend the service-life of metallic components2016Konferensbidrag (Övrigt vetenskapligt)
    Abstract [en]

    Corrosion is a common problem for many metallic components used today in a wide range of industries. Thermal spraying is a promising approach to properly protect the metallic structure from the deleterious effects of the environment that surrounds it. In this study, three types of coating systems (A: single layer of Cr3C2-NiCr, B: Ni/Cr3C2-NiCr and C: NiCr/Cr3C2-NiCr) were deposited using HVAF process. Electrochemical tests were employed to investigate the corrosion susceptibility of the above systems. OCP, polarization and EIS tests were performed in 3.5 wt.% NaCl solution at 25°C. Results showed that bi-layer coatings exhibited a better corrosion resistance than the single-layer coating. While coating system A demonstrated some signs of pitting due to the penetration of tiny chloride ions through the defects of the coating, which eventually led to the destruction of the substrate close to the interface, coating systems B and C showed much better anti-corrosion behavior. Moreover, the results confirmed that gradual changes of the composition from the top coating to substrate reduced the possibility of galvanic corrosion. SEM, EDAX, and XRD were used to characterize the corrosion products along the surface and the cross-section of specimens.

  • 44.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    HVAF thermal spray Fe-based coating: An environmentally acceptable alternative to cobalt-based coating2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fe-based coatings were widely used in the corrosive environment of various indus-tries. It was replacing expensive cobalt-based alloys, which face a ban in the future due to serious health and environmental risks. The aim of the present work was to compare low temperature corrosion behavior of some Fe- and Co-based coatings produced by High-Velocity Air Fuel (HVAF) thermal spraying. Polarization and elec-trochemical impedance spectroscopy (EIS) tests were carried out in 3.5 wt.% NaCl solution at 25°C. The microstructures were analyzed using optical microscopy (OM) and scanning electron microscopy (SEM) to characterize the morphologies of both Fe- and Co-based coatings and analyze the exposed products along the surface and cross-section of specimens. The results revealed that the high-chromium Fe-based coating protected the underlying substrate better than Co-based coating.

  • 45.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Microstructural and electrochemical characterization of Ni-based bi-layer coatings produced by the HVAF process2016Ingår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 304, s. 606-619Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bi-layer coating systems comprising a Cr3C2-NiCr coating with different underlying coatings of Ni, NiCr, NiCoCrAlY, and CoNiCrAlY were deposited on 304L stainless steel substrates using the high-velocity air fuel (HVAF) process. The corrosion behavior of the coating systems was studied using electrochemical and immersion tests in 3.5 wt% NaCl at 25 °C. The higher open-circuit potential (OCP) value of the NiCoCrAlY coating (− 120 mV/SCE) compared to the value of the Cr3C2-NiCr coating (− 230 mV/SCE) revealed that the underlying NiCoCrAlY coating was sacrificially protected by Cr3C2-NiCr coating. The polarization resistance (Rp) of the bi-layer coatings with the different underlying coatings of Ni, NiCr, NiCoCrAlY and CoNiCrAlY was approximately 77, 189, 487, and 74 kΩ·cm2 respectively, while the value was 101 kΩ·cm2 for the single-layer Cr3C2-NiCr coating and 30 kΩ·cm2 for the 304L substrate, which confirmed a higher corrosion protection of the NiCoCrAlY coating. The electrochemical impedance spectroscopy (EIS) results showed that the corrosion resistance of the 304L substrate was significantly improved by adding an intermediate layer of NiCoCrAlY to the Cr3C2-NiCr coating. Results of the immersion tests confirmed that the underlying coatings in the different bi-layer coating systems acted as protective barriers. Moreover, the NiCoCrAlY coating showed the best corrosion protection among the investigated underlying coatings.

  • 46.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Microstructure effect of intermediate coat layer on corrosion behavior of HVAF-sprayed bi-layer coatings2017Ingår i: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 26, nr 1-2, s. 243-253Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The inherent pores and carbides of Cr3C2-NiCr coatings significantly reduce the corrosion resistance, the former by providing preferential paths for ion diffusion and the latter by forming cathodic sites in galvanic couples (between NiCr and Cr3C2). Adding a dense intermediate layer (intermediate coat layer) between the Cr3C2-NiCr coating (top coat) and substrate increases the corrosion protection of the coating if the layer acts as cathode in connection to the top coat. In the present work, NiCr, NiAl, and NiCoCrAlY layers were deposited by high-velocity air fuel(HVAF) process as intermediate coat layers for the Cr3C2-NiCr top coat. Effects of coating microstructure on corrosion behavior of single- and bi-layer coatings were studied by open circuitpotential (OCP) and polarization tests in 3.5 wt% NaCl at room temperature. A zero resistanceammeter (ZRA) technique was used to study the galvanic corrosion of the coupledtop and intermediate coat layers. Methods such as SEM and XRD were employed to characterize the as-sprayed and corroded coatings and investigate the corrosion mechanisms.The results showed that the NiCoCrAlY coating not only presented a more positive corrosion potential (Ecorr) than the Cr3C2-NiCr coating, but also provided a better passive layer than the single-phase NiCr and NiAl coatings.

  • 47.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Bi-layer thermal spray coatings: A critical approach to extend the service-life of metallic components2016Konferensbidrag (Övrigt vetenskapligt)
  • 48.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd Forskningsmiljön industriprocesser. Amirkabir University of Tehran, Tarbiat Modares University of Tehran.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    Björklund, Stefan
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för maskinteknik.
    Corrosion performance of bi-layer Ni/Cr2C3–NiCr HVAF thermal spray coating2016Ingår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 369, s. 470-481Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    The corrosion behavior of three HVAF thermal spray coating systems (A: single-layer Ni, B: single-layer Cr2C3–NiCr coatings, and C: bi-layer Ni/Cr2C3–NiCr coating) was comparatively studied using immersion,salt spray, and electrochemical tests. Polarization and EIS results showed that the corrosion behavior of Cr2C3–NiCr coatings in 3.5 wt.% NaCl solution was significantly improved by adding the intermediate layer of Ni. It was illustrated that the polarization resistance of the bi-layer Ni/Cr2C3–NiCr and singlelayerCr2C3–NiCr coatings were around 194 and 38 k cm2, respectively. Microstructure analysis revealed that the bond coating successfully prevented the corrosion propagation toward the coating.

  • 49.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för tillverkningsprocesser.
    Nylén, Per
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avd för industriell produktion.
    Dizdar, S.
    Höganäs AB, Höganäs.
    Corrosion behavior of high-chromium Fe-based coatings produced by HVAF thermal spraying technique2015Konferensbidrag (Refereegranskat)
    Abstract [en]

    Fe-based coatings with different Cr content were prepared by high-velocity air fuel (HVAF) spraying on the surface of both carbon steel and stainless steel 304L. The corrosion behavior of the coatings were evaluated using polarization and electrochemical impedance spectroscopy (EIS) techniques in 3.5 wt.% NaCl solution. Microstructure of the coatings were evaluated by X-ray diffraction (XRD), optical microscopy (OM), scanning election microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDS) before and after corrosion testing. The experimental results indicated that Cr strongly increased the corrosion resistance of the coating. Furthermore, having an elemental composition closer to that of the substrate, the coatings showed lower susceptibility to galvanic corrosion, accordingly lower corrosion rate.

  • 50.
    Sadeghimeresht, Esmaeil
    et al.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Raman, Sudharshan
    Nanyang Technological University, Singapore.
    Markocsan, Nicolaie
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Avdelningen för avverkande och additativa tillverkningsprocesser (AAT).
    Joshi, Shrikant V.
    Högskolan Väst, Institutionen för ingenjörsvetenskap, Forskningsmiljön produktionsteknik(PTW).
    High Temperature Erosion-Corrosion behavior of HVAF- & HVOF-Sprayed Fe-based Coatings2017Konferensbidrag (Övrigt vetenskapligt)
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