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Björklund, S., Goel, S. & Joshi, S. V. (2018). Function-dependent coating architectures by hybrid powder-suspension plasma spraying: Injector design, processing and concept validation. Materials & design, 142, 56-65
Open this publication in new window or tab >>Function-dependent coating architectures by hybrid powder-suspension plasma spraying: Injector design, processing and concept validation
2018 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 142, p. 56-65Article in journal (Refereed) Published
Abstract [en]

The attractive properties achieved by Suspension Plasma Spraying (SPS), combined with the availability of high throughput capable plasma spray systems that permit axial feeding, provide encouragement to explore use of suspensions for next generation functional applications. This paper deals with realization of coatings with various pre-determined function-dependent architectures by employing a hybrid powder-suspension feedstock. Some illustrative application-relevant coating architecture designs are discussed, along with the specific benefits that can accrue by deploying a multi-scale powder-suspension feedstock combination. An elegant feedstock delivery arrangement to enable either simultaneous or sequential feeding of powders and suspensions to enable convenient processing of coatings with desired architectures is presented. As proof-of-concept, deposition of layered, composite and functionally graded coatings using the above system is also demonstrated using appropriate case studies

Keywords
Suspension, Hybrid feedstock, Layered, Composite, Functionally graded, Coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-11993 (URN)10.1016/j.matdes.2018.01.002 (DOI)
Note

Available online 4 January 2018

Available from: 2018-01-16 Created: 2018-01-16 Last updated: 2018-02-05Bibliographically approved
Kanhed, S., Awasthi, S., Midha, S., Nair, J., Nisar, A., Patel, A. K., . . . Balani, K. (2018). Microporous Hydroxyapatite Ceramic Composites as Tissue Engineering Scaffolds: An Experimental and Computational Study. Advanced Engineering Materials, 20(7), Article ID 1701062.
Open this publication in new window or tab >>Microporous Hydroxyapatite Ceramic Composites as Tissue Engineering Scaffolds: An Experimental and Computational Study
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2018 (English)In: Advanced Engineering Materials, ISSN 1438-1656, E-ISSN 1527-2648, Vol. 20, no 7, article id 1701062Article in journal (Refereed) Published
Abstract [en]

Bone‐tissue engineering mandates the development of multi‐functional bioactive porous hydroxyapatite (HAp) scaffolds. Herein, microwave sintered HAp/ZnO and HAp/Ag composite scaffolds with ≈5–19% porosity are developed using 0–30 vol% graphite as a porogen. The mechanical properties of the porous scaffold are analyzed in detail, revealing that even being more porous, the reinforcement of ZnO (9% porosity, hardness of 2.8 GPa, and toughness of 3.5 MPa.m1/2) has shown to have better hardness and fracture toughness when compared to Ag (5% porosity, hardness of 1.6 GPa, and toughness of 2.6 MPa.m1/2). The flexural strength obtained experimentally are complemented with a finite‐element technique that adopts microstructural features in visualizing the effect of porosity on stress distribution. The antibacterial efficacy and cytocompatibility of these composites are validated by increased metabolic activity and conspicuous cell‐matrix interactions. The anticipation of the results reveal that HAp/ZnO (9% porosity) and HAp/Ag (5% porosity) composites can be used as a potential multi‐functional bone implant scaffolds.

Keywords
Antibacterial, Cytocompatibility, Diametrical Compression Test, Hydroxyapatite, Object‐Oriented Finite Element Modeling (OOF2), Porosity, Silver, Zinc Oxide
National Category
Manufacturing, Surface and Joining Technology Biomaterials Science Metallurgy and Metallic Materials
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-12249 (URN)10.1002/adem.201701062 (DOI)000439735800012 ()
Available from: 2018-04-10 Created: 2018-04-10 Last updated: 2018-09-14Bibliographically approved
Goel, S., Olsson, J., Ahlfors, M., Klement, U. & Joshi, S. V. (2018). The Effect of Location and Post-treatment on the Microstructure of EBM-Built Alloy 718. In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications. Paper presented at 9th International Symposium on Superalloy 718 & Derivatives, Energy, Aerospace, and Industrial Applications (pp. 115-129). Springer
Open this publication in new window or tab >>The Effect of Location and Post-treatment on the Microstructure of EBM-Built Alloy 718
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2018 (English)In: Proceedings of the 9th International Symposium on Superalloy 718 & Derivatives: Energy, Aerospace, and Industrial Applications, Springer, 2018, p. 115-129Conference paper, Published paper (Refereed)
Abstract [en]

Additive manufacturing (AM) of Ni-based superalloys such as Alloy 718 may obviate the need for difficult machining and welding operations associated with geometrically intricate parts, thus potentially expanding design possibilities and facilitating cost-effective manufacture of complex components. However, processing AM builds completely free from defects, which may impair mechanical properties such as fatigue and ductility, is challenging. Anisotropic properties, microstructural heterogeneities and local formation of undesired phases are additional concerns that have motivated post-treatment of AM builds. This work investigates the microstructural changes associated with post-treatment of Alloy 718 specimens produced by Electron Beam Melting (EBM) for as-built microstructures at 3 build heights: near base plate, in the middle of build and near the top of the build. Two different post-treatment conditions, hot isostatic pressing (HIP) alone and a combined HIP with solutionising and two-step aging were examined and compared to the results for the as-built condition. The influence of various post-treatments on minor phase distributions (δ, γ″, carbides), overall porosity, longitudinal grain widths and Vickers microhardness was considered. The HIP treatment led to significant reduction in overall porosity and dissolution of δ phase, which led to appreciable grain growth for both post-treatment conditions. The variation in hardness noted as a function of build height for the as-built specimens was eliminated after post-treatment. Overall, the hardness was found to decrease after HIP and increase after the full HIP, solutionising and aging treatment, which was attributed to dissolution of γ″ during HIP and its re-precipitation in subsequent heat treatment steps.

Place, publisher, year, edition, pages
Springer, 2018
Series
The Minerals, Metals & Materials Series, ISSN 2367-1181, E-ISSN 2367-1696
Keywords
Additive manufacturing, Electron beam melting, Alloy 718, HIP, Heat treatment, Microstructure, XRD, Hardness, δ, γ″, Carbide
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-12346 (URN)10.1007/978-3-319-89480-5_6 (DOI)978-3-319-89479-9 (ISBN)
Conference
9th International Symposium on Superalloy 718 & Derivatives, Energy, Aerospace, and Industrial Applications
Available from: 2018-10-26 Created: 2018-10-26 Last updated: 2018-11-08Bibliographically approved
Goel, S., Björklund, S., Curry, N., Wiklund, U. & Joshi, S. V. (2017). Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties. Surface & Coatings Technology, 315, 80-87
Open this publication in new window or tab >>Axial suspension plasma spraying of Al2O3 coatings for superior tribological properties
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2017 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 315, p. 80-87Article in journal (Refereed) Published
Abstract [en]

Suspension plasma spray is a relatively new thermal spray technique which enables feeding of fine powder to produce advanced coatings for varied applications. This work investigates the difference in structure and performance of Al2O3 coatings manufactured using conventional micron-sized powder feedstock and a suspension of sub-micron to few micron sized powder. Axial injection was implemented for deposition in both cases. The effect of feedstock size and processing on the tribological performance of the two coatings was of specific interest. The coatings were characterized by Optical and Scanning Electron Microscopy, micro-hardness and scratch resistance testing, and their dry sliding wear performance evaluated. The suspension sprayed coatings yielded significantly higher scratch resistance, lower friction coefficient and reduced wear rate compared to conventional coatings. The improved tribological behaviour of the former is attributable to finer porosity, smaller splat sizes, and improved interlamellar bonding. (C) 2017 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2017
Keywords
Atmospheric plasma spray; Suspension plasma spray; Axial injection; Alumina; Coating; Microstructure; Micro-hardness; Scratch; Wear
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10931 (URN)10.1016/j.surfcoat.2017.02.025 (DOI)000399268100009 ()2-s2.0-85013027004 (Scopus ID)
Available from: 2017-09-20 Created: 2017-09-20 Last updated: 2018-06-18Bibliographically approved
Joshi, S. V., Goel, S., Björklund, S. & Wiklund, U. (2017). Hybrid powder-suspension Al2O3-ZrO2 coatings by axial plasma spraying: Processing, characteristics & tribological behavior. In: : . Paper presented at International Thermal Spray Conference & Exposition, ITSC 2017, Düsseldorf, Germany, June 7-9, 2017.
Open this publication in new window or tab >>Hybrid powder-suspension Al2O3-ZrO2 coatings by axial plasma spraying: Processing, characteristics & tribological behavior
2017 (English)Conference paper, Oral presentation only (Other academic)
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-11965 (URN)
Conference
International Thermal Spray Conference & Exposition, ITSC 2017, Düsseldorf, Germany, June 7-9, 2017
Available from: 2017-12-29 Created: 2017-12-29 Last updated: 2018-08-12Bibliographically approved
Goel, S., Björklund, S., Wiklund, U. & Joshi, S. V. (2017). Hybrid powder-suspension Al2O3-ZrO2 coatings by axial plasma spraying: Processing, characteristics & tribological behaviour. In: Proceedings of the International Thermal Spray Conference: . Paper presented at International Thermal Spray Conference and Exposition, ITSC 2017; Dusseldorf; Germany; 7 June 2017 through 9 June 2017 (pp. 374-379). ASM International, 1
Open this publication in new window or tab >>Hybrid powder-suspension Al2O3-ZrO2 coatings by axial plasma spraying: Processing, characteristics & tribological behaviour
2017 (English)In: Proceedings of the International Thermal Spray Conference, ASM International, 2017, Vol. 1, p. 374-379Conference paper, Published paper (Refereed)
Abstract [en]

The ability of suspension plasma spraying (SPS) to overcome difficulties associated with feeding of fine (submicron or nano-sized) powders and achieve more refined microstructures than possible in atmospheric plasma spraying (APS) is well established. In recent times, the use of axial injection plasma spray systems has yielded substantial enhancement in deposition rates/efficiencies due to improved thermal exchange between the plasma plume and injected feedstock. The present paper describes utilization of both the above advances in plasma spraying to create various function-dependent coating architectures through simultaneous and/or sequential spraying of hybrid powder-suspension feedstock. A specific variant of such hybrid axial plasma spraying that enables deposition of composite coatings by simultaneous injection of a powder and a suspension is discussed in particular detail. Results obtained using an Al2O3-ZrO2 material system as a case study reveal that composite coatings combining the micron-size features arising from the spray-grade Al2O3 powder and submicron or nano-sized features attributable to the ZrO2 suspension can be conveniently realized. The surface morphology, microstructure, and composition of these coatings, as well as their tribological behaviour determined using scratch and ball-on-disc tests, are presented herein. The utility of this method to develop a wide array of composite coatings is also discussed. © 2017 ASM International. All rights reserved.

Place, publisher, year, edition, pages
ASM International, 2017
Keywords
Alumina; Aluminum oxide; Deposition rates; Feedstocks; Microstructure; Plasma jets; Plasma spraying; Powder coatings; Tribology; Zirconia, Atmospheric plasma spraying; Ball-on-disc tests; Nano-sized features; Refined microstructure; Simultaneous injections; Suspension plasma spraying; Tribological behaviour; Various functions, Composite coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-12908 (URN)2-s2.0-85047507789 (Scopus ID)9781510858220 (ISBN)
Conference
International Thermal Spray Conference and Exposition, ITSC 2017; Dusseldorf; Germany; 7 June 2017 through 9 June 2017
Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2018-10-22Bibliographically approved
Awasthi, S., Goel, S., Pandey, C. P. & Balani, K. (2017). Multi-Length Scale Tribology of Electrophoretically Deposited Nickel-Diamond Coatings. JOM: The Member Journal of TMS, 69(2), 227-235
Open this publication in new window or tab >>Multi-Length Scale Tribology of Electrophoretically Deposited Nickel-Diamond Coatings
2017 (English)In: JOM: The Member Journal of TMS, ISSN 1047-4838, E-ISSN 1543-1851, Vol. 69, no 2, p. 227-235Article in journal (Refereed) Published
Abstract [en]

Electrophoretically deposited (EPD) nickel and its composite coatings are widely used to enhance the life span of continuous ingot casting molds in the steel, aerospace and automotive industries. This article reports the effect of different concentrations of diamond particles (2.5–10 g/L) on the wear mechanism of EPD Ni. The distribution of diamond particles in the Ni matrix was observed using Voronoi tessellation. Variation in COF was observed by a fretting wear test to be 0.51 ± 0.07 for Ni, which decreases to 0.35 ± 0.03 for the Ni-diamond coatings. The wear volume of the coatings with 7.5 g/L concentration of diamond was observed to be a minimum (0.051 ± 0.02 × 10−3 mm3) compared with other composite coatings. Further, the micro-scratch testing of the coatings also exhibited a reduced COF (0.03–0.12) for 7.5 g/L diamond concentration compared with Ni (0.08–0.13). Higher wear resistance of the diamond-added coatings (optimum 7.5 g/L concentration) is due to the balance between the dispersion strengthening mechanism and the enhancement of the load-bearing capacity due to the incorporation of diamond particles. Thus, these composites can be used for applications in automotive and aerospace industries. © 2016 The Minerals, Metals & Materials Society

Keywords
Aerospace industry; Automotive industry; Diamonds; Nickel; Nickel coatings; Wear resistance, Aerospace and automotive industries; Diamond coating; Diamond concentration; Diamond particles; Dispersion strengthening; Fretting wear test; Load-bearing capacity; Voronoi tessellations, Composite coatings
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10360 (URN)10.1007/s11837-016-2142-4 (DOI)000393106400013 ()2-s2.0-84991101916 (Scopus ID)
Note

First Online: 12 October 2016

Available from: 2016-12-20 Created: 2016-12-20 Last updated: 2017-04-20Bibliographically approved
Kanhed, S., Awasthi, S., Goel, S., Pandey, A., Sharma, R., Upadhyaya, A. & Balani, K. (2017). Porosity distribution affecting mechanical and biological behaviour of hydroxyapatite bioceramic composites. Ceramics International, 43(13), 10442-10449
Open this publication in new window or tab >>Porosity distribution affecting mechanical and biological behaviour of hydroxyapatite bioceramic composites
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2017 (English)In: Ceramics International, ISSN 0272-8842, E-ISSN 1873-3956, Vol. 43, no 13, p. 10442-10449Article in journal (Refereed) Published
Abstract [en]

The present work aims to the study of developing porosity in hydroxyapatite (HAp) scaffold by using graphite porogen (with 0-30 vol%) followed by engineering the changes achieved by conventional- (CS) and microwave sintering (MS) techniques. The generated porosity was controlled between similar to 6-27% as the porogen concentration increases in HAp scaffold. Voronoi tessellation was utilized in order to evaluate the distribution of pores. The enhanced mechanical properties including fracture toughness (0.83 MPa m(1/2)), fracture strength (7.5 MPa), and hardness (183.7 VHN) were observed for microwave sintered HAp scaffold with 8% porosity. The fitting between porosity and fracture strength elicited that microwave sintered HAp with 8% porosity provides maximum crack-propagation resistance while restricting grain size (similar to 0.23 mu m) and eliciting high extent of sintering (similar to 1.34) because of their rapid heating rates. The cell viability (MTT assay) and cell culture confirm the cytocompatibility of porous HAp for application as bone implant that need accelerated replacement of bone tissues.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2017
Keywords
Hydroxyapatite; Porosity; Voronoi tessellation; Mechanical property; Cytocompatibility
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-11398 (URN)10.1016/j.ceramint.2017.05.083 (DOI)000406438700111 ()2-s2.0-85020135751 (Scopus ID)
Available from: 2017-08-25 Created: 2017-08-25 Last updated: 2017-12-05Bibliographically approved
Goel, S., Björklund, S. & Joshi, S. (2016). Deposition of Novel Composite Coatings by Suspension-Powder Hybrid Plasma Spraying. In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016. Paper presented at 7th International Swedish Production Symposium, SPS16, Lund, Sweden, October 25–27, 2016 (pp. 1-8). Lund: Swedish Production Academy
Open this publication in new window or tab >>Deposition of Novel Composite Coatings by Suspension-Powder Hybrid Plasma Spraying
2016 (English)In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-8Conference paper, Published paper (Refereed)
Abstract [en]

Suspension Plasma Spray (SPS) is an emerging technique which overcomes the difficulties typically associated with feeding of fine (submicron or nano-sized) powders in conventional atmospheric plasma spraying (APS) to obtain superior coating properties for various engineering applications. The advent of plasma spray systems that allow axial injection of feedstock, which considerably improves thermal exchange between the plasma plume and the injected feedstock, has enabled substantial enhancement in deposition rates/efficiencies to make SPS techno-commercially exciting. The present study utilizes both the above advances in plasma spraying to demonstrate the ability to deposit novel coating architectures by sequential/simultaneous axial injection of both powder and a suspension feedstock. The results reveal that composite coatings uniquely combining the micron-size features arising from the spray-grade powder and the submicron or nano-sized features attributable to the suspension, can be conveniently realized using the above approach. Three different kinds of coating architectures were generated, namely layered, composite, and functionally graded. The sprayed coatings were extensively characterized for attributes such as surface morphology, microstructure, and composition particularly in the case of composite coatings.

Place, publisher, year, edition, pages
Lund: Swedish Production Academy, 2016
Keywords
Coating, Suspension Plasma Spray, axial injection, hybrid, layered, composite, functionally graded
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10241 (URN)
Conference
7th International Swedish Production Symposium, SPS16, Lund, Sweden, October 25–27, 2016
Available from: 2016-12-07 Created: 2016-12-07 Last updated: 2018-08-12Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-5676-7903

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