Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A comparative study on Ni-based coatings prepared by HVAF, HVOF, and APS methods for corrosion protection applications
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-7663-9631
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0002-9578-4076
University West, Department of Engineering Science, Division of Subtractive and Additive Manufacturing. (PTW)ORCID iD: 0000-0001-7787-5444
2016 (English)In: Journal of thermal spray technology (Print), ISSN 1059-9630, E-ISSN 1544-1016, Vol. 25, no 8, p. 1604-1616Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Materials Park, OH: ASM International, 2016. Vol. 25, no 8, p. 1604-1616
Keywords [en]
Thermal Spraying, Process optimization, Corrosion, OCP, Potentiodynamic polarization
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
URN: urn:nbn:se:hv:diva-9926DOI: 10.1007/s11666-016-0474-9ISI: 000390041000016Scopus ID: 2-s2.0-84994756460OAI: oai:DiVA.org:hv-9926DiVA, id: diva2:972689
Note

Ingår i lic avhandling

Available from: 2016-09-22 Created: 2016-09-22 Last updated: 2018-05-03Bibliographically approved
In thesis
1. Corrosion Behavior of HVAF-Sprayed Bi-Layer Coatings
Open this publication in new window or tab >>Corrosion Behavior of HVAF-Sprayed Bi-Layer Coatings
2016 (English)Licentiate thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Trollhättan: University West, 2016. p. 59
Series
Licentiate Thesis: University West ; 10
Keywords
Thermal spray coating, HVAF, Corrosion protection, Galvanic corrosion, Composition, Microstructure, EIS, Polarization, OCP
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-9929 (URN)978-91-87531-33-0 (ISBN)978-91-87531-32-3 (ISBN)
Presentation
2016-09-30, C118, University West, Trollhättan, 10:15 (English)
Supervisors
Available from: 2016-09-30 Created: 2016-09-22 Last updated: 2016-09-30Bibliographically approved
2. Ni-based coatings for high temperature corrosion protection
Open this publication in new window or tab >>Ni-based coatings for high temperature corrosion protection
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Place, publisher, year, edition, pages
Trollhättan: University West, 2018. p. 78
Series
PhD Thesis: University West ; 23
Keywords
Thermal Spray Coating; HVAF; High Temperature Corrosion Protection; Composition; Microstructure; Dispersed Oxide
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-12277 (URN)978-91-87531-70-5 (ISBN)978-91-87531-69-9 (ISBN)
Public defence
2018-05-31, F104, Trollhättan, 10:15 (English)
Opponent
Supervisors
Available from: 2018-05-04 Created: 2018-05-03

Open Access in DiVA

No full text in DiVA

Other links

Publisher's full textScopus

Authority records BETA

Sadeghimeresht, EsmaeilMarkocsan, NicolaieNylén, Per

Search in DiVA

By author/editor
Sadeghimeresht, EsmaeilMarkocsan, NicolaieNylén, Per
By organisation
Division of Subtractive and Additive Manufacturing
In the same journal
Journal of thermal spray technology (Print)
Manufacturing, Surface and Joining Technology

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 223 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf