Corrosion performance of bi-layer Ni/Cr2C3–NiCr HVAF thermal spray coating

• Published in: Applied surface science Vol. 369; pp. 470 - 481
• Main Authors: Sadeghimeresht, E., Markocsan, N., Nylén, P., Björklund, S.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 30.04.2016
• Subjects: Bonding; Coatings; Corrosion; EIS; Flame spraying; HVAF; HVAF Corrosion; Immersion test; Manufacturing and materials engineering; Nickel; Polarization; Production Technology; Produktions- och materialteknik; Produktionsteknik; Spray coating; Sprays; Thermal spray; HVAF; Polarization; Immersion test; Corrosion; Thermal spray; EIS
• ISSN: 0169-4332; 1873-5584; 1873-5584
• DOI: 10.1016/j.apsusc.2016.02.002

•The intermediate dense layer of Ni declined the corrosion rate of Cr2C3–NiCr coating.•Higher acidity of the electrolyte leads to higher corrosion rate and tendency for pitting.•Bi-layer Ni/Cr2C3–NiCr coating was the best system to protect the steel substrate.•Bi-layer HVAF thermal spray coating serves as a critical approach to extend the life of components. 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 3.5wt.% 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 single-layer Cr2C3–NiCr coatings were around 194 and 38kΩcm2, respectively. Microstructure analysis revealed that the bond coating successfully prevented the corrosion propagation toward the coating.