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

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.% NaCI 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 381 Omega cm(2), respectively. Microstructure analysis revealed that the bond coating successfully prevented the corrosion propagation toward the coating. (C) 2016 Elsevier B.V. All rights reserved.