High-temperature tribological behavior of thermally-treated supersonic plasma sprayed Cr3C2-NiCr coatings

Supersonic atmosphere plasma spraying (SAPS) can deposit Cr3C2-NiCr coatings in a very high efficiency to provide excellent anti-wear performance at high temperature. In the present work, the effect of post heat treatment on the microstructural evolution and the high-temperature wear performance (at 400 °C) of the Cr3C2-NiCr coatings was investigated. It is found that SAPS process facilitated the carbide dissolution/diffusion during particle flight while nano-sized carbides began to sufficiently precipitate from the supersaturated NiCr binder during post heat treatment. However, carbide decarburization could not be completely constrained and the volume fraction of carbide in the coating even thermally-treated at 750 °C was lower than that of original powders. The coating thermally-treated at 500 °C presented the highest hardness due to the precipitation strengthening of secondary carbides, which also induced the best wear-resistant property. Overall, the wear behavior of the coatings was correlated with the abrasive wear •SAPS process was effective in promoting carbide dissolution in the binder matrix.•Precipitation of secondary carbides during heat treatment improved coating hardness and high-temperature wear resistance.•Wear behavior of SAPS Cr3C2-NiCr coatings at 400 °C was featured of abrasive wear.