Influence of surface nitriding treatment on rolling contact behavior of Fe-based plasma sprayed coating

Fe–Cr coating was prepared by plasma spraying process. Gas nitriding treatment was conducted on the coating. Rolling contact fatigue (RCF) experiments were conducted using a ball-on-disc setup. RCF lifetime of the coating was calculated by two-parameter Weibull distribution. The worn morphologies of the coating were observed. Correlative failure mechanism was investigated based on fracture analysis and theoretical calculation. Results showed that the dense nitriding layer with high microhardness was formed on Fe-based coating surface. Unfortunately, the deposition of nitriding layer decreases RCF lifetime of the coating. The coating with nitriding layer always failed owing to cohesive delamination. The “born” microdefect and high brittleness of nitriding layer are the main reasons for the failures under rolling contact.