Fatigue failure mechanisms of plasma-sprayed CrC-NiCr cermet coatings in rolling contact

摘要

The aim of the present study was to address the fatigue behavior and failure modes of a series of plasma-sprayed CrC-NiCr cermet coatings in rolling contact under the same tribological condition at room temperature. The Weibull distribution plot of fatigue lives of the coated specimens was obtained. The failure modes and mechanisms of the coatings were studied on the basis of the worn surface observations of the failed coatings. Experiment results the RCF life data of the coatings exhibited higher scattering, since the bimodal distribution of the fatigue life data of the coatings was observed in the Weibull plot. Different failure modes, i. e., spalling and delamination, were observed during this investigation. However, the failure modes might be associated with the magnitude of contact stress, the microstructure of the coatings, the depth of the orthogonal shear stress and/or the maximum shear stress, and the bonding strength of the coatings. The coatings failed in the spalling type of failure generally exhibited the relatively high fatigue lives and the coatings failed in the interfacial delamination type of failure exhibited the low lives, resulting in the bimodal distribution of the fatigue life data in the Weibull plot.