Friction and wear behaviors of NiAl–Bi2O3–Ag–Cr2O3 composite coating in the thermal cycle of RT-800°C

ABSTRACT The differentials of the tribological characteristics of atmospheric plasma sprayed NiAl-25Bi2O3-15Ag-6Cr2O3 composite coating sliding against counterpart Al2O3 was evaluated when subjected to dead temperatures and thermal cycling from RT to 800 oC. The results reveal NiAl-25Bi2O3-15Ag-6Cr2O3 composite coating demonstrates the temperature-dependent friction, and the wear is strongly determined by the tribo-induced layer that transforms along with temperature. The competition between Bi2O3 and Ag in terms of thermally-induced diffusion influences the frictional behaviors. The tribo-layer formed at 800 oC provides the continuous function on lessening wear even though the temperature goes down to RT. The favorable lubricating performance of NiAl-25Bi2O3-15Ag-6Cr2O3 composite coating is correlated with the composition that consists of Bi2O3, Ag, NiO, Cr2O3 and Bi16CrO27, which will be clarified in this study.