Tribological behavior of plasma-sprayed Cr2O3 coatings on C/C composites sliding against different counterparts

In this study, Cr2O3 coating was fabricated on the surface of SiC-coated C/C composites by air plasma spray (APS) technique. Tribological behaviors of the Cr2O3 coatings sliding against stainless steel, WC-Co, Si3N4 and PTFE under low and high loads were investigated and compared. The results showed that the Cr2O3 coating significantly improved the wear resistance of C/C composite through reducing the wear rates. The wear rates rankings of the four friction pairs were Cr2O3/Si3N4 > Cr2O3/WC-Co > Cr2O3/stainless steel > Cr2O3/PTFE at all tested loads. While the friction coefficients were influenced by the applied loads. The Cr2O3/stainless steel pair displayed higher friction coefficients and lower wear rates compared with those of the Cr2O3/WC-Co and Cr2O3/Si3N4 pairs. Although the hardness of WC-Co was similar to that of Si3N4, the wear and friction behaviors of the Cr2O3/WC-Co and Cr2O3/Si3N4 pairs were quite different. The Cr2O3/PTFE pair displayed the lowest friction coefficient among the four kinds of friction pairs. The relevant wear mechanisms of different friction pairs were analyzed in detail.