Effect of hydrogen flow rate on microstructure and tribological properties of plasma-sprayed Cr2O3-65%TiO2 composite coatings

Atmospheric plasma spraying was used to deposit CT65 (Cr2O3-65 wt%TiO2) ceramic composite coatings on 304 stainless steel substrates. Coating structure, hardness, and compactness were evaluated by varying hydrogen flow rates (4, 6, and 8 L/min). The CT65 coating generated a slight phase change under different hydrogen flow rates, and the (Cr0.88, Ti0.12)2O3 solid solution phase was detected in the coating. The friction coefficients of these three coatings were maintained between 0.32 and 0.36. Increasing hydrogen flow rate reduced coating wear rate and transitioned wear mechanism from abrasive to adhesive. Friction film consisted of counterpart material transfer and coating solid solution. In addition, a wear behavior model diagram illustrated the friction-induced wear mechanism of CT65 composite coatings.