Tribological behavior of NiCr-base blended and nanostructured composite APS coatings by rig test

In the present paper, a nanostructured composite powder containing nano-sized Cr2O3 (<100 nm) is manufactured by spray drying and heat treatment. By wear and rig test at room temperature (RT), 200 °C, and 350 °C, respectively, the mechanical and tribological properties of atmospheric plasma spray (APS) blended (PS304) and composite coatings with same composition (60NiCr–20Cr2O3–10Ag–10BaF2/CaF2, wt.%) are compared. The results show that uniform microstructure of the composite coating could be obtained by eliminating the difference in physical and thermophysical properties of components in feedstock, which leads to the non-uniformity of blended coating due to their different in-flight trajectories of components in APS process. Therefore, the excellent wear resistance of composite coating benefits from its uniform and fine microstructure. Also, the wide and uniform distribution of plastic Ag lubricant could result in the formation of surface localized tribofilm as lubricant film to protect the coating from fracture and spallation.