Understanding the dry sliding wear behaviour of atmospheric plasma-sprayed rare earth oxide coatings

Highlights: ► The dry sliding wear behaviour of YSZ and LZ coatings was compared. ► Empirical relationships were derived to relate the wear parameters and wear rate. ► Wear resistance of LZ coating was high due to a robust tribofilm formation. ► Both coatings provide better wear resistance up to 8% porosity compared with base metal. -- Abstract: In this paper, the friction and wear behaviours of Yttria Stabilized Zirconia (YSZ) coatings; Lanthanum Zirconate (LZ) coatings and Inconel 738 base material (BM) sliding against a sintered tungsten carbide surface were studied and compared under unlubricated conditions. Sliding experiments were performed in a pin-on-disc configuration. Further, relationships among porosity, normal load and disc speeds with respect to wear loss were derived by using the response surface methodology, and the wear mechanisms were discussed adequately. It was found that the wear resistance of the ceramic coatings gets deteriorated with the increase in the percentage volume of porosity.