Plasma sprayed YSZ coatings deposited at different deposition temperatures, part 2: Tribological performance

In the first part, we reported that the comprehensive desirable properties (high hardness, toughness, cohesive strength and compressive residual stress, etc.) for wear-resistance coatings could be achieved by adjusting the deposition temperatures. In this part, we studied the role of deposition temperature on the tribological performance of YSZ coatings, and the friction mechanisms are analyzed in detail. Results show that changing the deposition temperature enables the coefficient of friction to be reduced to 0.39. Particularly remarkable is the huge boost in wear-resistance of the YSZ coating deposited at 900 °C under high load dry sliding, from 1.05 × 10−3 mm3·N−1 m−1 to 1.64 × 10−7 mm3·N−1 m−1. The excellent tribological performance results from the effective inhibition of generation of cracks and formation of amorphous film, which acts as a shield to protect YSZ coating from further wear. Our work presents a novel concept that utilizes wear debris as raw materials to form a shield with the aid of friction, thereby improving the tribological performance of thermal-sprayed ceramic coatings, which may lead to moving components with much higher security, reliability, and efficiency.