Effects of sliding velocity and ambient temperature on the friction and wear of a boundary-lubricated, multi-layered DLC coating

Wear rates of the coatings increased with increasing temperature. As temperature increased from 27 to 55 °C, friction coefficients increased, but wear rates of the ball decreased. With an increase in temperature from 55 to 160 °C, friction coefficients decreased until 110 °C then slightly increased, and wear rates of the ball increased. Increasing sliding velocity led to a decrease in friction coefficients and wear rates of both friction surfaces. Through surface analyses and observations, it was confirmed that graphitization of the worn DLC coatings, reactive tribofilms on the worn ball specimens, portion of the surface asperities in dry sliding contact, and corrosive wear of the ball specimens affect tribological characteristics.