Tribochemical effects on the friction and wear behaviors of diamond-like carbon film under high relative humidity condition

Friction and wear behaviors of diamond-like carbon (DLC) film in humid N-2 (RH-100%) sliding against different counterpart ball (Si3N4 ball, Al2O3 ball and steel ball) were investigated. It was found that the friction and wear behaviors of DLC film were dependent on the friction-induced tribochemical interactions in the presence of the DLC film, water molecules and counterpart balls. When sliding against Si3N4 ball, a tribochemical film that mainly consisted of silica gel was formed on the worn surface due to the oxidation and hydrolysis of the Si3N4 ball, and resulted in the lowest friction coefficient and wear rate of the DLC film. The degradation of the DLC film catalyzed by Al2O3 ball caused the highest wear rate of DLC film when sliding against Al2O3 ball, while the tribochemical reactions between DLC film and steel ball led to the highest friction coefficient when sliding against steel ball.