The role of MoS2 in hard overlay coatings of Al2O3 in dry sliding

Abstract

The role of MoS2 in Al2O3 ceramic coatings in dry sliding was examined experimentally. The result indicates that the tribological behaviour of pure Al2O3 ceramic coating is inconsistent. It is shown here that a reduction in wear volume of 2-9 times in magnitude is achieved when Al2O3 is codeposited with MoS2 in different ratios. The optimum percentage by weight of MoS2 to be codeposited with Al2O3 was found to be 40%. Increases or decreases in this percentage increase the wear volume, but the coating is still tribologically superior to pure Al2O3 coatings. The rupture and removal of this codeposited coating, unlike pure Al2O3 coatings, does not show any sign of catastrophic increase in wear volume. The rupture of codeposited Al2O3-MoS2 coatings is found to be very slow and is followed by the formation of a black coloured solid lubricant film on the contact surface. © 1992.