Tribological properties of ion beam deposited diamond-like carbon film on silicon nitride

Abstract

The present article reports on the physical characterization and tribological properties of diamond-like carbon (DLC) films deposited on structural Si 3N 4 substrates. The films were deposited by the direct ion beam deposition technique. The ion beam was produced by plasma discharge of pre-mixed methane and hydrogen gas in a Kaufman-type ion source. The deposited films were found to be amorphous and contained about 70% carbon and 30% hydrogen. The friction coefficient of an uncoated Si 3N 4 ball on a DLC coated Si 3N 4 disc starts at about 0.2, then decreases rapidly to 0.1–0.15 with increasing sliding distance. Increasing humidity results in a slight increase in friction coefficient, but a significant decrease in wear factor. The wear factor for the tests at ≈ 60% rh (relative humidity) are about an order of magnitude smaller than the tests at 30% rh.