Effect of source gas and deposition method on friction and wear performance of diamondlike carbon films

We investigated the tribological performance of diamondlike carbon (DLC) films derived from methane, acetylene, and hydrogen + methane source gases in a magnetron sputtering system and an ion-beam-deposition system. Films have been deposited on AISI 440C bearing-steel substrates and were tested in a pin-on-disk machine under a wide range of conditions in open air and in dry nitrogen. We found that the films grown in a hydrogen + methane plasma resulted in significantly lower friction coefficients (i.e. 0.01) and ball wear rates during tests in dry nitrogen (N(2)). The friction coefficients for the methane-derived films were also low (0.02 in dry N(2)) but the friction coefficients of the acetylene-produced films were 2- to 10-times higher than those recorded for the methane-and hydrogen + methane-grown films, especially in dry N(2). The methane- and hydrogen + methane-grown films also resulted in very small wear losses on counter-face balls, regardless of the test environments. Raman spectroscopy and electron microscopy were used to elucidate the structural chemistry of each film and correlate the findings with tribological performance. (C) 1997 Elsevier Science S.A.