Microstructure analysis of MoS2 deposited on diamond-like carbon films forwear improvement

A compound solid lubricating film containing a MoS2 top layer deposited on DLC interlayer by UBM sputtering technique was investigated for its tribolo gical applications in humid environments. TEM, Raman and XRD analysis revea led the amorphous nature of the MoS2 film which contains only short-range o rder in its lattice structure. The as-deposited MoS2 compound films showed well-bonded interfaces. The MoS2, however, is very susceptible to humidity and oxidation, which resulted in higher friction coefficients and lower wea r life. A friction coefficient of 0.05 was measured between steel balls and MoS2 in atmosphere of 90% RH. Excessive abrasive wear was identified, as a result of the wear debris and the oxidized transfer layers between MoS2 an d its counterpart. The inclusion of a supportive DLC interlayer has effecti vely improved the wear behavior of MoS2 films under various loading conditi ons. The overall wear mechanism of MoS2 was complicated due to its oxidatio n problem which needs to be resolved for successful usage of MoS2 in humid environments. (C) 1999 Elsevier Science S.A. All rights reserved.