Tribochemical Mechanisms of W/Mo Films in the presence of ZDDP

The tribological interaction between ZDDP and W/Mo films was conducted by the means of SRV wear tester in this study. And some surface analyses (e.g. scanning electron microscopy and X-ray photoelectron spectrometer) were adopted. The results show that the friction coefficients of the films in absence of ZDDP and in the presence of ZDDP were 0.11 and 0.08, respectively. However,the wear behaviors varied from film to film. The wear volumes of the W films in absence and presence of ZDDP were roughly the same (3.7×10^-13 m³). In the presence of ZDDP, the wear volumes of the Mo film and W-Mo film were markedly reduced, e.g. a 74.5% reduction for W-Mo film. This was mainly attributed to the high hardness of the films and the tribochemical films formed on the surfaces.