Synthesis and structural properties of Mo-Se-C sputtered coatings

Transition metal dichalcogenides have attracted considerable attention due to their self-lubricant properties. Their drawbacks, such us low load-bearing capacity or environmental sensitivity, have been partially overcome by alloying or doping with metals, carbon, or nitrides. Nevertheless, there is still a considerable potential for further improvement, since the majority of studies has been aimed at MOS(2) and WS(2) based coatings and the properties of diselenides remain almost unknown. Mo-Se-C coatings were prepared by non-reactive r.f. magnetron sputtering from carbon target with embedded MoSe(2) pellets. The carbon content and Se/Mo ratio determined by electron probe microanalysis increased from 29 to 68 at.% and from 1.7 to 2.0, respectively, as a function of the decreasing number of pellets. The coating structure analyzed by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy showed that Mo-Se-C was a mixture of amorphous carbon and Mo-Se phases, since no traces of molybdenum carbides were observed. Linear increase of the hardness from 0.7 (29 at.% C) to 4.1 GPa (685 at.% C) showed a significant improvement compared to values typical for pure MoSe(2) coating. (C) 2007 Elsevier B.V. All rights reserved.