| In the present work, attempts have been made to dope MoS2 films with moisture-repellent polytetrafluoroethylene (PTFE) by the co-sputtering technique, with the purpose to reduce the moisture sensitivity and to improve the tribological performance of the films. Several films have been produced by the combined direct current (DC) and radio frequency (RF) magnetron sputtering technique. These include pure MoS2, graded MoS2-PTFE and mixed MoS2-PTFE films. The resultant films were characterised by a variety of experimental and analytical techniques, scanning electron microscopy for film morphology examination, nanoindentation for hardness and elastic modulus evaluation, and ball-on-disc sliding tests for tribology measurement, for instance, friction coefficient and film wear-life. The experimental results showed that doping MoS2 with PTFE has several advantages over the pure MoS2 film. These include increased film hardness and modulus, and more importantly reduced friction coefficient and increased film wear-life, particularly after prolonged storage of the specimens in open-air environments. The performance of the films relies on the content of PTFE in the film, which is controlled by sputtering power and co-deposition time. By appropriate doping with PTFE, the tribological performance of the film under ambient conditions could be significantly improved. |
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