MoSx lubricant coatings produced by PVD technologies

Abstract

Among the different options for solid lubrication, MoS2 is probably the most attractive due to its extremely low friction levels. Recent developments in magnetron sputtering physical vapour deposition (PVD) technology have allowed the development of MoS2 composite thin films with more compact structures, low friction behaviour and enhanced wear resistance, reducing degradation by humidity. The present work provides an overview of recent developments in dry lubrication with MoS2 films deposited by modern sputtering PVD and how these MoS2 films alloyed with Ti or WC can outperform conventional unalloyed films not only under vacuum but also under atmospheric high humidity conditions. MoSx–WC composite films outperform MoSx–Ti films, showing endurance at 0·75 GPa as high as 1·2 million wear cycles, also significantly higher than the values obtained from unalloyed, conventional MoS2 thin solid films. The films also exhibit a steady state friction coefficient from 0·02 to 0·04. In addition, these films also show resistance to humid environment when tested under atmospheric conditions.