Nanomechanics and Tribology of Molybdenum-Disulphide Based Solid Lubricants for Space Applications

Molybdenum-disulphide solid lubricant coatings have an established history of use in space applications. However, limited understanding of their breakdown and failure mechanics has led to premature failure of several systems and missions. In the present study, high-resolution nanomechanical testing techniques are used to examine specific failure mechanics of both pure and co-deposited MoS2 coatings. Fundamental properties such as fracture and shear strength are determined in relation to the nanostructural characteristics of the coatings. It is found that purely nanocrystalline MoS2 shows impeded shearing within the structure compared to partially amorphous MoS2 which therefore increases the friction and wear rates. Furthermore, three state-of-the-art co-deposited coatings are tested under earth to low-earth-orbit specific environments. The newly developed prototype coating is found to outperform the best commercially available coatings under true application-specific conditions. This increased fundamental and application-specific understanding of MoS2 based coatings allows for precision tailoring of MoS2 coatings for reliable performance.M.A.S