Structural evolution and wear resistance of MoS₂–Based lubricant films irradiated by heavy ions

In this work, a 2 MeV Au²⁺ ion irradiation was implemented to simulate the neutron damage on magnetron sputtered MoS₂-based composite films. The irradiation damage mechanism and the wear resistance of films were accessed as a function of increasing Au²⁺ fluence. The XRD as well as the cross-section TEM images results reveal that the intrinsic crystallites of MoS₂ in Mo-S-Ti composite films are more easily to be destructed. At the low fluence of 1 × 10¹⁴ Au²⁺/cm², the irradiation damage peak was mainly distributed in depth of 0.45 μm – 0.7 μm in films. While, with the increase of the incident fluence, the disordering of MoS₂ crystallites near the film surface were also become serious, and they are fully amorphized at the end of the studied fluence of 3.3 × 10¹⁵ ion/cm² due to the accumulation effect induced by the ion collisions. Nonetheless, the tribotests in vacuum show that the lubricity of MoS₂ phases would not be immediately failured due to their damage of intrinsic structure of MoS₂ crystallites, and only enhancing the irradiation to the high dose (2, 5 and 1 dpa), a rapid degradation of lubricity will be observed.