Wear resistance of superior structural WS₂-Sb₂O₃/Cu nanoscale multilayer film

Transition metal dichalcogenides (TMDs) with layered structure exhibit very low friction coefficient but poor wear resistance in vacuum environments. To develop high wear resistance of WS₂ film, its nanostructure was optimized by co-introducing of Sb₂O₃ dopant and Cu sublayer using sputtering technique. Effects of co-doping on film nano/microstructure, mechanical and tribological performance were investigated by GIXRD, FESEM, HRTEM, nano-indentation tester, AFM, 3D non-contact surface mapping profiler, scratch tester and vacuum ball-on-disk tribometer. The results showed that the growth of WS₂ columnar platelets could be restricted by co-introducing of Sb₂O₃ dopant and thin Cu sublayer (about 1.6 nm), but not single-doping of even 10.0 at.% Sb₂O₃, leading to formation of amorphous WS₂ phase. As compared to the loose WS₂-Sb₂O₃ and pure WS₂ films, the dense multilayer films possessed high hardness and high H³/E², and those maximum values were 6.3 GPa and 2.7 × 10^-2 GPa, respectively. The doping 10.0 at.% Sb₂O₃ could double the film wear life to 2.7 × 10⁵ cycles in vacuum under high Hertzian contact pressure (about 1.0 GPa), and further introduction of Cu sublayer would make the multilayer film much longer wear life about to 1.1 × 10⁶ cycles. Wear mechanisms were discussed in terms of wear track morphology after different sliding cycles.