Modification of structure and wear resistance of closed-field unbalanced-magnetron sputtered MoS2 film by vacuum-heat-treatment

MoS2 film deposited was deposited by closed-field unbalanced-magnetron sputtering (CFUBMS), and its structural and tribological properties were modified by the heat treatment at temperature range of 100-500 degrees C in vacuum environment. Results revealed that as-deposited MoS2 film was composed of MoS2 plus a little MoO3 with a dense amorphous-like structure. After the vacuum heat treatment, MoS2 film was still very compact, but its microstructure was changed from amorphous-like to nano-crystalline states with the increase of heat treatment temperature. As a result, a MoS2 film with a microstructure of MoS2 nanocrystals embedded into its own amorphous matrix was obtained at middle temperature of 200 degrees C. Furthermore, MoO3 phase in the film was reduced to MoO2 after the vacuum heat treatment at high temperatures of 400 and 500 degrees C. Friction tests revealed that the wear resistance of MoS2 film in vacuum environment was significantly improved by the vacuum heat treatment at suitable temperature. The wear life of vacuum-heat-treated MoS2 film at 200 degrees C for 3 h was similar to 6.2 x 10(5) r, about four times longer than that of as-deposited MoS2 film.