Structural and Tribological Properties of WS₂ Films Deposited by Radio Frequency Unbalanced Magnetron Sputtering

WS₂ films with different degree of(002) preferential orientation were deposited on n-(100) Si substrates by radio frequency unbalanced magnetron sputtering. The chemical composition and microstructure of WS₂ films were characterized by energy dispersive X-ray spectroscopy and X-ray diffractometer, scanning electron microscopy. The mechanical and tribological perperties were measured by nano-indentation and tribo-meter in ball-on-disk mode. The results show that the tribological performance of WS₂ films in terrestrial was influenced by Ar flow rate. With the increment of Ar flow rate, the S/W ratio of the films firstly decreased, and then increased. The trend of (002) diffraction peak was in consistent with the S/W ratio, while hardness and elastic modulus were opposite to the S/W ratio. It is found that the failure took place quickly for WS₂ films with the low S/W ratio, high hardness and poor crystallinity of WS₂ films. Inversely, when the relatively high S/W ratio and sharp (002) diffraction peak simultaneously appeared, the low friction coefficient and excellent wear resistance were obtained as the effective transfer films presented. However, the wear resistance declined since the hardness of WS₂ films was not high enough to bear load.