Effects of water environment on tribological properties of DLC rubbed against stainless steel

The effects of water environment on tribological properties of DLC against stainless steel were studied for development of the hydraulic pumps, valves and cylinders based on metal. A ball-on-disk tribotester was developed for detailed examination of water environment, such as temperature (20–80 °C), dissolved oxygen (0.01–8 ppm), water pressure (0.1–20 MPa) and dissolved ions. DLC was deposited on the disk by the unbalanced magnetron spattering system. Pure water and quasi-tap water were used to study the effects of dissolved ions. The results showed that temperature and dissolved ions have a major impact on friction and wear of DLC. EPMA, XPS and AES indicated that tribofilm on the metal surface, which consists mainly of C, O and Fe, plays important role for the phenomena.