Friction and wear behaviors of different DLC films sliding against SiC and Si3N4 balls under high relative humidity

In this paper, the Pure-DLC, B4C-DLC and Si-DLC films were deposited on the AISI 304 stainless steel by unbalanced magnetron sputtering method. The tribological behaviors of the films sliding against SiC and Si3N4 balls were tested by a ball-on-disc tribometer under high relative humidity (90%). The results showed that the tribological behaviors for the films sliding against SiC exhibits more excellent than the corresponding film sliding against Si3N4, mainly showing lower friction coefficients and wear rates, narrower wear widths as well as lower fluctuant friction curves. There are two main reasons for the results. On the one hand, the films sliding against SiC ball exhibit the superior graphitization degree, smaller size of microcrystalline graphite and smaller disorder and sp2 hybrid bond content. On the other hand, the films sliding against Si3N4 ball show more abrasive particles during the friction process, which leads to the adsorbate of films on the surface to be more easily desorbed so that the σ bond reacted easily with water vapor and oxygen is more exposed and forms a strong covalent bond. [Display omitted] •The SiC and Si3N4 balls exhibit different tribological properties under different environments.•The Pure-DLC, B4C-DLC and Si-DLC film sliding against SiC ball presents excellent tribological properties.•The Pure-DLC sliding against SiC possess lower friction coefficient and disc wear rate.•The tribological mechanism for the films sliding against SiC and Si3N4 were discussed.