Preparation and tribological behaviors of DLC/spinel composite film on 304 stainless steel formed by cathodic plasma electrolytic oxidation

In this paper, the diamond-like carbon (DLC)/spinel composite film on 304 stainless steel was fabricated by cathodic plasma electrolytic oxidation (CPEO) in glycerin solution, and its microstructure, composition and phase constituents were characterized. The friction performance of the film under dry sliding against ZrO2 ceramic ball at ambient and high temperature up to 500 °C was evaluated. The thickness of the two-layer structure composite film reaches 18 μm under 260 V for 5 min discharge. The DLC/spinel composite film could significantly reduce the friction coefficient and improve the wear resistance of the 304 stainless steel especially at ambient temperature. The friction coefficients and wear rates of both the 304 stainless steel substrate and the composite film increase with increase of the environment temperature, but the wear process of the composite film was more stable than that of the stainless steel substrate even at high temperature. The wear mechanism of the composite film is adhesive wear at ambient temperature, but the slight plastic deformation along with adhesive could be found at high temperature.