Friction and wear of DLC films on 304 austenitic stainless steel in corrosive solutions

Diamond-like carbon (DLC) films are well known for their high hardness, low friction and excellent wear resistance. In the present work, the friction coefficient and wear resistance of DLC films deposited on 304 austenitic stainless steel were investigated in corrosive solutions. DLC films were deposited on the substrate by the CVD method using radio frequency (13.56 MHz) plasma. A mixture of methane (CH4) and hydrogen (H2) was used as processing gas. The CH4 concentration was varied from 20 to 100%. DLC films were subjected to friction and wear tests using a ball-on-flat surface friction apparatus in solutions of 3 mass% NaCl, 0.05 N HCl, 0.05 N H2SO4 and 0.05 N HNO3. The flat surface was oscillated against the alumina ball. In the tests performed within the corrosive solution, the friction coefficients of the DLC films and substrate were approximately 0.1 and 0.5, respectively. The DLC films deposited on the 304 substrate showed a remarkably lower volume of wear than the substrate alone. Accordingly, the DLC coating process was confirmed to be effective in decreasing the friction coefficient and improving the corrosion wear resistance of 304 in 3 mass% NaCl and acidic solutions.