Study on friction reduction by combining DLC film and surface patterning

In this study, we determined the friction characteristics of micro–textured surfaces coated with diamond–like carbon (DLC) film. The friction force was measured using a ball-on-plate type reciprocating friction test apparatus. The substrate specimens with DLC film were rubbed with Al₂O₃ ball having a diameter of 9.5 mm, under a load of 1 N and 5 N at a sliding speed of 5 mm/s. The measurements were conducted in ambient air and in a vacuum of 2.0 × 10-4 Pa. In ambient air, the non-textured substrate showed a wide range of friction coefficient from 0.1 to 0.24; the micro-grooved substrate showed stable friction coefficients of around 0.09. The friction coefficient on non-textured substrate exhibited a lower friction coefficient than micro-grooved substrate under the vacuum condition. This trend was the opposite of the friction coefficient in ambient air.