Surface texture effect on friction of a microtextured poly(dimethylsiloxane) (PDMS)

The effect of surface textures on the friction of a poly(dimethylsiloxane) (PDMS) elastomer has been investigated at both macro and microscales using a nanoindentation-scratching system. Friction tests were conducted by a stainless-steel bearing ball with a diameter of 1.6 mm (macroscale tests) and a Rockwell diamond tip with a radius of curvature of 25 mu m (microscale tests) under normal loads of 5, 10, and 25 mN and with a sliding speed of 1 mu m/s. Coefficient of friction (COF) on the pillar-textured surface was found to be much lower than that on the smooth surface of the same material, and it was reduced by about 59% at the macroscale tests and 38% at the microscale tests. The reduction of COF can be attributed to the reduced contact areas. The use of the JKR model revealed that the adhesion force has less effect on contacts under higher normal loads. COFs in different sliding directions on the groove-textured surfaces were compared, and a friction anisotropic behavior was identified and analyzed.