Dynamic Friction of SiC Surfaces: A Torsional Kolsky Bar Tribometer Study

A dynamic tribometer has been successfully developed utilizing torsional Kolsky bar (TKB) technique for tribo pairs subjected to dynamic compression and shear. The dynamic tribometric responses of ground finish (R a = 0.17 μm) and polished finish (R a = 0.10 μm) surfaces of silicon carbide (SiC) under compression loading up to 1.5 GPa and shear-sliding velocity to 3.8 m/s have been measured. The experimental results show Coulomb friction behavior. Hardening of shear response is found on both the ground and polished surfaces. Repeating tests on the same tribo-pair demonstrate that steady state shear response on polished surfaces can be achieved by cumulating shear-sliding distance. SEM observation of the tested surface shows that the tested surfaces are microscopically shear-damaged. The similar surface conditions after a relative longer shear-sliding distance on polished surfaces lead to the same steady state frictional coefficient, 0.61, for both finishing surfaces.