Preparation and tribological behavior of potassium stearate films

Potassium stearate films on hydroxyl silicon substrates were prepared by dip-coating. The tribological properties of the films sliding against AISI-52100 steel ball and Si₃N₄ ceramic ball were investigated with dynamic static friction coefficient measurement apparatus and universal micro-tribometer in ball-on-plate configuration. The morphologies of the wear tracks of the potassium stearate films and the counterparts were examined using a scanning electron microscope equipped with an energy-dispersive X-ray analyzer attachment. The potassium stearate films on the hydroxyl-terminated substrate showed better tribological properties under relative higher sliding velocity or sliding against Si₃N₄ ceramic ball. Because of the different chemical nature and larger surface roughness of steel ball and Si₃N₄ ball, transfer film of potassium stearate is more easily formed on ceramic ball, resulting in lower friction coefficient and longer wear life as compared to that of steel ball.