A study on the friction and wear behavior of PTFE filled with ultra-fine kaolin particulates

A solid lubricant composite material was made by compression molding PTFE and ultra-fine kaolin particulates. Composites from 0 to 15 wt.% were prepared. These composites were tested against a 45 carbon steel counterface on a reciprocating tribometer. The experimental conditions were a contact pressure of 7.5 MPa, a stroke length of 15 mm, and a reciprocating frequency of 1 Hz. The friction coefficient of the composites increased over unfilled PTFE from roughly 0.12 to 0.22, at filler concentrations of 10 wt.%, the wear resistance improved by almost two orders of magnitude as compared to the unfilled PTFE. Wear testing and SEM analysis showed that adhesive wear was probably the dominant mode of failure for a PTFE–10 wt.% kaolin composite.