Investigation of the influence of CaS, CaO and CaF2 fillers on the transfer and wear of nylon by microscopy and XPS analysis

The effect of CaS, CaO and CaF2 fillers on the transfer, friction and wear behaviors of nylon was studied. Sliding was performed in ambient atmosphere at a speed of 1.0 m s(-1) and a load of 19.6 N, and a pin-on-disk configuration was used. The filler content in nylon was fixed at 35% by volume. The counterface disk was made of hardened tool steel. The experimental results showed that CaO and CaS were effective in reducing the wear of nylon, but CaF2 increased it greatly. The tribochemical studies by XPS revealed that some CaS decomposed during sliding so that FeS and FeSO4 were produced. No such decomposition was found in the case of CaF2. The comparison of the bonding strengths of these fillers revealed that the bonding strengths of the compounds that decomposed were lower than that of CaF2 which did not decompose. It was concluded that FeS and FeSO4 increased adhesion between the composite transfer film and the steel substrate. Furthermore, the ability of the fillers to help in the formation of a uniform and continuous composite transfer film and to promote adhesion between the transfer film and its substrate contributed to increased wear resistance.