ROLE OF REINFORCING CERAMIC PARTICLES IN THE WEAR BEHAVIOR OF POLYMER-BASED MODEL COMPOSITES

The role of the ceramic particles in the wear behaviour of particulate composites was investigated by minimizing the influence of the often intricate metallic matrix (high speed steel, Al alloys, Mg alloys, ... ). For this, the metallic matrix was replaced by a soft and homogeneou s polymer matrix showing a very low wear resistance. Polymer-based mod el composites were thus obtained. Their dry sliding wear behaviour was studied by means of a pin-on-disc apparatus which measured friction a nd wear coefficients. A number of experiments were performed using dif ferent ceramic particle types (Al2O3, TiC, SiC, ...) and varying the p article size (5-100 mu m) and particle volume fraction (5, 10, 20, 30, 40%). An alumina counterbody was used since conventional steel was no t suitable for studying the wear of the ceramics due to high abrasion. Interrupted wear testing was also carried out to study the wear mecha nisms using scanning electron microscopy (SEM) observation of the wear tracks and cross-sections. A crack formation and particle detachment mechanism was identified for the unreinforced polymer material. The ad dition of ceramic particles decreased the wear coefficient up to 50 ti mes. Large particles (of about 100 mu m) were found to protect the pol ymer matrix better than small particles (of about 20 mu m). Particle v olume fraction higher than 20% did not increase significantly the wear resistance of the composites. Results were in keeping with those obta ined using metal matrix composites containing similar ceramic particle additions.