Evaluation of Sliding Wear Characteristics of Ceramic Matrix Composites for Cam Followers

Sliding wear characteristics of ceramic matrix composites (CMC) produced by the directed metal oxidation process(*) were evaluated using a block-on-ring wear test machine at 75-85°C under lubricated conditions. The ceramic matrix composite consisted of silicon carbide particulate in an aluminum oxide matrix that also contained a small amount of metal. For comparison, wear characteristics of alumina, silicon carbide, sialon and silicon nitride were also determined. The blocks of the test materials were tested against rings of SAE 4140 steel heat treated to 57-59 Rockwell C hardness. The optimized CMC composition showed wear performance similar to those of the best ceramic materials, silicon nitride and sialon, and was far superior to that of the cast iron.

The optimized CMC composition was also evaluated using a single cam wear tester (The Motor Industry Research Association (U.K.) tester) at various loads for up to 20 million cycles. The test load at which failure occurred was slightly higher than that for silicon nitride and chilled cast iron and was much higher than that for alumina (zirconia toughened alumina).

These results indicate that ceramic matrix composites produced by the directed metal oxidation process may be attractive candidate materials for sliding followers.