Preparation of Ti Matrix Composites of Ti-B-C-N Systems by Spark Sintering and Their Friction and Wear Characteristics

Abstract

The spark sintering technique was utilized for fabrication of titanium matrix composites consisting of a matrix of titanium and precipitated phases of TiB or TiN. Density of composites and amount of precipitated compounds could be controlled by variation of process parameters in the spark sintering. B₂CN or BN as starting powders was decomposed, and compounds consisting of Ti and N, or solid solutions of N and C in Ti matrix were formed. The hardness also increased by the increase of TiB or TiN contents. The spark sintering at the higher temperature, 1673 K, led to enough promotion of sintering and enough precipitation of TiB as a reinforced phase, which resulted in the increase of values in hardness. The wear was promoted by three different mechanisms, an adhesive type, abrasive type and a mixture of both types, depending on the TiB amount in composites. The amount of precipitated TiB of 11–17 vol% in composites was optimum for improvement of both friction and wear properties in tests under a ring (counterface: SUJ3)-on-disk (specimen: titanium matrix composites) configuration.