Friction and wear properties of in situ (TiB2 + TiC)/Ti3SiC2 composites

The non-lubricated, ball-on-flat sliding friction and wear properties of in situ (TiB2 + TiC)/Ti3SiC2 composites against bearing steel ball were investigated. The load was varied from 10 to 30 N. The material without TiB2 shows an increasing friction coefficient with the increasing load. However, for (TiB2 + TiC)/Ti3SiC2 composites, the friction coefficient shows an insensitivity to load. Both friction coefficient and wear rate initially increase and then dramatically decrease with TiB2 content increasing from 0 to 20 vol%. (TiB2 + TiC)/Ti3SiC2 composites with 15 vol% and 20 vol% TiB2 show excellent wear resistance, whose friction coefficient and wear rate are much lower than those of TiC/Ti3SiC2 composite. The enhanced wear resistance is mainly attributed to the facts that the hard TiB2 and TiC particles nail the surrounding soft matrix and decentralize the shear stresses under the sliding ball, a self-lubricating oxide debris forms on the wear surface, and the wear mode converts from adhesive wear to abrasive wear.