Wear and friction of transformation-toughened CMC and MMC

The sliding wear properties of transformation-toughened CMC and MMC coupled with high-speed steel have been studied at speeds in the range 0.9–9.4 m/s for MMC and 0.2–11.1 m/s for CMC and at a pressure of 5 MPa. It was shown that at low sliding speeds (0.2–4 m/s), both friction coefficient and wear rate of the yttria-doped tetragonal zirconia polycrystal ceramics (Y-TZP) increased with sliding speed and then decreased after reaching the maximum. The wear rate of TiC–NiTi increases with the increase in the sliding speed in the range of 0.9–9.4 m/s, whereas the friction coefficient followed an inverse trend. At low speeds, the tribological behavior of both ceramics and hard was controlled by the action of the transformation-toughening mechanism. In case of ceramics, a continuous transfer layer formed to serve as a protective transfer layer on the specimen surface during high-speed wear. In case of TiC–NiTi, softened or even melted binder is extruded from an interparticle area onto pin/disk interface and thus determines wear behavior of such a system at sliding speed higher than 4 m/s.