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 0.9-94m/s f or MMC and 0.2-11.1 m/s for CMC and at a pressure of 5 Wa. It was shown tha t at low sliding speeds (0.2-4 m/s), both friction, coefficient and wear ra te of the yttria-doped tetragonal zirconia polycrystal ceramics (Y-TZP) inc reased with sliding speed and then decreased after reaching the maximum. Th e wear rate of TiC-NiTi increases with the increase in the sliding speed in the range of 0.9-9.4m/s, whereas the friction coefficient followed an inve rse trend. At low speeds, the tribological behavior of both ceramics and ha rd was, controlled by the action of the transformation-toughening mechanism . In case of ceramics, a continuous transfer layer formed to serve as a pro tective transfer layer on the specimen surface during high-speed wear. In c ase of TiC-NiTi, softened or even melted binder is extruded from an interpa rticle area onto pin/disk interface and thus determines wear behavior of su ch a system at sliding speed higher than 4 m/s. (C) 2001 Elsevier Science B .V. All rights reserved.