EFFECT OF ZRO2, ADDITION ON MECHANICAL AN D TRIBOLOGICAL PROPERTIES OF TIB2-ZRO-COMPOSITES

TiB2-ZrO2-composites were produced by hot-pressing in argon. The mecha nical and tribological properties of the composites were investigated in relation to the amount and type of the ZrO2 added. Addition of ZrO2 reduced the sintering temperature of the TiB2-ZrO2-composites and led to growth inhibition of the TiB2 phase. ZrO2 also increased the bendi ng strength and fracture toughness of the composites. Tribological tes ts were carried out using laboratory tribometers under unlubricated os cillating sliding contact against Al2O3-, Si3N4- and SiC-counterbodies . Abrasive wear of the ceramics against 80 mesh SiC grits was studied by using an abrasive wheel test. During sliding contact the composites showed high wear resistance but caused extensive wear of the counterb odies and high friction coefficients compaired to self-mated monolithi c Al2O3- and ZrO2-ceramics. Volumetric wear loss of the TiB2-ZrO2-comp osites due to abrasive SiC grits was by a factor up to 30 lower than t hat of a commercial monolithic Al2O3. Wear resistance of the composite s increased with decreasing amount of ZrO2 and was higher for the comp osites with addition of partially stabilized tetragonal ZrO2 than for those with addition of monoclinic ZrO2.