EFFECT OF TEMPERATURE ON FRICTION AND OSCILLATING SLIDING WEAR OF DENSE AND POROUS 3Y-TZP ZIRCONIA CERAMICS

Microstructures of 3 mol% Y2O3-ZrO2 (3Y-TZP) with systematically varying porosity up to about 15% were produced by sintering. Hardness and fracture toughness of the; ceramics as well as the amount of tetragonal, cubic and monoclinic phase were measured. Wear tests were carried out on the different self-mated microstructures under dry reciprocating sliding contact using ringon-block geometries in air at five different contact temperatures up to 500 degrees C. The microstructures and worn surfaces were extensively analysed using scanning electron microscopy (SEM) and X-ray diffraction techniques. The experimental results revealed a reduction of the amount of wear (independent of porosity) by more than one order of magnitude compared with room temperature if the test temperature was increased to 250 degrees C. Between room temperature and 250 degrees C, wear increased with increasing porosity while at 500 degrees C the highest wear was measured on the dense structure. Microscopic observations showed that plastic deformation, surface layers consisting of compacted wear debris and also intercrystalline, transcrystalline or delamination type fracture influenced friction and wear.