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 varyi ng porosity up to about 15% were produced by sintering. Hardness and f racture toughness of the; ceramics as well as the amount of tetragonal , cubic and monoclinic phase were measured. Wear tests were carried ou t 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 wor n surfaces were extensively analysed using scanning electron microscop y (SEM) and X-ray diffraction techniques. The experimental results rev ealed a reduction of the amount of wear (independent of porosity) by m ore than one order of magnitude compared with room temperature if the test temperature was increased to 250 degrees C. Between room temperat ure and 250 degrees C, wear increased with increasing porosity while a t 500 degrees C the highest wear was measured on the dense structure. Microscopic observations showed that plastic deformation, surface laye rs consisting of compacted wear debris and also intercrystalline, tran scrystalline or delamination type fracture influenced friction and wea r.