MACHINING PERFORMANCE OF PHASE-TRANSFORMATION TOUGHENED ALUMINA AND PARTIALLY-STABILIZED ZIRCONIA COMPOSITE CUTTING TOOLS

Phase transformation toughened zirconia (TTZ) doped with yttria or cer ia has excellent properties such as higher order fracture toughness, t hermal shock resistance and moderate hardness. With these qualities, t hey are able to exhibit machining performance comparable to cold-compa cted Al2O3 cutting tools. With an addition of 20% aluminium oxide to T TZ, i.e. the composites of alumina and partially stabilised zirconia ( PSZ) exhibit improved toughness, enhanced thermal shock resistance and hardness. The alumina and PSZ composite ceramic tools exhibit cutting performance better than TTZ tools and comparable to zirconia toughene d alumina tools.