高強度正方晶ジルコニアセラミックスの作製と熱安定性評価

概要

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High fracture strength and high fracture toughness of yttria doped tetragonal zirconia polycrystal(Y-TZP), Y-TZP/Al2O3 composites and ceria doped tetragonal zirconia polycrystal(Ce-TZP) were fabricated by post-HIPing technology. The maximum fracture strength of Y-TZP/A12O3 composites was 2400MPa at 30°C. The maximum fracture toughness of Ce-TZP was 20MPam1/2. It was found that hot isostatic pressing was effective to eliminate fracture origins such as pore. Three approaches, alloying Y-TZP with 0-20wt% CeO2, dispersing 0-40wt% A12O2 into Y-TZP and decreasing the grain size of zirconia were examined to control the tetragonal to monoclinic phase transformation by low temperature annealing in air and in water at 60-700°C. The amount of the monoclinic phase formed decreased with increasing CeO2 contents and A12O3 dispersed, and with decreasing the grain size of zirconia. Thermal shock behavior of Y_TZP with various grain sizes was evaluated by the water quenching method and the tetragonal to monoclinic phase transformation was investigated by using Raman microprobe spectroscopy. The critical quenching temperature different of Y-TZP increased from 250°C to 425°C with increasing grain size from 0.4 to 3.0μm.