Effect of <TEX>$Ta_2O_5$</TEX> Alloying on Low Temperature Degradation of 3 mol% Y-TZP

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J. Korean Ceram. Soc. > Volume 29(8); 1992 > Article

Journal of the Korean Ceramic Society 1992;29(8): 630.

$Ta_2O_5$ 첨가가 3 mol% Y-TZP의 저온열화에 미치는 영향

김대준, 최두진¹

한국과학기술연구원 유전체세라믹스연구실
¹연세대학교 세라믹공학과

Effect of $Ta_2O_5$ Alloying on Low Temperature Degradation of 3 mol% Y-TZP

ABSTRACT

Ta2O5 alloying into 3 mol% Y2O3-stabilized tetragonal ZrO2 polycrystals (3Y-TZP) increased the degradation during aging at 265℃ and the fracture toughness; both are determined by the amount of transformed m-ZrO2. It was proposed that the mechanism underlying the t→m transformation when aged at low temperatures is attributed to the reorientation of (Zzr'V ). complexes parallel to [111] lattice direction, which is accompanied by a relaxation of TZP lattice during annealing at low temperature. A small strain which results from the reorientation gives rise to a localized mechanical instability, thus lowering the nucleation barrier so that the t→m phase transformation (degradation) proceeds. The amount of transformed m-ZrO2 during aging becomes greater as the chemical free energy change related to the transformation, ΔGo, increases with increasing the Ta2O5 alloying content.