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Alumina-Doped 2.5Y-TZP produced from Yttria-Coated pyrogenic Nanopowder

F. Kern

Journal of Ceramic Science and Technology, Vol. 2, No. 2 (2011), pp. 89-96

DOI: 10.4416/JCST2011-00001

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Abstract

Y-TZP ceramics are widely used owing to their high strength, toughness and abrasion resistance. In this study, pyrogenic zirconia nanopowders were coated with yttria via the nitrate route and blended with 0.5 vol% alumina. Powders were consolidated by hot pressing at 1200 – 1500 °C. The fine-grain TZP materials produced show high strength of 1 GPa. Despite the high toughness of > 9 MPa·√m and high transformability of > 60 %, the ceramics exhibit aging resistance similar to state-of-the-art co-precipitated . The parameters of the Mehl-Avrami-Johnson kinetics indicate that aging of coated 2.5Y-TZP proceeds at similar rate constants but more evenly at lower Avrami exponents, which makes the low-temperature degradation process more controllable and less catastrophic. After stress-induced transformation a new phase was identified in the fracture faces which may be an ordered defect structure formed during fast transformation. The phase was not detected after aging-induced transformation.

Keywords

Zirconia, hot pressing, mechanical properties, microstructure, low-temperature degradation, phase analysis

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