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Ytterbia-Neodymia Costabilized Zirconia – Alumina Nanocomposites

F. Kern

Journal of Ceramic Science and Technology, Vol. 3, No. 4 (2012), pp. 189-198

DOI: 10.4416/JCST2012_00021

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Abstract

Alumina-toughened zirconia composites are attractive materials for biomedical and demanding mechanical engineering applications as the added alumina increases hardness and strength while the fracture toughness of zirconia is preserved. In the present study an unstabilized pyrogenic zirconia nanopowder was coated with 1 mol% ytterbia and 2 mol% neodymia via the nitrate route, the powder was blended with 20 vol% submicron size alumina. Samples were hot-pressed at 1250 – 1450 °C for 1 h at 60 MPa axial pressure. Microstructure, phase composition and mechanical properties were investigated. The composites show proceeding phase separation with rising sintering temperature. Cubic precipitates are formed, leaving a highly transformable tetragonal zirconia matrix, which results in a combination of very high fracture resistance, threshold stress intensity and bending strength. The material thus combines high resistance to catastrophic failure in single loading events and good prospects for applications operating under cyclical loading conditions.

Keywords

Ceramics, mechanical properties, phase composition, microstructure

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