Influence of two-step sintering on microstructure evolution and mechanical properties of alumina-nanozirconia composites

Bartosz Wójtowicz, Waldemar Pyda

Quarterly No. 2, 2012 pages 132-137

DOI:

keywords: ZTA, two step sintering, microstructure, mechanical properties, composite

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abstract In this work we present the preparation of 2 and 12 vol.% zirconia alumina composites via filter pressing and pressureless sintering at a constant heating rate (CHR), by means of two-step sintering (TSS) and reverse two-step sintering (RTSS). Nanozirconia (10 nm) and microalumina (175 nm) powders were used. The resultant composites were characterized in terms of their microstructural (density, grain size) and mechanical (hardness, fracture toughness) properties. The heating schedule showed an insignificant effect on the density of the composites. TSS produced composites of the best properties and finest microstructure, while RTSS in the case of samples containing 12 vol.% of zirconia, produced the coarsest grains. The resultant densities were close to 95%, but the fracture toughness and hardness were reasonably good: (7.0±0.2) MPa•m^0.5 and (20.8±0.2) GPa for the TSS sample containing 12 vol.% zirconia, respectively.