Effect of a method of Al2O3 incorporation into 3Y-TZP materials on their microstructure and properties
Waldemar Pyda, Jadwiga Brzezińska-Miecznik, Zbigniew Pędzik, Anna Pyda Akademia Górniczo-Hutnicza, Wydział Inżynierii Materiałowej i Ceramiki, al. Mickiewicza 30, 30-079 Kraków
Annals 4 No. 11, 2004 pages 311-318
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abstract In the study, two methods of incorporation of Al2O3 inclusions into a polycrystalline matrix of tetragonal zirconia stabilised with yttria (3Y-TZP) were used and their influence on a microstructure and properties of 3Y-TZP/Al2O3 composites has been studied. The first method consisted in physical mixing of component powders by means of intensive milling. The second one utilised possibilities of the co-precipitation method of chemically homogeneous deposits followed by their calcination. An aqueous solution of zirconium, yttrium and aluminium salts was used. Green compacts were shaped by cold isostatic pressing under a pressure of 300 MPa and then they were pressurelessly sintered for 2 h at 1500÷1650°C in air. The composites contained from 0 to 20 vol.% of inclusions of a size which depended on the powder preparation method applied. Morphology and phase composition of the powders, microstructure of the green compacts and sintered materials was characterised. Bending strength and fracture toughness was measured in the case of the bodies of optimal density. The co-precipitation method with participation of aluminium cations enables to produce the composites which contained the alumina inclusions of the size falling in the nanometric range (100÷500 nm). The inclusions derived from this method were much smaller than those derived from the physical mixing one (300÷1200 nm). The composites with the former inclusions showed increased values of mechanical strength and slightly decreased values of fracture toughness. Key words: zirconia, alumina, particulate composites, co-precipitation, microstructure