EFFECT OF ALUMINA NANOPOWDER ADMIXTURE ON CONSOLIDATION OF 3Y(2)O(3)-ZrO2 MICROPOWDER IN PROSTHODONTIC APPLICATION CONTEXT

Zirconia micropowder stabilized with 3 mol% yttrium oxide is used to produce bisques, being the pre-sintered blanks intended for the manufacturing of all-ceramic dental restorations. The bisques should be characterized by mechanical strength and fracture toughness suitable for the precise milling of thin-walled items afterwards sintered to full density, ensuring good performance. The aim of this research was to study the effect of a 0.2 mass% nano-Al2O3 addition to the TZ-3Y Tosoh powder on its behaviour during low and high-temperature consolidation, and on the properties of green compacts, bisque-sintered and fully-sintered TZP materials. The bisque-sintered materials were manufactured at 500 divided by 900 degrees C, and characterized in terms of their densification, mechanical strength, hardness and fracture toughness, and compared to the Cercon and ICE Zirconia green materials. The materials sintered at 1200 divided by 1550 degrees C were analysed to show the influence of the alumina addition and presintering temperature on the densification and microstructure. Comparison was also made to sintered bodies derived from the Cercon and ICE Zirconia materials. Both unmodified and Al2O3 modified TZ-3Y powder can be used for the fabrication of bisques for dental applications. An increase in strength and hardness of the bisques with a pre-treatment temperature was observed, and it significantly affected their behaviour during milling; the bisques pre-sintered at 700 and 900 degrees C showed the best machining properties. The addition of 0.2 mass% nano-Al2O3 to the TZ-3Y powder contributed to lowering the final sintering temperature, and to obtaining a microstructure analogous to the Cercon derived one.