Degradação da microestrutura e da tenacidade a fratura da zirconia tetragonal policristalina com adições de itria em meio aquoso fisiologico

AUTOR(ES)
DATA DE PUBLICAÇÃO

1995

RESUMO

Recently, several studies have been focused on the use of yttria doped tetragonal zirconia polycrystal ceramics (Y-TZP s) as a biomaterial for the manufacturing of ceramic femoral heads and dental implants, because of their higher fracture toughness and strength when compared to alumina. However, there is still some controversy about the time dependent deterioration of the mechanical properties of zirconia ceramics, due to a phase transformation in aqueous environment. The present work aims at the study of possible time dependent changes on the fracture toughness and microstructure of two Y-TZP ceramics with different yttria contents, when immersed in Ringer s solution. The effects of yttria content, sintering time and temperature and immersion time and temperature on the tetragonal phase content and microstructure of these ceramics were studied, using x-ray diffraction analysis and SEM of the sample surface. Also, their fracture toughness was measured before and after aging in Ringer s solution using the Vickers indentation technique. The set of experiments envolved in this study was planned using a two level - four factor factorial design, and the results were analyzed using the Yates algorithm. Among the main variables, the yttria content showed the greatest effect on the fracture toughness reduction of the samples studied, the same applying to the immersion temperature on what concerns the increase in the microstructural degradation of the samples after aging in Ringer s solution

ASSUNTO(S)

oxido de zirconio planejamento experimental material ceramico - fratura materiais biomedicos estatistica - análise

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