ORAL REFERENCES: ICF100938OR IMPROVEMENT OF MECHANICAL PROPERTIES OF ALUMINA PARTICULATE COMPOSITES USING POLYCRYSTALLINE ALUMINA POWDER K. Kageyama, K. Ohi and H. Kato Department of Mechanical Engineering, Saitama University, Urawa, Saitama, 338-8570, Japan, ABSTRACT Alumina particulate zirconia and alumina particulate glass using polycrystalline alumina powder was fabricated by atmospheric sintering to investigate the influence of alumina grain distribution on the mechanical properties of alumina composites. Polycrystalline alumina powder was obtained by quenching and crushing sintered alumina body. Firstly, the fracture toughness of 20% of zirconia particulate alumina was slightly increased with the addition of polycrystalline alumina powder. On the other hand, the bending strength was kept almost constant with the addition of polycrystalline alumina powder. SEM observation of a crack path indicated that a crack propagated into alumina cluster formed by polycrystalline alumina powder and transgranular fracture often occurred in the cluster compared to the other region. Second, 50% of alumina particulate borosilicate glass was sintered using virgin alumina powder or polycrystalline alumina powder. Using polycrystalline alumina powder, sintered body was obtained at lower sintering temperature than that using virgin alumina powder and the average bending strength was improved by the addition of polycrystalline alumina powder, too. Some samples showed that mullite formation occurred during sintering and X-ray analysis indicated that the addition of polycrystalline alumina powder enhanced mullite formation in the samples. These results indicate that the addition of polycrystalline alumina powder can improve fracture toughness, bending strength, mullite formation and/or low temperature sintering of alumina particulate composites. KEYWORDS composite, alumina, zirconia, glass and mechanical properties. INTRODUCTION Ceramics or glass matrix composites have been studied to improve the poor mechanical reliability of ceramics and glass for the practical use in various industries [1-3]. Conventionally, microstructure of ceramics has been
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