J. Korean Ceram. Soc. > Volume 26(3); 1989 > Article
 Journal of the Korean Ceramic Society 1989;26(3): 305.
 습식법으로 제조한 수산화아파타이트 분말의 소결과 그 기계적 성질에 미치는 pHqus화의 영향 정형진, 김병호1, 신용규 한국과학기술원 무기재료연구실1고려대학교 재료공학과 Effect of pH Variation on the Sintering of Hydroxyapatite Powders Prepared by the Wet Method and their Mechanical Properties ABSTRACT Effect of pH variation in starting solution for the making of hydroxyapatite powder was studied in relation to the sinterability of the powder and their mechanical properties of the sintered hydroxyapatite ceramics. The sinterability of hydroxyapatite powder prepared at different pH was found to be improved with increase in pH value of the starting solutions. Thus the powders prepared from the higher pH solutions including 10.5, 11.0 and 11.5 could be well densified almost upto theoretical density by firing for 1 hr at 1,00$0^{circ}C$. But the powder based on pH 10 exhibited less sinterability even being fired at much higher temperature of 1,10$0^{circ}C$, it gave only 90-95% of theoretical density. On the other hand the powder prepared on the lowest pH value 9.5 could not be well densified and it could obtain only 78% of theoretical density even by firing at 1,30$0^{circ}C$ for 1hr. It was found that prismatic crystals of whitlockite were always included in the sintered bodies based on the lower pH values as a minority crystalline phase together with the major crystalline phase of hydroxyapatite and its inclusion might impair the sinterability of powder. However in the case of the higher pH, the powder contained only hydroxyapatite as a crystalline phase on sintering without any minorities. The sphere shape of crystals might help effectively the densification of the bodies. The best mechanical properties could be obtained from the body of pH 11 sintered at 1,10$0^{circ}C$, which gave 99.5% of theoretical density, 662Kg/$textrm{mm}^2$ of vickers hardness and 1,352Kg/$textrm{cm}^2$ of diameteral compression strength.
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