| 摘要 |
1522182 Calcium phosphate ceramics STERLING DRUG Inc 22 July 1975 [2 Aug 1974 7 July 1975] 30706/75 Heading C1A A polycrystalline, sintered ceramic for use as a bone or tooth substitute is made by reacting calcium ion with phosphate ions in aqueous medium at pH of 10-12 to produce a gelatinous calcium phosphate precipitate having a Ca:P molar ratio of 1À44-1À72, separating the precipitate from the solution and heating the precipitate to above 1000‹C but below the temperature at which appreciable decomposition of hydroxylapatite occurs and maintaining said temperature for a sufficient time to effect sintering and maximum densification. When the Ca:P molar ratio is in the range 1À62-1À72 a translucent, isotropic, polycrystalline hydroxylapatite having an average crystalite size of 0À2-3 microns, a density of 3À1-3À14 g/cm<SP>3</SP>, substantially no pores and having cleavage along smooth curved planes is obtained. When the Ca:P ratio is in the range 1À44-1À60, preferably 1À46-1À57 a dense isotropic two-phase ceramic is obtained comprising 14-98% hydroxylapatite and 2-86% whitlockite, said ceramic having substantially no pores and having cleavage along smooth curved planes. The reactants are preferably Ca(NO 3 ) 2 and (NH 4 ) 2 HPO 4 . 0À4-0À6% of an organic binder, e.g. collagen, may be added to the precipitate to prevent cracking during drying. Porous forms of the ceramic may be made by including 5-25% by weight of organic binders such as powdered cellulose, starch, cotton or collagen to the precipitate. Fluoride ions may be introduced into the ceramic, e.g. by standing in 0À5-5% aqueous NaF for 12 hours-5 days. |
