| 摘要 |
<p>An aqueous emulsion of minute particles of calcium hydroxide formed by bringing porous and minute particles of practically pure calcium oxide into reaction with an excess amount of water is brought into reaction with an aqueous solution of phosphoric acid in an inert atmosphere, a milky reaction mixture containing the reaction product, hydroxyapatite is obtained. After filtering, the separated cake is washed with water and dried to be an aggregate of hydroxyapatite having the following properties: Analytical value of an atomic ratio of Ca/P: 1.67 to 1.69, Mean size of dimention of hydroxyapatite of length: 150 to 1200 .ANG. width: 50 to 400 .ANG., and ratio of length/width: 3 to 10. Void: 0.2 to 0.8 cm3/g Mean pore-radius: 50 to 150 .ANG.. By firing the filtered cake, a ceramic material of hydroxyapatite having the following physical properties is obtained: Analytical value of Ca/P : 1.67 to 1.69, Mean crystal size : 4 to 20 microns, and Density : 3.14 to 3.16 g/cm3. The mean crystal size of the thus obtained material is larger than that of conventional synthetic ceramic material of hydroxyapatite. The ceramic material of the present invention is prepared from the purer raw materials than those used for preparing the conventional materials. In addition, even after firing of the aggregate of hydroxyapatite at a temperature of 1350.degree.C for one hour, no formation of whitlockite occurs, and no structural defects or decomposition occurs and the aggregate is excellent in thermal stability. This invention relates to hydroxyapatite, ceramic material, implant material and a process for preparing thereof. The ceramic material is hydroxyapatite ceramic having an excellent thermal stability.</p> |
