| 摘要 |
PURPOSE:To obtain purity tricalcium phosphate having superior biological compatibility at a low cost by thermally decomposing a reaction product formed by reacting calcium carbonate with phosphoric acid, adding calcium carbonate to a decomposition product, and calcining them. CONSTITUTION:Calcium carbonate is reacted with phosphoric acid to form hydrated calcium hydrogenphosphate CaHPO4. This reaction product is well washed to remove thoroughly unreacted phosphoric acid, etc., and it is dried and decomposed at about 500 deg.C to form calcium pyrophosphate Ca2P2O7. To the calcium pyrophosphate is added calcium carbonate by an amount (mol) almost equal to the amount of the calcium pyrophosphate, and they are mixed and calcined at about 1,200 deg.C to obtain desired tricalcium phosphate. When CaHPO4. 2H2O is formed by reacting calcium carbonate with phosphoric acid, the CaHPO4.2H2O forming region depends on the mixing ratio between CaCO3 and water at the beginning of reaction, the reaction temp. and pH, so CaHPO4.2H2O can be formed advantageously by setting conditions according to relation among them.
|
