Ceramics Based on a Powder Mixture of Calcium Hydroxyapatite, Monocalcium Phosphate Monohydrate, and Sodium Hydrogen Phosphate Homogenized under Mechanical Activation Conditions

摘要

Calcium phosphate ceramics, with the phase composition represented by β-calcium pyrophosphate β-Ca_(2)P_(2)O_(7), was obtained from a powder mixture of calcium hydroxyapatite Ca_(10)(PO_(4))_(6)(OH)_(2), monocalcium phosphate monohydrate Ca(H_(2)PO_(4))_(2)· H_(2)O, and sodium hydrogen phosphate Na_(2)HPO_(4). The powder mixture was preliminarily homogenized in acetone using a planetary mill. This treatment resulted in the chemical reaction between the starting components to form monetite, calcium hydrogen phosphate CaHPO_(4)(precursor of calcium pyrophosphate Ca_(2)P_(2)O_(7)). According to the XRD data, sodium hydrogen phosphate Na_(2)HPO_(4)when present in an amount of 5 wt % in the starting mixture had no effect on the phase composition of the powder after homogenization and of the ceramics after annealing. Sodium pyrophosphate Na_(4)P_(2)O_(7)formed from sodium hydrogen phosphate Na_(2)HPO_(4)as a result of thermal conversion had a significant effect on sintering mechanism and the microstructure of the ceramics. A ceramics with a low sintering temperature based on β-calcium pyrophosphate β-Ca_(2)P_(2)O_(7)was obtained for the first time from a powder system, upon preparation of which under mechanical activation conditions homogenization of components and synthesis of the main crystal phase precursor were combined.