Effects of Dispersed Medium and Mineralizer CaF_2 on the Synthesis of α-Tricalcium Phosphate

The starting powders selected for solid-state reaction to synthesize alpha-tricalcium phosphate (α-TCP) were CaHP04·2H2O and CaCO3. The effects of dispersed medium and min-eralizer CaF2 on the synthesis of α-TCP and phase transformation were investigated. The results show that a metastable high temperature phase (α-TCP) prepared by calcining the nonstoichiomet-ric hydroxyapatite powder with poor crystallization obtained by grinding the mixture in distilled water is more stable than those prepared by grinding the mixture in an ethanol system. A new and easy route, based on the solid-state reaction and the addition of CaF2, was developed to synthesize alpha-calcium phosphate (α-TCP). For samples containing 1.0wt% and 1.5 wt% CaF2, calcined in the range of 1350℃ to 1450℃ and 1350℃ to 1480℃, respectively, a pure phase α-TCP was obtained. The transition energy of β-TCP to α-TCP during cooling process is decreased by adding some mineralizer CaF2. It will be helpful to keep the metastable high temperature phase (α-TCP) at room temperature. The stability of α-TCP in the course of furnace cooling is also related to the content of CaF2.