CHARACTERIZATION AND HYDRATION REACTIVITY OF α–TRICAICIUM PHOSPHATE PREPARED BY HEATING WITH GYPSUM

Beta tricalcium phosphate (β-Ca3(PO4)2, β-TCP) mixed with gypsum (CaSO4・2H2O) was heated at 1300°C and 1400°C. The resulting products were characterized by DTA, XRD, FTIR, EDX and hydration reactivity. An inhibition effect on the transition of the low temperature form β to high temperature form α was observed with increasing the amount of gypsum. The substitution of SO4 for PO4 was suggested from increases of the β→α transition temperature and hydration reactivity. However both the substitution and the presence of S were not recognized by XRD, EDX and FTIR. Increasing the amount of gypsum resulted in the formation of hydroxyapatite (Ca5(OH)(PO4)3) at 1300°C and tetracalcium phosphate (Ca4(PO4)2O) at 1400°C. The hydration reactivity was in the order, pure α-TCP << α-TCP heated with gypsum. (Received Oct. 6, 2011; Accepted March 17, 2012)