| 초록 |
Bioactive glasses of the system SiO2-Na2O-CaO-P2O5 have been prepared by melting and annealing technique. The nucleation and crystallization mechanisms of a 46Na2O-27CaO-25SiO2-2P2O5(mol%) glass was investigated by differential Thermal analysis (DTA) and X-ray diffraction analysis. The average activation energy for crystallization, E, was determined to be 143±10KJ/mol by the Kissinger method and 141±10KJ/mol by Augis-Bennett method. The Avrami constants were 1.02≤n≤1.2, and it appeared one direction growth. A nucleation-rate-type curve was determined by plotting either the reciprocal of the temperature corresponding to the crystallization peak maximum, 1/TP, or the height of the crystallization peak, (δT)p, as a function of nucleation temperature, Tn. The temperature where nucleation can occur for this glass ranges from 550 to 620℃ and the temperature of maximum nucleation rate is at 600±10℃. |
