Crystallization kinetics of tape cast bioactive glass 45S5

The crystallization kinetics of tape cast bioactive glass 45S5 was studied using non-isothermal methods. XRD confirmed that Na2Ca2Si3O9 was formed during heating up to 1000degreesC. The modified Kissinger equation was used to determine that the activation energy for crystallization was 350 kJ/mol. The Avrami exponent, n, was determined to be 0.96 (Ozawa method) and 0.94 (Augis-Bennett method). Such results indicated that the particulate jet milled bioactive glass 45S5 (3 mum average particle size) undergoes surface crystallization during heat treatment. Previous results showed that the porosity of tape cast sintered bioactive glass 45S5 strongly influenced the in vitro bioactivity. Ease of crystallization of tape cast bioactive glass 45S5 suggested that it is fully crystalline prior to undergoing significant densification above 800degreesC. (C) 2003 Elsevier Science B.V. All rights reserved.