Nucleation and crystallization of cordierite glass

This paper presents the experimental results of a DTA investigation of the nucleation and crystallization in cordierite glass containing 7.9 mol% TiO2. The temperature of the maximum nucleation rate of mu-cordierite was determined to be T-n = 730 +/- 5 degrees C. The temperature T-n is lower than the transformation temperature T-g which indicates that homogeneous nucleation of mu-cordierite does not occur in this glass. The methods of DTA and optical microscopy agree in terms of determining T-n. The curve of the nucleation rate determined by DTA does not correspond to the curve determined by optical microscopy. The energy of activation for the crystallization of mu-cordierite was determined to be E-a = 497 +/- 50 kJ/mol. The nucleation of alpha-cordierite in this glass could not be investigated by DTA. In all the performed experiments, the glass crystallised into mu-cordierite which was then structurally transformed at higher temperatures to the phases: alpha-cordierite and rutile.