Author(s): Jo S, Kang S
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Abstract The effect of TiO2 on the degree of crystallization, thermal properties and microstructure for MgO-Al2O3-SiO2 glass-ceramics system containing 0-13 wt\% TiO2 and 0-1.5 wt\% B2O3 in which the cordierite is the main phase was studied. Using Kissinger and Augis-Bennett equations, the activation energy, 510 kJ/mol and Avrami constant, 1.8 were calculated showing the surface-oriented crystallization would be preferred. The alpha-cordierite phase was generated in the glass-ceramics of containing TiO2 of 0-5.6 wt\%. However, for the glass-ceramics of TiO2 content above 7 wt\%, an alpha-cordierite disappeared and micro-cordierite phase was formed. The glass-ceramics of no TiO2 added had spherical crystals of few tens nanometer size spread in the matrix. As TiO2 content increased up to 5.6 wt\%, a lump of dendrite was formed. In the glass-ceramics containing TiO2 7-13 wt\%, in which the main phase is micro-cordierite, the dendrite crystal disappeared and a few hundred nanometer sized crystal particles hold tightly each other were generated. The thermal conductivity of glass-ceramics of both a-cordierite and micro-cordierite base decreased with TiO2 contend added. The thermal conductivity of glass-ceramics of 1.5 wt\% TiO2 added was 3.4 W/mK which is 36\% higher than that of glass-ceramics of no TiO2 added. The sintering temperature for 1.5 wt\% TiO2 glass-ceramics was 965 degrees C which could be concluded as to apply to LTCC process for LED packaging.
This article was published in J Nanosci Nanotechnol
and referenced in Journal of Fundamentals of Renewable Energy and Applications