Crystallization Kinetics, Properties of α-cordierite Based Glass-ceramics Prepared by Glass Powder Sintering

The resulting glass-ceramics were prepared by glass powder sintering using stoichiometric and non-stoichiometric cordierite components with addition of B2O3. Properties of the glass-ceramics, including the non-isothermal crystallization kinetics, thermal, mechanical and dielectric properties were investigated. The a-cordierite based glass-ceramics can be easily prepared by using non-stoichiometric cordierite components, and B2O3 addition can promote the precipitation of a-cordierite and improve the crystallization ability of the MgO-Al2O3-SiO2 glass. Moreover, rich MgO and SiO2 in the glass composition did not affect the crystallization ability of the glass, but affect the type of precipitated crystal phase. The increase of B2O3 addition can prepare alpha-cordierite based glass-ceramics with a low coefficient of thermal expansion (CTE), but it also lower its softening point. In addition, the increase of B2O3 addition can also improve the compactness and mechanical strength of the glass-ceramics. The maximum flexural strength, elastic moduli, fracture toughness and bulk density of alpha-cordierite based glass-ceramics are (42.4 +/- 3.0) MPa, (34.0 +/- 2.9) GPa, (0.7 +/- 0.15) MPa.m(1/2), and 1.53 g/cm(3), respectively. And the as-prepared alpha-cordierite based glass-ceramics show good dielectric properties (epsilon as low as 3.5) with a low CTE of 4.22 x 10(-6) K-1.