Crystallization Process of Glass-Ceramic for Substrate of Hard Disks

The crystallization process of MgO-Al2O3-SiO2 glass containing TiO2 and ZrO2 was studied by means of DTA, thermal expansion curve and XRD. Magnesium aluminium titanate appearing at 780℃ promotes the crystallization of Mgpetalite at 800℃, and then those crystal phases transform to sapphirine, rutile and Zr/Ti solid solution at 930℃. β-quartz solid solution appears at 1030℃ and transforms at temperature higher than 1125℃ to α-cordierite, cristobalite and enstatite, while rutile and Zr/Ti solid solution transform to zircon and magnesium titanate. According to the crystallization process, a glass-ceramic with sapphirine as the main phase can be prepared at the temperature between 930℃ and 1050℃. The glass-ceramic with a fine-grained structure has large elastic modulus (120GPa) and good surface properties, and is an excellent material for substrate of hard disks.