Abstract: MgO-Al2O3-SiO2 (MAS)-based glass ceramics were prepared by melting method with pure chemical reagents.The effects of CaO content on crystallization behavior、phase composition、microstructure、physical and chemical properties of glass ceramics were investigated by DSC,XRD,SEM,and performance testing methods.The results show that a certain content of CaO could reduce the activation energy of crystallization,which as a result can promote the glass crystallization;On the other hand,with the increase of CaO,the main crystal phase transfers from sapphirine to α-cordierite,crystal morphology from rod like crystal into dendrite,the grain size decreases at first and then increases;with the addition of 3wt; CaO,the thermal expansion coefficient and the relative dielectric (εr) of glass ceramics show the lowest value,are 3.89 × 10-6℃-1 and 10.09 (1 MHz),respectively;the Vickershardness of samples reach the maximum when no CaO is added,is 10.52 GPa.

Key words: MgO-Al2O3-SiO2 (MAS)-based glass ceramics were prepared by melting method with pure chemical reagents.The effects of CaO content on crystallization behavior、phase composition、microstructure、physical and chemical properties of glass ceramics were investigated by DSC,XRD,SEM,and performance testing methods.The results show that a certain content of CaO could reduce the activation energy of crystallization,which as a result can promote the glass crystallization;On the other hand,with the increase of CaO,the main crystal phase transfers from sapphirine to α-cordierite,crystal morphology from rod like crystal into dendrite,the grain size decreases at first and then increases;with the addition of 3wt; CaO,the thermal expansion coefficient and the relative dielectric (εr) of glass ceramics show the lowest value,are 3.89 × 10-6℃-1 and 10.09 (1 MHz),respectively;the Vickershardness of samples reach the maximum when no CaO is added,is 10.52 GPa.