LAUSR

Abstract The influences of different alkali metal oxides, sintering methods, process conditions on the crystallization behavior and densification of CaO-Al2O3-SiO2-Fe3O4-R2O (R=Na, K) glass ceramics were investigated. It can be concluded that the initial crystallization temperature and crystallization peak temperature of glass containing K2O were higher than those of glass containing Na2O, respectively. The increase of sintering temperature promoted the precipitation of crystalline phase in glass ceramics, meanwhile, the crystalline phases transformed from single magnetite to magnetite and CaFeSi2O6. The glass ceramics obtained by powder-sintering showed a low degree of densification. The fully dense glass ceramics containing Na2O can be obtained by hot pressing sintering above 680 °C for 2 h. However, due to the high viscosity of the glass containing K2O, the degree of densification of K2O containing glass ceramics was relatively low even after the hot pressing sintering. Magnetite based glass ceramics can be used as candidates for magnetic materials.