Fabrication of magnetically controllable glass ceramics with completely dense microstructure by hot pressing

Completely dense magnetite-based aluminosilicate glass ceramics with adjustable magnetic properties were successfully synthesized by method of hot pressing. The influences of sintering conditions and magnetite contents on magnetic properties and microstructure of samples were analyzed. It was found that increases in sintering temperature and time could improve the densification degree of samples. However, precipitation of crystalline phases from glass would worsen the densification of samples. The optimum parameters of hot pressing were 950 degrees C for 1 h, under which condition, the glass ceramics containing 10-65 wt.% magnetite showed a fully dense microstructure. As the magnetite content increased from 10 to 65 wt.%, magnetization and area of hysteresis loops of glass ceramics increased, while coercivity showed an opposite trend. However, when the magnetite content increased to 70 wt.%, pores appeared and the degree of densification decreased.