Methods: Six sets of K2O-MgO-SiO2-F- glasses were prepared by using B2O3 and P2O5as sintering aid, respectively. Green bodies of the glass powder were formed by gelcasting and sintered at 800,850,900,950,1000°C for 6h,resectively. The sintering and crystallization behavior were studied by thermal shrinkage , X-ray diffraction and SEM.
Results:The shrinkage rate of the glass with 2wt% B2O3 and P2O5 was highest ,while the rate of the glass with 5wt% P2O5 was lowest. Compared with the glass ceramics made by the common procedure, i.e., direct crystallization of glass melts, an additional crystal other than fluorosilicic mica was precipitated in the glass ceramics generated by sintering of glass powder.
Conclusion:The density and shrinkage measurements of the sintered bodies showed that the glass powder of pure K2O-MgO-SiO2-F- system had poor sinterability, while glass powder with minor addition of P2O5 and/or B2O3 showed good sinterability. This result was also verified by SEM.