Glass sintering process has more advantages when compared to casting process in glass-ceramic fabrication. However, there is a disadvantage in the process-one must complete the glass sintering before crystallization starts to reduce the porosity of glass-ceramic. The crystallization of glass occurs through either internal or surface crystallization mechanisms, depending on the glass composition and other factors which are not easily controlled artificially. In either case, nucleation and crystal gr owth are involved during the glass sintering with internal factors (composition, nucleating agents, glass powder (size, surface)) an d external factors (temperature, time, atmosphere, heating source, etc.), which affect the crystallization process. This paper answers, "How do the factors affect glass sintering in silicate glass systems?" in order to control microstructures in glass- ceramics. Following a review of earlier work, as a case study, glass powder sintering was discussed on a heating sources, microwave heating in sinter glass-ceramics.

Keywords: Crystallization, Glass-ceramic, Nucleation, Crystal growth