Sintering and devitrification of glass-powder compacts in the akermanite–gehlenite system

The sintering and devitrification behavior of glass-powder compacts with four compositions, Ca2Mg0.5Al1.0Si1.5O7, Ca2Mg0.6Al0.8Si1.6O7, Ca2Mg0.7Al0.6Si1.7O7, and Ca2Mg0.8Al0.4Si1.8O7, corresponding to akermanite–gehlenite ratios (mol%) of 50/50, 60/40, 70/30, and 80/20 were investigated. Glass frits were prepared by the classical melt quenching technique in water. The structure of the glasses was investigated using FTIR and NMR, whereas the sintering behavior was studied by DTA and HSM. Sintering precedes crystallization only in Ca2Mg0.5Al1.0Si1.5O7 glass while in the remaining glass compositions maximum densification was achieved slight after the onset of crystallization. However, the ratios of final area/initial area (A/A 0) of the glass-powder compact ranging from 0.63 to 0.66 imply towards good densification levels (95–98 %) achieved in the investigated glasses. Qualitative and quantitative XRD analyzes were performed in glass-powder compacts heat treated at 900 and 1000 °C. Merwinite was found to crystallize first followed by decomposition at higher temperatures to form akermanite-like phase.