Investigation of the factors affecting the foam ability of SiO2-Al2O3-MgO-CaO glass

In the present work, Foaming and crystallisation behaviors of compacted glass powders based on a diopside glass-ceramic composition were investigated through the sintering route. The foaming agent was 2wt.%SiC particles.The results indicated that the lack of foaming of the base glass was due to high softening point and crystallization tendency . Therefore the effect of PbO and B2O3 on the foaming ability of glasses was investigated. According to our finding, addition of PbO improved foaming ability ,via improving wettability of glass - SiC particles,increasing of optical basicity and widening the temperature interval between dilatometric softening point and the onset of crystallization temperature. The glass- SiC wetting angle was decreased from 85° for the lead-free glass to 55° for the glass that contains 15 wt.% PbO. While with addition of B2O3, foaming ability of base glass in spite of widened the temperature interval between the dilatometric softening point and the onset of crystallisation wasn’t improved.