Processing of lightweight, high-strength porcelains using an alumina cement to replace feldspars and clays

New lightweight, high-strength porcelain bodies, using only nonplastic raw materials such as glass microspheres, quartz, and alumina cement, were fabr icated and the effect of quartz particle size was investigated. Decreases i n the green strength, relative to an increasing content of glass microspher es, were attributed to the decrease in the density and the relative decreas e in the volume of alumina cement. The phases in the fired body mere glass, alpha-quartz, cristobalite, anorthite, and a small amount of alpha-alumina . The large quartz particles (10-32 mu m in size) could not be densified to closed porosity, because of underfiring, whereas smaller quartz particles (4-10 mu m in size) permitted densification to closed porosity at 1300 degr ees C. The high flexural strength when using medium-sized quartz particles (6-20 mu m, content of 30 wt%) was attributed to a stronger prestress and h igher density that was due to better vitrification.