Fabrication of new porcelain body using nonplastic raw materials by slip casting

New porcelain bodies using only nonplastic raw materials, such as volcanic glass, quartz, alumina and aluminous cement, were fabricated, and their properties were investigated. Green strength increased with increasing Al2O3 content at the constant amount of volcanic glass and aluminous cement, caused by the increase of green bulk density with small sized Al2O3 addition. The phases in the fired body were glass, alpha-quartz, cristobalite, anorthite and alpha-Al2O3. High flexural strength with 10 wt% Al2O3 addition was attributed to a strong residual stress induced by the large difference in the thermal expansion coefficient between the glass matrix and the quartz grains, and an additional prestress was induced by Al2O3 grains. Higher density and fewer fracture origin were also indicated as potential factors leading to the strengthening effect. (C) 2002 Kluwer Academic Publishers.