A new approach to anorthite porcelain bodies using nonplastic raw materials

New anorthite porcelain bodies using only nonplastic raw materials, such as feldspar, quartz, and aluminous cement, without using a binder were fabricated, and their properties were investigated. The green strength was relatively high due to hardening by the hydration reaction of the aluminous cement with the Feldspar in a moist atmosphere. The phases found in the green body were feldspar, CaAl2O4, CaAl4O7, alpha-quartz and a small amount of CaAl2Si2O8.4H(2)O. The phases in the fired body were alpha-quartz, anorthite, glass and a small amount of alpha-Al2O3; cristobalite formed only at a quartz content of 60 wt.%. Higher flexural strength at a composition containing 30 wt.% feldspar is attributed both to fewer crack origins as a result or appropriate vitrification and to greater residual stress caused by the larger difference in the thermal expansion coefficient between the glass matrix and the quartz and anorthite grains. (C) 2002 Elsevier Science Ltd. All rights reserved.