Processing of ultra white porcelainized stoneware based on anorthite

Abstract

In this study, to increase the whiteness of the porcelainized stoneware new body formulation containing wollastonite, calcined alumina, quartz and Ukranian ball clay has been adopted. This formulation was designed to develop basically anorthite (CaO.Al2O3.2SiO(2)) crystals in the microstructure and fabricated by powder pressing and sintering. The densification behaviour, flexural strength and aesthetical (colour parameter analysis) properties of this body were investigated by measuring the bulk density, flexural strength and the colour descriptors. It was found that it is possible to sinter the anorthite-based body formulation to a high-density in the 1200-1225degreesC sintering temperature range which produced samples with the flexural strength value around 110 MPa. The resultant porcelainized stoneware has a high degree of whiteness, which is comparable to the whiteness of bone china. Typical L*, a* and b* values obtained from sintered samples were 91, -0.3, 6.0 respectively.