A new porcelainised stoneware material based on anorthite

Abstract

The aim of the present study is to design and develop an alternative composition for making porcelainised stoneware, which has better properties than the conventional porcelainised stonewares. Contrary to the conventional porcelainised stonewares, this new body is designed to develop basically anorthite (CaO(.)Al(2)O(3)(.)2SiO(2)) crystals in the microstructure and to have a high crystalline to glassy phase ratio, after processing at 1200-1225 degreesC temperature ranges. To obtain the anorthite crystals, wollastonite, calcined alumina, quartz, Ukranian Ball Clay and some magnesia were used as raw materials. Technological properties, such as density, water absorption, firing shrinkage, flexural strength, thermal expansion behaviour and aesthetical properties were measured. X-ray diffraction (XRD) and scanning electron microscopy (SEM) studies were also carried out to analyse the microstructure. It was found that anorthite based material enables all the porcelainised stoneware requirements to be met and the material contains approximately 70% crystalline and 30% glassy phases. The flexural strength, 110 MPa, was two times higher than that of the conventional materials. (C) 2004 Elsevier Ltd. All rights reserved.