Composition effects on the whiteness and physical-mechanical properties of traditional sanitary-ware glaze

Whiteness and physical-mechanical characteristics of sanitary glazes are usually controlled and improved by changing chemical composition of the raw materials. In this study, ten glazes of industrial interest, with different composition, were prepared by spraying, using the traditional ceramic substrate, and then thermally treated in industrial tunnel kiln at temperature of 1250 °C. The obtained glazes were characterized by X-ray diffraction in order to reveal their mineralogical composition, also confirmed by FTIR spectra, and were observed by backscattered electron images to study their microstructure and to derive the thermal expansion coefficients. Whiteness characteristics were obtained by a Micro color colorimeter data station. The results showed a difference of 10% between calculated and experimentally derived thermal expansion coefficients and the improvement of whiteness (up to 85.7%) and flexural strength (47.61 MPa) at a maximal content of zircon (14.5 wt%) and a low content of ZnO (2.5 wt%).