Development of low-firing B-fluxed stoneware tiles

In a global period of economic recession, innovation is a key requisite to get over this critical phase and prompt an upturn in the economy. Even the market of traditional ceramics is in a stalemate and producers desperately seek for new ideas which may supersede the long-used stoneware tiles. This paper presents the full characterization of a new potential class of ceramics named low-temperature stoneware tiles, highlighting their advantages and disadvantages. The body formulation and the firing process are both covered by an Italian Patent. This innovative product exhibits technological and esthetical features analogous to those of the traditional stoneware tile bodies but is fired at a maximum temperature of 950°C, about 250°C lower than the firing temperature of stoneware tiles. This is possible thanks to the addition of a B-rich frit to the mixture composed of quartz, feldspars, and clays. The frit acts as a low-temperature flux and promotes the melting of the feldspars. Within the fired body, the residual phases are quartz and feldspars. The newly formed phases can be β-spodumene if Li is present in the frit or spinel if Mg is present in the natural materials. The best body formulations have been characterized with mineralogical, microscopic, and technological methods. The major weakness of these ceramic bodies is their unresistance to acids. The chemical nature of the sintered matrix, with a high content of alkalies and B, triggers off the tendency of the ceramic body to react in contact with acidic solutions. Another penalty factor is the cost of the B-rich frit used in the formulation of the ceramic mixture which increases the overall cost of the ceramic body. © 2009 The American Ceramic Society.