Investigation of stain resistance of the porcelain tiles doped by spodumene

The polishing step which is the last porcelain tile production process allows obtaining a very smooth and glossy surface. While this process results in a material removal from tile surface it leads to emerge the superficial defects and closed pores. All of these defects lead to worsen the stain resistance of the porcelain tiles. A better understanding of the role of the surface microstructure on stain resistance is also fundamental in order to improve the tile performance. Aim of this study is to investigate the influence of the composition on stain resistance of the porcelain tiles. In accordance to this aim; firstly, spodumene (max 4 wt %) was used in stead of Na feldspar in a standard porcelain tile compositions. On the one hand, the difference between thermal expansion coefficients of quartz and the glassy matrix has a strong effect by subjecting the glassy matrix to microscopic residual compressive stress. Particle detachment and cracks around quartz particles also gives rise to become more sensitive bodies against to stain. Because of these effects, it was also prepared to porcelain tile compositions without quartz content to enhance stain resistance of the porcelain tiles. The results showed that spodumene addition provides to increase stain resistance by forming a low viscosity liquid phase during firing with a decrease of both closed porosity and average pore size, also with increasing bulk density. It was also observed that resistance to stain of the porcelain tiles was increased through removal quartz content. On the other hand, it was detected that lithium alumina silicate phases was formed as a result of reactions between spodumene-quartz and spodumene-clay. This new phase brings in a new aspect in terms of stain resistance of the porcelain tiles. It was determined that microcracks around the quartz particles which is one of the most important effect on stain resistance was filled by lithium alumina silicate phasesKeywords: Stain resistance, porcelain tile, spodumene, quartz content, microstructure,