Effects of Alumina and White Fused Alumina Addition on Transparent Wall and Floor Tile Glazes

In tile manufacturing, α-Al₂O₃ is the main type of alumina used in ceramic body and glaze formulations. This raw material acts as an opacifier in porcelain tile bodies and as a matting agent in glazes. White fused alumina (WFA) is produced by fusing calcined alumina in an electric arc furnace under carefully controlled conditions. It is usually employed in floor tile glazes in order to increase their abrasion resistance. The aim of this study was to establish a better understanding of how alumina and white fused alumina addition affects the thermal behavior and aesthetic properties of wall and floor tile transparent glazes. It was shown that both alumina and fused alumina increased the softening temperatures of the standard glaze composition. Corund was the main detected phase in tile glazes incorporated with fused alumina. This result suggested that white fused alumina did not react with glassy phase to form any other crystalline phases. This result can be attributed to higher refractoriness of white fused alumina. Presence of anorthite and gahnite phases was, on the other hand, observed in the glazes with alumina addition. It was further shown that alumina was more effective in increasing opacity and reducing glossiness compared to white fused alumina.