Characterization of ceramic tiles prepared from two clays from Sergipe — Brazil

We report an investigation of stain formation after use of clay–ceramic floor tiles produced by an industry from Sergipe, Brazil. Two types of raw materials have been used (C1 and C2) and test specimens were prepared at firing temperatures of 1000, 1120 and 1140 °C, being afterwards immersed in muriatic acid, evidencing stain formation for C1 tiles. After ICP chemical analysis, the original clays and tiles were characterized by powder X-ray diffraction (XRD) and TGA measurements, evidencing that C1 contained a higher carbonate percent than C2. Tile specimens were evaluated by X-ray diffraction (XRD), scanning electron microscopy (SEM), flexural strength, apparent density, linear shrinkage, and water absorption. In contrast to tiles prepared from C2, those prepared from C1 presented higher interparticle porosity and both linear shrinkages and water absorption variations with temperature were very incipient, suggesting that the high porosity and the low sintering caused the low staining resistance.