Titania slag as a ceramic pigment

The phase transformations and colouring mechanisms that occur during the ceramic processing of titania slag were investigated using XRF-EDS, XRD, DRS and laboratory-scale application in glazed and unglazed tiles. The slag transforms to pseudobrookite, undergoing a drastic colour change during firing as a consequence of thermal oxidation with Fe2+ to Fe3+ and Ti3+ to Ti4+ reactions. The intense brown colour imparted by titania slag is stable at both low (up to 1050 degrees C) and high (around 1200°C) temperatures and is suitable for porcelain stoneware tiles. In through-body application, titania slag enables 'spotting' effects to be achieved.