Production and Characterization of ZrO₂–Al₂O₃–K₂O Based Ceramic Whitening Agents

Zircon-containing whitening agents are indispensable components increasing the cost of ceramic tiles. In the ceramic industry, the developing of unique and low-cost whitening agents with comparable final product quality is an essential motivation. In this study, a unique ZrO₂–Al₂O₃–K₂O-based whitening agent was developed by mixing zircon silicate, Al₂O₃, K-feldspar, and marble with various weight concentrations to reduce costs and give a valid alternative to the commercially available R6-coded ZrO₂–Al₂O₃–Na₂O whitening agent. To test the innovative ZrO₂–Al₂O₃–K₂O-based whitening agent’s efficiency, a systematic characterization procedure was utilized to reveal factors affecting the tile opacity, including size, shape, and distribution of opacifier particles and the incident light wavelength. First, x-ray diffraction and x-ray fluorescence analyses examined the initial grain sizes and structural properties of the whitening agent constituents. Second, a wet milling process in industrial mills was utilized to produce a homogenized ZrO₂–Al₂O₃–K₂O-based composite whitening agent. Structural, mineralogical, and morphological properties of the final product were determined after the drying process. The efficiency of the wet milling process was proved according to scanning microscopy analysis revealing homogenous particle size distribution of constituents with mainly composed of ZrO₂, Al₂O₃, and SiO₂ phases. Energy dispersive x-ray analysis reveals that Si–Al–O–Zr and Ca were major elements whereas Na was obtained as minor element.