Development of Zr‐free augite glass‐ceramic glaze with high opacity for ceramic tiles

Abstract The development of cost‐effective, nonradioactive zirconium (Zr)‐free opaque glazes represents a critical objective for sustainable ceramic manufacturing. This study successfully prepared an augite‐based glass‐ceramic glaze within the CaO–MgO–Al ₂ O ₃ –SiO ₂ system using economical industrial raw materials. The glaze was prepared via a frit route, involving melting the raw materials, quenching the melt to obtain a frit, ball‐milling the frit into a slurry, and finally dip‐coating and firing. Systematic investigation revealed that firing at 1150°C produced an optimal microstructure dominated by augite (24.9 wt.%) and cristobalite (20.4 wt.%) crystals, with a refined grain size of ∼1.4 µm. The resulting glaze exhibited properties comparable to conventional ZrSiO ₄ ‐based systems, achieving a superior L ^* value of 89.21 (+77.6% vs. ceramic body), whiteness of 76.1% (+561.7% vs. ceramic body), and Vickers hardness of 7.10 GPa. These findings confirm that augite‐based opaque glazes are a technically viable and more sustainable alternative, offering valuable insights for the development of low‐temperature‐fired, Zr‐free ceramic glazes.