Study on self-glazed ceramic tiles based on geopolymer gel casting

Abstract

The preparation of ceramic materials from alkali-activated geopolymers has formed a new research direction. This study focuses on the preparation of ceramic tiles based on geopolymer alkali activation and by gel casting to investigate the mechanism of natural glaze formation and its microstructure evolution. For this reason, different Si/Al ratios (3.0–4.5) with different sintering temperatures (1080–1170 ℃) were chosen for the experiments to be discussed. The results showed that gel casting is conducive to the natural formation of the glaze and the close combination with the body. The amount and viscosity of the liquid phase on the surface of the sample at high temperatures will affect the forming effect of the glaze. Therefore, higher Si/Al ratio and sintering temperature are more conducive to the development and formation of the glass glaze. The optimum sintering temperature of the sample was 1110 ℃, the Si/Al ratio was 3.5, and the holding time was 2 h. Under these preparation conditions, the linear shrinkage was 18%, the rupture modulus was 48.08 MPa, the water absorption was 0.02%, the bulk density was 2.42 g∙cm−3, and the thickness of the glaze layer was about 190 µm.