WANG Chao ^{1, 2}, ZHANG Li ¹

(1. Wuxi Institute of Arts and Technology, Yixing 214206, Jiangsu, China; 2. Research and Development Center of Ceramic Material and Process Engineering in Jiangsu Province, Yixing 214206, Jiangsu, China)

Abstract: Fancy glaze composed of R₂O-RO-SiO₂-B₂O₃-Al₂O₃ multi-component system and low-priced iron oxide colouring agent was successfully prepared by adjusting the formula composition. The effects of iron oxide content and chemical composition on glaze surface color were discussed. The microstructure of glaze layer was studied by scanning electron microscopy (SEM). The results showed that iron oxide could easily render varied colors to the R₂O-RO-SiO₂-B₂O₃-Al₂O₃ glaze such as yellow, green and blue, mainly caused by crystallization and phase-separation. Cellular split phase structure prompted the diversity of glaze color and texture. But the glaze was easily crystallized with excessive iron oxide, which inhibited the growth of cellular split phase structure and made the glaze color saturated. The chemical composition of B₂O₃ and alkalis significantly affected the effect of phase-separation. Glaze phase splitting effect was significantly reduced when the n(B₂O₃)/n(Al₂O₃) was from 2.01 to 1.19, and n(R₂O)/n(RO) from 0.28 to 0.40.

Key words: glaze material; phase-separation; crystallization; iron oxide