Microchemistry and Microstructure of Some Opaque Glaze/Tile Interfaces in Relation to their Physical Properties

摘要

Physical properties of some double- and once-fired glazed tiles were assessed in the light of the microchemistry and microstructure of their interfaces as investigated using a computer-controlled electron-probe microanalyzer. The properties investigated are melting temperatures and thermal expansion of glazes, as well as crazing resistance and gloss of glaze surfaces. The double- and once-fired glaze layers are strongly bound to their ceramic tiles, as indicated by high resistance to crazing. The application of zircon-ZnO opacifying mixtures in the presence of 5.0-8.0 wt% B_2O_3 leads to maximizing the gloss of glaze surfaces. Increasing B_2O_3 content enhances bubble formation whereas a mat layer results at the surface of once-fired glazes containing higher zircon and ZnO contents at the expense of B_2O_3. The recrystallization of silicate phases, especially in double-fired glazes, is hindered by minimizing the lime and alkali oxides content in the presence of up to 10wt% ZnO.