Effect of leucite crystals on the strength of glassy porcelain

Porcelains with leucite crystals dispersed into various glass matrices were prepared for investigating the effects of the leucite crystals on the mechanical strength of glassy porcelain. The strength of glassy porcelains containing leucite crystals was affected by the differences of thermal expansion coefficients, compositions and deformation temperatures of the glass matrices. In the case of a large mismatch of thermal expansion between the leucite crystals and boro-silicate glass, the strength decreased with increasing amount of leucite. In leucite porcelains using a feldspar glass matrix, there was little or no effect of leucite on the strength. However, the strength of porcelains consisting of leucite crystals and a soda-lime glass matrix was enhanced with increasing leucite content, compared with that of the glassy matrix alone. Such an increase in strength is considered to be because the interface between the glassy matrix and leucite particles occurred in continuous phases, with an effect due to fusion occurring during the transition from leucite particles to the glass phase.