Effect of Added Alumina on the Feldspathic Porcelain Bodies

The effects of size (0.88-11μm) and shape of alumina particles on the densification, flexural strength and microstructure were investigated in the quartz-feldspar-kaolinite system. Relative density and flexural strength were demonstrated to have linear relationships and the slope of these lines (κ-value) was dependent upon the size and shape of alumina particles. The flexural strength reached its maximum value when particles of 2μm diameter were used. This phenomenon is explainable for coarse alumina due to the enlargement of the Griffith flaw for a small number of particles, but can not be explained in the case of fine alumina. The shape of alumina particles did not affect the flexural strength or the fracture toughness in any of our experiments.