Characteristics Of Initial Stages Of "Sitallization" Of Glasses Nucleated With Zirconium Dioxide

The effect of zirconium dioxide on the initial stages of sitallization (devitrification of glass into glass-ceramic materials) is studied and compared with the effect of titanium dioxide. 5wt% Zr02 was the minimum concentration inducing sitallization in the glasses studied, and 6wt% Zr02 was the maximum solubility. The precipitation of the tetragonal modification of Zr02 is characteristic for the initial stages of crystallizationof glasses nucleated with Zr02. Micro-inhomogeneities in crystalling zirconium glasses are larger and less frequent than in crystallizing titanium glasses. Among the properties of the two nucleating agents which are similar is their effect on the coefficient of thermal expansion.