CRYSTAL-GROWTH INHIBITOR IN BINARY BOROSILICATE GLASS COMPOSITE GALLIUM OXIDE

The effect of gallium oxide on cristobalite formation in binary borosi licate glass composite, containing a low-softening borosilicate glass (BSG) and a high-softening high-silica glass (HSG), has been studied. X-ray diffraction results show that with a small amount of gallium oxi de, 2.5-10 vol%, the precipitation of cristobalite at elevated tempera tures is prevented. This result is further evidenced by linear thermal expansion measurement, in which, in contrast to the gallium oxide-fre e sample, the thermal expansion coefficients (TCE) of the composite wi th gallium oxide remain unchanged with sintering time at temperatures investigated and, moreover, are very close to the theoretically calcul ated values.