Cristobalite Phase Formation in Glass/Ceramic Composites

The effect of several different aluminum‐containing ceramic additions to borosilicate glass on suppressing cris‐tobalite precipitation has been examined. The results showed that mullite or aluminum nitride suppresses cristo‐balite formation more effectively than alumina or spinel. Although both follow a simple rule of mixtures, glass/mullite composites can be fabricated with lower dielectric constants than glass/alumina composites, while maintaining a thermal expansion coefficient close to Si. Electron micro‐analysis using X‐ray energy dispersive spectroscope showed that the measured interdiffusion coefficient between alumina and glass is in good agreement with the data which have already been published.