Effect of alumina addition on properties of glass/ceramic composite

A series of glass/ceramic composites were prepared from pyrex borosilicate glass with silica. The effects of 15 vol.-% alumina addition on cristobalite formation in this system have been studied. Cristobolite formation in the composites has been found to decrease with addition of alumina, which may be attributed to a strong coupling reaction between Al3+ from alumina and K+ from pyrex borosilicate glass. The resulting glass/ceramic composites containing alumina have low thermal expansion coefficient owing to the presence of a lower amount of cristobalite in the glass matrix. The formation of cristobalite limits the efficiency of the ceramic substrate when used in circuit boards.