ORIGIN OF CRISTOBALITE FORMATION DURING SINTERING OF A BINARY MIXTUREOF BOROSILICATE GLASS AND HIGH-SILICA GLASS

It was shown previously1 that cristobalite precipitates out of a mixtu re of borosilicate glass (BSG) and high silica glass (HSG) when sinter ed at temperatures ranging from 800 to 1200-degrees-C. In this paper, both direct and indirect evidences are presented to conclude that the formation of cristobalite originates in HSG. It is proposed that the c ristobalite is formed as a result of dissolution of HSG in BSG and pre cipitation at heterogeneously nucleated sites. The process of dissolut ion and precipitation continues until the whole HSG particle is consum ed.