Accession Number : AD0617940

Title :   THE KINETICS OF THE TRANSFORMATION OF QUARTZ TO TRIDYMITE IN THE PRESENCE OF OTHER OXIDES.

Descriptive Note : Technical rept. (Doctoral thesis),

Corporate Author : MICHIGAN UNIV ANN ARBOR COLL OF ENGINEERING

Personal Author(s) : Madden,Gerald I.

Report Date : JUN 1965

Pagination or Media Count : 70

Abstract : The investigation is concerned with the kinetics of the transformation of quartz to tridymite, two of the polymorphs of silica (SiO2). The transformation was studied by heating quartz in the presence of other oxides in the temperature and composition range of tridymite stability. The systems studied were: Na2O-SiO2, PbO -SiO2, FeO -SiO2, and Cu2O-SiO2. The formation of cristobalite as an intermediate metastable phase in the tridymite stability range was reconfirmed. The reaction proceeds slowly at temperatures near the upper range of tridymite stability. As the firing temperature is decreased the rate is increased until a maximum is reached. Below this point the rate again decreases. A semilogarithmic plot of time versus temperature gives a C-curve. The rate of transformation was shown to be dependent on the amount of liquid present and the type of oxide added to the original quartz. As the amount of liquid is increased the rate of transformation is increased. The rate of transformation is affected by the type of liquid as follows: Na2O (fastest), PbO, FeO, Cu2O (slowest). An empirical relationship was developed to describe the kinetics of the transformation process.

Descriptors :   (*SILICON COMPOUNDS, DIOXIDES), (*QUARTZ, TRANSFORMATIONS), PHASE STUDIES, SODIUM COMPOUNDS, LEAD COMPOUNDS, IRON COMPOUNDS, COPPER COMPOUNDS, OXIDES, REACTION KINETICS, CRYSTAL GROWTH, GLASS, REFRACTORY MATERIALS

Distribution Statement : APPROVED FOR PUBLIC RELEASE