Mechanical Properties and Chemical Reactivity in Mullite—Glass Systems

Abstract

Mullite‐glass systems were studied by vacuum hot‐pressing sized mullite crystal particles with known glass compositions. During the hot‐pressing at relatively low temperatures, significant chemical reactivity was observed between mullite and a soda borosilicate glass. This reaction led to the precipitation of a silica‐rich crystalline phase in the glass matrix and to a change in the mullite structure as evidenced by the X‐ray diffraction pattern. Wetting studies at elevated temperatures indicated an interfacial chemical reaction. The modulus of rupture increased when the second crystalline phase was present. Increased volume fraction of the crystalline phase and development of a stronger interfacial bond between mullite and glass may be the primary factors responsible for the increase in mechanical strength.