Factors controlling crystallization of miserite glass-ceramic

Abstract

Objective: The purpose of this study was to investigate a range of variables affecting the synthesis of a miserite glass-ceramic (GC).

Methods: Miserite glass was synthesized by the melt quench technique. The crystallization kinetics of the glass were determined using Differential Thermal Analysis (DTA). The glasses were ground with dry ball-milling and then sieved to different particle sizes prior to sintering. These particle sizes were submitted to heat treatment regimes in a high temperature furnace to form the GC. The crystal phases of the GC were analyzed by X-ray diffraction (XRD). Scanning electron microscopy (SEM) was used to examine the microstructure of the cerammed glass.

Results: XRD analysis confirmed that the predominant crystalline phase of the GC was miserite along with a minor crystalline phase of cristobalite only when the particle size is <20 μm and the heat treatment at 1000°C was carried out for 4h and slowly cooled at the furnace rate. For larger particle sizes and faster cooling rates, a pseudowollastonite crystalline phase was produced. Short sintering times produced either a pseudowollastonite or xonotolite crystalline phase.

Significance: The current study has shown that particle size and heat treatment schedules are major factors in controlling the synthesis of miserite GC.

Keywords: Cooling rate; DTA; Heat treatment; Miserite glass-ceramic; Particle size; Pseudowollastonite; SEM; XRD; Xonotolite.