TiO2 and ZrO2 Controlled Crystallization and Microstructure in SiO2-MgO-Al2O3-B2O3-K2O-F Glass

Description

Abstract: The crystallization concert and microstructural evolution of SiO₂MgO-Al₂O₃-K₂O-B₂O₃-F glasses with excess nucleating agent CeO₂, TiO₂ and ZrO₂ content (5 mol%) were studied. Opaque mica glass-ceramics were prepared from such glasses by controlled heat-treatment at 1050^oC; and the evolved phases are identified as fluorophlogopite mica, KMg₃(AlSi₃O₁₀)F₂ by XRD study. The flurophlogopite mica crystallization is improved in presence of TiO₂ and ZrO₂ nucleating agents. As observed from FESEM study, the glass-ceramic morphology with hexagonal card like mica-flake crystals restructured to be interlocked in presence of ZrO₂ content. Nanocrystalline microstructure is obtained in presence of CeO₂ content. As obtained from dilatometry, highest thermal expansion coefficient (greater than 12 x10^-6/K, at 50-800) is observed in ZrO₂ containing (5 mol%) glass-ceramic, and it is compatible with other SOFC components. So, ZrO₂ containing SiO₂-MgO-Al₂O₃-K₂O-B₂O₃-F glass can be useful for SOFC sealing application.

Author: Mrinmoy Garai

Keywords: Glass, Crystallization, Glass-Ceramics, Microstructure, Fluorophlogopite