Microstructure, mechanical and thermal properties of boron oxide added steatite ceramics

Abstract

Steatite ceramics have been fabricated using coarse starting materials such as talc, clay and barium carbonate with addition of boron oxide (B₂O₃). Microstructure, mechanical and thermal properties of the steatite ceramics as a function of B₂O₃ addition have been investigated. B₂O₃ has been found to be a useful flux to densify MgO–Al₂O₃–SiO₂–BaO (MASB) steatite powders. Highly dense and crystalline ceramics, predominantly composed of protoenstatite and clioenstatite together with small amounts of residual glassy phase, were obtained after sintering at a low temperature such as 1200°C. Scanning electron microscopy (SEM) analysis indicated that large pores were seen in B₂O₃ free samples, while pore elimination and enhancement of densification for B₂O₃ added compacts were promoted by the viscous flow of B₂O₃. Bending strength of the steatite ceramics increased with B₂O₃ content. The thermal expansion and average linear thermal expansion coefficient of B₂O₃ free samples were higher than those of B₂O₃ added compositions.

Keywords:

• STEATITE
• BORON OXIDE
• DENSIFICATION
• BENDING STRENGTH
• THERMAL EXPANSION