Hierarchical structural silica-fiber-woven/mullite-whisker material prepared by surface etching and gas-phase reaction

Abstract

Hierarchical structural silica-fiber-woven/mullite-whisker material was prepared by surface etching and gas-phase reaction. In the material, the silica-fiber-woven served as the substrate, and a mass of mullite whiskers grew on the silica fibers by fluorine-catalyzed gas-phase reactions (mixed AlF₃–SiO₂ powders were used as the raw material). The silica-fiber-woven was first etched by fluorine-rich gas, which was produced in the gas-phase reaction. The etching pits on the silica fibers offered nucleate sites for the mullite whiskers' growth. The volume density, tensile strength and thermal conductivity of the hierarchical structural silica-fiber-woven/mullite-whisker material were 0.572 g cm⁻³, 0.441 MPa and 0.1233 W m⁻¹ K⁻¹, respectively, indicating the suitability of the material for use as a heat-sealing/insulation gasket at high temperatures.