Heat Insulating Properties of Mullite Hollow Fibers Prepared by Using the Template of Reed Fibers

Mullite fibers have a wide range of applications in thermal insulation. Currently, most mullite fibers produced have solid structures, limiting their heat-insulating properties. In this study, we present a method for producing mullite fibers with hollow structures using reed fibers as templates. The reed fibers were immersed in a solution containing aluminum nitrate and ethyl orthosilicate, followed by high-temperature sintering to obtain mullite hollow fibers with excellent heat-insulating properties. The microstructures, phases, pore size distributions, and thermal conductivities of the resulting fibers were analyzed. The results demonstrated that mullite hollow fibers exhibited lower thermal conductivities compared to solid mullite fibers, mainly due to the more effective prevention of air convection facilitated by the hollow structures. The introduction of hollow structures into mullite fibers using reed fibers as templates offers a promising approach for improving thermal insulation performance. This finding highlights the enhanced heat-insulating capabilities of mullite hollow fibers.