Thermal insulating properties of hollow mullite fibers prepared on a ceiba bio-template

Abstract Ceiba fibers have excellent thermal insulating properties because of their hollow structures. Mullite fibers are widely used in heat-insulating refractory materials because of their low thermal conductivity and excellent thermal shock stability. However, unlike ceiba fibers, conventional mullite fibers have solid structures, which limits further development of the thermal insulating properties of mullite fibers. Inspired by their hollow structure, we used ceiba fibers as a template for preparing hollow mullite fibers. We immersed ceiba fibers in a precursor solution of Al(NO3)3 and ethyl orthosilicate (TEOS). The impregnated ceiba fibers were then dried and sintered at a high temperature to obtain hollow mullite fibers. The synthesis process, microstructures, phases, pore size distributions, and thermal conductivities of the resulting fibers were analyzed. The results showed that mullite fibers inherited the hollow structure of the ceiba fibers, and the resulting thermal conductivity was markedly reduced compared to solid mullite fibers.