Low-cost and temperature-resistant mullite fiber sponges with superior thermal insulation and high-temperature PM filtration

Fibrous ceramic sponge materials which have compressibility and temperature resistance are pressingly desired in high temperature environment as thermal insulator, energy absorber and high temperature air filter. However, due to the complex preparation process, poor flexibility and mechanical strength, the application of ceramic sponge materials faces many obstacles. Here, elastic layered mullite fiber sponge with high compressibility and temperature-resistance ranging from liquid nitrogen to 1300℃ obtained by solution blow spinning method is reported. It has admirable thermal insulation performance with the thermal conductivity only of 0.0265 W m−1K−1, and has good air filtration performance for inhalable particulate matter (PM) at high temperature. Under 800 ℃, the average filtration efficiency of sponge with basis weight of 36 mg cm−2 for PM0.3-2.5 and PM2.5-10 produced by burning incense are 99.23 % and 99.78 %, and the pressure drop is 49 Pa under the airflow velocity of 4 cm s−1. In the actual filtration test for automotive exhaust gas of mullite fiber filter, the filtration efficiencies of particles with sizes ranging from 0.3 to 10 μm are all higher than 98 %. The mullite fiber sponge emerges as a prospective substitute of extant thermal insulation and high temperature air filter.