Fabrication of mullite micro/nano fiber-based porous ceramic with excellent mechanical and thermal insulation properties

Mullite fiber-based porous ceramics is one of the most commonly used high-temperature insulation materials. However, how to further reduce the thermal conductivity and improve the strength of such materials has been a challenge in the field of high-temperature insulation. In this paper, mullite micro/nano fiber-based porous ceramic was prepared by introducing mullite nanofibers into mullite microfiber-based porous ceramics and the effect of microfiber/nanofiber weight ratio on the samples properties were characterized and analyzed. Results showed that the compressive strength and high-temperature thermal insulation properties of the porous ceramics increased significantly with an increase in the nanofiber content. For the porous ceramics with similar density (about 0.50 g/cm3), the compressive strength of the sample with a microfibers/nanofibers weight ratio of 1:2 was 1.43 MPa, which was much higher than that of the porous ceramics prepared with only microfibers (0.26 MPa). Meanwhile, the backside thermal equilibrium temperature of the sample with a microfiber/nanofiber weight ratio of 1:2 at 900 degrees C environment was 355.8 degrees C, which was much lower than that of the porous ceramic prepared with only microfibers (476.5 degrees C). In addition, in order to investigate the temperature resistance of mullite micro/nano fiber-based porous ceramics, the sintering temperatures was increased from 1400 degrees C to 1500 degrees C. Results shows that the high-temperature thermal insulation performance of mullite micro/nano fiber-based porous ceramics with high mullite nanofiber content decays more seriously. The back-temperature test showed that the thermal equilibrium temperature of the samples with a mullite micron/nanofiber weight ratio of 1:1 in 900 degrees C environment increased rapidly from 386.3 degrees C to 454.2 degrees C when the sintering temperature was increased from 1400 degrees C to 1500 degrees C. The preparation of mullite micro/nanofiber-based porous ceramics provides a new strategy to improve the performance of fiber-based porous ceramics.