Electrospun barium hexaaluminate fibrous membranes for high‐temperature thermal insulation

Barium hexaaluminate (BaAl 12 O 19 , BAO) presents as a highly promising fibrous material for high‐temperature insulation due to its high melting point, low thermal conductivity, and exceptional chemical and phase stability. The magnetoplumbite crystal structure, characterized by alternating stacks of spinel and mirror phases, may serve as a powerful strategy to overcome the high‐temperature brittleness and structural failure of conventional oxide fibers by effectively suppressing grain coarsening. Using electrospinning combined with high‐temperature thermal treatment, BAO fibrous membranes were successfully prepared in the present work. The pyrolysis process, phase composition evolution, microstructure, and grain size changes of the BAO precursor fibrous membranes were systematically characterized. Additionally, thermal conductivity, high‐temperature stability, thermal insulation performance, and fire retardancy of BAO fibrous membranes were also tested. The results indicated that the BAO fibrous membranes possessed room temperature thermal conductivity as low as 32.1 mW·m −1 ·K −1 , small average linear shrinkage of 2.76% at 1300°C, and good structural integrity even at 1430°C. The excellent high‐temperature stability and thermal insulation performance of the BAO fibrous membranes make them promising for applications in extreme environments such as aerospace thermal protection and industrial high‐temperature gas filtration.