Preparation and heat-insulating properties of Al 2 O 3 -ZrO 2 (Y 2 O 3 ) hollow fibers derived from cogon using an orthogonal experimental design.

Bionic design is efficient to develop high-performance lightweight refractories with sophisticated structures such as hollow ceramic fibers. Here, we report a four-stage procedure for the preparation of Al 2 O 3 -ZrO 2 (Y 2 O 3 ) hollow fibers using the template of cogon-a natural grass. Subsequently, to optimize the thermal performance of the fibers, four sets of preparation parameters, namely, x (Al 2 O 3 ), solute mass ratio of the mixture, dry temperature, and sintering temperature were investigated. Through an orthogonal design, the optimal condition of each parameter was obtained as follows: x (Al 2 O 3 ) was 0.70, solute mass ratio of the mixture was 15 wt%, dry temperature was 80 °C, and sintering temperature was 1100 °C. Overall, Al 2 O 3 -ZrO 2 (Y 2 O 3 ) hollow fibers show relatively low thermal conductivity (0.1038 W m -1 K -1 at 1000 °C), high porosity (95.0%), and low density (0.05-0.10 g cm -3 ). The multiphase compositions and morphology of Al 2 O 3 -ZrO 2 (Y 2 O 3 ) hollow fibers, which may contribute to their thermal properties, were also discussed.