Abstract: The thermal insulation nanomaterial is a new thermal protection material with excellent thermal insulation performance for aerospace craft. Using the self-developed transient heating simulation system designed for high-speed aircraft, the high-temperature insulation performance of the Al₂O₃ nanomaterial is investigated with the experimental method and numerical simulation to provide important references for the thermal protection design of aerospace craft. The results show that for the Al₂O₃ nanomaterial plate with thickness of only 10 mm, when the front surface temperature was 1 200 ℃ (1 800 s), the temperature difference between the front and back surfaces was 880.9 ℃, the back surface temperature reduced by 73.4%, and the thermal insulation performance was stable. A comparison between the nanomaterial plate with the lightweight ceramic plate of a space vehicle shows that the temperature on the back surface of the ceramic plate was 56% higher than that of the nanomaterial plate. These results indicate that the Al₂O₃ nanomaterial has excellent thermal insulation performance, and is thus applicable in thermal protection of spacecraft and hypersonic vehicle. When the temperature was over 1 200 ℃, it was observed by Scanning Electron Microscope (SEM) that Al₂O₃ nanometric particles accreted rapidly, and the size of the cavities between particles increase significantly. The fibers inside the material were found melt, and the number, depth and width of cracks on the surface of the plate increased observably. These affected the thermal conductivity of the material surface. In addition, when the temperature was higher than 1 200 ℃, large deformation due to shrinkage and bending appeared on the edges of the nanomaterial plate. Experimental results demonstrate that the Al₂O₃ nanomaterial should be used at the temperature lower than 1 200 ℃.

Key words: nanomaterial, high temperature, thermal insulation performance, aerospace craft, thermal protection material