Abstract: With the rapid development of fields such as aerospace, national defense and military industry, and deep-sea exploration, the research and development of thermal protection materials for extreme environments (ultra-high temperature, strong radiation, severe thermal shock) has emerged as one of the core topics in the international field of materials science. Three-dimensional porous ceramic nanomaterials (such as aerogels and sponges) are considered as ideal candidate materials for the next generation of thermal protection systems due to their high-temperature resistance, corrosion resistance and low density. However, the inherent drawbacks of ceramic materials, including high brittleness and poor mechanical stability, make them prone to catastrophic fracture under thermo-mechanical coupling conditions, severely restricting their engineering applications. Therefore, there is an urgent need to develop new types of ceramic nanofiber materials that possess flexibility and mechanical strength at high temperatures.
This paper proposed a dual-phase toughening mechanism, in which amorphous silica was introduced as a second phase into the zirconia system to inhibit the ZrO2 crystalline phase transformation and crack propagation, thereby effectively improving the performance of ceramic materials. Firstly, by adjusting the Zr/Si molar ratio in the spinning solution, ZrxSi(1-x)O2 ceramic nanofiber membranes with gradient density were prepared. The differences in their microscopic morphology and macroscopic mechanical properties were compared, and a Zr0.5Si0.5O2 dual-phase ceramic nanofiber membrane with excellent comprehensive performance was obtained. On this basis, by further utilizing conjugate electrospinning technology and the polarization effect, the rapid preparation of an integrated, fluffy dual-phase ceramic nanofiber sponge was achieved. Benefiting from the synergistic effect of self-crimped fibers and the dual-phase structure, this material achieved a coupled optimization of flexibility and thermal insulation performance.
The experimental results show that when the Zr/Si molar ratio is 1:1, the mechanical properties of the dual-phase ceramic nanofiber membrane reach an optimal state, with a strain of 2.5%, a tensile strength of 0.18 MPa, and a toughness of 10.39 MJ/m3. Furthermore, by employing conjugate electrospinning technology and a high-temperature calcination process, an integrated, self-crimped dual-phase ceramic nanofiber sponge was prepared. The single fibers in this sponge exhibit a coexisting crystalline/amorphous dual-phase structure. The incorporation of the amorphous phase SiO2 effectively inhibits the growth of ZrO2 grain size, mitigates the structural fission of martensitic transformation in ZrO2 fibers during temperature fluctuations, and significantly enhances the flexibility of the fibers, resulting in a curvature radius of 1.13 μm for single fibers. At the same time, the fluffy, arched layer structure of the sponge can store more stagnant air, which greatly enhances its thermal insulation performance, lowering its thermal conductivity to as low as 27.8 mW/(m K). Additionally, the sponge demonstrates resilience under high-temperature conditions, making it an ideal candidate material for high-temperature thermal protection in aerospace applications and structural thermal insulation in extreme operating conditions.

Key words: electrospinning, conjugate forming, crystalline/amorphous dual-phase structure, ceramic nanofiber sponge, high-temperature thermal insulation

摘要： 为实现陶瓷纳米纤维海绵的一体化常压成型，首先通过调控前驱体纺丝液中无机组分的比例，利用静电纺丝工艺，制备出了不同硅锆摩尔比例的陶瓷纳米纤维膜，并对其形貌与力学性能进行表征，从而确定了最佳纺丝液浓度。接着采用共轭静电纺丝技术，在常压下制备出了自带卷曲纤维的双相陶瓷纳米纤维海绵，最后对其形貌与隔热性能进行评估。结果表明：当硅锆摩尔比为1∶1时，双相陶瓷纳米纤维海绵单纤维具有良好的韧性，曲率半径可达1.13 μm，平均晶粒尺寸为6.19 nm。此外，利用共轭静电纺丝制备的双相陶瓷纳米纤维海绵展现出优异的隔热性能，在密度为5.6 mg/cm³时，其导热率为27.8 mW/(m·K)。研究结果可为新型隔热材料的制备提供新的思路。

关键词: 静电纺丝, 共轭成型, 结晶/非晶双相结构, 陶瓷纳米纤维海绵, 高温隔热