Si3N4纳米线在气凝胶复合泡沫陶瓷中的原位自生长及增强机理研究

Aerogel impregnated ceramic foams are novel integrated thermal protection and insulation materials with transnormal performances including high strength, high temperature resistance, low density and low thermal conductivity, making them promising materials in the thermal protection areas for aeronautics, aerospace and ships. However, the intrinsic brittleness and the microstructure of the aerogel matrix make it difficult to maintain the integrality of its nanostructure under mechanical and thermal vibration conditions. It is an effective way to improve the mechanical properties of the aerogel intrinsically to introduce nanowires into the aerogel matrix homogeneously at nanoscale and form an interpenetrating network. In this project, a new idea of in-situ self-growth of nanowires during the reaction sintering process is put forward, a composite system is designed with Si3N4 nanowires decorated Si3N4 foams prepared in a single-step as the scaffold and the following impregnated SiO2 aerogel as the thermal insulation matrix. The regulation principle of the pore structure of the Si3N4 ceramic foam will be investigated, the controlled in-situ growing mechanism and the synergistic reinforcing mechanism of the SiC nanowires with the ceramic foam will be studied, and the heat-transfer mechanism and the failure behavior of the composite will be analyzed. The success of this project will provide new designing ideas and scientific bases for the integrated thermal protection and insulation materials with strong background requirements and theoretical significance.

气凝胶复合泡沫陶瓷是一种具备“高强度、耐高温、低密度、低热导”超常规性能的新型防/隔热一体化材料，在航空航天及舰船热防护领域均极具应用前景。然而，气凝胶的固有脆性和微观结构特点使其在机械和热振动条件下难以保持纳米结构的完整性。将纳米线引入气凝胶基体中，使两者在纳米尺度上均匀复合形成三维互穿网络，能够从本质上改善气凝胶基体的力学性能。本项目提出了在反应烧结过程中实现纳米线原位自生长的新思路，设计了以一步制备的Si3N4纳米线修饰Si3N4泡沫陶瓷为骨架，溶胶浸渍法引入SiO2气凝胶为隔热基体的复合材料体系，系统研究Si3N4泡沫陶瓷的孔隙结构调控原理，揭示Si3N4纳米线的可控生长机制及其与泡沫陶瓷的协同增强机理，分析复合材料的失效行为与传热机理。本项目的成功实施能够为热防护材料的防/隔热一体化提供新的设计思路和科学依据，具有强烈的背景需求和重要的理论意义。

气凝胶复合泡沫陶瓷是一种具备“高强度、耐高温、低密度、低热导”超常规性能的新型防/隔热一体化材料，在航空航天及舰船热防护领域均极具应用前景。本项目提出了利用自生长纳米线从本质上改善气凝胶力学性能的新思路，设计了在反应烧结过程中实现纳米线原位生长的新方法，制备了以Si3N4纳米线修饰Si3N4泡沫陶瓷为骨架，柔性SiO2气凝胶为隔热基体的新材料体系。系统研究了Si3N4泡沫陶瓷的孔隙结构调控原理，揭示了Si3N4纳米线的可控生长机制，合成了柔性和多级孔SiO2气凝胶，阐述了复合材料的失效行为与传热机理。执行期间项目组成员共发表论文17篇，其中SCI收录11篇，EI收录14篇。申请国家发明专利7项，已获授权2项。培养博士研究生1人，硕士研究生3人。