含过渡金属超支化聚硼硅氮烷合成及热解转化陶瓷高温宽频吸波特性研究

Stealth technology is an important guarantee for anti-detection and enhancing penetration capability of aircrafts. As important material basis for stealth technology, microwave absorbing materials face on the great challenge and demand to overcome the stealth obstacle of hypersonic aircraft and high temperature apparatus of aircraft engine, i.e. nozzle trailing and regulation. This proposal mainly aims to give a principle solution for whether materials are able to stealth, extension of stealth, functionality combining mechanical structure under high temperature. We design and synthesize hyperbranched polyborosilazanes with tunable carbon content as preceramic precursors. The relationship between molecular structure, topology, organic-inorganic transition and ceramic multi-phases of pyrolytic SiBCN multiphase ceramic will be studied via introducing novel metal organic frameworks and metal coordination compounds. The dielectronic properties and microwave dispassion mechanism under high temperature for siliconboron carbonitride (SiBCN) multiphase ceramics will be clear to regulate the microwave absorbing properties. The effective absorption frequency range of SiBCN multiphase ceramics will be extended by using multi-layered design approach. The ceramic layer with different dielectric constant will be designed and prepared to achieve impedance matching, superposition of attenuation and frequency broadening. Furthermore, the SiBCN multiphase ceramics with high temperature absorbing and mechanical properties will be prepared based on the advantages of forming methods of polymer-derived ceramics. The achievement in the future of the project will give fundamental theory for stealth technology of hypersonic aircraft and engines, achieve the precise design of preceramic precursors toward functionality as well as broaden and deepen the application of special functional polymers in the field of aviation and aerospace stealth technology.

隐身技术是反制探测的重要手段，高超音速飞行器气动部位及航空发动机尾喷管等高温环境下的隐身是目前瓶颈和短板，对具有吸波材料提出了挑战和需求。本项目从碳基元可控超支化聚硼硅氮烷陶瓷前驱体分子结构及热解陶瓷分层结构设计出发，探究高温吸波机理及吸波频率拓宽机制，利用新型Co-MOF、Ni-MOF与过渡金属配合物调控SiBCN陶瓷介电特性及吸波特性。研究前驱体分子结构、拓扑结构、有机-无机转变过程与SiBCN陶瓷相态结构之间关系；明晰高温状态下陶瓷介电特性和电磁波极化损耗机制；通过不同阻抗和损耗组分的多层设计，实现阻抗匹配、衰减叠加及高温吸波频宽拓宽。作为特种高分子陶瓷前驱体在高温吸波材料领域应用的关键理论创新，项目预期成果将为高超飞行器、航空发动机高温隐身技术提供理论基础支撑，对于实现陶瓷前驱体特种高分子面向功能需求导引的精准分子结构设计及拓宽深化特种高分子在吸波材料领域中的应用具有重要学术价值。

隐身是反制探测的重要手段，飞行器热端部件在高温环境下的隐身对电磁波吸收材料提出了新的挑战和需求。本项目从分子设计出发，采用含硼单体与氨气、正丁胺和二氯二苯基硅烷胺解反应合成出碳基元可调的超支化聚硼硅氮烷陶瓷前驱体，以此为基础设计制备SiBCN高温吸波材料。以过渡金属Fe、Co、Ni和Cu为配位中心，以含羧基官能团和巯基官能团等为有机配体，合成了十余种MOF化合物，热解转化制备了多种形貌与化学组成的宽频吸波剂，最大有效吸收频宽EAB达8.8GHz。用含过渡金属MOF与超支化聚硼硅氮烷前驱体进行改性，通过陶瓷相态调控实现了含过渡金属 SiBCN 复相陶瓷高温吸波功能，在600-800℃的测试温度下，ZIF-67@SiBCN陶瓷的最低反射系数为-30dB，有效吸波范围几乎覆盖整个X波段(EAB为3.95GHz)，通过多层设计可进一步拓宽有效吸波频宽。项目组在Chem. Mater.、ACS Appl. Mater. Interfaces、J. Am. Ceram. Soc.、Sci. China Mater.、Carbon等学术期刊发表SCI论文17篇，论文被SCI引用448次，入选ESI高被引论文1篇；申请中国发明专利10项（已授权8项），参加学术会议并做报告4次，获得2020年教育部技术发明二等奖、2021年中国复合材料学会科学技术二等奖，负责人2021、2022连续入选“科睿唯安”全球高被引科学家，获得2020年国家杰出青年科学基金资助。本项目实现了特种高分子陶瓷前驱体在高温吸波材料应用领域的关键理论创新，成果将为飞行器热端部件高温隐身技术提供理论基础支撑，具有重要的科学意义和应用价值。