SiBN透波陶瓷纤维微观结构调控与力学性能研究

Hypersonic vehicles are in high demand for new types of ceramic fiber having high-temperature resistant and wave-transparent property. SiBN series ceramic fiber is shown remarkable properties in meeting this demand. After many years of research, a feasible procedure for preparing and developing SiBN series ceramic fiber has been established. However, the tensile strength of the fiber is less than 1.0 GPa and it is still a long way to obtain continuous fiber with structural-functional integration. There is therefore the need for further in-depth and systematic research to be carried out in order to achieve this goal. This project is proposed to research the response relationship between the mechanical properties and microstructure and defects of SiBN ceramic fiber by Shanghai Synchrotron Radiation Facility SAXS、XAFS dynamic characterization techniques, in situ investigation of the microstructure evolution process of the as-spun fiber derived to SiBN ceramic fiber, establish the microstructure model of SiBN ceramic fiber, reveal the regulatory mechanism of pyrolysis process parameters on microstructure of the fiber, understand the number, morphology and the evolution law of the nano pore in SiBN ceramic during the process of pyrolysis. Establish the tensile fracture mechanical behavior model, analysis the real effect of microstructure and defects on mechanical properties of the SiBN fier, build the structure-activity relationship of the SiBN ceramic fiber. The project will supply the theoretic support for the preparation of SiBN continuous fiber, will lay the foundation for its application in hypersonic vehicles.

高超声速飞行器迫切需要新型高温透波陶瓷纤维。国内外对SiBN系陶瓷纤维寄予厚望。我们经多年努力，建立了SiBN纤维制备方法及研发基地，但纤维抗拉强度还低于1.0GPa，离结构功能一体化的连续纤维要求还有很大距离，必须开展深入系统的基础研究。项目拟利用上海同步辐射光源SAXS、XAFS动态表征技术开展微观结构及缺陷对SiBN纤维力学性能的影响机理研究，原位考察前驱体初生纤维裂解为SiBN陶瓷纤维的微观结构演变过程，建立SiBN纤维微观结构模型，揭示裂解工艺参数对SiBN纤维微观结构的调控机制，明确纤维裂解过程中微纳米孔隙数量、形态、以及结构的演变规律；建立SiBN纤维拉伸破坏力学行为模型，分析微观结构及缺陷对力学性能的真实影响规律，构筑SiBN纤维微观结构与力学性能的构效关系模型。本项目的实施将会为解决SiBN高温透波连续纤维的制备提供理论支撑，为其在高超声速飞行器等战略武器上应用奠定基础。

SiBN陶瓷纤维具有优异的耐高温性能、介电性能和力学性能，有望取代石英纤维成为新型耐高温透波纤维，用于耐高温透波陶瓷基复合材料的增强材料，在航天航空领域有广泛应用前景，是高性能透波陶瓷材料领域的研究热点之一。但目前制备的SiBN纤维离结构功能一体化的连续纤维要求还有很大距离，必须开展深入系统的基础研究。本项目研究了SiBN前驱体纤维裂解过程中化学结构的转变规律，对纤维裂解气氛的流量、组成、裂解温度、保温时间和升温速率等工艺参数进行优化调控，得到具有优异透波性能的SiBN碳含量的边界条件；研究了SiBN前驱体纤维结构稳定性影响因素，阐明SiBN陶瓷纤维前驱体的空气水解稳定性机理，获得SiBN纤维缺陷与纤维力学性能关系；调控SiBN纤维化学结构，建立工艺流程短且适合放大制备的“一步法”合成SiBN陶瓷纤维前驱体的技术路线，并进一步利用Materials Studio软件计算以及拉曼光谱等方法分析前驱体合成机理和裂解机理。项目研究成果对前驱体转化氮化物透波陶瓷纤维的可控制备提供理论指导和技术支撑。