新型h-BN纳米片/Si3N4透波复合材料的微结构控制与高温损伤机理

With the development of hypersonic aircraft, silicon nitride had been a new generation of high-temperature wave-transparent materials with the priority. For the demand of high performance wave-transparent materials from hypersonic aircraft radome (window), in this project, h-BN nanosheets/Si3N4 composites will be fabricated using graphene analogues of h-BN nanosheets as the raw materials, which are expected to be wave-transparent materials with high thermal conductivity and high toughness, and therefore possessing excellent thermal shock resistance. This project provides a new thought for preparation of Si3N4-based wave-transparent materials with high performance. The effects of size, number of layers and content of the h-BN nanosheets on phase transitions, densification and grain growth of Si3N4 based composites will be studied, to achieve the control of microstructure and optimization of performance of Si3N4 based composites. The interface formation mechanism and toughening mechanism of the h-BN nanosheets/Si3N4 composites will be clarified. The influence of microstructure on the mechanical, thermal and dielectric properties of h-BN nanosheets/Si3N4 composites will be revealed. The phase evolution at the environmental conditions of low oxygen pressure, long time and high temperature and their impacts on the mechanical, thermal and dielectric properties of h-BN nanosheets/Si3N4 will be studied, The damage mechanism of h-BN nanosheets/Si3N4 composites in extreme environments will also be clarified. This study may provide theoretical and technical support to preparation and application of Si3N4 based wave-transparent materials with high-performance.

针对高超音速飞行器天线罩(窗)对高性能透波材料的需求，本项目采用具有高性能的类石墨烯结构h-BN纳米片制备h-BN纳米片/Si3N4复合材料，有望获得高热导率及高韧性的Si3N4基透波材料，从而提高其抗热冲击性能，为高性能Si3N4基透波复合材料的制备提供一种新的思路。拟系统研究BN纳米片的尺寸、层数及含量等对Si3N4基复合材料相转变、致密化及晶粒生长的影响规律，实现Si3N4陶瓷复合材料微结构的控制和综合性能的优化；阐明h-BN纳米片/Si3N4复合材料的界面形成机制及强韧化机理；揭示h-BN纳米片/Si3N4复合材料微结构对复合材料力/热/电性能的影响规律；阐明h-BN纳米片/Si3N4透波材料在低压有氧、长时中高温环境条件下的物态物相演变规律及其对力/热/电综合性能的影响规律，揭示其在极端环境下的损伤机理，为高性能Si3N4基透波材料的制备及应用提供理论和技术支撑。

随着高超音速飞行器的发展，氮化硅陶瓷成为重点发展的新一代耐高温透波材料。针对高超音速飞行器天线罩(窗)对高性能透波材料的需求，本项目采用纳米h-BN前驱体氨气氮化工艺制备了纳米h-BN /Si3N4复合材料，获得了高热导率及高韧性的Si3N4基透波材料，从而提高其抗热冲击性能，为高性能Si3N4基透波复合材料的制备提供一种新的思路。同时，发现了纳米BN对纳米氮化硅的烧结行为、相转变、显微组织及力学性能的影响规律，制备出稳定致密的近纯相Si2N2O材料，与Si3N4相比，Si2N2O具有更好的抗氧化性能，在高性能透波材料中具有更广泛的应用潜力。.系统研究了纳米h-BN的含量等对Si3N4基复合材料相转变、致密化及晶粒生长的影响规律，实现了Si3N4陶瓷复合材料微结构的控制和综合性能的优化；阐明了纳米h-BN /Si3N4复合材料的界面形成机制及强韧化机理；揭示了纳米h-BN /Si3N4复合材料微结构对复合材料力/热/电性能的影响规律；阐明了纳米h-BN片/Si3N4透波材料在低压有氧、长时中高温环境条件下的物态物相演变规律及其对力/热/电综合性能的影响规律，揭示其在极端环境下的损伤机理，为高性能Si3N4基透波材料的制备及应用提供理论和技术支撑。