纳米孪晶B-C-N超硬材料的结构与性能研究

纳米孪晶化高压合成技术为显著提高超硬材料的硬度、韧性和热稳定性三大关键性能指标开辟了一个新的途径。本项目拟采用化学法制备的B-C-N粉体为原料，经液体射流法处理后制备出洋葱结构B-C-N纳米粉。采用洋葱B-C-N为前驱物，用高温高压法合成出纳米孪晶结构B-C-N超硬块材。研究原料配比、合成温度、保护气氛和保温时间等可控制的参数对所获得的洋葱结构的B-C-N前驱物的粒度、成分和组织结构等粉体特征的影响规律。测定纳米孪晶B-C-N块材的硬度、压缩强度、断裂韧性和抗氧化温度等特性，研究洋葱B-C-N的成分、粒度以及温度、压力和保温时间等对纳米孪晶结构B-C-N块材结构和组织的影响。采用第一性原理计算方法与透射电镜测试分析相结合，确定出具有高硬度、高韧性B-C-N块材的组织结构特征，阐明B-C-N块材力学性能、抗氧化性能与其微观结构的关系，制备出系列新型B-C-N超硬材料。

The nano-twinning high pressure synthesis technology opens a new way to significantly improve the three key performance indexes of hardness, toughness and thermal stability of superhard materials. This project plans to use B-C-N powder prepared by chemical method as the raw material, and prepare onion B-C-N nanoparticles after being treated by liquid jet method. The novel nanotwinned B-C-N superhard material will be synthesized by high temperature and high pressure method using onion B-C-N as precursor. The effects of controllable parameters such as raw material ratio, synthesis temperature, protective atmosphere and holding time on the particle size, composition and structure of onion B-C-N precursor will be studied. The hardness, compressive strength, fracture toughness and oxidation temperature of nanotwinned B-C-N will be detected, and the effects of the composition, particle size, temperature, pressure and holding time of onion B-C-N on the structure of nanotwinned B-C-N materials will be investigated. The structure characteristics of bulk nanotwinned B-C-N with high hardness and high toughness will be determined by the combination of first-principles calculation method and transmission electron microscopy. The relationship between mechanical properties, antioxidant properties and microstructure of bulk nanotwinned B-C-N will be expounded. A series of novel bulk nanotwinned B-C-N superhard materials will be prepared.