各向同性热解石墨的碳陶复合制备与机理研究

Isotropic pyrolytic graphite has become one of bulk pure carbon materials possessing the most outstanding comprehensive properties, but it should be composited for further improvement of its properties. In this proposal, the structure and properties of isotropic pyrolytic graphite were attempted to be improved via compouding with carbides of relatively high strength, high hardness, high temperature anti-ablation. By using chemical vapor deposition of technical superiority, especially on dense sintering and homo-mixing, the carbide and carbon particles were speculated to be simultaneously, size-controllably formed in the gas phase and consequently co-deposited into a microsize or nanosize carbides dispersion reinforced isotropic pyrolytic graphite composite material. The structure and properties of this composite were analyzed and the strengthening effects were exproled.Based on the “viscous droplet” mechanism for carbon deposition and the strong support from in situ TEM gas phase reaction experiments, the co-deposition reaction mechanism was discussed, with the aim to reveal the formation and evolution of composite structure during deposition and effects on properties. This research will provide an important experimental and theory foundation for the production and design of high performance isotropic pyrolytic graphite carbide composite.

各向同性热解石墨是目前综合性能最佳的块体纯碳材料之一，而复合化是提高其性能的有效途径。本项目提出利用碳化物陶瓷具有高强度、高硬度、耐磨损、耐高温烧蚀等特性，通过碳-陶复合改善各向同性热解石墨的结构和性能。发挥化学气相沉积的独特技术优势，以在气相中同步或原位形成尺寸量级均匀可控的碳化物陶瓷颗粒和碳粒并共沉积为设想，解决它们的致密复合和均匀分散难题，制备具有微米甚至纳米级碳化物陶瓷颗粒弥散强化的各向同性热解石墨复合材料，研究其结构与性能及其强化效应。基于碳的“粘滞小滴”机理，利用原位气相反应（in situ TEM）试验，对“粘滞小滴”的结构特性及在复合反应条件的形成与变化规律进行研究，探讨复合沉积的反应机理，从而为高性能各向同性热解石墨-碳化物陶瓷材料的设计与制备提供实验依据和理论基础。