石墨与金刚石相互转变间新型碳同素异形体的截获及碳/碳自身复合材料的合成

The synthesis of new carbon materials has always been a research focus. However, the microscopic mechanism that explains the transformation from graphite to diamond remains unclear. So far, researchers have not reached a consensus on whether there are other allotropes of carbon before graphite is transformed into diamond. In this context, it is intended to intercept and capture new carbon allotropes during the transformation between graphite and diamond by taking high-temperature and high-pressure measures, with a view to discovering the methods for preparing high performance carbon-carbon composites. This project will investigate how the microstructure of graphite and diamond evolves in different high-temperature and high-pressure conditions, clarify the correlation of volume content of each phase and microstructure to material properties, and make it possible to regulate the microstructure and properties of carbon materials at high pressure. The findings will assist in understanding the microscopic mechanism that explains the transformation from graphite to diamond, and provide important experimental evidence for solving the long-standing problem above. Meanwhile, they will also lay a foundation for developing high performance carbon-carbon composites.

新型碳材料的合成一直是科学研究的热点。其中人们对于石墨向金刚石转变的微观机制尚不清晰，石墨转变成金刚石之前是否存在其他碳同素异形体至今无统一的看法。据此，我们拟采用高温高压手段开展对石墨与金刚石相互转变间新型碳同素异形体的截获研究，探索制备高性能碳/碳自身复合材料的方法。本项目将研究石墨与金刚石在不同高温高压处理条件下组织结构的演化规律，阐明材料中各相体积含量和微观组织结构对材料性能之间的关系，实现碳材料组织结构和性能的高压调控。本项目的研究将有助于理解石墨变金刚石的微观机理，为这一由来已久的科学问题提供重要的实验依据；同时为开发高性能碳/碳自身复合材料奠定基础。

本项目在新型碳同素异形体探索和碳碳复合块材合成方面的研究中取得了一定的进展：1）采用第一性原理计算方法设计了多种新型碳晶体结构，对这些新型碳结构的电学和力学性能进行了研究，发现这些新型碳结构都具有很好的拉伸性能；2）采用不同粒径纳米金刚石为原料与炭黑按不同比例混合，合成了具有优良力学性能的碳/碳复合材料，其中金刚石与炭黑按质量百分比9：1混合烧结得到的样品的杨氏模量为19.9GPa，纳米压痕硬度为2.38GPa，弹性回复率达到了80.6%；3）提出两种石墨/氮化硼超结构可用于解释[Haigh S. J. et al., Nat. Mater. 2012, 11, 764−767]文献报道实验观察到的结构。.通过本项目的研究，不仅提出了多种新型碳晶体结构，并且合成出具有优良力学性能的碳/碳复合材料，丰富了功能碳材料家族成员；发表带本项目资助号的学术论文2篇，培养硕士研究生5名。