纳米立方氮化硼聚晶材料（NPcBN）的制备是目前超硬材料领域的研究热点，有序层状 BN 经位移型相变转化为 NPcBN 的机制已被广泛研究，而关于采用非晶 BN 为初始材料合成 NPcBN 的研究鲜见报导。本项目致力于实验研究高温、高压、无触媒参与下，无序非晶 BN 经重构转变为 NPcBN 的相变机理，选用非晶 BN 作为初始材料，在自行研制的六面顶大腔体超高压装置上，实现非晶 BN 到 NPcBN 的相转变；通过高倍透射电镜、X 射线衍射研究不同温度、压强条件下截获块体材料的相组成及微观结构；采用同步辐射 X 射线衍射及拉曼光谱技术，在金刚石压砧超高压装置中原位研究非晶 BN 在高温高压下的结构变化，探索非晶 BN 转化为 NPcBN 的相变机理；比较有序 BN、无序非晶 BN 为初始材料合成 NPcBN 热力学条件及力学性能的差异，优化高性能 NPcBN 块材的制备途径。

Nano-polycrystalline cubic BN (NPcBN) is a hot research topic in the superhard material domain, the sp2 hybrid state in BN could form sp3 hyrid state by martensitic mechanism or reconstructive mechanism under high temperature-high pressure (HTHP). The mechanism for the martensitic transformation of highly ordered hBN/rBN to NPcBN without catalyst under HTHP has been studied extensivly. This project will focus on the experimental studies of the mechanism for the transformation of amorphous BN to NPcBN without catalyst under HTHP, We aim to induce the formation of NPcBN from amorphous BN using the large-volume cubic press designed by ourself which could generate pressures up to about 35 GPa. In order to explore the mechanism for the transformation of amorphous BN to NPcBN, the phase composition and microstructure of the material obtained at different temperature and pressure will be studied by HRTEM and XRD, the changes of the amorphous BN in a diamond anvil cell will be monitored by in situ synchrotron radiation XRD and Raman spectrum measurements. In order to obtain the NPcBN with high hardness and high fracture toughness, We will study the differences of mechanical properties for the NPcBN synthesized form different BN precursor.