超硬金刚石芯-BCN合金壳层复合材料的高压制备与结构性能调控

金刚石作为已知最硬的超硬材料具有广泛的工业应用，然而金刚石具有固有缺陷：金刚石化学惰性和热稳定性较差，不适合切削铁族金属材料；在钻、磨、削的极端环境下易于石墨化。由于金刚石与立方氮化硼（cBN）结构上的近亲关系，可通过cBN包覆金刚石，经过高温高压固溶强化，形成纳米金刚石块材为芯，表层为B-C-N固溶体外壳的超硬合金，能有效提高金刚石的热稳定性并保持超高硬度。本项目拟对超硬金刚石芯-BCN合金壳层复合材料的高压制备及结构与性能调控展开系统研究，通过改变初始材料的复合密封方式，获取先进新型超硬材料及其制备工艺，完成对其结构与性能的有效调控。申请人希望复合不同表层碳化程度的金刚石与不同壁厚的cBN壳层，改进现有二级增压装置，调控温度-压力-时间等要素，合成不同外壳与内芯结构的超硬样品，建立其结构与性能完备表征数据库，探索发展具备实际应用的大腔体高压制备技术，促进其实际应用。

Diamond is the hardest known superhard material with widespread industrial applications, but it also has intrinsic limitations. Diamond is unsuitable for high-speed cutting of ferrous materials owing to its poor chemical inertness. Chemical reaction with iron family materials or graphitization will occur in the surface of diamond under high stress and temperature. Diamond will possess excellent thermal stability and mechanical performance through high pressure and high temperature treatment forming B-C-N solid solutions layer on its surface. . In this project, because of their affinity in structural lattices and covalent bonding character, the applicant desires to synthesize superhard polycrystalline diamond-cored alloy by adopting graphitized diamond powder on surface and hollow cBN pillar and carry out systemically investigation of synthetic process, regulation and control laws of the structure and properties of samples, and acquire the superhard diamond-cored composites with B-C-N solid solution shell specimens as well as preparation technology that can be devoted to practical industrial application. Moreover, this project means to eliminate C-C bonds in B-C-N solid solutions and keep nanoscale polycrystalline diamond as cores of diamond-cored alloy via treating sealed diamond in cBN tube at HPHT and characterize the corresponding physical and chemical properties of samples. . By consecutive improving and optimizing the static pressure assembly and adjusting pressure-temperature-time ingredient, the applicant expects to synthesize a series of large size (~5 mm) superhard diamond-cored alloy and founds complete database of correspondence between properties and structures and thickness of B-C-N solid solutions shell. To facilitate the practical industrial applications of superhard polycrystalline diamond-cored alloys, the applicant will explore to develop practical static pressure synthetic technology of these alloys.