本课题面向航空难加工材料开展纳米立方氮化硼（cBN）/梯度纳米金刚石（GNCD）多层结构涂层刀具的制备及其机械性能与切削性能的应用基础研究。本课题提出改变气氛交替调制生长cBN和GNCD膜，通过纳米晶与多层结构提高涂层韧性，使刀具涂层获得良好的综合力学性能，从而提高切削性能。本课题研究cBN和NCD抑晶生长机理，形成晶粒可控的制备工艺。研究纳米cBN/GNCD多层结构涂层制备工艺及其调制生长机理。研究cBN和GNCD的调制结构对其微观结构和界面特征的影响。本课题研究纳米cBN/GNCD多层结构对涂层硬度、弹性模量、断裂韧性、残余应力以及摩擦磨损等性能的影响机理，得到多层结构与机械性能的内在联系以及cBN/GNCD多层结构的增韧机制。本课题开展纳米cBN/GNCD多层结构涂层刀具的制备，研究切削过程中涂层破损、磨损与失效机理，建立cBN/GNCD多层涂层性能演化模型。

The project is about the research on the preparation, mechanical properties and cutting performance of cubic boron nitride (cBN) and gradient nanocrystalline diamond (GNCD) nano_multilayer structure tool coatings for difficult-to-cut materials in aviation industry. The cBN/GNCD multilayer structure tool coating is deposited by alternating reactant gas components. The toughness of the coating layer is improved by nanocrystalline and multilayer structure, so that the cutting tool coating can obtain good comprehensive mechanical properties to improve the cutting performance. The nanocrystalline cBN and diamond deposition mechanism is studied to obtain the crystalline size controllable deposition technology. The cBN/GNCD multilayer coating preparation process and its modulation deposition mechanism are studied in this project. The effects of multilayer modulated structure on the microstructure and interface characterization are investigated. The study is carried out on the effects of multilayer modulated structure on the hardness, elasticity modulus, fracture toughness, residual stress and frictional wear of the coating to discover the internal relation between nanocrystalline multilayer structure and mechanical property and the toughening mechanism of cBN/GNCD multilayer structure. The cBN/GNCD coated inserts are prepared to investigate the damage, wear and failure mechanism of the tool coating in cutting process and to establish the evolution model of cutting performance of the tool coating.