仿生结构层状复合刀具制备及其高速切削损伤演变、失效机理研究

The cutting tool is one of the key factors of advanced manufacturing technology for machining difficult-to-cut materials. The study of damage evolution and failure mechanism is the important basis for the development of biomimetic laminated cutting tool materials in high speed machining process. Biomimetic design principles provide new methods and approaches to create new materials．The nacre structure is introduced into the designing and fabricating of cutting tools. Based on the multiscale analysis, interface optimization and collaborative strengthening and toughening mechanism, the biomimetic laminated composites cutting tool materials with excellent performance will be designed and prepared. The method for establishing the nonlinear multiscale coupling model of high speed machining will be explored. The relationship among the damage evolution, failure mechanism, microstructure, interfacial laminated properties and mechanical properties is established, which provides a good foundation for further research on the initiation, propagation of crack and failure process in heterogeneous materials. Because of the specificity of mimic nacre structure, it is particularly important and urgent to do in-depth research of preparation technology, optimization design of interface layer, high-speed cutting performance, damage evolution and failure mechanism of layered structure composite tool materials. In order to form the interaction of self-adaptive structure and mechanism, the effective integration of surface high hardness, residual compressive stress, inner high strength, thermal stress relaxation and collaborative strengthening mechanisms will be established. Similarly, in order to study the impact of micro-damage on the macro-failure of heterogeneous materials, the evolution from microscopic damage to macroscopic failure will be explored. In addition, the failure mechanism, such as brittle fracture, of biomimetic laminated composite cutting tools will be revealed. For improving the tool reliability, cutting efficiency and tool life, the research has great theoretical and practical significance.

刀具是实现高速切削加工的关键因素之一，而切削过程中刀具损伤演变机制及失效机理的研究是刀具材料开发的重要依据。本项目拟将贝壳珍珠层结构引入刀具材料设计与制备，通过多尺度分析、界面优化设计及"微/细观"协同强韧化机制的有效结合，制备出具有表层高硬度、表面残余压应力与内层的高强度、高韧性、热应力缓解及协同强韧化机制进行有效结合的仿生结构层状复合陶瓷刀具，使刀具材料形成一种对高速切削过程多场耦合作用的"自适应"结构与机制。探索高速切削加工过程中仿生结构层状复合刀具损伤演变、失效机理及其与刀具材料微观结构、界面层性能、力学性能和切削参数等之间的关系。由于仿生结构层状复合刀具材料的特殊性，深入研究其制备工艺、界面优化设计、高速切削性能、损伤演变过程，揭示其脆性断裂等失效机理，对于提高该类刀具的切削可靠性、加工效率和延长刀具寿命，都具有重要的理论和现实意义。

本项目将贝壳珍珠层结构引入刀具材料设计与制备，制备出具有表层高硬度、表面残余压应力与内层的高强度、高韧性、热应力缓解及协同强韧化机制进行有效结合的仿生结构层状复合陶瓷刀具。探索高速切削加工过程中仿生结构层状复合刀具损伤演变、失效机理及其与刀具材料微观结构、界面层性能、力学性能和切削参数等之间的关系。.在四年资助期间，（1）根据工件材料、刀具材料热-物理性能、切削参数对温度场、应力场的影响等，进行了热化学耦合及化学热力学分析，确定刀具材料组分体系；（2）根据分析结果，进行了纳米颗粒分散工艺、材料烧结工艺研究，初步制备出性能较好的宏观均质刀具材料，找出其烧结规律，测试力学性能；（3）完善优化设计结果及制备工艺参数，制备出符合要求的仿生结构层状复合刀具材料，测试其力学性能，进行SEM和TEM等观察；（4）制备出复合要求仿生结构层状复合刀具，对316L不锈钢、淬硬钢、合金钢进行了高速切削实验，研究加工匹配性，分析了刀具的磨损和破损机理。.材料残余应力模型分析表明：仿生结构陶瓷刀具材料烧结制备时，根据层数和层厚比，可在表层产生残余压应力，利于提高刀具材料的力学性能。采用三层结构，层厚比为8的情况下，表面层产生的应力峰值可达-439.98Mpa。层间温度与热应力模型分析表明：随着层数和层厚比的不断增加，刀尖处首层与次层界面上的温度值与热应力值逐渐上升，而刀尖处底层与次底层界面上的温度值与最大拉应力值则逐渐下降。.烧结制备的仿生结构层状陶瓷刀具表层材料力学性能较单一组分刀具材料力学性能皆有提高。通过对比切削淬硬45钢、淬硬T10A等棒料，实验结果表明，仿生结构层状陶瓷刀具切削性能优于对比刀具。.由于仿生结构层状复合刀具材料的特殊性，深入研究其制备工艺、界面优化设计、高速切削性能、损伤演变过程，揭示其脆性断裂等失效机理，对于提高该类刀具的切削可靠性、加工效率和延长刀具寿命，都具有重要的理论和现实意义。