切削镍基高温合金的刀-屑界面形膜机制及刀具抗磨损机理研究

The low thermal conductivity, high chemical reaction and serious work hardening lead to great affinity with tool and serious tool wear in machining nickel-based alloy, which are the bottleneck restricting the development of the high-efficiency machining technology. Tribochemical reaction can be excited easily in the condition of high temperature and high pressure as a result of serious firction at tool-chip interface. The generated chemical film may have good or bad effects on tool wear in the service process, and then make the tribological system have some kind of unique characteristics. The tribochemical reaction mechanism, the effects of characteristics of generated chemical film on tool wear and anti-wear mechanism need to be revealed. This project intends to study the mechanical and thermal dynamic variation of tool-chip tribological system, to reveal and characterize its friction characteristics in machining nickel-based alloy. The thermo-mechanical conditions of film nucleation at tool-chip interface, stability and equilibrium conditions of chemical film were studied to reveal the formation mechanism of film at tool-chip interface, and then reveal the anti-wear mechanism. At last, cutting conditions optimization will be performed to make cutting process go in the state of minimum tool wear rate. The completion of the project will help to reveal the anti-wear mechanism based on the formation mechanism of film and control tool wear. The research results will provide theoretical support for the development and application of the cutting technology and tribology in machining difficult-to-cut material.

镍基高温合金的低导热性、高化学活性、严重的加工硬化等特点引起切削过程中切削温度高，与刀具亲和力强，导致刀具磨损严重，这一直以来是严重制约其高效切削技术进一步发展的关键问题。刀-屑界面在摩擦高温高压下易引发摩擦化学反应，生成的化学膜在服役过程中对刀具磨损具有正面或负面的影响，使整个摩擦系统具有某种独特的结构特性，其摩擦化学反应机理、化学膜的性质特征对刀具磨损的影响规律有待揭示。本申请拟研究切削镍基高温合金时刀-屑界面摩擦系统的力、热动态变化规律，揭示并表征该摩擦系统的特性；研究刀-屑界面薄膜形核热-力学条件以及界面薄膜稳定性与平衡条件，揭示界面形膜机制，进而揭示刀具抗磨损机理；进行工艺优化，使切削过程在刀具磨损率最小状态下进行。课题的完成将有助于揭示切削镍基高温合金时基于刀-屑界面形膜机制的刀具抗磨损机理以及刀具磨损控制，对难加工材料切削技术及切削摩擦学的发展和应用提供理论支撑。

镍基高温合金以其较高的强度和良好的抗氧化、抗燃气腐蚀能力，广泛应用于航空发动机上的导向器、涡轮叶片、涡轮盘和燃烧室等热端部件。但是由于它的低导热性、高化学活性、严重的加工硬化等特点引起切削过程中切削温度高，与刀具亲和力强，导致刀具磨损严重，这一直以来是严重制约其高效切削技术进一步发展的关键问题。刀-屑界面在摩擦高温高压下易引发摩擦化学反应，生成的化学膜在服役过程中对刀具磨损具有正面或负面的影响，使整个摩擦系统具有某种独特的结构特性，其摩擦化学反应机理、化学膜的性质特征对刀具磨损的影响规律有待揭示。.针对这些问题，本项目完成了切削镍基高温合金时刀-屑界面摩擦系统的力、热动态变化规律的研究，揭示并表征出摩擦系统的特性；通过计算得出了刀-屑界面薄膜形核热-力学条件，以及界面薄膜稳定性与平衡条件；利用分子动力学仿真分析，深入分析了刀-屑界面工件与刀具材料原子间交互作用机理；研究了刀-屑界面薄膜稳定性及平衡条件，揭示出切削过程中接触区形膜机制及发生摩擦润滑效应的内因，进而揭示刀具抗磨损机理。最后，基于抗磨损机理研究结果，针对采用不同刀具的切削实验，进行了工艺优化，使切削过程在刀具磨损率最小状态下进行。课题的研究成果将有助于揭示切削镍基高温合金时基于刀-屑界面形膜机制的刀具抗磨损机理以及刀具磨损控制，对难加工材料切削技术及切削摩擦学的发展和应用提供理论支撑。