高速磨削硬脆材料亚表面损伤机制的理论与试验研究

High efficient grinding of hard brittle materials is a worldwide problem, and the most critical issue is the large subsurface damage after grinding which causes a long period of subsequent polishing processing and the exorbitant processing cost. Therefore, the revelation of micro-mechanism of subsurface damage in grinding process and effectively control the subsurface damage of materials after grinding is very significant. In order to obtain a good machined quality with high efficient and low damage, this project aims to investigate the interaction between abrasive grain and workpiece, the brittle-ductile transition behavior of hard brittle materials, and the initiation, propagation and interaction of various subsurface micro-defects during high speed grinding. The brittle-ductile transition mechanism with thermo-mechanical coupling effects and the micro-mechanism of subsurface damage will be revealed. Besides, to systematically and quantitatively analyze the design of grinding parameter, prediction models will be built to evaluate the depth of subsurface damage layer and the critical grinding depth of ductile removal. The correlation between surface accuracy and subsurface damage will be discussed as well. On one hand, the study can provide the scientific evidence for the design and development of grinding parameters with high speed and high efficiency, low damage or even no damage during brittle materials grinding. On the other hand, the basic theories for developing the processing technologies and equipments in high-speed precision grinding will be provided as well.

硬脆材料高效磨削是当今磨削加工领域的一大难题，其制约瓶颈是磨削造成材料亚表面损伤严重，致使后续研抛周期长、加工成本高。因此，探明硬脆材料磨削过程中亚表面损伤的微观机制，有效控制和减少材料亚表面损伤是解决这一工业难题的关键科学问题之一。本项目研究高速磨削过程中磨粒与工件之间的作用规律、高速磨削条件下硬脆材料的脆塑性激变行为以及亚表面微观缺陷形核、扩展及其交互作用；揭示热-力耦合作用下材料的脆塑转变机制和材料亚表层损伤演化的微观机制；建立硬脆材料高速磨削条件下亚表面损伤层深度以及塑性域磨削临界磨削深度的预测模型，并探讨表面精度与亚表面损伤的内在关联。为开发设计硬脆材料高速高效低损伤乃至无损伤磨削加工工艺提供科学依据，为发展高速精密磨削加工技术和装备提供理论基础。

随着现代高科技及产业化发展，功能陶瓷、单晶硅等硬脆材料的应用日益广泛。采用超硬磨料在高速条件下对硬脆材料进行磨削加工几乎成为唯一的加工手段。硬脆材料高效磨削是当今磨削加工领域的一大难题，其制约瓶颈是磨削造成材料亚表面损伤严重，致使后续研抛周期长、加工成本高。因此，探明硬脆材料磨削过程中亚表面损伤的微观机制，有效控制和减少材料亚表面损伤是解决这一工业难题的关键科学问题之一。本项目充分结合理论分析，分子动力学模拟及有限元仿真，多尺度研究并揭示了高速磨削过程中磨粒与工件之间的作用规律、高速磨削条件下硬脆材料的材料去除行为、亚表面缺陷形核和发展、材料热分配/传导及材料脆塑性激变现象；研究了热-力耦合效应、变质层（亚表面含孔/夹杂/预制裂纹/元素偏聚等）等因素影响下的高速磨削行为，总结了复杂因素对磨削行为的影响规律并揭示其影响机制；研究了硬质钛合金、高熵合金、单/双/多晶铜及纳米孪晶铜等新型材料的高速磨削行为，揭示偏析、孪生、孔/颗粒增强相等因素对亚表面损伤的影响规律和影响机制；建立了多种硬脆材料高速磨削数学模型，可用于预测材料去除率、亚表面损伤程度、磨削力、裂纹扩展、应力强度因子、加工路径韧脆性等，并通过考虑热-力耦合效应和变质层完成更复杂情形下的磨削行为预测。这些研究成果为开发设计硬脆材料高速高效低损伤乃至无损伤磨削加工工艺提供科学依据，为发展高速精密磨削加工技术和装备提供理论基础。