基于扫描电子显微镜的纳米切削机理研究

发布时间：2018-01-22 07:42

本文关键词： 纳米切削纳米精度运动装置扫描电子显微镜金刚石刀具表面完整性　出处：《天津大学》2015年博士论文　论文类型：学位论文

【摘要】：纳米切削技术近年来得到了迅速发展,纳米切削推挤机理的揭示,为切削理论的研究开辟了更加广阔的研究领域。基于新机理的一系列核心问题的探索,成为制造领域亟待解决的重要课题。目前对纳米切削机理的研究主要基于超精密机床加工、原子力显微镜探针刻划、分子动力学模拟以及自主研发的纳米切削系统来开展。然而,上述方法对于纳米切削机理的深入研究存在着明显不足。因此本文基于纳米切削机理研究中亟需实验验证的现状,开展了一系列的实验探索,具体内容如下:(1)研制了基于扫描电子显微镜的原位纳米切削系统。该系统能实现直线、斜线、正弦曲线等多自由度切削的精确控制及在线观测,有利于更直观地研究纳米切削机理。利用聚焦离子束加工技术对单晶金刚石刀具进行加工,制备出不同刃口半径的直线刃刀具。(2)对纳米切削系统的定位精度、刚度、可重复性、蠕变漂移特性以及极限切削能力进行了测试。基于图像处理手段对纳米切削系统进行了双闭环反馈控制,修正该系统的蠕变漂移。输入切削厚度为10 nm、50 nm、100 nm时,实际切削厚度分别为10.6 nm、54.9 nm、105.4 nm。结果表明,该切削系统能够实现纳米级加工精度,满足纳米切削加工要求。(3)研究了切削厚度对单晶铜材料切屑形态的影响,发现当切削厚度小于40 nm时,没有形成传统切削时明显的剪切带,而当切削厚度约为50 100 nm时,属于剪切去除和推挤去除的临界区域。分析了晶体取向、刃口半径以及切削速度对单晶硅脆塑转变临界厚度的影响规律。通过对切屑变形的测量,研究了切削速度和刀具刃口对切削变形的影响规律。对不同刀具刃口条件下的最小切削厚度进行了研究,发现最小切削厚度随刀具刃口的增大而增大,并且二者比值介于0.36 0.51之间。(4)通过显微拉曼光谱分析了单晶硅材料的纳米切削表面完整性,发现在纳米切削过程中,存在着晶态转变和相变。对硅片切屑的测试结果表明,单晶硅转变为非晶硅和多晶硅,而多晶硅占主要成分。研究了切削参数对单晶铜和单晶硅亚表面损伤层厚度、残余应力、晶态变化、相变等的影响规律。
[Abstract]:Nano-cutting technology has been developed rapidly in recent years. The discovery of the mechanism of nano-cutting pushing and extrusion has opened up a broader research field for the research of cutting theory and a series of core problems based on new mechanism have been explored. At present, the research on the mechanism of nano-cutting is mainly based on ultra-precision machine tool processing and atomic force microscope (AFM) probe description. Molecular dynamics simulations and home-grown nanoscale cutting systems. The above methods have obvious shortcomings for the further study of nano-cutting mechanism. Therefore, based on the current situation of the research of nano-cutting mechanism, which needs to be verified by experiments, a series of experimental exploration has been carried out in this paper. The main contents are as follows: (1) A scanning electron microscope (SEM) based in situ nanoscale cutting system is developed. The system can realize the precise control and on-line observation of straight lines, sloping lines, sinusoidal curves and other multi-degree-of-freedom cutting. It is helpful to study the mechanism of nanoscale cutting more intuitively. The focused ion beam machining technology is used to process single crystal diamond tools. The positioning accuracy, stiffness and repeatability of the linear cutting tool with different cutting edge radius were prepared. The creep drift characteristic and the limit cutting ability were tested. Based on the image processing method, the double closed loop feedback control was carried out to correct the creep drift of the system. The input cutting thickness was 10 nm. The actual cutting thickness is 10.6 nm ~ 54.9 nm ~ 105.4 nm at 100 nm. The results show that the cutting system can achieve nanoscale machining accuracy. The effect of cutting thickness on the chip morphology of single crystal copper is studied. It is found that when the cutting thickness is less than 40 nm, there is no obvious shear band when the cutting thickness is less than 40 nm. When the cutting thickness is about 50 ~ 100nm, it belongs to the critical region of shearing and squeezing removal. The crystal orientation is analyzed. The influence of cutting radius and cutting speed on the critical thickness of brittle plastic transition of monocrystalline silicon is studied. The chip deformation is measured. The influence of cutting speed and cutting edge on cutting deformation is studied. The minimum cutting thickness under different cutting edge conditions is studied. It is found that the minimum cutting thickness increases with the increase of cutting edge. And the ratio of the two is between 0.36 and 0.51.) the surface integrity of monocrystalline silicon is analyzed by Raman spectroscopy, and it is found that it is in the process of nanocrystalline cutting. There are crystal state transition and phase transition. The results of silicon chip chip test show that monocrystalline silicon is transformed into amorphous silicon and polysilicon. The effect of cutting parameters on the thickness, residual stress, crystal state change and phase transition of subsurface damage layer of single crystal copper and monocrystalline silicon were studied.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TG501

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