基于光偏转原理的AFM光电检测系统设计

利用光偏转原理设计并实现了原子力显微镜(AFM)的光电检测系统,研究了影响光偏转噪声的影响因素。设计了新型螺旋式嵌套结构调节准直光斑,使激光发散角降低到0.053°,利用压电陶瓷特性设计了高精度三维调节结构,可以在α,β,γ方向精准调节偏转角度,36mm的聚焦焦距满足了小型化、集成化的设计目标。基于该高灵敏度光电检测系统的设计,AFM系统得到了清晰的硅材料表面台阶结构,系统分辨率达到了0.1nm,为今后的亚原子测量奠定了实验基础。

稀土La^(3+)离子在高岭石表面吸附的原位AFM研究

离子吸附型稀土矿是我国优势矿产资源,该类型矿床中,稀土元素主要是以离子的形式吸附在高岭石、埃洛石和铁锰氧化物等次生矿物上。本文主要通过原子力显微镜(AFM)的微观区域的力学测量功能,结合DLVO理论,研究原位水环境下稀土La^(3+)对高岭石不同表面(Si面和Al面)Stern电位的影响,揭示高岭石对La^(3+)的吸附能力随Si面和Al面表面性质不同而变化。实验结果表明:当La^(3+)浓度从0增加至1.0 mmol/L时,高岭石Si面的Stern电位由−46 mV转变为4 mV,表明高岭石Si面对La^(3+)有吸附作用;而Al面的Stern电位(在28~31 mV之间波动)几乎没有变化,表明高岭石Al面对La^(3+)的吸附作用不强。该研究表明在pH=4~6的风化壳条件下,高岭石Si面对La^(3+)的吸附可能占主导作用,Al面的贡献相对较小。本研究从微观角度揭示了稀土元素在高岭石不同表面的吸附特征,明确了高岭石不同表面对稀土元素吸附的贡献,为阐明风化壳中稀土的富集机制提供信息。

Nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in aerospace community:a comparative analysis

The aerospace community widely uses difficult-to-cut materials,such as titanium alloys,high-temperature alloys,metal/ceramic/polymer matrix composites,hard and brittle materials,and geometrically complex components,such as thin-walled structures,microchannels,and complex surfaces.Mechanical machining is the main material removal process for the vast majority of aerospace components.However,many problems exist,including severe and rapid tool wear,low machining efficiency,and poor surface integrity.Nontraditional energy-assisted mechanical machining is a hybrid process that uses nontraditional energies(vibration,laser,electricity,etc)to improve the machinability of local materials and decrease the burden of mechanical machining.This provides a feasible and promising method to improve the material removal rate and surface quality,reduce process forces,and prolong tool life.However,systematic reviews of this technology are lacking with respect to the current research status and development direction.This paper reviews the recent progress in the nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in the aerospace community.In addition,this paper focuses on the processing principles,material responses under nontraditional energy,resultant forces and temperatures,material removal mechanisms,and applications of these processes,including vibration-,laser-,electric-,magnetic-,chemical-,advanced coolant-,and hybrid nontraditional energy-assisted mechanical machining.Finally,a comprehensive summary of the principles,advantages,and limitations of each hybrid process is provided,and future perspectives on forward design,device development,and sustainability of nontraditional energy-assisted mechanical machining processes are discussed.

Stress-assisted corrosion mechanism of 3Ni steel by using gradient boosting decision tree machining learning method

Traditional 3Ni weathering steel cannot completely meet the requirements for offshore engineering development,resulting in the design of novel 3Ni steel with the addition of microalloy elements such as Mn or Nb for strength enhancement becoming a trend.The stress-assisted corrosion behavior of a novel designed high-strength 3Ni steel was investigated in the current study using the corrosion big data method.The information on the corrosion process was recorded using the galvanic corrosion current monitoring method.The gradi-ent boosting decision tree(GBDT)machine learning method was used to mine the corrosion mechanism,and the importance of the struc-ture factor was investigated.Field exposure tests were conducted to verify the calculated results using the GBDT method.Results indic-ated that the GBDT method can be effectively used to study the influence of structural factors on the corrosion process of 3Ni steel.Dif-ferent mechanisms for the addition of Mn and Cu to the stress-assisted corrosion of 3Ni steel suggested that Mn and Cu have no obvious effect on the corrosion rate of non-stressed 3Ni steel during the early stage of corrosion.When the corrosion reached a stable state,the in-crease in Mn element content increased the corrosion rate of 3Ni steel,while Cu reduced this rate.In the presence of stress,the increase in Mn element content and Cu addition can inhibit the corrosion process.The corrosion law of outdoor-exposed 3Ni steel is consistent with the law based on corrosion big data technology,verifying the reliability of the big data evaluation method and data prediction model selection.

基于AFM的SBS改性沥青老化过程力学特性研究

为了探究改性沥青在老化过程中宏观与微观性能的变化,制备了掺量为5.5%的SBS改性沥青,并进行了短期与长期老化试验,分析了其基本性能指标。采用温度扫描与频率扫描试验研究了SBS改性沥青的流变性能,采用AFM试验分析了其表面微观形貌和耗散力,并结合力曲线分析了其黏附力及杨氏模量在老化前后的变化。研究结果表明,短期老化对SBS改性沥青流变性能的影响较小,长期老化对其流变性能影响显著,弹性模量和黏性模量均增大,呈现出变硬、变脆的特性;AFM试验表明SBS改性沥青在老化后高度增大,且蜂状结构尺寸增大、数量增多,黏附力和耗散力均降低,杨氏模量增大,验证了宏观流变试验的结果。

In-situ AFM and quasi-in-situ studies for localized corrosion in Mg-9Al-1Fe-(Gd) alloys under 3.5 wt.% NaCl environment

Revealing the localized corrosion process of Mg alloy is considered as one of the most significant ways for improving its corrosion resistance.The reliable monitor should be high distinguishability and real-time in liquid environment.Herein,Mg-9Al-1Fe and Mg-9Al-1Fe-1Gd alloys were designed to highlight the impact of intermetallic on the corrosion behaviour.In-situ AFM with a special electrolyte circulation system and quasi-in-situ SEM observation were used to monitor the corrosion process of the designed alloys.SEM-EDS and TEM-SAED were applied to identify the intermetallic in the designed alloys,and their volta potentials were measured by SKPFM.According to the real-time and real-space in-situ AFM monitor,the corrosion process consisted of dissolution of anodicα-Mg phase,accumulation of corrosion products around cathodic phase and shedding of some fine cathodic phase.Then,the localized corrosion process of Mg alloy was revealed combined with the results of the monitor of corrosion process and Volta potential difference.

On dry machining of AZ31B magnesium alloy using textured cutting tool inserts

Magnesium alloys have many advantages as lightweight materials for engineering applications,especially in the fields of automotive and aerospace.They undergo extensive cutting or machining while making products out of them.Dry cutting,a sustainable machining method,causes more friction and adhesion at the tool-chip interface.One of the promising solutions to this problem is cutting tool surface texturing,which can reduce tool wear and friction in dry cutting and improve machining performance.This paper aims to investigate the impact of dimple textures(made on the flank face of cutting inserts)on tool wear and chip morphology in the dry machining of AZ31B magnesium alloy.The results show that the cutting speed was the most significant factor affecting tool flank wear,followed by feed rate and cutting depth.The tool wear mechanism was examined using scanning electron microscope(SEM)images and energy dispersive X-ray spectroscopy(EDS)analysis reports,which showed that at low cutting speed,the main wear mechanism was abrasion,while at high speed,it was adhesion.The chips are discontinuous at low cutting speeds,while continuous at high cutting speeds.The dimple textured flank face cutting tools facilitate the dry machining of AZ31B magnesium alloy and contribute to ecological benefits.

Field-assisted machining of difficult-to-machine materials

Difficult-to-machine materials (DMMs) are extensively applied in critical fields such as aviation,semiconductor,biomedicine,and other key fields due to their excellent material properties.However,traditional machining technologies often struggle to achieve ultra-precision with DMMs resulting from poor surface quality and low processing efficiency.In recent years,field-assisted machining (FAM) technology has emerged as a new generation of machining technology based on innovative principles such as laser heating,tool vibration,magnetic magnetization,and plasma modification,providing a new solution for improving the machinability of DMMs.This technology not only addresses these limitations of traditional machining methods,but also has become a hot topic of research in the domain of ultra-precision machining of DMMs.Many new methods and principles have been introduced and investigated one after another,yet few studies have presented a comprehensive analysis and summarization.To fill this gap and understand the development trend of FAM,this study provides an important overview of FAM,covering different assisted machining methods,application effects,mechanism analysis,and equipment design.The current deficiencies and future challenges of FAM are summarized to lay the foundation for the further development of multi-field hybrid assisted and intelligent FAM technologies.

原子力红外显微镜(AFM-IR):成像原理及方法综述

综述了基于原子力显微镜的红外光谱(Atomic force microscopy-based infrared spectroscopy,AFM-IR)的特点,测量和检测原理及其技术优势。AFM-IR是能在纳米尺度对不同材料进行表征的新兴技术,该技术可以以远低于常规光学衍射极限的分辨率检测材料的化学成分,同时提供不同组分的分布图谱。AFM-IR的原理是利用原子力显微镜(AFM)悬臂梁的振动检测样本因吸收红外辐射脉冲产生的热膨胀,因此AFM-IR在继承了AFM的纳米级分辨率的基础上结合了红外光谱的化学分析能力,克服了二者原有的缺点并实现了优势互补。这项新技术在过去十多年备受关注并获得了长足的发展,因其操作简便、系统稳定、样品制备要求相对较低,以及与红外光谱直接相关而无需数学建模或额外数据后续处理,已被广泛用于材料科学、生命科学等诸多领域。

基于HoFiBiAFM的点击率预测模型

在推荐系统中,FiBiNET、AFM等深度学习模型能够关注特征的重要性进行点击率预测。其中FiBiNET的深层模型使用DNN网络相当隐式地对特征交互进行建模,但是使用DNN学习高阶特征可能导致低阶特征交叉被稀释。通过叠加多层SENET注意力机制的方式学习高阶重要性特征,并加入高阶注意力分解机共同更新特征表示,构成一种新的点击率预测模型HoFiBiAFM。通过在Movielens-100K和Movielens-1M数据集上分别与其他CTR预测模型进行分类任务和回归任务的对比实验,结果验证了HoFiBiAFM模型的点击率预测效果。

Approach for Polishing Diamond Coated Complicated Cutting Tool: Abrasive Flow Machining(AFM)

Lower surface roughness and sharper cutting edge are beneficial for improving the machining quality of the cut?ting tool, while coatings often deteriorate them. Focusing on the diamond coated WC?Co milling cutter, the abrasive flow machining(AFM) is selected for reducing the surface roughness and sharpening the cutting edge. Comparative cutting tests are conducted on di erent types of coated cutters before and after AFM, as well as uncoated WC?Co one, demonstrating that the boron?doped microcrystalline and undoped fine?grained composite diamond coated cutter after the AFM(AFM?BDM?UFGCD) is a good choice for the finish milling of the 6063 Al alloy in the present case, because it shows favorable machining quality close to the uncoated one, but much prolonged tool lifetime. Besides, compared with the micro?sized diamond films, it is much more convenient and e cient to finish the BDM?UFGCD coated cutter covered by nano?sized diamond grains, and resharpen its cutting edge by the AFM, owing to the lower initial surface roughness and hardness. Moreover, the boron incorporation and micro?sized grains in the underly?ing layer can enhance the film?substrate adhesion, avoid the rapid film removal in the machining process, and thus maximize the tool life(1040 m, four times more than the uncoated one). In general, the AFM is firstly proposed and discussed for post?processing the diamond coated complicated cutting tools, which is proved to be feasible for improving the cutting performance

Effect of tool geometry on ultraprecision machining of soft-brittle materials:a comprehensive review

Brittle materials are widely used for producing important components in the industry of optics,optoelectronics,and semiconductors.Ultraprecision machining of brittle materials with high surface quality and surface integrity helps improve the functional performance and lifespan of the components.According to their hardness,brittle materials can be roughly divided into hard-brittle and soft-brittle.Although there have been some literature reviews for ultraprecision machining of hard-brittle materials,up to date,very few review papers are available that focus on the processing of soft-brittle materials.Due to the‘soft’and‘brittle’properties,this group of materials has unique machining characteristics.This paper presents a comprehensive overview of recent advances in ultraprecision machining of soft-brittle materials.Critical aspects of machining mechanisms,such as chip formation,surface topography,and subsurface damage for different machining methods,including diamond turning,micro end milling,ultraprecision grinding,and micro/nano burnishing,are compared in terms of tool-workpiece interaction.The effects of tool geometries on the machining characteristics of soft-brittle materials are systematically analyzed,and dominating factors are sorted out.Problems and challenges in the engineering applications are identified,and solutions/guidelines for future R&D are provided.

Laser machining fundamentals:micro,nano,atomic and close-to-atomic scales

With the rapid development in advanced industries,such as microelectronics and optics sectors,the functional feature size of devises/components has been decreasing from micro to nanometric,and even ACS for higher performance,smaller volume and lower energy consumption.By this time,a great many quantum structures are proposed,with not only an extreme scale of several or even single atom,but also a nearly ideal lattice structure with no material defect.It is almost no doubt that such structures play critical role in the next generation products,which shows an urgent demand for the ACSM.Laser machining is one of the most important approaches widely used in engineering and scientific research.It is high-efficient and applicable for most kinds of materials.Moreover,the processing scale covers a huge range from millimeters to nanometers,and has already touched the atomic level.Laser–material interaction mechanism,as the foundation of laser machining,determines the machining accuracy and surface quality.It becomes much more sophisticated and dominant with a decrease in processing scale,which is systematically reviewed in this article.In general,the mechanisms of laser-induced material removal are classified into ablation,CE and atomic desorption,with a decrease in the scale from above microns to angstroms.The effects of processing parameters on both fundamental material response and machined surface quality are discussed,as well as theoretical methods to simulate and understand the underlying mechanisms.Examples at nanometric to atomic scale are provided,which demonstrate the capability of laser machining in achieving the ultimate precision and becoming a promising approach to ACSM.

Failure mode change and material damage with varied machining speeds:a review

High-speed machining(HSM) has been studied for several decades and has potential application in various industries, including the automobile and aerospace industries. However,the underlying mechanisms of HSM have not been formally reviewed thus far. This article focuses on the solid mechanics framework of adiabatic shear band(ASB) onset and material metallurgical microstructural evolutions in HSM. The ASB onset is described using partial differential systems. Several factors in HSM were considered in the systems, and the ASB onset conditions were obtained by solving these systems or applying the perturbation method to the systems. With increasing machining speed, an ASB can be depressed and further eliminated by shock pressure. The damage observed in HSM exhibits common features. Equiaxed fine grains produced by dynamic recrystallization widely cause damage to ductile materials, and amorphization is the common microstructural evolution in brittle materials. Based on previous studies, potential mechanisms for the phenomena in HSM are proposed. These include the thickness variation of the white layer of ductile materials. These proposed mechanisms would be beneficial to deeply understanding the various phenomena in HSM.

基于音叉式AFM测量的软件控制研究

基于音叉式原子力显微镜(AFM)的基本原理,设计了一个幅度调制模式下的测量控制系统,该控制系统的主要实现功能为针尖接近、针尖工作点位置保持和样品的表面形貌测量。实验得到针尖在不同激励电压下的接近曲线,针尖分别在100 mV、200 mV、500 mV、1 V激励下,工作区间大小为4.7 nm、8.5 nm、12.1 nm、15.7 nm,灵敏度分别为0.0423 V/nm、0.0564 V/nm、0.0861 V/nm、0.0831 V/nm。实验得到针尖工作点位置保持过程中的纳米位移台位置变化曲线,针尖工作点的正向偏移值为2.3 nm,负向偏移值为1.3 nm。表面形貌测量采用X轴双向扫描模式,即在纳米位移台于X轴方向上的往返过程中分别测量1次表面形貌数据,对正向扫描和反向扫描的数据进行计算处理;正向扫描的间距误差为5.2 nm,高度误差为0.3 nm,反向扫描的间距误差为6.4 nm,高度误差为0.5 nm。

Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying(NCES)Using Different Types of Vegetable Oils as Base Fluids of External Fluid

The current study of minimum quantity lubrication(MQL)concentrates on its performance improvement.By contrast with nanofluid MQL and electrostatic atomization(EA),the proposed nanofluid composite electrostatic spraying(NCES)can enhance the performance of MQL more comprehensively.However,it is largely influenced by the base fluid of external fluid.In this paper,the lubrication property and machining performance of NCES with different types of vegetable oils(castor,palm,soybean,rapeseed,and LB2000 oil)as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids.The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances.The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid,NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7%and 7.6%-26.5%,respectively.The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2%and 3.6%-11.2%lower than those for NCES with other vegetable oils as the base fluids of external fluid,respectively.When LB2000/multi-walled carbon nanotube(MWCNT)water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1,NCES showed the best milling performance.This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid.

基于增量自适应支持向量机的AFM尖端磨损识别

为了提高纳米加工刀具磨损状态在线监测的精度与泛化能力,提出一种基于增量自适应支持向量机的基于原子力显微镜(AFM)尖端磨损识别方法。该方法以横向力的峰-峰值和方差作为特征变量,通过移动视窗获取增量数据;以维持Kuhn-Tucher定理所要求的最优化条件为准则,在当前支持向量机解结构基础上自适应修改正则化参数C和核参数σ,以获得更新支持向量机结构,并对增量数据及受其扰动的原数据进行分类;根据尖端失效点数量走势,判定尖端磨损程度。实验证明该算法在识别精度与时间上可满足在线检测要求。与定向非循环图支持向量分类器对比,该算法具有更强的鲁棒性与更高的泛化能力。

基于AFM探测分析不同白血病分型患者外周血红细胞形貌和超微结构的差异

原子力显微镜(AFM)凭借独特的优势已经成为细胞生物学领域的重要研究手段。文章使用AFM分别研究人体血液中正常红细胞、急性髓系白血病(AML)和急性淋巴细胞白血病(ALL)分型红细胞,分析并比较三者的细胞形态和超微结构,进一步探究其变化对生理功能的影响。研究结果表明,AFM可以清晰地观察到病变红细胞的形态、各项细胞参数发生变化,能够为病变红细胞的辨别提供依据。同时,AFM可以清晰地观察到不同红细胞膜表面的形态与超微结构差异,有望为红细胞相关疾病的诊断和治疗提供一种有效的观察分析手段。

Prediction of Wearing of Cutting Tools Using Real Time Machining Parameters and Temperature Using Rayleigh-Ham Method

Wear of cutting tools is a big concern for industrial manufacturers, because of their acquisition cost as well as the impact on the production lines when they are unavailable. Law of wear is very important in determining cutting tools lifespan, but most of the existing models don’t take into account the cutting temperature. In this work, the theoretical and experimental results of a dynamic study of metal machining against cutting temperature of a treated steel of grade S235JR with a high-speed steel tool are provided. This study is based on the analysis of two complementary approaches, an experimental approach with the measurement of the temperature and on the other hand, an approach using modeling. Based on unifactorial and multifactorial tests (speed of cut, feed, and depth of cut), this study allowed the highlighting of the influence of the cutting temperature on the machining time. To achieve this objective, two specific approaches have been selected. The first was to measure the temperature of the cutting tool and the second was to determine the wear law using Rayleigh-Ham dimensional analysis method. This study permitted the determination of a law that integrates the cutting temperature in the calculations of the lifespan of the tools during machining.

A New Dynamics Analysis Model for Five-Axis Machining of Curved Surface Based on Dimension Reduction and Mapping

The equipment used in various fields contains an increasing number of parts with curved surfaces of increasing size.Five-axis computer numerical control(CNC)milling is the main parts machining method,while dynamics analysis has always been a research hotspot.The cutting conditions determined by the cutter axis,tool path,and workpiece geometry are complex and changeable,which has made dynamics research a major challenge.For this reason,this paper introduces the innovative idea of applying dimension reduction and mapping to the five-axis machining of curved surfaces,and proposes an efficient dynamics analysis model.To simplify the research object,the cutter position points along the tool path were discretized into inclined plane five-axis machining.The cutter dip angle and feed deflection angle were used to define the spatial position relationship in five-axis machining.These were then taken as the new base variables to construct an abstract two-dimensional space and establish the mapping relationship between the cutter position point and space point sets to further simplify the dimensions of the research object.Based on the in-cut cutting edge solved by the space limitation method,the dynamics of the inclined plane five-axis machining unit were studied,and the results were uniformly stored in the abstract space to produce a database.Finally,the prediction of the milling force and vibration state along the tool path became a data extraction process that significantly improved efficiency.Two experiments were also conducted which proved the accuracy and efficiency of the proposed dynamics analysis model.This study has great potential for the online synchronization of intelligent machining of large surfaces.