陶瓷球高效超光滑磁流变柔性抛光新工艺研究

目的为实现陶瓷球表面的高效超光滑抛光,提出一种集群磁流变抛光陶瓷球的新工艺。方法在传统V型槽抛光陶瓷球的基础上增加集群磁极和上盘旋转动力,配制适当的磁流变抛光液,通过在上下抛光盘的集群磁极,形成磁流变抛光垫包覆陶瓷球,进行研磨抛光加工。然后,基于陶瓷球工件几何运动学和动力学分析得到球体各运动参数的影响关系,利用机械系统分析软件ADAMS对成球过程进行动态仿真,可以看出该抛光方法能够主动控制球体的运动,实现球面抛光轨迹的快速均匀全包络。最后,根据仿真结果,通过调整上下抛光盘的转速比、偏心距和加工间隙等参数,控制陶瓷球的自转角,实现球面的快速高效超光滑抛光。结果用自行设计的陶瓷球集群磁流变抛光实验装置,对氮化硅陶瓷球进行抛光2.5 h,表面粗糙度Ra从60 nm左右下降到10 nm左右,球形误差为0.13μm,达到了陶瓷球轴承氮化硅球的国家标准(G5水平)。结论集群磁流变抛光方式可以实现球面抛光轨迹的快速均匀全包络,实现陶瓷球表面的高效超光滑抛光,值得进一步深入探讨研究。     

新型钢抛光液中磨料的种类及其性能研究进展

磨料在抛光液中主要起机械作用,磨料的理化性质,如硬度、粒径、浓度等,是影响化学机械抛光(Chemical Mechanical Polishing,CMP)性能的重要因素,对抛光效率有较大影响。针对我国抛光液对外依赖、需求量大,但精度等指标达不到市场要求等问题,同时由于磨料在抛光液的抛光性能中起着至关重要的作用,因此寻求效果更好的改性磨料或新型磨料材料,以促进化学机械抛光技术的发展势在必行。故此,归纳汇总近年来国内外研制出的新型钢抛光液,聚焦于抛光液磨料这一重要组分中不同物质的物化性质及其作用,对抛光性能(如材料去除率、表面粗糙度和光泽度等)的影响等,分类别阐述了不同物质的优劣势、复配协同作用以及在现有抛光液中的效果,为之后抛光液配方研究中磨料的选择提供参考。归纳总结发现,混合与复合磨料较单一磨料有较大的提升,稀土掺杂、核/壳结构等改进存在较大的研究价值,组分间的复配协同作用对抛光性能的提升有一定作用。最后,基于目前钢抛光液应用中存在的问题以及现有的具有前景的技术,对钢抛光液中磨料的发展进行了展望。     

导体镶嵌型巨电流变抛光液及其对硅材料的抛光

目的 解决现有电流变抛光液在电场下强度低和使用寿命短等问题。方法 分析现有电流变抛光液的缺点及其原因,提出将新型巨电流变液——导体镶嵌型电流变液应用于抛光领域,并研制出以二氧化硅为磨料,以镶嵌了纳米碳的二氧化钛为电介质颗粒的硅油基电流变抛光液。测定添加了不同粒径磨料抛光液的剪切强度与电场强度、温度、使用时间的关系。搭建简易的旋转式电流变抛光装置,对不同粒径磨料的电流变抛光液在硅片表面的抛光效果进行试验。结果 碳镶嵌二氧化钛基电流变抛光液具有高剪切强度(>30kPa)、低漏电流(<1μA)、高温度稳定性(25～125℃)、长使用寿命和对少量磨料不敏感等优点。抛光实验结果表明,在电压2.5 kV下,硅片经过添加了2μm磨料的电流变抛光液持续抛光3 h后,其表面粗糙度从206nm降至6.4nm。之后再采用添加200nm磨料和20nm磨料的抛光液先后继续精抛后,其粗糙度降至0.46 nm和0.36 nm。结论 碳镶嵌二氧化钛基巨电流变抛光液能有效降低表面粗糙度,改善表面质量,很好地应用于精密抛光领域,展示出良好的应用前景。     

基于稳定pH值的硅衬底晶圆抛光液成分优化

目的 探究不同配比方案配制pH值相同的抛光液对抛光去除速率、抛光液寿命和表面粗糙度的影响,优化硅衬底晶圆抛光液,使其满足半导体产业的发展要求。方法 以二氧化硅水溶胶为磨料,通过设置有机碱、pH缓冲剂、pH稳定剂的不同配比来调节和稳定抛光液的初始pH值(11.0~12.0),在最佳工艺参数下循环使用抛光液对2英寸(1英寸≈2.54 cm)硅衬底晶圆进行抛光实验。研究不同配比下抛光液pH值、抛光去除速率随抛光液循环使用时间的变化情况。对比实验结果,分析各种成分在抛光过程中的作用,以及对抛光效果产生的影响,得出最佳配比方案,优化抛光液方案。结果 通过优化硅衬底晶圆的抛光液方案,使抛光去除速率达到0.804 μm/min,抛光液的寿命延长了约114.29%,抛光后硅衬底晶圆的表面粗糙度最低为0.156 nm。结论 得到了抛光液的最佳配比方案,有机碱的质量分数为1.0%,pH缓冲剂的质量分数为1.1%,并加入pH稳定剂调节pH,使其抛光去除速率、抛光液寿命、表面粗糙度都得到很大提升。     

固结磨料研磨与抛光的研究现状与展望

分析了传统游离磨料研磨抛光存在的缺点和固结磨料的研磨抛光的优点;阐述了固结磨料研磨抛光的材料去除机制以及固结磨料研磨盘抛光技术在氮化硅陶瓷加工、半导体制程中的应用;介绍了多种固结磨料研磨盘、抛光垫的制作方法;并展望了固结磨料的研磨抛光的发展趋势。     

CMP抛光半导体晶片中抛光液的研究

本文分析了化学机械抛光(CMP)半导体晶片过程中抛光液的重要作用,总结了抛光液的组成及其化学性能(氧化剂、磨料及pH值等)和物理性能(流速、粘性及温度)对抛光效果的影响规律,研究发现:酸性抛光液常用于抛光金属材料,pH最优值为4,碱性抛光液常用于抛光非金属材料,pH最优值为10～11.5;氧化剂能有效提高金属材料的抛光效率和表面平整度;磨料的种类、浓度及尺寸会影响抛光效果;分散剂有助于保持抛光液的稳定性;抛光初始阶段宜采用较低流速,然后逐渐提高;抛光液的粘性会影响晶片与抛光垫之间的接触模式、抛光液的均布、流动及加工表面的化学反应;抛光液温度的升高有助于提高抛光效率.最后本文指出了抛光液循环使用的重要意义及常用方法.     

抛光液中磨料和化学成分对单晶MgO基片化学机械抛光的影响

采用扫描电子显微镜和高分辨粒径分析仪对不同抛光液中磨料形貌、平均粒径大小和粒径分布范围进行观测分析,研究了SiO2磨料特性及各种无机酸对单晶MgO基片抛光材料去除率和表面粗糙度的影响.试验结果表明,使用粒径分布较窄的球形磨料和磷酸反应剂配制成抛光液,可以得到较高的材料去除率和较低的基片表面粗糙度.通过对抛光参数的进一步优化,采用抛光压力42 kPa,抛光转数100 r/min和抛光液流量30 mL/min,对单晶MgO基片进行化学机械抛光加工,单晶MgO基片抛光材料去除率可达到400 nm/min,抛光后的基片表面粗糙度Ra降低至0.4 nm.该抛光工艺已具有一定的实用价值.     

氧化锆陶瓷大抛光模磁流变抛光试验研究

目的研发一种高效、高质量氧化锆陶瓷超光滑表面加工技术。方法采用大抛光模磁流变抛光方式加工氧化锆陶瓷,利用自主研发的磁流变平面抛光装置,配制含有金刚石磨粒的磁流变抛光液,通过设计单因素实验,研究抛光时间、工作间隙、工件转速和抛光槽转速等主要工艺参数对氧化锆陶瓷平面磁流变加工性能的影响,并对材料去除率和表面粗糙度进行分析。结果在工作间隙为1.4 mm、工件转速为100 r/min、抛光槽转速为25 r/min的工艺条件下,表面粗糙度在达到饱和之前随时间的增加而降低。抛光30 min达到饱和,表面粗糙度Ra达到0.7 nm。继续延长抛光时间,表面粗糙度不再改善。氧化锆陶瓷的材料去除率随着工件转速和抛光槽转速的增加而增大,随着工作间隙的增大而减小。当工件转速为300 r/min时,材料去除率可以达到1.03 mg/min;抛光槽转速为25 r/min时,材料去除率可以达到0.80 mg/min;工作间隙为1.0 mm时,材料去除率最高可达0.77 mg/min。结论采用大抛光模磁流变抛光方法可以提高氧化锆陶瓷的材料去除率,同时获得纳米级表面粗糙度,实现氧化锆陶瓷的高效超光滑表面加工。     

磁流变抛光技术的工艺试验

本文研究了利用自行配制的水基磁流变抛光液和抛光样机,进行了以抛光去除效率和表面粗糙度为考核指标的工艺实验,试验中所用工件为直径12mm的BK7玻璃零件,其初始表面粗糙度的均方根值为RMS1．41nm,经抛光后得到理想的表面粗糙度的均方根值为RMS0．61nm的玻璃工件,结果表明：随着磁流变抛光磁场强度的增加,抛光去除效率逐渐提高,但表面粗糙度的值随之降低;抛光盘转速的提高能促进抛光效率的提高,降低表面粗糙度值;抛光盘与工件间的间隙的减小有利于提高抛光效率但同时使表面粗糙度变差。     

pH 值和表面活性剂对硅溶胶 CMP 抛光液的影响

目的研究pH值以及表面活性剂种类对CMP抛光液稳定性及抛光性能的影响。方法向硅溶胶中加入酸性或碱性pH值调节剂,配制不同pH值的CMP抛光液;通过添加不同类型的表面活性剂,研究表面活性剂对抛光液的稳定机理。结果硅溶胶CMP抛光液pH值为9.5时,加入非离子表面活性剂,抛光90 min后,铝合金表面粗糙度降低了55.4%,光亮度增加了131%,抛光质量较好。结论弱碱环境下,抛光液的稳定性和抛光性能优良,非离子表面活性剂有利于CMP抛光液的稳定性。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

Thermodynamics Study on the Decomposition of Chromite with KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

Influence of Heat Treatment on Damping Behaviour of the Magnesium Wrought Alloy AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.     

电化学噪声数据处理方法概述

综述了常见的电化学噪声数据处理方法,介绍了直流趋势剔除、统计分析、快速傅立叶变换(FFT)法计算功率谱密度(PSD)以及小波变换处理电化学噪声信号的基本过程,并阐释了各种数学处理及所得参数的物理意义。