磁流变变间隙动压平坦化加工力特性研究

磁流变变间隙动压平坦化加工利用工件的轴向低频振动使磁流变液产生挤压强化效应,可以有效提高加工效果并使光电晶片快速获得纳米级表面粗糙度。通过旋转式测力仪试验研究不同变间隙参数对磁流变变间隙动压平坦化加工过程中抛光正压力的影响规律,结果表明,在工件轴向低频振动作用下,抛光正压力形成脉冲正值和负值周期性的动态变化过程;将工件轴向低频振动过程分解为下压过程与拉升过程,下压速度和拉升速度对动态抛光力有不同的响应特性;随着最小加工间隙的减小抛光正压力会急剧增大;设置最小加工间隙停留时间观察抛光正压力变化,可以发现在工件最小加工间隙停留期间抛光力从峰值逐渐衰减并趋于平稳;挤压振动幅值对抛光正压力影响较小。建立了磁流变变间隙动压平坦化加工材料去除模型,弄清了在动态压力作用下,磨料更新及其附加运动机制,研究了磁流变变间隙动压平坦化加工过程中磨料颗粒对工件表面柔性划擦和微量去除的作用机理,为磁流变变间隙动压平坦化加工的工艺优化提供了理论依据。     

集群磁流变效应平面抛光力特性试验研究

集群磁流变平面抛光加工硬脆材料可以高效率获得纳米/亚纳米级表面粗糙度,其中集群磁流变效应抛光垫对加工表面的作用力(抛光力)是材料去除的关键因素,搭建了集群磁流变平面抛光三向测力平台,对模拟的集群磁流变抛光加工过程抛光力(切向力F_t和法向力F_n)进行了系统试验研究。结果表明,2'单晶硅片试验条件下集群磁流变平面抛光切向力Ft最大达到32.25 N、法向力Fn最大达到62.35 N、F_t/F_n值为0.46~0.77;对抛光力影响最大的工艺参数是磁场强度和加工间隙,其次是羰基铁粉与磨料质量分数、磁流变液流量、抛光盘转速,工件摆幅与速率影响最小。集群磁流变平面抛光力大小以及Ft/Fn值随着工件材料硬度的增大而增大,具有低正压力高剪切力特征,有利于提高硬脆材料的超光滑平坦化抛光加工效果。     

磷化铟的动态磁场集群磁流变抛光工艺实验

为实现磷化铟高质量表面的绿色加工,使用动态磁场集群磁流变抛光对单晶磷化铟进行正交抛光实验,研究各工艺参数（抛光盘转速、工件转速、磁极转速和偏摆速度）对抛光速率及抛光表面粗糙度的影响。利用回归分析法建立反映材料去除率及表面粗糙度与抛光工艺参数关系的回归方程。结果显示：在抛光工艺参数中,工件转速对材料去除率影响最大,偏摆速度影响最小;对表面粗糙度影响最大的是抛光盘转速,磁极转速影响最小;在优化工艺参数（抛光盘转速40 r/min、工件转速500 r/min、磁极转速30 r/min、偏摆速度200 mm/min）下对单晶磷化铟抛光3 h后,表面粗糙度由Ra33 nm降至Ra 0.35 nm,材料去除率为2.5 μm/h,表明采用动态集群磁流变抛光的方法加工单晶磷化铟,可以得到高质量加工表面;建立的材料去除率及表面粗糙度回归模型,拟合优度判定系数分别为0.984 2和0.937,表明利用回归分析法建立的磷化铟磁流变抛光的材料去除率及表面粗糙度回归模型,能够有效地预测磷化铟集群磁流变抛光效果。     

基于固结磨粒的单晶蓝宝石自旋转磨削加工方法

利用固结磨粒自旋转磨削加工方法，通过金刚石磨削和化学机械磨削实现了蓝宝石晶片的高效、高质量平坦化加工。采用不同磨粒粒径的金刚石砂轮实现了蓝宝石晶片较高的材料去除率或较好的表面质量。开发了高磨粒浓度Cr2O3砂轮，采用化学机械磨削对金刚石磨削后的蓝宝石晶片进行平坦化加工。实验结果表明，化学机械磨削能够去除金刚石磨削的表面和亚表面缺陷，最终获得表面粗糙度Ra＜1 nm、无/微损伤的蓝宝石晶片。通过理论分析单颗金刚石磨粒的磨削力，发现磨粒粒径是影响材料去除率和表面质量的主要影响因素。通过XPS分析证明了Cr2O3和蓝宝石之间的固相反应过程。     

铝合金阳极氧化膜的集群磁流变平面抛光试验研究

为获得抛光均匀的铝合金阳极氧化膜表面,采用集群磁流变平面抛光技术对铝合金阳极氧化膜进行抛光试验,探讨加工间隙、工件转速、抛光盘转速、偏摆幅度、加工时间等加工参数对其表面粗糙度和材料去除率的影响规律。结果表明:随着加工间隙的增大,工件表面粗糙度先减小后增大,材料去除率则递减;随着工件转速或偏摆幅度的增加,工件的表面粗糙度均先迅速减小后缓慢增大,材料去除率则先增加后减小;随着抛光盘转速的增加,工件的表面粗糙度和材料去除率均先减小后增加;随着加工时间的延长,表面粗糙度迅速减小之后趋于稳定。在文中试验条件下,在加工间隙1. 1 mm、工件转速350 r/min、抛光盘转速60 r/min、偏摆幅度10 mm、加工10 min左右时工件表面粗糙度从原始的332. 9 nm下降至5. 2 nm,达到了镜面效果。     

集群磁流变效应抛光垫的磨粒“容没”效应机理研究

针对集群磁流变抛光加工方法,研究了集群磁流变效应抛光垫对磨粒的"容没"机理。通过建立磨粒"容没"模型,并在磁流变抛光工作液中掺杂大尺寸磨粒对K9光学玻璃与硅片进行抛光加工实验,发现在粒径为0.6μm的磨粒中掺杂粒径为1.8μm的金刚石粉进行抛光后的表面质量优于粒径为1.1μm的磨粒加工的表面质量,且发现随着掺杂磨粒尺寸的增大,加工表面的Ra、Rv值虽有增大,但增长幅度远小于同等状况下游离磨粒加工的增长幅度。研究结果表明:集群磁流变效应抛光垫的磨粒"容没"效应能够使粒径不同的磨粒均匀作用于工件表面,显著减小甚至消除大尺寸磨粒对加工表面造成的损伤。     

圆柱型永磁体磁流变抛光头设计及其参数优化

针对传统加工技术存在表面损伤、加工效率低的问题,将极具前景的面接触式超精密磁流变抛光技术应用到3C制造业中。对圆柱型永磁体磁流变抛光头在加工过程中的抛光垫的形貌进行了研究分析,发现圆柱型永磁体磁流变抛光头在加工过程中存在一种"环状效应",利用"环状效应"对圆柱型永磁体磁流变抛光头进行了结构设计,并对其进行了设计理念分析;对圆柱型永磁体抛光头在6061的铝合金工件上进行了单因素抛光实验,通过实验获得了最优参数。研究结果表明:该圆柱型永磁体磁流变抛光头能够实现环状加工区域的高效光滑平坦化加工,工件表面粗糙度达到52 nm,材料去除率达9.1μm/min,大大提高了磁流变抛光的效率,为面形精度在微米级的超光滑平面的制造提供了一种高效的加工方法。     

不同粒径金刚石固结磨料抛光硫化锌晶体研究

磨粒粒径是影响抛光最重要的参数之一,是决定加工效率和工件表面质量的关键要素。采用1~3μm、2~4μm、3~5μm 3种粒径的金刚石固结磨料抛光垫加工硫化锌晶体,分析磨粒粒径对工件表面质量和材料去除率的影响。实验结果表明,磨粒粒径对硫化锌晶体的固结磨料抛光影响显著,随着磨粒粒径的增大,固结磨料抛光硫化锌晶体的材料去除率增大,而表面质量变差。2~4μm金刚石固结磨料抛光垫加工硫化锌晶体可同时获得高材料去除率和优表面质量,材料去除率达到100 nm/min,表面粗糙度为4.37 nm。     

水膜吸附夹持方式在蓝宝石抛光中的可行性研究

针对目前蓝宝石抛光加工中所使用的石蜡粘贴夹持方式和抛光抛光吸附垫吸附夹持方式在抛光质量和成本等方面所存在的问题,提出了水膜吸附夹持方式,对水膜吸附环境下,吸附表面对蓝宝石晶片的法向吸附力和切向吸附力进行了测量,并分别与抛光吸附垫对蓝宝石晶片的法向吸附力和切向吸附力进行了比较,将切向吸附力作为主要评价指标,判断在蓝宝石晶片抛光加工中使用水膜吸附夹持方式的可行性。实验结果表明:单从吸附能力的层面考虑,在蓝宝石晶片抛光加工中使用水膜吸附夹持方式是可行的;45#钢比玻璃更适合作为吸附表面材料;确定吸附表面的粗糙度时应考虑蓝宝石晶片的表面粗糙度。     

单晶SiC基片的集群磁流变平面抛光加工

基于集群磁流变效应超光滑平面抛光理论及研制的试验装置,对单晶SiC基片进行了平面抛光试验研究。研究结果表明,金刚石磨料对单晶SiC基片具有较好的抛光效果;加工间隙在1.4mm以内抛光效果较好,30min抛光能使表面粗糙度值减小87%以上;随着加工时间的延长,表面粗糙度越来越小,加工30min时粗糙度减小率达到86.54%,继续延长加工时间,加工表面粗糙度趋向稳定。通过优化工艺参数对直径为50.8mm(2英寸)6H单晶SiC进行了集群磁流变平面抛光,并用原子力显微镜观察了试件加工前后的三维形貌和表面粗糙度,发现经过30min加工,表面粗糙度Ra从72.89nm减小至1.9nm,说明集群磁流变效应超光滑平面抛光用于抛光单晶SiC基片可行有效且效果显著。     

ABRASIVE-BASED NANO-FINISHING TECHNIQUES: AN OVERVIEW

The surface finishing techniques can be divided into two categories: traditional and advanced. To overcome some of the problems of traditional finishing techniques, hybridized processes have been evolved by the researchers. Some of the advanced finishing processes that have been reviewed are abrasive flow machining (AFM), magnetorheological finishing (MRF), magnetorheological abrasive flow finishing (MRAFF), magnetic abrasive finishing (MAF), chemo mechanical polishing (CMP), etc. Most of these processes have been developed in the recent past and they can be employed to produce optical, mechanical, and electronic components with micrometer or sub-micrometer form accuracy and surface roughness within nanometer range with hardly any surface defects. However for large size flat components, MAF seems to be the most suitable finishing process. In MAF, DC power supply is given to the electromagnet hence intermixing of ferromagnetic abrasive particles during the process does not take place and the worn out cutting edges keep interacting with the workpiece surface. As a result, the finishing rate is quite low. The use of pulsed DC power supply to the electromagnet results in pulsating flexible magnetic abrasive brush (P-FMAB), which substantially enhances the finishing rate. The on-line measurement of the forces has helped in understanding the mechanism of material removal during Static-FMAB (S-FMAB) and Pulsating-FMAB. The magnitude of normal magnetic force (originating indentations) in P-FMAB has been found to be dynamic in nature and substantially high in magnitude as compared to S-FMAB.     

超声波磁流变复合抛光中几种工艺参数对材料去除率的影响

提出了一种光学抛光的新方法——超声波磁流变复合抛光。介绍了该抛光方法的基本原理和实验装置,进行了超声波磁流变复合抛光实验,采用轮廓仪实测了光学玻璃超声波磁流变抛光材料去除轮廓曲线。通过该项工艺实验,研究了五种工艺参数(磁场强度、超声振幅、抛光工具头与工件的间隙、抛光工具头转速、工件转速)对光学玻璃材料去除率的影响。在一定实验条件下,获得的材料去除率为0.139 μm/min,并获得了超声波磁流变复合抛光工艺参数与材料去除率的关系曲线,得出了光学玻璃超声波磁流变复合抛光的材料去除规律。     

Analysis of magnetorheological abrasive flow finishing (MRAFF) process

A new precision finishing process called magnetorheological abrasive flow finishing (MRAFF), which is basically a combination of abrasive flow machining (AFM) and magnetorheological finishing (MRF), has been developed for nano-finishing of parts even with complicated geometry for a wide range of industrial applications. In this paper microstructure of the mixture of magnetic and abrasive particles in magnetorheological polishing fluid (MRPF) has been proposed, and normal force on the abrasive particles is calculated from the applied magnetic field. A model for the prediction of material removal and surface roughness achieved has also been presented. And, finally theoretical results are compared with the experimental data available in the literature, and they are found to agree well.     

高浓度硼扩散硅片CMP工艺研究

"叉指式微加速度计"的研制,需要使用高浓度硼扩散硅片,而硅片经过高浓度硼扩散后,硅片双面生长了一层硼硅玻璃,很难将其去除,不能在高浓度硼扩散层上制作更好的"叉指式微加速度计"结构.针对上述问题,在CMP研磨抛光工艺中,针对上述问题,在CMP研磨抛光工艺中,选择合适的研磨料和抛光料以及研磨盘和抛光盘,通过对浆料浓度、流量大小、抛光温度进行改进,优化研磨抛光工艺流程及工艺参数,以完成高浓度硼扩散硅片的表面平坦化.     

Effects of particle size, polishing pad and contact pressure in free abrasive polishing

The objective of this research is to better understand the mechanisms of material removal in the free abrasive polishing process. Experiments were carried out to understand the effects of particle size, polishing pad and nominal contact pressure on the wear rate and surface roughness of the polished surface. A theoretical model was developed to predict the relationship between the polishing parameters and the wear rate for the case of hard abrasive particles sandwiched between a soft pad and a workpiece (softer than the abrasive particles). Experimental results and theoretical predictions indicate that the wear rate increases with an increase in particle size, hardness of polishing pad and nominal contact pressure, and with a decrease in elastic modulus of the polishing pad. Surface roughness increases with an increase in particle size and hardness of polishing pad, and nominal contact pressure has little effect on the roughness. A dimensionless parameter, wear index which combines all of the preceding parameters, was introduced to give a semi-quantitative prediction for the wear rate in free abrasive polishing. It is also suggested that when polishing hard material, in order to achieve a high materials removal rate and a smooth surface, it is preferable to use diamond as the polishing particles because of their high deformation resistance.     

超声磁力复合研磨钛合金锥孔的试验研究

为了提高钛合金锥孔的研磨质量和研磨效率,提出了采用超声波振动辅助磁力研磨的复合加工方案。加工时,磨粒在磁场束缚下切削锥孔表面,并对其进行不断撞击,且因为磁场力、超声振动力和离心力等综合影响的原因,磨粒的切削轨迹呈现明显的多向性。针对钛合金锥孔,与传统磁力研磨法进行试验对比,并分析研磨后试件的材料去除量、表面粗糙度和表面形貌等来验证超声磁力复合研磨的效果。结果表明：超声磁力复合研磨加工效率得到提高;锥孔的材料去除量增加至1.6倍;研磨后锥孔平均表面粗糙度由原始的R_a1.23 μm降至R_a0.25 μm,下降率是传统工艺的1.3倍;试件表面的微波峰、凹坑和加工纹理均被去除,锥孔表面质量得到显著提高,且试件形状精度得到改善。     

Polishing characteristics and mechanism in magnetorheological planarization using a permanent magnetic yoke with translational movement

Translational movement was integrated into a magnetorheological planarization process that uses a permanent magnet yoke with a straight air gap as magnetic source in order to improve surface planarity. The effects of the process conditions, including stroke and velocity of the translational movement, work and excitation gaps and concentration of carbonyl iron particles, on the polishing forces, surface roughness and volumetric removal rate were systematically investigated. The results showed that translational movement had insignificant effect on the polished surface finish, but considerably improved the surface planarity. The surface quality and volumetric removal rate were found to be affected by carbonyl iron particles concentration, and work and excitation gaps. Based on the parametric study, theoretical and empirical models were established for predicting the polishing forces, surface roughness and volumetric removal rate in this magnetorheological process.     

磁流变抛光的确定量加工模型与影响因素

根据抛光区内的受力分析，建立了磁流变超精密抛光的确定量加工模型，并通过工艺实验予以证明。研究了磁流液在磁场作用下的成核特点，分析了各工艺参数对磁流变抛光的材料去除率及表面粗糙度的影响规律。