三相旋流抛光磨粒运动的测量与微气泡补偿

研究了气液固三相旋流流场抛光机理和规律。设计了三入口的抛光加工流道,对气液固三相旋流抛光流场进行了数值模拟。基于模拟结果设计了气液固三相磨粒流旋流流场测量平台,并通过粒子图像测速法(PIV)测量了微气泡补偿条件下气液固三相旋流抛光的流场参数,获得了微气泡补偿区域流场的运动图像、速度矢量图和涡量图。PIV测量试验数据显示:在微气泡补偿区域,磨粒速度主要集中在30m/s到80m/s,同一测量点高速磨粒出现频率明显增加,少数磨粒速度达到100m/s以上;磨粒平均速度从33.8m/s增大到44.2m/s,经4h抛光后硅片表面最大粗糙度从10.4μm下降到1.3μm。理论和试验研究表明,气液固三相旋流抛光流场中微气泡溃灭引发的空化冲击效应可增大磨粒动能,提高抛光效率,实现B区域的均匀化抛光。     

共轨管微小孔磨粒流抛光实验研究与表面粗糙度预测

针对共轨管微小孔电火花加工表面的光整加工问题,采用磨粒流抛光工艺,并通过正交实验探索了加工参数及其交互作用对孔道表面粗糙度的影响规律;基于二阶响应曲面模型和幂函数模型分别建立了表面粗糙度预测多元非线性回归模型。研究结果表明:加工参数对抛光效果的影响显著,而交互作用对其影响较小;抛光压强、磨料浓度及加工时间对孔道表面粗糙度的影响均为负效应,磨粒粒径大于148μm时对表面粗糙度的影响为正效应,粒径小于该临界值时表现为对抛光效率的正效应影响;在最优参数组合条件下,孔道表面粗糙度值(Ra)由初始的1.31μm降至0.20μm;二阶多项式回归模型相对于幂函数回归模型有更高的预测精度,相关系数高达0.990,预测误差在9.54%以内。     

不锈钢孔磨粒流抛光工艺参数的选择

针对磨粒流抛光加工不同孔径的工艺参数确定不合理,从而导致加工质量无法达到要求的实际生产问题,采用流体数值模拟方法对磨粒流抛光过程中流体磨料在抛光孔的流动状态进行数值模拟分析,得到了进口压力与孔径和孔深的变化关系。实际加工试验验证了数值模拟结论的正确性,并结合数值模拟给出了可用于指导实际生产的不同孔径及其孔深的磨粒流加工工艺参数的选取规则。     

深孔钻表面磨粒流抛光精化工艺与应用

以深孔钻为研究对象,研究磨粒流抛光对刀具表面的影响因素,并对传统磨粒流抛光工艺进行优化,提出刀具旋转抛光方案,并通过正交试验研究抛光压力、刀具转速、加工时间、磨料浓度等工艺参数对刀具表面粗糙度的影响规律。试验结果表明:磨粒流抛光可以有效改善刀具表面质量,并显著改善深孔钻的排屑能力,进而有效提高刀具的切削性能。     

喷油嘴微孔磨粒流抛光数值模拟与试验

以喷油嘴喷孔为研究对象,采用kε固液两相Mixture湍流模型对磨粒流抛光过程中流场分布规律进行数值模拟,并通过正交试验探索了抛光压力、磨料浓度、磨粒粒径及加工时间等工艺参数对被抛光微孔表面粗糙度的影响规律。结果表明：喷油嘴微孔磨粒流单向循环抛光加工有利于改善喷孔结构;流道表面粗糙度与各加工参数均成负相关关系,且受抛光压力及磨料浓度影响显著。通过试验获得了最优参数组合,在此条件下喷油嘴微孔表面粗糙度值(Ra)由初始的1.16μm降至0.20μm。     

激光面加工熔凝区的低压磨粒流抛光影响因素的实验研究

为研究低压磨粒流抛光激光面加工熔凝区的可行性,构建旋转式低压磨粒流抛光装置对激光加工铜片进行抛光实验,并采用不同评定方法描述磨料种类、挤压力、抛光时间对抛光效果的影响.结果表明:采用低压磨粒流抛光可有效去除激光面加工熔凝区;在低压范围内,材料去除量会随磨料含量、抛光时间呈非线性增长,随挤压力呈接近线性增长;抛光初期表面粗糙度变化幅度较小,抛光一段时间后变化幅度会显著增大.     

激光诱导空泡微孔抛光机理及实验研究

针对微孔抛光的问题,提出了一种新的抛光方法,该方法利用激光聚焦水中产生空泡,并利用激光等离子体冲击波、空泡溃灭冲击波和射流推送磨粒进行微孔抛光。通过高速摄影仪和高频动态压力传感器对激光诱导空泡机理进行了研究。利用不同激光脉冲能量、脉冲次数和脉冲频率对304不锈钢管进行抛光实验,发现随着激光脉冲能量（7~21.6mJ）和脉冲次数（0~7000）的增加,微孔表面粗糙度也随之改善;同时激光在低脉冲频率（1~10Hz）情况下,改变脉冲频率的大小对微孔的抛光效果影响不大。对微孔在不同位置的抛光效果进行了对比分析,发现孔入口1~1.5mm处的抛光效果较好,孔中和孔尾的抛光效果不佳。通过激光诱导空泡微孔抛光机理和实验研究,表明微孔抛光过程是激光等离子体冲击波、空泡溃灭冲击波和射流共同作用的过程,并得到了激光微孔抛光的一般规律。     

模具液流悬浮抛光动态参数研究

为解决模具复杂型腔及异形孔自动化抛光问题,首先建立了模具液流悬浮抛光系统,开发了液流动压力监测平台,实现了抛光工具位置及转速控制;之后结合液流动压理论,分析了模具材料去除模型,获得了流场与压力分布规律;接着通过试验研究了转速和间隙对液流动压力的影响规律;最后优选了6 000 r/min转速和60μm间隙对模具工件进行了...     

GMR硬盘磁头自由磨粒抛光极尖沉降的研究

磁头表面极尖沉降(PTR)是影响硬盘存储密度的关键因素之一。采用修正环形浮动块研磨抛光机和自由磨粒抛光方式抛光GMR硬盘磁头,并用原子力显微镜测试磁头的PTR,抛光试验表明:PTR与抛光盘表面形貌参数、磨粒大小、抛光压力和抛光盘转速有关。抛光盘表面取合适的形貌参数可以获得小的PTR;磨粒越小,PTR越小;抛光压力越大,PTR越小;抛光盘转速越小,PTR越小。研究结果有助于优化抛光工艺,在获得最佳PTR的同时,兼顾效率与成本的因素。     

剪切增稠抛光磨料液的制备及其抛光特性

为了实现对工件的剪切增稠抛光(STP),采用机械混合与超声波分散法制备了一种Al2O3基STP磨料液,并研究了它们的抛光特性。利用应力控制流变仪考察其流变性能,通过扫描电镜和光学轮廓仪研究了单晶硅加工后表面显微组织的变化,并测量其表面粗糙度。结果表明:STP磨料液具有剪切变稀和可逆的剪切增稠特性,达到临界剪切速率后,会形成Al2O3"粒子簇";当剪切速率增大至1000s-1,储能模量,耗能模量和耗散因子都增至最大值,此时主要表现为类似固体的弹性行为,有利于形成类似"柔性固着磨具"。在STP加工单晶硅过程中,采用塑性去除的材料去除方式。随着抛光时间的延长,硅片去除速率先增大后减小;表面粗糙度不断减小并趋于稳定。实验显示,磨粒浓度不宜过高,否则会因剪切增稠效应造成黏度过大,导致流动性差而影响抛光质量。当Al2O3质量分数为23%时,抛光25min后,硅片表面粗糙度Ra由422.62nm降至2.46nm,去除速率达0.88μm/min,表明其能实现单晶硅片的高效精密抛光。     

Finishing of structured surfaces by abrasive polishing

A new polishing process for the finishing of structured optical elements was introduced by the authors. Abrasive polishing using pin type and wheel type polishing tools made of polyamide was applied to improve the surface roughness of structured molds exhibiting fly-cut and precision ground V-grooves. Surface roughness of abrasive polished sides of V-grooves was found to be about 5 nm Ra. Furthermore, material removal rates were determined according to Preston's equation resulting in increasing removal rates with increasing polishing pressure and relative velocity. Material removal in abrasive polishing of structured surfaces was observed to be caused mainly by two-body abrasion but also by three-body abrasion, depending on relative velocity and polishing pressure. Tribological investigations showed that in abrasive polishing of structures mainly micro-ploughing and less micro-cutting occurs.     

利用复合磨粒抛光液的硅片化学机械抛光

为了提高硅片的抛光速率,利用复合磨粒抛光液对硅片进行化学机械抛光.分析了SiO2磨粒与聚苯乙烯粒子在溶液中的ζ电位及粒子间的相互作用机制,观察到SiO2磨粒吸附在聚苯乙烯及某种氨基树脂粒子表面的现象.通过向单一磨粒抛光液中加入聚合物粒子的方法获得了复合磨粒抛光液.对硅片传统化学机械抛光与利用复合磨粒抛光液的化学机械抛光进行了抛光性能研究,提出了利用复合磨粒抛光液的化学机械抛光技术的材料去除机理,并分析了抛光工艺参数对抛光速率的影响.实验结果显示,利用单一SiO2磨料抛光液对硅片进行抛光的抛光速率为180 nm/min;利用SiO2磨料与聚苯乙烯粒子或某氨基树脂粒子形成的复合磨粒抛光液对硅片进行抛光的抛光速率分别为273 nm/min和324 nm/min.结果表明,利用复合磨粒抛光液对硅片进行抛光提高了抛光速率,并可获得Ra为0.2 nm的光滑表面.     

Application of magnetic abrasive polishing to composite materials

Magnetic abrasive polishing (MAP) is an advanced machining process that can produce smoother surfaces in many material types. The present study conducted an experimental assessment of MAP for a newly developed, non-ferrous and aluminum-based composite material. A permanent magnet was installed under the workpiece to enhance its magnetic flux density, which had proved insufficient for effective MAP. The success of the permanent magnet in improving the surface roughness of the non-ferrous material was verified.     

无磨料低温抛光的工艺方法研究

对无磨料低温抛光这种全新的工艺方法进行了系统的研究,包括抛光设备、抛光冰盘的制备、工件盘的制备、抛光盘的修整、抛光后工件的清洗、抛光后表面粗糙度的测量等。并用此种方法对石英晶体进行了抛光实验,得到了Ra0．53mm的超光滑表面,结果证明这是一种获得超光滑表面的新方法。     

Copper polishing with a polishing pad incorporating abrasive grains and a chelating resin

This study sought to decrease dishing and erosion as they cause reduced yield in copper chemical mechanical polishing (Cu-CMP), which is a multilayer interconnect process that is a part of the overall semiconductor manufacturing process. We prepared a polishing pad that incorporated abrasive grains (AC Pad) and used a chelating resin in the matrix (resin). Moreover, we studied whether this polishing pad was applicable to the Cu-CMP process. Results indicated that the pad was selectively abrasive to copper (Cu) and that in the polishing of patterned wafers, it vastly decreased dishing to 1/8th and erosion to half of their respective levels in abrasive polishing. Therefore, the pad has considerable potential for use in Cu-CMP.     

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.     

气-液-固三相磨粒流光整加工及其工艺参数优化

考虑用流体抛光法加工大尺度工件存在效率低下问题,本文提出了一种气-液-固三相磨粒流抛光方法。该方法在约束流场中引入微纳米气泡,利用气泡在溃灭时释放的能量加速驱动磨粒运动,从而有效提升抛光效率。实验显示:在加工过程中,离心泵的发热会导致流体黏度下降,进而影响工件近壁面的湍动能和动压力的大小及分布,而加工工件近壁面的湍动能和动压力会对表面纹理的均匀性和材料的去除效率有重要影响。针对上述实验结果,文中基于对磨粒流抛光机理的研究,提出一种通过改变入口流速来补偿温升带来的湍动能和动压力变化的方法,实验求得了抛光流体温度从20℃到60℃之间的9个均等点对应的最优入口流速值。实验表明,相对未加入气泡时,该抛光方法的加工效率得到提高,而调速补偿明显提升了工件表面加工质量。     

Abrasive removal depth for polishing a sapphire wafer by a cross-patterned polishing pad with different abrasive particle sizes

The paper establishes a new theoretical model for abrasive removal depth for polishing a sapphire wafer using chemical mechanical polishing with a polishing pad that has a cross pattern. The theoretical model uses binary image pixel division to calculate the pixel polishing times. An abrasive contact model for single-pixel multiple abrasive particles, to estimate the contact force between a single abrasive particle and the wafer, is then established. When the contact force is calculated, it is possible to calculate the abrasive depth of a single abrasive particle on the surface of the sapphire wafer. Using this theoretical model, carring a numerical simulation with a slurry of the same concentration, but with different abrasive particle diameters, determines the removal volume and average abrasive removal depth at each pixel position and the surface condition of the wafer. The simulation result is also compared with experimental data, in order to verify that the new model is feasible.     

A phenomenological model of polishing of silicon with diamond abrasive

A phenomenological model of polishing hemispherical silicon asperities with spherical diamond abrasives is presented. Removal of the asperity material is quantitatively determined by a removal rate constant K. It is based on our molecular dynamics (MD) simulation studies considering the probability of removal of asperity atoms by an abrasive. The dependence of the removal rate constant K on the diameter and velocity of abrasives, number of asperities and abrasives per unit area, and cutting depth has been investigated. The rate constant K is found to be insensitive to the density of asperities, but linearly dependent on the density of abrasives.