Challenges in Processing Diamond Wire Cut and Black Silicon Wafers in Large-Scale Manufacturing of High Efficiency Solar Cells

Texturing of diamond wire cut wafers using a standard wafer etch process chemistry has always been a challenge in solar cell manufacturing industry. This is due to the change in surface morphology of diamond wire cut wafers and the abundant presence of amorphous silicon content, which are introduced from wafer manufacturing industry during sawing of multi-crystalline wafers using ultra-thin diamond wires. The industry standard texturing process for multi-crystalline wafers cannot deliver a homogeneous etched silicon surface, thereby requiring an additive compound, which acts like a surfactant in the acidic etch bath to enhance the texturing quality on diamond wire cut wafers. Black silicon wafers on the other hand require completely a different process chemistry and are normally textured using a metal catalyst assisted etching technique or by plasma reactive ion etching technique. In this paper, various challenges associated with cell processing steps using diamond wire cut and black silicon wafers along with cell electrical results using each of these wafer types are discussed.

Force Modeling for Ultrasonic-assisted Wire Saw Cutting SiC Monocryatal Wafers

The advantages, such as a small cutting force, narrow kerf and little material waste make wire saw cut- ting suitable for machining precious materials like SiC, Si monocrystal and a variety of gem. As regards wire saw cutting fo wafer, however, in traditional wire saw cutting process, the cutting efficiency is low, the wear of wire saw is badly, the surface roughness of wafer is poor etc, which have a seriously impact on the cutting process stability and the use of wafers. Ultrasonic-assisted machining method is very suitable for processing a variety of non-conduc- tive hard and brittle materials, glass, ceramics, quartz, silicon, precious stones and diamonds, etc. In this paper, the force model of ultrusonic-assisted wire saw cutting of SiC monocrystal wafer, based on the kinematic and experi- mental analysis were established. The single factor and orthogonal experimental scheme for different processing pa- rameters such as wire saw speed, part rotation speed of and part feed rate, were carried out in traditional wire saw and ultrasonic-assisted wire saw cutting process. The multiple linear regression method is used to establish the static model among the cutting force, processing parameters and ultrasonic vibration parameters, and the model signifi- cance is verified. The results show, as regards ultrasonic-assisted wire saw cutting of SiC monicrystal wafer, both the tangential and normal cutting forces can reduce about 24. 5%-36% and 36. 6%-40%.

切削液对金刚石线锯切割β-Ga_(2)O_(3)晶片表面质量的影响

为了开发出更适合β-Ga_(2)O_(3)晶片切片的切削液,探讨金刚石线锯切片过程中不同切削液对β-Ga_(2)O_(3)晶片表面质量的影响,通过测量接触角和表面张力,研究不同切削液对β-Ga_(2)O_(3)晶片表面的润湿性。采用粗糙度测量仪、非接触式测厚仪和扫描电镜(SEM)对晶片表面进行测试表征,研究去离子水、添加AEO-9的水基切削液和乳化切削液在不同工艺参数下对切割(010)面β-Ga_(2)O_(3)晶片的表面粗糙度、表面形貌、总厚度变化以及亚表面损伤层深度的影响。结果表明:与去离子水相比,添加AEO-9的水基切削液和乳化切削液均能有效降低β-Ga_(2)O_(3)表面的接触角和表面张力,表明2种切削液均可提高晶片表面润滑性;乳化切削液的效果随着工艺参数的变化而波动很大,只有在低切削热和大切削力的条件下,才能明显优化晶圆表面质量,而水基切削液可稳定地获得较高的晶片表面质量,更适用于β-Ga_(2)O_(3)晶片切割。

优化的CAN与1-Wire总线温度采集系统设计

针对长距离、大规模、高密度的温度场测量应用,研究了一种基于CAN总线与1-Wire总线的经济型系统解决方案。该方案以Cortex-M3处理器为核心,对CAN总线与1-Wire总线接口的硬件电路进行优化,增强了网络的稳定性。同时,从工程实际应用出发,阐述了大规模测点的优化管理与维护。该方案现已成功应用于某电厂200 MW机组的锅炉金属壁温在线检测系统,具有较好的工业应用前景。

CUTTING REGULARITY AND DISCHARGE CHARACTERISTICS BY USING COMPOSITE COOLING LIQUID IN WIRE CUT ELECTRICAL DISCHARGE MACHINE WITH HIGH WIRE TRAVELING SPEED

The analysis of cutting regularity is provided through using and comparing two typical cooling liquids. It is proved that cutting regularity is greatly affected by cooling liquid＇s washing ability. Discharge characteristics and theoretic analysis between two electrodes are also discussed based on discharge waveform. By using composite cooling liquid which has strong washing ability, the efficiency in the first stable cutting phase has reached more than 200 mm^2/min, and the roughness of the surface has reached Ra〈0.8 μm after the fourth cutting with more than 50 mm^2/min average cutting efficiency. It is pointed out that cutting situation of the wire cut electrical discharge machine with high wire traveling speed （HSWEDM） is better than the wire cut electrical discharge machine with low wire traveling speed （LSWEDM） in the condition of improving the cooling liquid washing ability. The machining indices of HSWEDM will be increased remarkably by using the composite cooling liquid.

TC4钛合金HF-HNO_(3)化学抛光的表面质量和元素机理分析

为了提升电火花线切割(Wire cut Electric Discharge Machining,WEDM)加工后的TC4钛合金表面质量,减少表面重熔层厚度,采用不同浓度配比(1∶4、1∶6和1∶8)的HF-HNO_(3)酸蚀溶液对钛合金试件进行化学抛光处理。实验结果表明,HF-HNO_(3)酸蚀溶液能使钛合金重熔层得到显著去除,表面微裂纹得到有效控制;当HF-HNO_(3)酸蚀溶液的浓度配比为1:6时,试件能获得最低的表面粗糙度和最大的表面粗糙度下降率,并且抛光前后钛合金表面元素含量发生了不同程度的变化,Ti、Al和V元素质量分数分别提高了21.5%、41.3%和13.2%,而O、C元素质量分数分别降低了82.5%和33.6%;HF-HNO_(3)酸蚀溶液可显著改善TC4钛合金试件电火花线切割加工后的表面缺陷。钛合金重熔层结构的主要成分与化学抛光后氧化膜的主要成分相似,但与氧化膜的结构不同,这对TC4钛合金试件表面质量提升具有重要意义。

Layer regrouping for water-flooded commingled reservoirs at a high water-cut stage

Layer regrouping is to divide all the layers into several sets of production series according to the physical properties and recovery percent of layers at high water-cut stage, which is an important technique to improve oil recovery for high water-cut multilayered reservoirs. Dif- ferent regroup scenarios may lead to different production performances. Based on unstable oil-water flow theory, a multilayer commingled reservoir simulator is established by modifying the production split method. Taking into account the differences of layer properties, including per- meability, oil viscosity, and remaining oil saturation, the pseudo flow resistance contrast is proposed to serve as a characteristic index of layer regrouping for high water-cut multilayered reservoirs. The production indices of multi- layered reservoirs with different pseudo flow resistances are predicted with the established model in which the data are taken from the Shengtuo Oilfield. Simulation results show that the pseudo flow resistance contrast should be less than 4 when the layer regrouping is implemented. The K-means clustering method, which is based on the objec- tive function, is used to automatically carry out the layer regrouping process according to pseudo flow resistances. The research result is applied to the IV-VI sand groups of the second member of the Shahejie Formation in the Shengtuo Oilfield, a favorable development performance is obtained, and the oil recovery is enhanced by 6.08 %.

Surface Damage in Wire cut Silicon Wafers

The surface damage and the damage depth in wire-cut silicon wafers and inner-diameter (ID) cut silicon wafers were studied by means of thickness meter, scanning electron microscopy (SEM) and double crystal X-ray diffractometer. The results show that the surface of wire-cut silicon wafers is rougher than that of ID-cut silicon wafers and the surface damage in wire-cut silicon wafers is more serious than that in ID-cut silicon wafers, while the damage depth in wire-cut silicon wafers is smaller than that in ID-cut silicon wafers. The possible reasons for the generation of surface damage in wire-cut silicon wafers were also discussed.

Cutting Characteristics of CFRP Boards Using Electroplated Diamond Wire Tools

CFRP （carbon fiber reinforced plastic）, which is composed of carbon fibers in a resin matrix, is an extremely strong and light composite material that has found use in the aerospace and automotive industries. CFRP boards are very difficult to machine using common machining processes. Various machining artifacts, such as burrs and delamination, occur frequently when machining CFRP. Adequate techniques for machining CFRP have not yet been established. Recently, electroplated diamond wire machining technology has found use in cutting hard, brittle materials such as silicon and sapphire. In this study, we used an electroplated diamond wire saw to cut a CFRP workpiece. We quantified the cutting forces imposed on the workpiece and observed the surface state of the workpiece after cutting. We demonstrated that an electroplated diamond wire tool is suitable for the high-quality machining of CFRP boards.

DK7725E CNC Wire Cut EDM

The machine,a silver medal winnerfrom the state,is produced by theChangfeng Machinery General Factory.The products have been sold in the UK,Poland,Australia,Thailand,Singapore,

DK7732-1 Electric Spark CNC Wire-Cuffing Machine

The machine tool is one of the new products developed and produced by the Shanghai No.8 Machine Tool Plant. It adopts a lift adjustable wiretrame and molybdenum filament tensioning mechanism with large cutting thickness and high machining precision. It is equipped with an advanced IBM-PC 386 microcomputer-controlled system, with strong performance and CRT display. Man/

Preliminary Study on Water Demand Law of 1-0 Rooted Cuttings of Populus szechuanica

In order to provide theoretical basis and technical support for the afforestation and artificial water supply of P.szechuanica in arid areas,the characteristics of water consumption of P.szechuanica were explored,and the law of water demand of P.szechuanica was grasped.In this paper,potted seedlings of 1-0 rooted cuttings of P.szechuanica were taken as research objects,and change situation of water consumption under different water control gradients was measured regularly by using weighing method,further analyzing dynamic change of water consumption of P.szechuanica and revealing water demand law of 1-0 rooted cuttings of P.szechuanica.The results showed that total change of water consumption of 1-0 rooted cuttings of P.szechuanica had"slow-fast-slow-fast"double-peak trend in the growth period of the current year,and corresponded with univariate linear relation(R^(2)=0.7137),with significant difference.In whole growth period,water consumption in August was the highest,which was 2.7 times of that in June and July and 1.5 times of that after September.In different water control treatments,the dynamic changes of daily and monthly water consumption were significantly different.In seven water control treatments,monthly water consumption was between(6315.95±1690.70)and(10105.28±3065.30)g/month,and mean was(8211.07±2308.23)g/month.With intensification of water control treatment,water consumption increased,but there was no seedling death due to water shortage.P.szechuanica has great plasticity in water demand,and can survive in both arid and humid environments.Meanwhile,it is revealed that P.szechuanica is the most widely distributed tree species in the region.

RULED SURFACE MACHINING BY 4-AXES SIMULTANEOUS CONTROL WIRE-EDM

On the tasis of study in the mathematical model of 3-dimensional ruled surface (RS),this paper introduces a new concept of distance paramcter (DP) and also puts forward that themethod of modeling a RS depends on not only two boundary curves but also DP. According toabove theory, the formulas to calculate corresponding point coordinates to any kind of top and bot-tom profile of a workpiece and formulas to calcuate the maximum inclination angle of ruling linehave been obtained. Then a different top and bottom RS mathining method including profile withline-are combination as well as parametric curves has been achieved by 4-axes simultancous con-trol programming proposed.

Over Voltage Fault due to Disconnection of Consumer’s Transformer Neutral Wire

Practically,the load currents in three phases are asymmetric in the power system.It means that the impedances are different in all three phases.If the consumer’s transformer neutral cut off and/or was disconnected from the neutral of power supply source,then there will be some trouble and failure occurred.The current in the neutral wire drops down to zero when the neutral wire is cut off and the phase currents of all three-phase equal to each other since there was no return wire.The currents are equal but the voltages at the phase consumers are different.Especially for residential single-phase consumers,the voltage at the consumers of the phase varies differently for three phase systems when the neutral wire was disconnected at consumer side and even the voltage at the consumers one or two of those three phases becomes over nominal voltage or reaches nearly line voltage.In this case,the electronic appliances in that phase will be fed by high voltage than the rated value and they can be broken down.In the power system of UB(Ulaanbaatar)city,there are some occasional such kind of failures every year.Obviously,many electronic appliances were broken down due to high voltage and the electricity utility companies respond for service charge of damaged parts.

T/CMTBA 1010—2021《数控往复走丝电火花线切割机床性能评价规范》团体标准解读

介绍了《数控往复走丝电火花线切割机床性能评价规范》团体标准的制定背景、目的和主要内容,并在检验项目、关键指标等方面与现行行业标准进行了比对,解读了该团体标准的先进性、科学性和实用性。

慢走丝线切割成本估算研究

慢走丝线切割中,零件表面质量要求越高,相应加工时间也就越长,加工时间的长短直接影响加工成本。通过引入粗糙度系数的概念,将加工总时间折算为与切割加工相关的时间,建立了慢走丝线切割成本估算模型,并采用切割实验验证了粗糙度对加工时间仅有较小的影响,合理降低了粗糙度系数取值。最后运用构建的成本模型计算某工件的加工成本,验证了该模型的合理性。

基于响应面与狼群算法的电火花线切割加工性能与放电能耗建模及优化

结合电火花线切割加工绿色、精密、高效的发展趋势,提出面向加工性能与放电能耗的电火花线切割加工工艺建模与多目标优化方法。针对电火花线切割加工GH4169高温合金材料开展正交试验设计,以脉冲宽度、放电间隙、管数、加工限速为输入,以放电能耗EEV、表面粗糙度Ra和材料去除率MRR为输出,构建了电火花线切割加工性能与放电能耗多目标优化响应面模型,并采用改进的狼群算法对模型进行优化求解。优化结果与实验结果对比表明,Ra、EEV和MRR的平均误差均不高于10%,且随机优化实验结果优于75%以上的正交试验设计的实验结果,验证了优化模型及求解方法的有效性。

基坑盖板下逆作车站地下连续墙托换破除技术

附属结构与地铁车站连通常需要对地下连续墙进行破除,当地下连续墙上设有临时承重盖板时破除的施工难度更大,风险更高。以某地铁盖挖逆作车站的地下连续墙破除施工为依托,提出了利用局部破除体作为临时竖向支撑进行托换破除的施工方法。首先,采用数值计算分析了不同托换间距对盖板结构体系的受力影响,综合施工进度和作业空间考虑,确定预留1m宽的临时托换柱和不大于12m的破除间距为控制指标,能够满足各受力结构体系在临时托换施工下的承载性能要求;其次,对盖板下地下连续墙破除及切割块转运施工进行了详细分析,给出了分块尺寸、切割块吊装、预留柱节点等关键施工环节的控制指标与做法。实施结果表明:利用既有地下连续墙作为临时托换结构进行破除地下连续墙的施工方法,安全可靠,施工速度快,成本经济。

分层供液电火花线切割加工研究

分别采用常规供液和分层供液对缸筒类零件进行电火花线切割加工对比试验。结果表明,分层供液可在火花放电全过程实现电极丝顺向运丝加工,解决了常规供液方式下电极丝逆向运丝导致的缸筒类零件内部供液不足的问题;提高了极间工作液流速与流量,增强了排屑能力,扩大了放电间隙,改善了极间放电条件,从而提高了火花放电效率和稳定性,对工件切割速度的提高和表面加工质量的改善有重要意义。

基于正交试验的MS-WEDM第二次切割工艺参数优化

研究MS-WEDM多次切割中第二次切割参数对表面质量和切割速度的影响规律,寻求最优参数组合,有利于提高多次切割的加工质量。采用单因素试验研究第二次切割参数的脉宽、脉间、功放、丝速等参数对表面粗糙度和切割速度的影响规律,选取4水平4因素进行正交试验,用综合评分法将表面粗糙度和切割速度的多目标优化问题转化为加权综合评分的单目标问题。结果表明:更优的加工参数方案为脉冲宽度6μs、脉冲间隔5μs、功放1个、丝速6 m/s,并通过试验验证,其表面粗糙度为1. 54μm,切割速度为149. 43 mm^2/min,加权综合评分为0. 26。