An experimental investigation into soft-pad grinding of wire-sawn silicon wafers

Silicon is the primary semiconductor material used to fabricate microchips. A series of processes are required to manufacture high-quality silicon wafers. Surface grinding is one of the processes used to flatten wire-sawn wafers. A major issue in grinding of wire-sawn wafers is reduction and elimination of wire-sawing induced waviness. Results of finite element analysis have shown that soft-pad grinding is very effective in reducing the waviness. This paper presents an experimental investigation into soft-pad grinding of wire-sawn silicon wafers. Wire-sawn wafers from a same silicon ingot were used for the study to ensure that these wafers have similar waviness. These wafers were ground using two different soft pads. As a comparison, some wafers were also ground on a rigid chuck. Effectiveness of soft-pad grinding in removing waviness has been clearly demonstrated.     

用于气体保护焊的自动混气设备

介绍了一种用于焊接现场的气体保护焊的自动混气设备，该设备能精确控制气体混合比例。设备主要由气体传输、气体混合、信号检测和电气控制几大部分组成。计算机适时采集、显示混合气体的混合比例、输出压力、气体湿度等信息，超限发出声光报警。混气设备通过气体分析仪、比例阀和计算机形成闭环控制，从而实现气体混合比例的精确控制。     

碳氮共渗提高空心圆柱滚子轴承寿命的研究

通过GCr15钢碳氮共渗,在表层获得大量的残余奥氏体。磨损中,马氏体组织剥落,残余奥氏体则成小岛状,进而在表面迁移发生形变诱发马氏体相变,使耐磨性得以提高。同时,共渗在空心滚子内表面造成的压应力对改善弯曲疲劳性能有利。     

丙烯酸树脂在医用黏合剂中的应用

讨论了丙烯酸树脂在医用黏合剂中的应用及进展。     

气相色谱——质谱法对土壤中多种农药残留的测定方法

用GC -MS法测定土壤中的农药残留物 ,快速准确 ,回收率 83 %～ 112 %,平均变异系数在 4.8%～ 15 .2 %之间。为科学监测、合理利用土壤资源提供了依据     

Preparation of fluoroacrylate nanocopolymer by miniemulsion polymerization used in textile finishing

Latex based on fluoroacrylate (TAN) and other comonomers was prepared via miniemulsion polymerization in the presence of stearyl trimethyl ammonium chloride (STAC) and 2, 2′‐azobis (2‐amidinopropane) dihydrochloride (ABAP) as a water soluble initiator. Light transmittance studies demonstrated that the light transmittance of prepared emulsions increases with the amount of TAN, STAC, cosolvent DPM, and hydrophobe DM. Given suitable reaction temperature and quantities of TAN, STAC, DPM, and DM, a copolymer emulsion of fluoroacylate with a particle size of 50 nm was produced. The water repellency tested on polyester fabrics displayed greater effectiveness than that of commercial products with higher fluorine content. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1466–1472, 2004     

西门子CP340与RKC温控仪表的ASC Ⅱ码通信

介绍西门子CP340与RKC温控仪表的ASCⅡ码通信方法，采用轮询方式访问RS-485网络上的每块温控仪表。使橡胶挤出机的温度控制系统处于西门子PLC系统管理之中，方便橡胶挤出机的温控系统的现场维护和监控。     

氧化铝增强无机硅酸锌涂层的电化学阻抗谱研究

无机硅酸锌涂层是一种广泛使用的钢铁重防腐涂层。采用在涂料填料中加入氧化铝的方法可以得到具有更好耐磨性能的富锌涂层。本实验研究利用电化学阻抗谱法(EIS)研究了氧化铝的加入对涂层腐蚀防护性能的影响,结果表明氧化铝颗粒的加入使涂层的腐蚀防护性能略有提高。     

火焰原子吸收光谱法测定高纯石英粉中痕量钙

系统地研究了用空气——乙炔火焰原子吸收光谱分析法测定高纯石英粉中钙的最佳条件，建立了14％的乙醇作为增感剂，在2％盐酸介质中，0．4％ LaCl3溶液作为释放剂，用塞曼火焰原子吸收法测定的可行性方案，探讨了共存元素对钙的干扰及其消除。方法操作简便快速，干扰少，方法相对标准偏差小于3％，适用于日常分析石英粉中的杂质。     

Selective oxidation of styrenes under oxygen catalyzed by cobalt chloride

The cobalt(II) chloride-catalyzed oxidative cleavage of -methylstyrene with oxygen in t-BuOH gives acetophenone and formaldehyde in good yield. The competing reactions between C=C cleavage and formation of polymeric products are strongly affected by the solvent, cobalt catalyst and concentration used, as well as the reaction temperature. A free radical mechanism involving a cyclic peroxide intermediate is proposed to give the cleavage products. Oxidation of various alkenes using CoCl₂/t-BuOH/O₂ system shows that only activated styrenes can be oxidized effectively. The reactivity of various styrenes and their selectivity towards giving cleavage products or polymers are strongly influenced by the electronic and steric properties of the substrate.