印制板组装焊后清洗工艺

无论是有铅工艺还是无铅工艺,大多数EMS均采用免清洗技术,但对于要求比较严格的军用类、医疗器械类及汽车电子类生产厂家则仍然要求焊后清洗.作为军品类电子产品印制板组装件清洗后的洁净度满足GJB5807-2006军用印制板组装件焊后清洗要求:三级电子产品,用五倍放大镜检查印制板组装件表面应无残留物存在,印制板表面离子残留物含量不大于1.56μg(NaCl)/cm2.通过试验研究发现:在清洗剂一定的情况下,选用不同的焊膏,焊后清洗的效果不同;另外,焊接结束与清洗前间隔时间的长短,也是影响清洗效果的重要因素.采用Loctite CR37 63Sn37Pb和Alpha UP78 63Sn37Pb两种焊膏与VIGON A 200的水基清洗剂在焊后1 h之内进行清洗,可得到较好的清洗效果.     

新型常温水基金属清洗剂配方的研制

论述了一种新型清洗机专用常温洗涤水基金属清洗剂的配方组成，并对清洗剂的性能进行了测试。结果表明，该清洗剂去污力强，清洗效果好，清洗率达到98．5％以上，低泡，使用安全，尤其对碳钢具有良好的清洗和防锈性能。     

铝合金水基清洗剂的开发

开发了铝合金水基清洗剂,水基清洗剂以水代替有机溶剂,在保证清洗效果的前提下,降低了清洗成本,提高了铝合金产品表面质量,改善了生产环境,消除了生产安全隐患。     

矩形片式电阻半导体激光钎焊无铅焊点的热循环试验

选用Sn-Ag-Cu无铅钎料,采用半导体激光软钎焊和红外再流焊两种方法对0805型矩形片式电阻元件进行钎焊,并对采用不同方法得到的钎焊焊点进行热循环试验.结果表明,激光软钎焊矩形片式电阻焊点的力学性能优于传统红外再流焊工艺所获得的电阻焊点的力学性能;片式电阻焊点的剪切力随热循环次数的增加呈现下降趋势,在热循环次数相同时,激光软钎焊焊点的力学性能优于红外再流焊焊点.随着热循环次数的增加,片式电阻焊点的剪切断裂的方式由明显的韧性断裂逐渐向脆性断裂转变.     

超声波清洗技术的特点及应用

超声波清洗与其它清洗相比具有洗净率高、残留物少、清洗时间短、清洗效果好,凡是能被液体浸到的被清洗件,超声对它都有清洗作用.不受清洗件表面形状限制,如深孔、狭缝、凹槽,都能得到清洗.由于超声波发生器采用D类工作放大,换能器的电声效率高,因此超声清洗具有高效节能.它是一种真正高速、高质量、易实现自动化的清洗技术.若清洗剂采用非ODS清洗剂则具有绿色环保清洗作用.超声清洗对玻璃、金属等反射强的物体其清洗效果好,而不适宜纺织品、多孔泡沫塑料、橡胶制品等对声吸收强的材料.     

低温高效低泡水基冷轧铝板清洗剂的研究与开发

目的解决冷轧铝板在冬季常温清洗中,由于水温低造成水基清洗剂洗净率低、易发泡等问题。方法在3℃下研究了两种嵌段醇醚非离子表面活性剂的复配体系的去污性能及其清洗液的泡沫行为,以及羧酸胺缓蚀剂、烷基磷酸酯OPS75E的复配体系对钢材、铝材的缓蚀作用。结果开发了一种在低温下低泡、高效的水基铝板带清洗剂,最佳配方(以质量分数计):无水偏硅酸钠0.8%~2%,葡萄糖酸钠5%~8%,羧酸胺缓蚀剂2%~4%,OPS75E 1%~3%,PAA 1%~3%,有机胺酯TPP 3%~5%,NF7305 5%~8%,RPE31102%~4%,水63%~80.2%。在3℃及以上温度下,该清洗剂无泡,且能有效抑制清洗中由于油污皂化引起的泡沫,使用浓度3%、清洗时间2 min时,对冷轧铝带洗净率可达99%以上。结论该清洗剂清洗效果较好,对碳钢、铝材有很好的缓蚀性能,各项性能符合JB/T 4323.1—1999标准。     

高效水基金属清洗剂的研制

水基金属清洗剂由表面活性剂及多种添加剂组成。经复配实验发现,非离子表面活性剂：阴离子表面活性剂＝1：1－1：1．5（质量比）时,可获得较高的除油率。添加防锈剂B1或N1,P－M无铬钝化剂后,在不同的温度范围内有良好的清洗性和防锈性。     

输油管道废弃清洗剂技术现状和发展趋势探讨

随着油田产量下降和腐蚀风险，我国约3000多公里管道存在报废处置需求，《安全生产法》对管道清洗提出更高要求，管道清洗存在油蜡残余物风险较高。阐述了常用清洗剂、优缺点和适用条件，物理化学技术清洗剂性能不能保证管道清洗质量。研发新型高效报废管道清洗剂，室内测试清洗剂在15℃溶解速率为0.56mm/min，溶垢能力为1.1g/g，现场应用清洗效果良好。从清洗性能和安全环保方面阐述了未来高效清洗剂研究重点和发展趋势。     

某新型清洗剂在弹药弹筒表面漆膜清洗上的应用

目的用某新型清洗剂代替酒精、汽油应用于弹药弹筒表面漆膜清洗。方法选取先进、可靠、安全环保的某新型清清洗剂,应用于弹药弹筒表面漆膜中间过程中漆膜上的油污、汗渍、红丹、记号笔、药粉等污物的清洗。通过对弹药弹筒表面漆膜的特点、漆膜上各类污渍的组成以及对漆膜中间清洗工艺过程进行分析,同时针对上述特点,拟定清洗剂选用原则,结合清洗剂的组成、特点、除污机理,通过对清洗剂进行应用试验,从清洗剂安全性能、清洗后漆膜附着力性能、清洗后漆膜耐盐雾性能、清洗剂的清洗效果、清洗剂的挥发速度、清洗剂气味等几个方面进行试验。结果某新型清洗剂具备清洗效果好、挥发速度快、清洗效率高等优点,清洗后对弹药弹筒表面漆膜无影响,满足弹劳逸结合漆膜清洗质量要求。结论某新型清洗剂可以代替酒精和汽油在弹药弹筒表面漆膜清洗上进行应用,具有环保、无毒等特点,在弹药弹筒表面漆膜清洗应用领域具有推广意义。     

钛双极板表面原位生成TiN涂层的性能研究

目的降低钛合金表面的接触电阻,提高其抗腐蚀性能。方法 TA2纯钛表面进行活化后,原位反应生成TiN涂层。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱仪(EDS)分析表面形貌和成分,使用直流表面电阻和界面接触电阻(ICR)来评价涂层的导电性,在模拟质子交换膜燃料电池(PEMFC)环境中测试其抗腐蚀性能。结果经过TiN处理后的TA2纯钛双极板表面致密,其生长方式为沿(111)晶面择优生长。在750℃反应2 h获得的试样的直流表面电阻和ICR电阻最低,抗腐蚀性能最佳。压力为120N/cm^2时,电阻率稳定在6.7 m?/cm^2。在模拟PEMFC环境中的表面腐蚀电流为0.816μA/cm^2,经过恒电位扫描后的SEM显示,其表面完整,H2气氛中涂层界面完整,空气气氛中出现较多点蚀。结论在TA2纯钛表面原位反应生成TiN涂层有助于提高基体表面的抗腐蚀性和导电性。     

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.     

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.     

The Mirror with Patterns of Auspicious Animals and Grapes——Exquisite cast mirror and the technology of surface tin-enrichment by rubbing-in and infiltration of tin-rich powder

<正>Bronze mirrors were used by the Chinese people before the introduction of the glass mirror.Only after it was replaced by the glass mirror did the bronze mirror gradually retreat from people's lives.Different styles of bronze mirrors were made in different historical periods,particularly in the Warring States Period,the Han and Tang Dynasties,which were the three peaks of the development of bronze mirror arts in ancient China.The casting techniques were exquisite.The surface of the bronze mirror was smooth and bright enough to reflect one's image,and there were scarcely any casting defects on the mirror surface.On the back of the bronze mirror,there were rich depictions of Arts and Humanities,and the ornamentations were also     

The 9th China International Diecasting Congress & Exhibition

The 9th China International Diecasting Congress ＆ Exhibition was held on July 22-24, 2014 at Shanghai New International Expc Centre. This exhibition was the most successful over the years, with over 6890 visitors and 155 exhibitors, and the exhibition area increased by 30% from 9,500 square meters in 2012 to 12340 square meters. Die casting enterprises from a total of 24 countries and regions, including China mainland, Chinese Taiwan and Hong Kong, South Korea, Japan, Germany, India, Thailand, Malaysia, the United States, Russia, Australia, Iran, Ukraine, Brazil, Colombia, Singapore, Austria, Canada, Croatia, France, Turkey, United Kingdom, Vietnam, attended the congress and exhibition.     

Introduction of the Fluid Control Engineering Institute of Kunming University of Science and Technology

正The Fluid Control Engineering Institute of Kunming University of Science and Technology was set up in 1996.The researches of institute concentrate on electro-hydraulic(pneumatic)servo/proportional control and hydromechatronics.The Institute is committed to research and development of electro-hydraulic control of high-end technical equipment in ferrous metallurgy refining produc-     

RARE METALS Volume Contents

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Antimony Induced Crystallization of Amorphous Silicon

Antimony induced crystallization of PVD (physics vapor deposition) amorphous silicon can be observed on sapphire substrates. Very large crystalline regions up to several tens of micrometers can be formed. The Si diffraction patterns of the area of crystallization can be observed with TEM (transmission electron microscopy). Only a few and much smaller crystals of the order of 1μm were formed when the antimony layer was deposited by MBE (molecular beam epitaxy) compared with a layer formed by thermal evaporation. The use of high vacuum is essential in order to observe any Sb induced crystallization at all. In addition it is necessary to take measures to limit the evaporation of the antimony.     

A CUMULATIVE FATIGUE DAMAGE RULE UNDER THE ALTERNATIVE OF CORROSION OR CYCLIC LOADING

Fatigue damage increases with the applied loading cycles in a cumulative manner and the material deteriorates with the corrosion time. A cumulative fatigue damage rule under the alternative of corrosion or cyclic loading was proposed. The specimens of aluminum alloy LY12-CZ soaked in corrosive liquid for different times were tested under the constant amplitude cyclic loading to obtain S-N curves. The test was carried out to verify the proposed cumulative fatigue damage rule under the different combinations among corrosion time, loading level, and the cycle numbers. It was shown that the predicted residual fatigue lives showed a good agreement with the experimental results and the proposed rule was simple and can be easily adopted.