铝及铝合金不溶性钎剂的研制

近年来迅速发展起来的ＮＯＣＯＬＯＫ方法,在铝钎焊工艺中广泛应用。研制的铝及其合金的钎剂即为该方法用钎剂,该钎剂的特点是不溶于水,不吸潮,无腐蚀。本研制找出了批量生产低能耗化学合成法生产氟铝酸钾钎剂的合成工艺方法。研制的产品应用于汽车空调器铝蒸发器、铝散热器及不锈钢复合锅底的钎焊工艺中,取得了满意的效果     

J—16-A 型无腐蚀有机钎剂

J—16—A 型钎剂系配合锡铅钎料用于铜材钎焊的一种钎剂,是专为用于内燃机、发电机散热器芯在炉中进行钎焊的一种无腐蚀有机钎剂;同时也适用于具有类似工艺的其他产品的钎焊。多年来我国普遍用于锡—铅钎焊的钎剂是 ZnCl_2系无机盐钎剂,该类钎剂呈酸性,能有效地去除金属表面氧化膜及增加钎料的流动性,是较好的钎剂,但其焊后残余物留存在焊件表面,具有腐蚀性,且不易洗净。广泛用于各种内燃机、发电机     

低腐蚀钎剂在散热器生产中的应用

无机软钎剂ZnCl_2水熔液的助焊性虽能满足散热器软钎焊的要求,但鉴于它较强的腐蚀性,90年代初,国内研究者借鉴国外的经验,开发出残留物少、腐蚀性较弱的软钎剂（低腐蚀钎剂）,并在全国多家散热器厂进行推广应用。本文介绍东风汽车公司散热器厂对低腐蚀钎剂的应用情况。1 助焊性试验用低腐蚀钎剂与现生产使用的ZnCl_2饱和水溶液在相同焊接条件下按GB11364一89标准规定进行对比试验,每个试样做三次,取其平均值作为试验数据。     

KF-KBr-AlF3-CsF钎剂去除6061铝合金表面氧化膜机制

研制了一种新型铝合金无腐蚀钎剂,该钎剂具有较低的熔点和良好的去膜能力,可用于6063,6061等含镁铝合金的钎焊,解决了传统无腐蚀钎剂无法钎焊含镁铝合金的问题.文中对钎剂的去膜机理进行了深入研究,通过X衍射分析了钎剂和纯氧化镁粉末及铝板表面的氧化物反应的产物,通过分析得出:KF-KBr-AlF3-CsF钎剂的中Cs+的强金属性,夺取了氧离子,从而使氧化镁膜溶解破裂;MgO和大多数Al2O3是通过化学反应而除去的,而MgAl2O4和部分Al2O3是通过物理作用去除的.     

中温氟铝酸盐铝钎剂的研究现状和发展趋势

Nocolok 钎剂虽具有无腐蚀、不溶于水等优点,但其操作温度过高,一多半的铝舍金不能用其进行钎焊.重点介绍了3种中温氟铝酸盐钎剂,但由于其价格昂贵或有毒,其应用受到了一定的限制.笔者认为:钎剂未来的发展方向将会在继续保持钎剂无腐蚀、不溶性的基础上,考虑常用铝合金的不同固相线熔点和特性,研发出匹配于常用钎焊铝合金的钎荆系列,同时还进一步降低钎剂的熔化温度,提高钎剂活性,增加钎剂的稳定性,使Nocolok系列钎荆适用于更多种的铝合金.     

Al/Cu管异种材料火焰钎焊连接

采用火焰钎焊技术，实现了Al/Cu管异种材料的中温钎焊连接。所采用的改进型的CsF-AlF3钎剂Si粉含量在1％时，钎焊接头的抗裂性能最好。本试验所采用的钎剂具有熔点低、免清洗、无腐蚀、钎剂活性佳和接头抗裂性能好等优点，该技术达到了国内领先水平。     

铝/铝钎焊用Al-Si-Zn系钎料的研究

采用Al-Si-Zn系钎料对铝-铝金属进行火焰钎焊和炉中钎焊试验,通过XRD,SEM和EDS对钎料和接头的微观组织进行分析,并检测接头的力学性能。此外,通过盐雾腐蚀试验和电化学腐蚀试验分别对接头和钎料的耐蚀性进行了分析。研究结果表明:Al-5.1Si-40.2Zn钎料配合CsF-AlF_3无腐蚀钎剂钎焊的铝-铝接头具有优良的抗腐蚀性能,接头经过30天盐雾腐蚀试验后,接头抗剪强度基本没有下降。     

6063铝合金中温钎焊工艺

采用73Ai-20Cu-2Ni-5Si中温箔带钎料,对6063铝合金进行氩气保护炉中钎焊工艺研究。根据铺展、填缝试验,选择合适的表面处理方式、钎剂和钎焊规范,结果表明:3%CsF-AlF_3+97%KF-AlF_3无腐蚀钎剂具有较高的活性及较好的去膜效果,适合含Mg铝合金钎焊;化学清洗和物理清洗表面处理方式均能有效去除钎料表面氧化膜;使用3%CsF-AlF_3+97%KF-AlF_3钎剂,钎料在580℃,10 min规范下钎焊的剪切强度达到126 MPa;经固溶、时效处理后,钎焊接头强度明显提高,这种接头经盐雾腐蚀后接头剪切强度仍达到150 MPa。     

缓冲式水箱散热器芯子的钎焊

分析了钎焊质量对散热器芯子冷却效果的影响,介绍了利用现存焊接设备的改进措施,讨论了焊接工装的设计,叙述了钎焊材料及钎剂的加工与配制方法,着重讲述了钎焊前的准备及钎焊工艺操作过程,试验确定了其钎焊参数。     

LY12铝合金中温钎焊技术

采用改进的KF -CsF -AlF3 中温无腐蚀钎剂与Ag -Al-Cu -Zn中温钎料实现了对LY12铝合金的中温钎焊 ,钎焊接头的抗剪强度可达到母材强度的 80 % ,对接接头钎缝的抗拉强度可达到母材强度的 70 % ,突破了“热处理强化铝合金通常不能钎焊”的传统论断。     

Effect of fluxing chemical: An option for Zn-5wt.%Al alloy coating on wire surface by single hot dip process

The corrosion of wire is one of the primary causes for premature failure. The ideal way to overcome this problem is to provide corrosion protection right at the time of manufacturing. It is well established fact that Zn-5 wt.% Al alloy coating on steel surface provides much better protection against corrosion than the conventional pure Zn coating. Conventional fluxing operation is done on wire surface using zinc and ammonium chloride mixture before dipping in molten zinc bath. Galvanization bath temperature of about 415 °C for Zn-5 wt.% Al alloy coating on wire surface develops black spots of AlCl₃ when conventional flux is used. Double dip process is being followed for Zn alloy coating on wire surface due to non availability of suitable flux. An effort has been made to develop a suitable flux to obtain Zn-5 wt.% Al alloy coating on wire surface by single hot dip process. A salt mixture (containing zinc, ammonium, sodium, potassium, cobalt and lead chloride) was formulated based on the decomposition temperature of individual chloride salts. Differential thermal and thermo gravimetric analysis indicate the temperatures for complete decomposition of conventional and formulated flux are 445 and 410 °C, respectively. The lower decomposition temperature of formulated flux is ensured black spot free Zn-5 wt.% Al alloy coating. Alloy coated wire consists of alternative layers of zinc rich and aluminium rich phases. The performance of alloy coated wires has been evaluated by salt spray and Tafel tests. The alloy coated wire shows around 4 times improvement of corrosion performance against aggressive chloride environment compared to pure zinc coated wire. This can be attributed to the fact that aluminium rich phase prevents dissolution of zinc rich phase.     

Corrosion performance and mechanical properties of joined automotive materials

The automotive industry envisions that an optimized vehicle in terms of performance and cost can be achieved only by using different materials at different vehicle locations in order to utilize the functionality of the different materials to a full extent. Currently, steel and aluminum are the most important construction materials for the mass production of automotive structure. However, other materials such as magnesium alloys and stainless steel are also used. The use of dissymmetric assemblies of materials in the automotive industry has also led to the development of joining technologies other than spot welding and arc welding such as clinching, adhesive bonding, laser welding, and MIG brazing. However, and despite the development of these new joining technologies, there are still important gaps of knowledge with regards to the corrosion performance of different joint populations using dissymmetric and symmetric materials. Materials commonly used in the automotive industry including steel and aluminum‐based susbtrates were assembled with different combinations using various joining techniques in order to evaluate their corrosion performance as well their mechanical properties after cyclic accelerated corrosion tests. The results indicated a relationship between the corrosion inside the confined joint and the decrease of the mechanical properties of the assemblies.     

含镁铝合金光束钎焊性能的研究

含镁铝合金光束钎焊性能的研究表明,ＭｇＯ是恶化其钎焊性能的重要原因。ＣｓＦ－ＡＬＦ３混盐对ＭｇＯ的去膜能力较差,因而不能解决含镁铝合金的非腐蚀钎焊难题。另一方面,ＣｓＦ－ＡＬＦ３混盐的熔点较ＮＯＣＯＬＯＫ钎剂低,无腐蚀性,对Ａｌ２Ｏ３的去膜效果好,对不含镁铝合金的光束钎焊来说,仍是一种有发展前任的低熔点新型非腐蚀性钎剂。     

Vanadia-based coatings of self-repairing functionality for advanced magnesium Elektron ZE41 Mg–Zn–rare earth alloy

A smart vanadia protective coating of self-repairing functionality that has proven to provide superior corrosion resistance for several magnesium and aluminum alloys has successfully been designed by our group. A newly developed series of magnesium alloys, namely ZE41 alloy, has recently been proposed for automotive, electronics and aerospace applications. The advanced ZE41 alloy possesses very low density, high specific strength, and good castability and weldability characteristics compared to aluminum and steel based alloys. However, the corrosion resistance of ZE41 alloy in the presence of corrosive chloride environment is relatively low. The possibility of utilizing such coatings to add self-repairing functionalities to ZE41 alloy was discussed in this paper. The electrochemical corrosion behavior of the vanadia coatings over ZE41 alloy was investigated in 3.5% NaCl solution using EIS, linear polarization and cyclic voltammetry techniques. The optimum conditions for obtaining protective vanadia coatings of self-repairing abilities and improved localized corrosion resistance were determined. Surface examination of the coatings was investigated using SEM-EDS and macroscopic imaging.     

Auflösungskinetik verschiedener Metallisierungen für Leiterplatten in Abhängigkeit von den verwendeten Flußmittel‐Aktivatoren

Resolution kinetics of different metallizations in dependence to flux‐activators The field of application for electronic assemblies expands continuously. Especially in automotive and telecommunication systems the use of electronic assemblies increases. At the same time the increasing numbers of electronic functions and the decreasing of the pin distance leads to smaller and smaller dimensions under extreme environmental conditions – especially variations in temperature and humidity. By using electrochemical analysis methods such as free corrosion potential and current‐density potential curves which until today have only been used sporadically as test procedures in electronics and, if at all, only in relation to the final result of individual measurements, it is in fact possible to estimate reliability already in advance. This enable us to assess new material / flux combinations in a selection procedure, and thus to further reduce development times and costs. This is of particular importance in view of the prohibition of lead‐containing soldering materials, since there are hardly any findings about the proneness of substitute combinations to subsequent migration and corrosion.     

Corrosion behaviour of an industrial shot-peened and coated automotive spring steel AISI 9254

A high-strength low-alloy steel, AISI 9254 (54SiCr6), is widely used for suspension spring production in the automotive industry. In this work, industrially manufactured zinc phosphate coated helical springs are subjected to detailed microstructural and surface analysis for better understanding of corrosion evolution. The material’s free corrosion potential and anodic/cathodic behaviour were investigated in NaCl solutions and corrosion propagation mechanisms were studied using potentiostatic polarisation on cross-sectional and external surfaces. The bulk material is fully martensite with uniformly distributed MnS inclusions, while the spring surface has a 2–3?μm mechanically deformed region introduced by shot-peening and a thin zinc phosphate coating. The corrosion open circuit potential of bulk material and shot-peened spring surface was about –0.7V_SCE without significant difference, while phosphated surface is more noble (more positive potential). MnS inclusions, stimulating the anodic attack in the steel, influence corrosion propagation and pit morphology to a large extent that can have an impact on the spring performance.     

Comparison of corrosion protective performance of nanostructured polyaniline and poly(1-naphthylamine)-based alkyd coatings on mild steel

Nanostructured materials have been establishing themselves as modern generation of high performance materials in many areas ranging from automotive engineering to bioengineering owing to a vast array of their unique properties. Improvements in environmental impact can also be achieved utilizing nanostructure particulates in coating and eliminating the requirement of toxic inhibitors such as chromates. The paper reports a comparative study on the corrosion resistance performance of soya oil alkyd containing nanostructured polyaniline (PANI) and poly(1-naphthylamine) (PNA) composite coatings. The corrosion protective performance was evaluated by physico-mechanical properties, corrosion rate, open circuit potential measurements, and SEM studies. The PNA/alkyd composite coatings were found to show far superior corrosion resistance performance as compared to PANI/alkyd system.     

LOCALIZED CORROSION OF MICROCRYSTALS OF 1Crl8Ni9Ti STAINLESS STEEL

The resistances against localized corrosion of 1Cr18Ni9Ti microcrystals with normal grainsize and bcc structure obtained hy magnetron sputtering have been compared.The two kindsof microcrystals with (110) and (211) textures respectively were obtained under differentsputtering conditions.Both microcrystals were found to have better resistance against local-ized corrosion than the crystal with normal grain.The microcrystal with (110) preferredorientation has larger resistance to localized corrosion than that with (211) preferredorientation.     

The corrosion performance of magnesium alloy AM-SC1 in automotive engine block applications

The magnesium alloy AM-SC1 has been developed as a creep-resistant automotive engine block material. This paper outlines its corrosion performance under laboratory test conditions, considering corrosion on both the external and internal surfaces. This study found that AM-SC1 has a corrosion performance comparable to AZ91 when subjected to an aggressive salt-spray environment or in galvanic-coupling environments. This article further demonstrates that, with the appropriate selection of a commercially available engine coolant, the internal corrosion of AM-SC1 can be maintained at a tolerable level. In addition, internal corrosion resistance can be significantly improved by the addition of fluorides to the coolant solution. It is concluded that AM-SC1 can be successfully used in an engine environment provided that some simple corrosion-prevention strategies are adopted. For more information, contact Guangling Song, University of Queensland, Brisbane, Australia; +61 7 3365 4197; fax +61 7 3365 3888; e-mail g.song@minmet.uq.edu.au.     

低磷低锌复合阻垢缓蚀剂JA-211B在炼铁高炉净循环冷却水中的应用

文章报道了宝钢集团上海梅山钢铁股份有限公司2^#炼铁高炉净循环冷却水用低磷低锌阻垢缓蚀剂JA-211B的试验开发和应用情况。经现场应用1年,从停炉体风打开水冷设备检查情况表明,JA-211B取得了很好的阻垢、缓蚀效果。