机车铝热交换器的真空钎焊

铝合金在热交换器的制造中应用越来越广泛。结合实践详细介绍了制造机车铝热交换器的真空钎焊工艺。     

Brazing of beryllium with aluminium brazing alloys

It is shown that the activation of the surface of beryllium components with titanium results in efficient wetting with aluminium brazing alloys. The experimental results show that the application of aluminium brazing alloys, alloyed with titanium, produces high-quality butt and lap brazed joints with the tensile strength of up to 150 MPa.     

Induction diffusion brazing of copper to aluminium

The aim of this research was to develop an induction diffusion brazing to obtain a sound joint between copper and aluminium. A foil interlayer was used to bond copper to aluminium at 600°C for 2?s under a bonding pressure of 9?MPa. The failure of tensile test is in the aluminium side and no failure occurs when the joint is bent to 180°. The electrical resistivity of joint is lower than that of aluminium. The interfacial intermetallic compounds layers are Cu₉Al₄ and CuAl₂ with the total thickness of 2?μm. No voids and oxide scale are found in the joint. Heat treatment shows that induction diffusion brazing is superior to conventional flash welding to maintain electrical stability and mechanical integrity of copper to aluminium joint.     

铝合金与不锈钢钎焊用钎剂性能研究

针对Al及其合金与不绣钢钎焊中存在的因钎剂的腐蚀性及钎料的润湿性等引起钎焊接头强度下降的问题，研制出一种以LiCl-NaCl为基，并配以其它成分的Al基钎剂。对钎剂的配制机理进行了分析，并用试验的方法对其钎焊性能进行了研究。对钎焊接头及其界面作扫描电镜(SEM)、透射电镜(TEM)、X射线衍射和拉力试验等分析发现，钎剂对钎料的润湿性能良好，有效地阻止了钎料在钎焊期间的氧化。对接头进行腐蚀性试验，发现焊缝的抗腐蚀性较强，能够满足一般环境的使用要求。     

Plasma arc brazing in sheet metal construction

Abstract

Because of the high heat input required, conventional welding methods may not always be ideal for mild and high strength steel sheets. A possible alternative in some applications is plasma brazing, which can also serve as a supplement to other joining techniques. A characteristic feature of the process is the separation between the energy input and filler material. Compared with high heat processes, plasma brazing causes considerably less distortion of joints or panels. Almost no spatter results from the process. The brazed seams exhibit sound mechanical properties as well as good appearance. However, there are difficulties associated with brazing some high strength steels using the filler wires commercially available at present.     

铝合金真空钎焊的发展

综述性地介绍了铝合金真空钎焊发展的当前状况、铝合金真空钎焊的原理、常用的钎焊材料、铝合金真空钎焊的设备及工艺,最后指明了铝合金真空钎焊在今后的发展方向。     

Diode laser brazing of aluminium alloy to steels with aluminium filler metal

Abstract

Diode laser brazing of aluminium alloy (A5052) to interstitial free steel (IF steel) or type 304 stainless steel (SUS304) was conducted using aluminium filler metal (BA4047) with Nocolock flux. The processing parameters of laser power, wire feed rate and travel speed were varied. The strength of lap joints of A5052 on steels was evaluated by tensile shear test. The joint strength of A5052/steels was increased with increasing laser power and reached the maximum strength, more than approximately 80% of the A5052 base metal strength, at a laser power of 1300 W. Voids and incomplete penetration of filler metal were observed at the A5052/braze layer interface when the laser power was below 1100 W. The Fe–Al intermetallic compounds were formed at the steel/braze layer interfaces and grew drastically when the laser power exceeded 1300 W. Superior brazability of A5052/steels was found at brazing conditions corresponding to a temperature of filler metal droplet of 1050–1250 K.     

Reduction of metal ions on aluminium in molten flux during aluminium brazing

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大型真空铝钎焊炉控制系统

介绍了大型真空铝钎焊炉控制系统的开发.该控制系统所实现的功能主要是温度控制和逻辑控制,要求的控制点数多,各个被控对象互相关联.控制系统核心为可编程序控制器.用CX-Programmer软件编程的方法来实现对各个机械系统的控制和设置各种保护功能.可编程序控制器具有灵活方便、易于维护的优点.最终调试结果和真空炉投入使用后的状态表明,该控制系统不但可以达到控制目标,还可以保证设备长期无故障运行.     

Study of structural heredity in brazing of aluminium alloys

Possibility analysis data of application gas-dynamic sputtering technique to eliminate defects in complex metal objects are covered. It is shown that usage of zinc addition in the powder composition allows for a hermetization problem efficient solution and for defects elimination with the help of DIMET portable equipment for metal coating sputtering.     

Effects of flow of liquid filler metal and base metal composition on erosion characteristics during aluminium brazing

When automotive heat exchangers such as radiators and condensers are manufactured, serious erosion caused by the molten filler metal from the header occasionally occurs on the tubes during brazing. In our previous study, we proposed a novel experimental method which consisted of using a feeder and a base plate on a gutter made for the flow of molten filler, and we quantitatively evaluated the relationship between the volume of flowing molten filler and the level of erosion.

We used Al–12%Si molten filler to investigate the effect of chemical composition, in particular, the Si content of the base plane, on the level of erosion. When Al–0–1.2%Si alloys that have a solidus temperature that is higher that their brazing temperature were used, the level was almost constant irrespective of the Si content of the base metal. However, when Al–0–2.0%Si alloys that have a solidus temperature that is lower than their brazing one are used, the level increases.     

TIG brazing technology for zinc-coated sheet steel for bodywork

We propose a method for the assessment of the state of welded joints in terms of arc voltage signals and feed rate appraisal. The signals were recorded during laboratory tests. For the appraisal of the signals, we applied numerical parameters such as, for instance, kurtosis. On the basis of analysis results, we developed diagnostic rules which were written in the binary diagnostic matrix. The proposed method has been implemented in the form of software, the correctness of which has been verified on experimental data.     

用于铝合金生产的高硅含量铝-硅中间合金的试制

用户需求w(Si)=55%~60%的高硅含量铝-硅中间合金,通过理论分析,确定了试制工艺,试制出了w(Si)=57.36%~58.12%的高硅含量铝-硅中间合金,通过在实验室的使用和工业生产中试用,验证了所制得的铝-硅中间合金的应用效果良好,为其在工业生产中应用奠定了基础。     

钛种板与铜耳的电阻钎焊技术

为实现钛种板与紫铜铜耳的焊接,采用自行改制的交流电阻焊机,使用银基钎料对钛板与紫铜进行电阻钎焊工艺试验.结果表明,选择合理的电阻钎焊工艺参数,可以实现钛与紫铜的良好焊接.焊缝微观结构通过光学显微镜、EPMA等进行分析,发现焊缝结合紧密连续,无明显焊接缺陷,钎料和母材元素相互扩散充分.另外对焊接电流、焊接时间、焊接压力等参数对接头力学性能的影响进行研究,结果在最佳工艺参数下得到的接头抗剪强度可达70 MPa以上.现有条件下使用功率为200 KVA的电阻焊机可以实现搭接面积为70 mm ×50 mm的钛种板和铜耳的焊接,并满足一定条件下的使用要求,直接应用于工业生产.     

Capillary filling process during ultrasonically brazing of aluminium matrix composites

Abstract

Alumina borate whisker reinforced aluminium metal matrix composites were ultrasonically brazed in air. The liquid filler metal (FM) of a Zn–Al eutectic alloy could get into the clearance between composite couples by the action of ultrasonic capillarity. The velocity of the FM getting into the clearance decreases with increasing clearance width. The time exhausted to remove completely the oxide film on the surface increases with increasing clearance width. The oxide film could be removed completely and the metallurgical bonding formed under the action of ultrasonic vibration for sufficient time. The shear strength of the bond could reach up to 145 MPa (the nominal strength of the Zn–Al filler alloy).     

铝/钛异种合金激光深熔钎焊试验分析

采用3500W板条式扩散冷却CO2激光器,利用激光深熔钎焊原理对3mm厚6061铝合金和钛合金进行异种金属激光焊接.聚焦激光作用在铝合金一侧为深熔焊,熔化的铝合金浸润钛合金界面形成钎焊接头.拉伸试验发现,断裂均发生在界面处,通过Olympus金相显微镜观察发现断口存在部分未熔合.结果表明,降低焊接速度,并采用合适的偏焦量,负离焦量和偏转角度可以改善界面的熔合.