LF6铝合金散热器振动钎焊润湿界面微观组织特征

研究了LF6铝合金散热器模拟件非真空条件下的振动钎焊,重点考查了振动作用对钎料润湿性的影响和钎缝结合界面的微观组织特征。结果表明,采用2s的超声波振动可有效去除钎料/母材界面的氧化膜,实现二者良好的润湿结合。盖板涂覆钎料时钎料中残留的缩孔、氧化膜夹杂是引起钎缝缺陷的主要原因。振动钎焊可成功实现翅片与盖板的组合焊接,钎缝成形良好,为铝合金板式散热器的焊接提供了一条新途径。     

钎剂对铝合金与不锈钢大气钎焊性影响的二重性

异种材料间钎焊,不仅需选钎料,而且对与钎料、母材相匹配的钎剂的选用同样也很重要.特别是对熔点差异大、且氧化膜厚的两待焊母材,迅速及时同步去除两母材表面的氧化膜是接头达成的必要条件.本研究采用电阻炉和Ⅺm、EDX、SEM等手段进行了不同钎剂供给量及钎剂与不锈钢表面反应时间的调查实验和测试分析,其结果为:使用钎剂去除不锈钢的氧化膜使润湿能够产生,其一定程度的反应时间是必要的.覆盖母材钎焊面及钎料的适量的钎剂供给量以上,钎剂的量对钎焊性基本没有影响.钎料润湿不锈钢后再次与铝合金施焊前,彻底干净去除钎剂残渣是十分必要的,否则日后接头会再次开裂.所以钎剂对钎焊性有利弊二重影响,正确使用钎剂的重要性不可忽视.     

锌铝合金软钎剂的研究及分析

研制了多种有机和无机软钎剂,对各钎剂进行了对比实验,确定了适合锌铝合金钎焊的无机软钎剂.对该钎剂进行了不挥发物含量、腐蚀率试验.结果表明:ZnCl2-NH4Cl-KF钎剂可以有效去除锌铝合金表面氧化膜和钎焊过程中形成的氧化物;促进钎料的润湿;钎剂残渣的腐蚀性小,残余少且清除容易.     

Ga_2O_3对CsF-RbF-AlF_3钎剂/Zn-Al钎料在铝和钢表面润湿铺展性能的影响

研究了添加微量Ga_2O_3的CsF-RbF-AlF_3钎剂和Zn-Al钎料在6063铝合金和Q235低碳钢上的润湿、铺展性能的反应规律。结果表明,添加极微量的Ga_2O_3即能够显著促进Zn-Al钎料在6063铝合金和Q235低碳钢上的润湿、铺展,其最佳添加量应控制在0.001%~0.003%(质量分数)。对钎剂残渣的XRD分析结果和化学反应热力学计算表明,微量Ga_2O_3的添加,一方面能够促进CsF-RbF-AlF_3钎剂溶解、反应去除6063铝合金和Q235低碳钢表面的氧化膜;另一方面,在钎焊过程中,由于Ga_2O_3被还原成金属Ga,Ga元素具有"集肤效应",富集于钎料和母材的界面,大大降低了钎料与母材间的界面张力,从而促进了钎料在母材上的润湿、铺展。     

铝合金与不锈钢钎焊性能影响因素的研究

本研究使用Al-Si钎料对各种铝合金与不锈钢在电阻炉中实施了钎焊.对接头成败、钎焊界面间铝合金、钎料和钎剂成分的元素扩散状况和组织变化进行了EDX,EPMA分析;并用XRD检测了钎剂对不锈钢的影响;还根据试验结果对熔融钎料层的消失即等温凝固时间进行了理论推定;进而将推定结果和Al-Si与Al-Zn系重叠扩散的理论解析进行了对比考察、验证.其结果为:铝合金与不锈钢的空气中钎焊要得到强固的接头是很困难的;使用钎剂去除不锈钢的氧化膜并使其产生湿润所需的时间比铝合金要长:接头不能形成的主要原因是钎料在对不锈钢产生润湿前,先与铝合金产生润湿、反应后急速等温凝固:而此等温凝固是由钎剂中的Zn扩散到钎科及铝合金母材中所致.     

泡沫石墨与铝合金的超声辅助钎焊技术

泡沫石墨具有密度小、导热性能优良等优点,该材料与铝合金连接而成的部件,在换热器、热管理器件、电子行业,尤其是太阳能电站有广阔的应用前景。采用超声波辅助活性钎焊技术解决了由于泡沫石墨与铝合金在大气条件下钎焊时存在的冶金不相容和物性不匹配问题。为此从活性钎料的设计和研制入手,通过成分设计,降低钎焊温度,减小活性元素烧损及氧化,改善钎料的润湿性。引入超声波,有助于钎料和基材表面氧化膜的破碎和清理并制定超声波辅助活性钎焊工艺规范,推动泡沫石墨的广泛应用。     

铝合金真空钎焊

本文研究了非钎焊板型式的铝合金的真空钎焊,确定了各种元素对铝硅钎料润湿性的影响。加入1～1.5％Mg,可取得满意的结果。再加入少量的铋,可进一步提高钎料的润湿性和降低对钎焊真空度的要求。将工件放在盒内,再把盒放入真空炉中加热进行钎焊,可显著提高钎焊质量。要使钎料能填缝流动,应在钎焊区域中另加少量的镁。本文对钎焊时镁的作用进行了研究。镁蒸气穿过氧化膜缝隙,同铝发生合金化,钎料熔化后沿合金化的表面铺展,并且把氧化膜抬起,从而产生润湿。真空钎焊可得到高质量的钎焊接头。     

Ga2O3对CsF-RbF-AlF3钎剂在铝、钢表面润湿铺展性能的影响

本文研究了添加微量Ga2O3的CsF-RbF-AlF3钎剂和Zn-Al钎料在6063铝合金和Q235低碳钢上的润湿、铺展性能的反应规律。试验结果表明,添加极微量的Ga2O3即能够显著促进Zn-Al钎料在6063铝合金和Q235低碳钢上的润湿、铺展,其最佳添加量应控制在0.001~0.003wt.%范围。对钎剂残渣的XRD分析结果和化学反应热力学计算表明,微量Ga2O3的添加,一方面能够促进CsF-RbF-AlF3钎剂溶解、反应去除6063铝合金和Q235低碳钢表面的氧化膜;另一方面,在钎焊过程中,由于Ga2O3被还原成金属Ga,Ga元素具有“集肤效应”,富集于钎料和母材的界面,大大降低了钎料与母材间的界面张力,从而促进了钎料在母材上的润湿、铺展。     

波导组件钎焊接头开裂原因分析

为了查明3A21(LF21)铝合金波导组件钎焊接头在例行试验中开裂的原因,采用了破坏性解剖和X射线探伤相结合的检验方法对钎焊面的内部质量进行了检验和分析,同时对所采用的钎剂、钎料、钎焊工艺流程和操作过程进行了调查和分析,认为焊前清理不够,氧化膜去除不够彻底,操作技术不熟练,钎科在钎焊面上没有能够充分地润湿、铺展和填隙,...     

超声作用下Sn-Ag-Ti(-Al)活性钎料在石墨表面的铺展行为

研究了锡基活性钎料在多孔石墨表面的润湿铺展过程,采用高速摄像机对超声波作用下钎料铺展过程的外部特征进行了捕捉,结合超声波在石墨表面传播特性以及钎焊接头界面微观形貌,对超声波作用下锡基活性钎料在石墨表面铺展过程进行了详细描述,分析了超声波在铺展过程中起到的作用,研究了影响钎料铺展的因素。结果表明,在钎焊过程中加以超声波辅助,能实现活性钎料在石墨表面的铺展。与刚性基体不同的是超声波在石墨表面振幅衰减很快,这使得超声波作用下的声致铺展作用在石墨表面很难进行,但随着石墨表面的孔洞被钎料填充,振幅衰减逐渐减小,声致铺展作用逐渐加强,在超声波功率足够大的情况下,液态钎料可以在石墨表面铺展。钎料表面氧化膜是阻碍钎料铺展的关键因素,通过施加超声波可去除钎料表面氧化膜促进钎料铺展。     

Wetting Characteristics of Novel-type 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi Solder Alloy

6061 aluminum alloy has many advantages, and soldering is the most attractive joining method for 6061 aluminum alloy. In order to expand application of 6061 aluminum alloy, a novel 63Sn-29.2Pb-6Zn-1Ag-0.38Cu-0.42Bi solder alloy was prepared. The melting characteristic and microstructure of the solder were analyzed by differential scanning calorimetry and scanning electron microscope. Its spreading on the 6061 aluminum alloy was also studied. The results show that its melting temperature range is 456.34-463.68 K, and the temperature interval between the solidus and the liquidus is 6.34 K. The solder on 6061 aluminum alloy had better wetting characteristics. A precursor film appears ahead of the spreading droplet. The microstructure at the interface between the solder and the 6061 aluminum alloy was analyzed. It was clear that the intermetallic compound, Ag₂Al phase, was formed at the interface between the solder and the 6061 aluminum alloy.     

Joint strength of aluminum ultrasonic soldered under liquidus temperature of Sn–Zn hypereutectic solder

In order to obtain high-strength aluminum joints, ultrasonic soldering of 1070 aluminum was conducted under liquidus temperature of Sn–Zn hypereutectic solder. A device for ultrasonic soldering was assembled, which propagated ultrasonic vibrations in a direction perpendicular to joining surfaces. This device joined 1070-Al using quasi-melting Sn–Zn hypereutectic solder without using any artificial spacers. The strength of the solder joints was evaluated by tensile tests. The optimum joining conditions were determined, and the effects of solder compositions and soldering temperature on the joint strength and the solder layer thickness were examined. In this ultrasonic soldering process, the highest tensile strength was obtained for the solder joints fabricated at 220 °C for the Sn–23Zn and Sn–40Zn solder compositions. The joint strength was equivalent to that of 1070-Al heat treated at 220 °C. The sound joints were obtained at 300 °C using Sn–82Zn solder, the liquid phase volume fraction of which was theoretically only 0.24. The present work also revealed that the thickness of retained solder layer in the joint after ultrasonic soldering could be estimated. Accordingly, ultrasonic soldering under the liquidus temperature of Sn–Zn hypereutectic solder could be a spacer-free soldering method to obtain high-strength aluminum joints.     

Residual stresses in welded joints in 1460 aluminium alloy

In order to obtain high-strength aluminium butt joints with corrosion resistance, ultrasonic soldering of A1070 rods was conducted using quasi-melting Sn–xZn (x = 23, 40, 82 mass%) hypereutectic alloy. Ultrasonic vibrations were applied at soldering temperatures ranging 220–300°C through A1070 rods without a solder bath.

The tensile strength of the solder joints with Sn–23Zn or 40Zn alloy were higher than that of the joint soldered with Sn–9Zn eutectic alloy. The joints soldered with Sn–23Zn or 40Zn alloy showed the same strength as A1070 rods which employed the same heat treatment as the ultrasonic soldering process. The thickness of the hypereutectic solder layer in the joints was thicker than that of the Sn–9Zn solder layer because unmelted α-Zn solid solution should have prevented the solder from being pressed out of the joint gap by the applied pressure during soldering. Tensile tests of the joints after immersion in NaCl aqueous solution revealed that the corrosion resistance of the joints soldered with hypereutectic alloy was higher than that of the joint soldered with Sn–9Zn alloy. It is considered that the improvement was achieved by the thick hypereutectic solder layer which should have reduced the notch effect in the joints.     

钎焊温度对AA4045/AA3003复合层焊缝组织及性能的影响

为了获得组织性能良好的钎缝,通过改变钎焊温度,对AA4045/AA3003铝合金复合板材料进行炉中气氛保护钎焊。通过焊缝显微组织分析,以及焊件水压检漏测试、氦气检漏测试和盐雾腐蚀试验,分析钎焊温度对接头组织性能的影响。结果表明,在网带速率为800mm/min的条件下,设定钎焊温度为610～615℃,实际钎焊温度为608～612℃时,钎焊焊缝组织性能良好;钎焊温度低于608℃时,焊缝有未焊透现象,工件漏气现象明显;钎焊温度高于612℃时,由于温度过高,促使元素扩散和铝合金的溶解加剧,导致接头区域有溶蚀发生,并且随温度的升高,溶蚀现象趋于严重。     

Rapid Ultrasonic-Assisted Soldering of AZ31B Mg Alloy/6061 Al Alloy with Low-Melting-Point Sn–xZn Solders Without Flux in Air

A novel ultrasonic-assisted low-temperature soldering was developed to join AZ31B Mg alloy and 6061 Al alloy with a series of Sn–x Zn solders. The average maximum shear strength of the joints reaches up to 87.5 MPa at soldering temperature of 300 °C under ultrasonic assistance for only 5 s using Sn–20 Zn solder. The fracture path propagates completely in the soldering seam. The results indicate that the microjet generated by ultrasonic pressure in liquid solder could strike and splinter the Mg_2Sn intermetallic compounds into small pieces, which contributes to the enhancement of the joint strength. In addition, the primary Al(Zn) solid solution phase formed during cooling stage could also strengthen the joint due to the prevention of microcracks propagation.     

Optimal Design of Co/In/Cu Sputtering Target Assembly Using Finite Element Method and Taguchi Method

Target assembly is a key consumable material for producing thin fi lm used in the electronic packaging and devices. The residual stresses induced during the process of soldering are detrimental to the performance of target assembly. In this work, the intensity and distribution of the soldering residual stress of Co/In/Cu target assembly subjected to a 20 W/(m~2 K) cooling condition corresponding to the actual air cooling process were studied, based on fi nite element simulation and Taguchi method, to optimize the sputtering target assembly. Effects of different control factors, including solder material, thickness of solder layer, target and backing plate, on the soldering residual stress of target assembly are investigated. The maximum residual stress is calculated as 9.28 MPa in the target located at 0.16 mm from target–solder layer interface and at a distance of 0.78 mm from symmetry axis. The optimal design in target assembly has the combination of indium solder material, cobalt target at 12 mm thick, solder layer at 0.8 mm thick, copper backing plate at 15 mm thick. Moreover, solder material is the most important factor among control factors in the target assembly.     

Selection of soldering temperature for ultrasonic-assisted soldering of 5056 aluminum alloy using Zn-Al system solders

The conditions for sound butt-joints of 5056 aluminum alloy containing 4.6 mass% Mg using Zn-xAl (x = 5, 13, and 38 mass%) solder at the relevant temperatures were investigated. Each solder foil was inserted between faying surfaces of 5056 aluminum rods. Ultrasonic vibration at a frequency of 19 kHz was applied to the faying surfaces through an aluminum substrate at soldering temperatures for 4 s in air. The strength of obtained solder joints was measured by tensile tests. The microstructure in the solder layer after the soldering process was evaluated with an SEM-EDX. The results of tensile tests revealed that joints soldered under the liquidus temperature of Zn-Al solders showed higher strength than joints soldered over the liquidus temperature. In the joints soldered over the solder liquidus temperature, the joint strength decreased with an increase in soldering temperature. It was caused by the formation of MgZn₂ in the solder layer due to dissolution of 5056-Al into the solder liquid during the soldering process. On the other hand, ultrasonic-assisted soldering under the solder liquidus temperature suppressed dissolution of 5056-Al and improved the joint strength by reducing the formation of MgZn₂.     

钢/铝管磁脉冲辅助半固态钎焊界面行为

结合电磁成形技术和半固态钎焊技术,提出了一种钢/铝管磁脉冲辅助半固态钎焊工艺,利用电磁脉冲产生的洛伦兹力使铝外管高速碰撞半固态钎料,通过半固态钎料中固相颗粒对母材表面径向压缩和轴向剪切作用去除母材表面氧化膜,实现钢铝异种管材的无钎剂钎焊. 在不同工艺参数下进行了钢/铝管磁脉冲半固态钎焊试验,研究了钎焊接头界面元素的扩散行为和金属间化合物的生长机理. 结果表明,焊缝组织主要为α-Al以及富锌相,铝侧界面处的Al₂O₃氧化膜破碎与去除情况良好,钢侧界面处有薄层FeAl₃金属间化合物形成,各部位均获得较好的冶金结合.