PDC复合片的真空钎焊及针缝重新合金化

通过对ＰＤＣ复合片真空钎焊的研究，提出了钎缝重新合金化概念，在实验中采用复合钎料真空钎焊ＰＤＣ复合片，取得了钎缝完全重新合金化的效果，钎缝接头的剪切强度均在３００ＭＰａ以上。同时，对复合钎料强化钎缝的机理进行了探讨。     

PDC复合片的真空钎焊及钎缝重新合金化

通过对ＰＤＣ复合片真钎焊的研究，提出了钎缝重新合金化概念，在实验中采用复合钎料真空钎焊ＰＤＣ复合片，取得了钎缝完全重新合金化的效果，钎缝接头的剪切强度均在３００ＭＰａ以上。同时，对复合钎料强化钎缝的机理进行了探讨。     

CuO辅助Ag_(72)Cu_(28)共晶钎料在大气环境中实现Al_2O_3陶瓷钎焊的界面反应

采用CuO辅助Ag_(72)Cu_(28)共晶钎料的方法,在大气环境中实现了Al_2O_3陶瓷的钎焊,研究了钎焊接头的剪切强度、微观形貌以及界面反应产物和界面反应机理。结果表明:该方法可以得到结合良好的Al_2O_3陶瓷接头;在钎焊温度为1 050℃、保温时间为10min、CuO质量分数为10%的条件下进行钎焊时,接头的剪切强度最高,为39.04 MPa;在钎焊过程中,由于陶瓷表面CuO的存在使熔融铜向陶瓷表面富集并发生反应,从而实现钎料的润湿和铺展;在钎焊接头中可见清晰的界面过渡层,界面反应产物主要为CuAl_2O_4及CuAlO_2相。     

Cu颗粒增强复合钎料钎焊接头的蠕变断裂及强化机理

测定不同应力和温度下Cu颗粒增强复合钎料及基体钎料钎焊接头蠕变寿命,分析Cu颗粒增强复合钎料及其基体钎料63Sn37Pb钎焊接头蠕变断裂机理。结果表明：Cu颗粒增强复合钎料钎焊接头蠕变寿命优于基体钎料。Cu颗粒表面金属间化合物形成及Cu颗粒对富Pb层阻碍作用是复合钎料钎焊接头蠕变性能改善的主要因素。钎焊接头铜基板上一薄层富Pb相的形成是蠕变裂纹产生的根源。     

Ag-Cu-Ti活性钎料真空钎焊钨、石墨与铜的研究

研究了Ag-Cu-Ti活性钎料高真空钎焊钨与铜与石墨与铜，结果表明，钎焊钨与铜时可获得接近母材铜强度的接头，剪切断裂发生在铜与Ag-Cu-Ti之间的扩散层中，钎焊石墨与铜时接头最大强度为32MPa，剪切断裂主要发生在近石墨与钎缝金属界面的石墨中，高强度结合界面是通过活性元素Ti向钨或石墨扩散并与之反应而形成的。     

钎料对金属/陶瓷钎焊接头残余应力的影响

采用热弹塑性有限元方法,在考虑材料性能参数随温度变化的情况下,分析了采用Ag-Cu-Ti钎料钎焊Al2O3陶瓷与镍丝钎焊接头在钎焊过程中产生的应力大小和分布情况.结果表明：钎焊过程中,在钎料与陶瓷界面的陶瓷侧会产生较大的残余拉应力,影响了钎焊接头的连接强度.在此类连接结构中,钎料对接头残余应力的影响是主要的,而钎料性能参数及厚度是决定接头残余应力大小的重要因素.在选择金属/陶瓷钎焊用钎料时,为降低接头残余应力,除考虑钎料与陶瓷的润湿性和界面反应程度外,钎料的性能参数和厚度同样重要.     

混合稀土含量对Zn9.3Al7Cu合金钎料润湿性能及显微组织的影响

在Zn9.3Al7Cu合金钎料中添加了质量分数分别为0,0.1%,0.3%,0.5%的由镧粉和钕粉组成的混合稀土,研究了混合稀土含量对该合金钎料熔点、润湿性能、显微组织,以及对其钎焊铜/铝接头剪切强度的影响。结果表明:合金钎料的显微组织均由η(Zn)相、ε(CuZn5)相、β(ZnAl)共析相组成,混合稀土的添加使大树枝状的ε(CuZn5)相细化、分布变均匀;随着混合稀土含量的增加,合金钎料的熔点逐渐降低,润湿性能及其钎焊铜/铝接头的剪切强度均先增大后下降;当混合稀土质量分数为0.1%时,钎料在铜板和铝板上的铺展面积均达到最大,分别比未添加稀土的提高了20.4%和46.6%,其润湿铝板的界面变得连续,没有缺陷;合金钎料钎焊铜/铝接头的剪切强度也达到最大,为66.5MPa,比未添加稀土的提高了32.5%。     

用Al箔进行TiCp/Si3N4复相陶瓷的连接

用Ａｌ箔进行了ＴｉＣｐ／Ｓｉ３Ｎ４复相陶瓷的连接，用四点弯曲的方法测定不同连接工艺下的连接强度，并对接头界面进行ＳＥＭ，ＥＰＭＡ和ＸＲＤ分析，结果表明，由于陶瓷与钎料界面反应和界面残余应力的综合影响，随着钎焊温度和保温时间的增加，接头强度先增后降，微观分析表明，Ｓｉ３Ｎ４与Ａｌ的反应及Ｔｉ，Ｓｉ的界面扩散将影响接头的力学性能。     

多层复合钎料钎焊Ti(C,N)基金属陶瓷与45钢接头的组织

采用由Ag-Cu-Ti+Mo钎料、铜箔和Ag-Cu钎料组成的多层复合钎料,对Ti(C,N)基金属陶瓷和45钢在不同温度(890,920,950℃)和不同时间(10,20,30min)下进行了真空钎焊,根据接头截面形貌和剪切强度确定了最佳钎焊温度和保温时间,并分析了最佳工艺下钎焊接头的显微组织。结果表明:随钎焊温度的升高或保温时间的延长,Ag-Cu-Ti+Mo钎料与金属陶瓷间的界面反应层厚度增大,铜钛金属间化合物增多,两侧钎料区中的铜基固溶体增多,接头的剪切强度先增后降;最佳钎焊工艺为钎焊温度920℃、保温时间20min,此时接头剪切强度最大,从金属陶瓷向45钢,接头组织依次为Cu3Ti2+Ni3Ti金属间化合物,银基固溶体+铜基固溶体+钼+铜钛金属间化合物,铜,银基固溶体+铜基固溶体。     

高体积分数SiC_p增强6063Al基复合材料的真空加压钎焊

在580℃、保温40min、压力为4kPa的钎焊条件下,采用Al70-Cu22.3-Si6.1-Mg1.6膏状钎料对增强相体积分数为60%的SiCp/6063Al复合材料进行真空加压钎焊,通过扫描电镜和剪切试验等研究了钎料对复合材料基体及SiC增强相的润湿机理以及钎焊接头的显微组织、剪切断口形貌。结果表明:在试验条件下,钎料对复合材料的润湿性较高,可通过扩散及机械压渗作用与基体、SiC颗粒分别形成冶金结合和机械锁合,接头的抗剪强度均值为71.6MPa;钎料与基体合金的反应界面消失,钎料对大块SiC增强相的润湿性一般,二者之间存在较小的间隙;断裂发生在钎料层以及钎料与复合材料界面的母材侧。     

Cu基钎料电弧钎焊接头强度及断口分析

研究用钨极氩弧焊作为热源,用Cu3Si1Mn钎料、56Cu8Mn26Zn钎料分别钎焊A3钢板及1Cr18Ni9Ti不锈钢板。试验结果表明,在钎料/母材界面分别存在Si、Mn富集带,经XRD分析表明,Si是以Fe2Si相形式存在,而Mn是以固溶体形式存在;用Cu3Si1Mn、56Cu8Mn26Zn钎料钎焊A3钢板接头抗拉强度试样均断在母材,抗拉强度为308.2～308.7MPa,钎焊1Cr18Ni9Ti不锈钢板,拉伸均断在钎缝,其抗拉强度分别是331.5 MPa、382.9 MPa;拉伸断口分析发现,断裂起裂点在搭接钎缝的根部,主要是母材成分与少量的钎料成分混合、溶解而成,是脆性断口;止裂点在钎缝金属中（Cu3Si1Mn钎料）或在近界面上（Cu3Si1Mn钎料）,是塑性断口。     

陶瓷表面加弧辉光离子镀钛改性及其钎焊性

针对常规钎料难以润湿陶瓷表面的问题，利用加弧辉光离子镀膜技术在Si3N4陶瓷表面预沉积了一层高活性的Ti膜。为充分发挥Ti的活性作用，在活性镀Ti层表面进行了二次电镀Ni。试验表明，在钎焊过程中二次镀Ni层可有效保护Ti膜不被氧化，镀膜陶瓷与金属钎焊接头的剪切强度也显著提高。采用BAg72Cu-V钎料时，镀膜Si3N4陶瓷与金属钎焊接头的剪切强度可达205MPa。     

ZrO2陶瓷与钛合金非晶钎焊

由于陶瓷的线膨胀系数与金属的线膨胀系数相差很大,因此在通过焊接连接陶瓷与金属时,热作用势必会在接头区域会产生幅值较大的残余应力,进而降低接头的力学性能,严重时甚至会导致连接陶瓷接头的断裂。这使得陶瓷与金属的连接是一个广受关注但又未能得到很好解决的科学问题。采用非晶钎料实现ZrO2陶瓷与Ti-6Al-4V合金的钎焊连接,研究焊接工艺参数对接头的组织与性能的影响。结果表明接头界面组织结构为ZrO2陶瓷/Cu2Ti4O+(Ti,Zr)2Cu/TiO+Ti2O/CuTi2+(Ti,Zr)2Cu/ CuTi2/Ti-6Al-4V合金。钎焊温度、保温时间和冷却速度对界面组织结构有最大的影响,主要体现在反应层的厚度和脆性(Ti,Zr)2Cu相的变化。接头的剪切强度随钎焊温度、加热时间和冷却速度的增加而降低。最佳工艺参数为焊温度1 173 K,保温时间10 min,冷却速度5 K/min,其钎焊接头剪切强度可以达到165 MPa。     

Al_2O_3陶瓷与Q235钢的活性钎焊

采用二元Cu-Ti活性钎料连接氧化铝陶瓷与Q235钢,研究了反应温度、保温时间等钎焊工艺对接头组织与接头强度的影响,分析了接头的微观组织和界面产物。试验结果表明,界面分为3层结构,即液态钎料填充陶瓷微孔形成的反应层、合金钎料层、钢侧扩散层。XRD分析结果表明,界面产物为Cu3Ti3O、TiFe、TiFe2和Cu基固溶体。钎焊温度1050℃,保温时间30min时,接头抗剪强度达到99.3MPa。     

Effect of brazing temperature on the shear strength of Inconel 600 joint

In this study, Inconel 600 alloy was brazed by using Cusil ABA which is an active filler alloy in a high-vacuum condition under a pressure of 1?×?10^?4 Pa. Three brazing temperatures (830, 865, and 900 °C) were chosen based on the solidus temperature of AgCuTi filler alloy in order to investigate the effects of these temperatures on the performance of the brazed joint. Brazing processes were carried out over a period of time (15 min) to ensure that the filler alloy was melted completely. The performance of the brazing process was evaluated in terms of bonding strength by shear test, whereas microstructural analysis was performed to investigate the bonding morphology. The results revealed that a maximum value of shear strength (223.32 MPa) was obtained at a brazing temperature of 865 °C compared with other temperatures. It was also observed morphologically that the highest shear strength was influenced by the formation of two reaction layers that crossed in the center of the brazed area due to interdiffusion effect of several constituents from the Inconel 600 alloy and active brazing filler.     

Inhibition of intermetallic formation during diffusion bonding of high-carbon steel

Diffusion bonding of high-carbon steel was carried out in vacuum brazing furnace at temperature 900–1,050 °C for 0.5 h under uniaxial load using Ni foil interlayer. Microstructure of assemblies was studied along with effect of diffusion of chemical species in reaction zone and mechanical properties. Microstructure of substrate was changed from martensite to austenite at bonding temperature and subsequently to ferrite–pearlite during cooling to ambient temperature. Diffusion zone did not exhibit formation of any intermetallic compounds. Bond strength was governed by degree of solid solution hardening and contact area of mating surfaces depending on joining parameters. In this respect, maximum ultimate strength of ~532 MPa was obtained along with shear strength of ~792 MPa for the joint processed at 1,050 °C, which was higher than literature reports on martensitic steel.     

Molecular dynamics simulation of tensile behavior of diffusion bonded Ni/Al nanowires

Interfaces play key roles in determining mechanical properties of materials. In current work we perform molecular dynamics simulations of diffusion bonding to evaluate the effect of temperature on the morphology of the Ni/Al interface and the strength of the diffusion bonded Ni/Al nanowires. The centro-symmetry parameter is adopted to identify defect atoms generated. Simulation results show that the thickness of the Ni/Al interface has strong dependence on the temperature of diffusion bonding. Following uniaxial tension tests indicate that the yield strength of Ni/Al nanowires is smaller than both the single crystalline Ni and Al nanowires, because of the Ni/Al interface acting as dislocation source and the mobilization of pre-existing dislocations at high temperature. It is shown that the mechanical properties of diffusion bonded Ni/Al nanowires strongly depend on the temperature.     

铝(铝合金)与不锈钢的过渡层钎焊工艺及机理分析

研究了铝(铝合金)与不锈钢的镍／铜过渡层钎焊的工艺方法以及焊缝的组织与力学性能，并对各连接界面进行了机理分析。对焊缝的XRD、SEM和TEM等分析发现焊缝与母材之间没有生成铝与铁脆性的金属间化合物。结果表明，镍／铜电刷镀层能有效地阻挡铝、铁等原子扩散，焊缝与镀铜界面上虽然生成了少量的AlCu2，但没有降低焊缝的抗剪强度。     

Application of cold spraying for flux-free brazing of aluminium alloy 6060

In the present study, samples of aluminium alloy 6060 were coated by cold spraying with a powder of brazing alloy Al12Si. The influence of the process gas temperature on particle velocities and coating build-up was investigated. The coated samples were heat-treated in air and under argon atmosphere to investigate the wetting behaviour of the deposited Al12Si and the diffusion processes between Al12Si coatings and substrates. Coated samples were brazed flux-free under argon atmosphere by an induction heating system. The microstructure of the coated, heat-treated, and brazed samples was investigated. The shear strength of the brazed joints was determined. The results show that the brazing alloy Al12Si could be very well deposited on the substrate by cold spraying. The particle velocity increased with increasing process temperature. Correspondingly, the thickness of Al12Si coatings increased with increasing process temperature. The heat treatments showed that a very good metallurgical bond between the Al12Si coatings and the substrate could be realized by the deposition using cold spraying. The coated samples could be well brazed without fluxes. The coating thickness and overlap width influenced the shear strength of the brazed joints. The highest shear strength of brazed joints amounts to 80 MPa.