钨/低活化钢钎焊用铁基非晶钎料与接头微结构

为了连接W和CLF-1 RAFM钢,设计出由低活化元素组成的Fe-B-Si、Fe-B-Si-Sn、Fe-B-Si-Cr-(Sn)、Fe-B-Si-P-(Cr,Sn)、Fe-B-Si-Mn-(Ga,Sn)和Fe-B-Si-(Cr,Mn,Ga,Ta,Sn)系列Fe基非晶钎料,结合熔体快淬技术制备出非晶合金箔带,并对W/CLF-1 RAFM钢接头微结构进行了对比研究。采用X-射线衍射仪对箔带样品与焊缝进行了相鉴定;通过差热分析测量了非晶箔带的熔化温度和液相线温度;利用光学金相和电子探针分析了焊缝组织形貌和元素分布。结果表明,利用Fe-B-Si、Fe-B-Si-Cr和Fe-B-Si-Mn-Sn非晶钎料可获得结构完整的W/CLF-1钢接头;前两种钎料得到的焊缝组织基体相为α-Fe固溶体,而含Mn钎料形成的焊缝基体为马氏体组织;在高温钎焊过程中,这些Fe基非晶钎料中的高B含量促使FeWB、FeW2B2和Fe3B型金属间化合物在焊缝中形成,并有效地阻止了W元素向低活化钢基体长程扩散。所设计的低活化Fe基非晶钎料可用于W和低活化钢的连接和接头性能研究。     

Ag箔钎焊YBCO高温超导块材

采用Ag箔在两种不同的工艺条件下对YBCO高温超导块材进行了钎焊连接,钎焊完成后,分别对原始超导块材和钎焊接头进行磁悬浮力测量和俘获磁场测试、以评价钎焊质量.磁悬浮力的测试结果表明,在两种工艺条件下,钎焊接头的磁悬浮力分别可达原始块材的69.88%和79.37%.俘获场测试结果表明,单畴原始母材的俘获场为单峰,钎焊接头的俘获场为双峰;同时,钎缝区域的俘获磁场强度较低,没有完全恢复接头母材的超导环流,而限制了钎焊接头超导性能的提高.     

溅射Al对AlN的“润湿”与钎焊

由于润湿性不佳, 难以实现金属钎料对陶瓷的无过渡层直接钎焊, 本文在研究了溅射Al薄膜对AlN的“润湿”作用的基础上, 通过磁控溅射的方法在AlN表面沉积Al基薄膜作为钎料, 在真空条件下对AlN陶瓷进行了直接钎焊. 采用高景深光学显微镜、扫描电子显微镜和X射线能量分散谱表征了钎焊接头和剪切断口的组织及形貌. 结果表明, 高能量溅射Al粒子对AlN的撞击可以形成只有850 ℃以上高温才可获得的Al-N化学键, 实现Al对AlN的“润湿”, 使Al基薄膜钎料能够在较低的温度(≥ 510 ℃)对AlN直接钎焊. 此方法获得的Al/AlN接头的剪切强度达到104 MPa, 含3.8 at.% Cu的Al合金钎料接头强度可进一步提高到165 MPa, 它们的剪切断裂都产生于钎缝金属之中; 增加钎料中的Cu含量至9.1 at.%后, Cu在钎缝与陶瓷界面的偏聚使接头的剪切强度降低为95 MPa. Al-20 at.% Ge合金可以将钎焊温度降低至510 ℃, 但Ge在钎缝与陶瓷界面的偏聚使接头在48 MPa发生断裂.     

塑料超声焊接头熔化状态与强度

对塑料超声焊接头熔化状态影响其质量的因素进行了研究．通过对焊接接头熔融体温度、粘度、剪切速率等材料物理参数的测试分析发现,焊接压力和振幅对接头熔化层的尺寸及流动状态影响很大,随焊接振幅和焊接压力的增大,塑料熔融体的温度提高,粘度减小,熔化层的厚度而减小．利用光学显微镜观察了接头的组织形貌,发现接头熔化层组织具有明显的熔体流动方向性,焊接振幅和焊接压力越大,熔体剪切速率越大,接头熔化层内组织取向越明显．接头剪切和弯曲强度的测试结果表明,接头力学性能具有明显的各向异性,为获得合适熔化层厚度和组织取向程度,必须合理选取焊接工艺规范,这样才能取得满意焊接接头质量．     

Cu/CuCrZr钎焊用Cu-Mn基多元固溶体钎料和接头结构

为了解决CFC与Cu Cr Zr合金的冶金连接问题，以二元合金Cu₆₂Mn₃₈(at.%)为基础成分，采用低熔点Ga作为主要合金化元素和微合金化元素Cr和Si，设计了系列固溶体钎料合金Cu₆₂Mn_37-xGa_xCr_0.5Si_0.5(x=0～10,at.%)。利用电弧熔炼、铜模吸铸和冷轧制备了100μm厚的钎料箔带。采用Cu₆₂Mn₃₁Ga₆Cr_0.5Si_0.5钎料在不同工艺条件下(875～900℃，保温15～25min)制备了无氧铜和Cu Cr Zr合金钎焊接头。通过热分析和X-射线衍射分析了钎料熔化行为和相组成；采用光学显微镜、扫描电镜、电子探针和力学性能拉伸机对接头的组织形貌、成分分布和力学性能进行了分析。结果表明，在880℃/保温25min钎焊工艺下可获得无缺陷CFC/Cu Cr Zr接头结构，焊缝的Cu固溶体基体内有少...     

第二代高温超导带材焊接及力学性能研究

第二代高温超导已进入产业化初期, 尽管单根带材长度已达千米量级, 但由于千米级单根带材生产成品率偏低以及大型超导装置对带材长度实际需求远超出单根长度制备能力, 因此, 焊接技术成为高温超导大规模应用的关键技术之一. 接头电阻及其力学性能是评估焊接接头的重要技术指标. 本文提出了改进型接头和“隐形”接头两种制作方法, 并对其接头电阻以及力学性能进行了表征, 同时与常规搭接接头进行了对比分析. 结果发现,(1) 与常规搭接头相比, 改进型和“隐形”接头的厚度分别降低了15 % 和36 % , 有效减小了焊接头处和原带材厚度差异. (2) 超导面-超导面焊接, 获得接头电阻最小; 接头电阻随接头长度的增加而减小, 但幅度降低. (3) 常规搭接头、 改进型和“隐形”焊接头均具有良好的轴向抗拉性能, 通过扭转和8 天液氮浸泡后, 临界电流无衰退, 电阻保持一致. (4) 改进型和“隐形”接头的临界弯曲直径(20 mm) 与原带材(非接头处) 相当, 通过卷对卷传输法测试时接头无损伤, 而常规搭接头的临界弯曲直径(40 mm) 大于原带材, 在通过卷对卷测试时, 接头出现开裂甚至断开现象.根据具体应用场景, 选择合适接头制作方式, 对推动第二代高温超导产业化具有重要意义.     

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采用了TIG对核聚变用316LN奥氏体不锈钢进行焊接,并对焊接接头进行了焊后热处理,利用光学显微镜、扫描电镜分析手段研究了焊后热处理对焊接接头微观组织和力学性能的变化.试验结果表明,焊缝中为奥氏体组织,并未发现第二相析出物存在.焊后热处理对接头的拉伸性能影响不大,均断裂在母材位置,但显著提高了接头的延伸率.接头低温冲击试验也展现了良好的抗低温冲击性能.断口分析发现,接头呈韧性断裂.     

正火和回火处理过程中W/Fe/RAFM钢接头W/Fe界面组织和剪切性能的演化

对热等静压(HIP)扩散焊制备的W/Fe/RAFM钢接头进行了正火和回火处理,以恢复其中RAFM钢的 组织和性能。采用电子探针微分析器(EPMA)和掠入射X射线衍射(GIXRD)对W/Fe界面组织的演化进行了分析,采 用剪切测试和扫描电镜(SEM)对接头连接性能的演化进行了测试和分析。结果表明,正火处理后,RAFM钢中的C 元素扩散到了W/Fe界面,Fe₂W相中W和C元素含量增加,这导致了接头剪切强度增加,而纯铁中间层强度的增加 则导致了接头剪切位移下降。回火处理后,W/Fe界面形成了W/Fe₂W/Fe₃W₃C/Fe的界面结构,回火态接头Fe₂W相 的成分和纯铁中间层强度与HIP态接头基本相同,因此回火态接头室温剪切性能基本与HIP态接头一致。     

316L/RAFM钢电子束焊对接接头的微观组织与力学性能研究

在150kV/39mA的焊接参数下进行了316L/RAFM钢电子束焊工艺实验,对接头微观组织与力学性能进行了测试分析。在存在磁偏转的情况下,有效焊接深度达到了18mm,且焊接接头性能良好。     

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对EAST偏滤器热沉冷却水过渡接头在等离子体破裂时受到的主要电磁载荷进行了分析计算,提出了新的过渡接头结构.通过新结构在极端载荷下的有限元分析以及开展的焊接预研和测试,对接头结构及制作方案进行了优化,最终完成了偏滤器热沉冷却水过渡接头的设计,并成功运用于EAST偏滤器热沉的改造中.     

银铜钛膏状钎料钎焊石墨和铜合金接头的微观组织及性能

利用银铜钛(Ag-Cu-Ti)膏状钎料采用真空钎焊的方法对两种不同石墨和铜合金进行钎焊连接实验，研究了钎焊温度、中间缓冲层、母材尺寸等工艺参数对接头性能的影响。采用自行设计模具对接头的剪切强度进行了测试，利用扫描电镜和配带的X射线能谱分析仪分析了接头界面组织形貌及元素物相成分。研究结果表明：当钎焊温度为910℃，保温时间10min时，Ag-Cu-Ti膏状钎料能够与石墨和无氧铜两侧母材形成良好的结合界面；与GA石墨相比，阿泰克石墨与无氧铜接头强度更高；采用1mm无氧铜做中间缓冲层钎焊石墨和铬锆铜时，能有效缓解钎焊热应力，接头强度有明显提高。     

异种金属界面液态钎料的润湿铺展

采用高速摄影及其数据分析处理系统,对低碳钢-不锈钢异种金属界面液态钎料润湿铺展的动态过程进行了分析研究。试验结果表明,采用台阶加热能保证形成可靠的异种金属钎焊接头,从而提高了钎焊质量。     

Active metal brazing of Al2O3 to Kovar® (Fe–29Ni–17Co wt.%) using Copper ABA® (Cu–3.0Si–2.3Ti–2.0Al wt.%)

The application of an active braze alloy (ABA) known as Copper ABA® (Cu–3.0Si–2.3Ti–2.0Al wt.%) to join Al₂O₃ to Kovar® (Fe–29Ni–17Co wt.%) has been investigated. This ABA was selected to increase the operating temperature of the joint beyond the capabilities of typically used ABAs such as Ag–Cu–Ti-based alloys. Silica present as a secondary phase in the Al₂O₃ at a level of ~5 wt.% enabled the ceramic component to bond to the ABA chemically by forming a layer of Si₃Ti₅ at the ABA/Al₂O₃ interface. Appropriate brazing conditions to preserve a near-continuous Si₃Ti₅ layer on the Al₂O₃ and a continuous Fe₃Si layer on the Kovar® were found to be a brazing time of ≤15 min at 1025 °C or ≤2 min at 1050 °C. These conditions produced joints that did not break on handling and could be prepared easily for microscopy. Brazing for longer periods of time, up to 45 min, at these temperatures broke down the Si₃Ti₅ layer on the Al₂O₃, while brazing at ≥1075 °C for 2–45 min broke down the Fe₃Si layer on the Kovar® significantly. Further complications of brazing at ≥1075 °C included leakage of the ABA out of the joint and the formation of a new brittle silicide, Ni₁₆Si₇Ti₆, at the ABA/Al₂O₃ interface. This investigation demonstrates that it is not straightforward to join Al₂O₃ to Kovar® using Copper ABA®, partly because the ranges of suitable values for the brazing temperature and time are quite limited. Other approaches to increase the operating temperature of the joint are discussed.     

HL-2M偏滤器CFC/CuCrZr靶板的非晶钎焊工艺研究

在采用商用的STEMET-1101非晶钎料、温度为710~750°C的真空钎焊下,对CFC/OFC(氯氟烃/无氧铜)复合块与CuCrZr(铬锆铜)的钎焊进行了研究。首先,通过X-射线衍射(XRD)和差式扫描量热分析对钎料的结构和熔化行为进行了表征;然后,通过光学显微镜、电子探针微分析和拉伸试验等方法对焊缝的组织形貌、元素成分分布、相结构和力学性能进行了分析;最后,通过高热负荷装置对CFC/OFC/CuCrZr钎焊模块的热疲劳性能进行测试。结果表明,在710~750°C钎焊温度内焊缝由Cu固溶体、(Cu, Ni)3P和Ni(Cu ,Cr)2P金属间化合物组成,焊缝平整无裂纹;特别是在750°C/15min情况下,抑制了焊缝金属间化合物的连续分布,OFC/CuCrZr的焊接强度大于OFC的抗拉强度,CuCrZr/CuCrZr的结合强度为210MPa,并呈现部分韧性断裂。在750°C/15min情况下制备的CFC/Cu/CuCrZr模块可以承受1000次7MW·m^-2的循环热负荷。     

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The brazing process of chlorofluorocarbon/oxygen-free-copper (CFC/OFC) composite mockup and CuCrZr at 710~750°C by vacuum brazing and with STEMET-1101 amorphous filler is studied. Firstly, the microstructure and melt behaviors of the filler are characterized by means of XRD and differential scanning calorimetry and then the organism form, elemental distributions, phase structures, and mechanical property in the bonding seams are studied by using optical microscopy, electron probe microanalysis and tensile tests. The thermal fatigue property of CFC/OFC/CuCrZr brazing mockup is measured with the high heat flux facility. The results show that the bonding seam consists of Ni(Cr, Cu)2P particles, Cu(Ni)3P phase and Cu matrix in brazing temperature of 710~750°C, which is smooth and crack-free. Especially, a continued intermetallic phase network in the bonding seam is depressed in the case of 750°C/15min treatment. The welding strength of the OFC/CuCrZr is higher than tensile strength of OFC. The bonding strength of CuCrZr/CuCrZr joint is 210MPa and fracture is partly ductile. The CFC/Cu/CuCrZr mockup prepared in the case of 750°C/15min treatment can tolerate 7MW·m^-2 high heat flux under 1000 cycles.     

Interfacial reaction of intermetallic compounds of ultrasonic-assisted brazed joints between dissimilar alloys of Ti6Al4V and Al4Cu1Mg

Ultrasonic-assisted brazing of Al4Cu1Mg and Ti6Al4V using Zn-based filler metal (without and with Si) has been investigated. Before brazing, the Ti6Al4V samples were pre-treated by hot-dip aluminizing and ultrasonic dipping in a molten filler metal bath in order to control the formation of intermetallic compounds between the Ti6Al4V samples and the filler metal. The results show that the TiAl(3) phase was formed in the interface between the Ti6Al4V substrate and the aluminized coating. For the Zn-based filler metal without Si, the Ti6Al4V interfacial area of the brazed joint did not change under the effect of the ultrasonic wave, and only consisted of the TiAl(3) phase. For the Zn-based filler metal with Si, the TiAl(3) phase disappeared and a Ti(7)Al(5)Si(12) phase was formed at the interfacial area of the brazed joints under the effect of the ultrasonic wave. Due to the TiAl(3) phase completely changing to a Ti(7)Al(5)Si(12) phase, the morphology of the intermetallic compounds changed from a block-like shape into a lamellar-like structure. The highest shear strength of 138MPa was obtained from the brazed joint free of the block-like TiAl(3) phase.     

Experiments and analysis of thin tungsten slice and W/Cu brazing for primary collimator scraper in CSNS/RCS

According to the requirements for the beam collimation system of the rapid cycling synchrotron(RCS)of China Spallation Neutron Source(CSNS),the main structure of a scraper of primary collimator is made by W/Cu brazing,in which the thickness of tungsten slice is 0.17 mm.In order to get the best mechanical properties,the brazing temperature is suggested to be controlled under the recrystallization temperature of tungsten,while the recrystallization temperature is affected directly by the thickness of tungsten.Because of little research and application on the brazing of thin tungsten slice of 0.17 mm and copper,tensile tests are done to get the mechanical properties of tungsten slices which experience different brazing temperatures.In keeping the inner relationships between the mechanical properties and temperature,another experiment is done by using SEM to scan the microstructures including the size and distribution of crystals.Finally we determine the recrystallization temperature of tungsten slice of 0.17 mm,and get the best parameters of W/Cu brazing for scrapers of primary collimator in CSNS/RCS.     

氩孤钎焊加热区比热流分布的动态分析

通过对不同弧长、不同电流氩弧的高速摄影拍摄以及利用影片数据分析处理系统对其动态过程的研究,发现用高斯函数模拟氩弧钎焊加热区的比热流q(r)分布特性时,理论计算值与测量值符合得较好.实验结果表明,氩弧钎焊时采用大电流的焊接规范既不经济亦无必要.因为,由q(r)分布模型可知,当弧长不变增加焊接电流时,氩弧钎焊加热区半径变小,而q_m急剧增大,往往诱发液态钎料过热,毛细填充作用不强等问题,使钎焊质量下降;当焊接电流不变增加弧长时,加热区半径显着增大,q_m减小,反而有利于保证氩弧钎焊质量和生产效率.