外加磁场对异种金属焊接质量的影响

为探讨电磁搅拌抑制异种金属焊缝缺陷、改进焊接质量的可行性，研究了外加磁场对异种金属焊接质量的影响。采用TIG焊接后，分别分析焊缝外观、裂纹状况、内部质量和组织变化等，综合评价外加磁场对焊接质量的影响趋势。     

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。     

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。     

低温外科设备治疗探针高频钎焊研究

治疗探针是低温外科设备的关键器件.在临床手术过程中,治疗探针的探杆部分(非冷冻区)通常需与人体正常组织紧密接触.为不伤及这些非冷冻组织,对于这种细直径探杆狭小隔层空间的绝热,只能采用高真空加以实现.为获得并维持探杆隔层空间的高真空,必须保证冷冻探针金属组件焊接的质量.文中详细介绍了冷冻探针金属组件的材料处理和高频钎焊技...     

基于神经网络遗传算法的激光熔钎焊参数优化

针对激光钎焊熔深难以控制的问题,选取激光焊接功率、焊接速度等激光焊接过程中所涉及的控制参数建立基于BP人工神经网络的激光钎焊模型。根据激光钎焊模拟实验的历史数据对焊接熔深进行预测,采用遗传算法对控制参数进行优化,得到目标焊接熔深。运用MATLAB软件建立了针对铝合金/镀锌钢的激光熔钎焊过程的参数的BP人工神经网络模型,并利用遗传算法的并行和群体搜索策略,对其控制参数进行了优化,使得焊接熔深能通过过程参数精确控制,提高了接头性能。     

激光无铅钎焊速度的影响因素(英文)

为了提高激光无铅钎焊的速度,对影响激光无铅钎焊速度的因素(如激光的参数、所用钎料和基体的特性、钎焊的系统结构等)进行了分析研究。研究认为,在激光器、钎料及基体等已定的情况下,相对于那些受到机械惯性制约的移动激光加工头或移动工作台的激光钎焊系统,一种配备了振镜扫描系统和f-theta聚焦透镜的激光钎焊系统具有更高的钎焊速度。另外,对激光钎焊过程中激光束的扫描路径进行了优化,这种优化能在不增加硬件成本的基础上大大缩短总扫描路程,较大程度地提高激光钎焊速度。最后通过实例对激光钎焊的快速性进行了验证。     

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.     

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.     

钢-铅粘接结构的粘接强度对超声体波反射与 透射特性的影响*

针对多层异种金属粘接结构中粘接强度的超声检测与表征困难的问题,采用线性弹簧模型和等效弹性模量模型来分别表征界面粘附强度和内聚强度,推导了超声体波斜入射N层粘接结构的反射与透射系数表达式。通过在不同入射面和入射声波模式等条件下,同时连续改变两种参数来系统研究粘接层界面粘附强度与内聚强度变化对超声波反射与透射特性的影响关系,确定了能够敏感表征粘接强度的超声参量,为粘接强度的无损检测与评价提供理论依据。     

Fe-B-Si非晶钎焊W/CLF-1接头组织和性能研究

通过电弧熔炼制备了Fe75B16.67Si8.33非晶合金,通过真空钎焊获得了钨/低活化钢接头.通过对钎焊接头表面形貌、微观组织、成分和力学性能的表征,发现在1250℃保温10min下所获得的钎焊接头界面无孔洞、裂纹等宏观缺陷,接头组织中生成了Fe固溶体、Fe3B和FeWB金属间化合物,拉伸强度高达450MPa.     

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.     

HL-2Mƫ����CFC/CuCrZr�а�ķǾ�ǥ�������о�

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.     

电感耦合等离子体发射光谱法测定银基钎料中银,铜,锌和镉的含量

本文叙述用电感耦合等离子体发射光谱法直接测定银基钎中角，铜，锌和镉，考察了光谱干扰和酸度的影响，在优化的操作条件下可以获得满意的分析结果，相对标准偏差４～７％，加标回收率为９４％～１０５％，该方法简便可靠，适合角基钎料的多元素同时测定。     

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.     

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.