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。     

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...     

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。     

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.     

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.     

磁控溅射沉积薄膜实验参数优化光谱诊断

采用磁控溅射仪、Omni-λ300系列光栅光谱仪、CCD数据采集系统和光纤导光系统等构成的等离子体光谱分析系统,采集了以Cu和Al为靶材、氩气为工作气体,射频磁控溅射法沉积硅基薄膜时的等离子体发射光谱。以CuⅠ324.754 nm,CuⅠ327.396 nm,CuⅠ333.784 nm,CuⅠ353.039 nm,AlⅠ394.403 nm和AlⅠ396.153 nm为分析线,研究了Cu和Al等离子体发射光谱强度随溅射时间、溅射功率、靶基距和气体压强等实验参数的变化。并与射频磁控溅射沉积薄膜实验参数的选择进行对比,表明发射光谱法对射频磁控溅射薄膜生长条件的优化有着很好的指导作用。     

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。     

液态Sn-Cu钎料的黏滞性与润湿行为研究

金属熔体的黏度和表面张力都是与液态结构相关的敏感物理性质, 且存在一定的相互关系. 对于微电子封装材料而言, 黏度和表面张力均是影响其工艺性能的重要参量. 本文利用回转振动式高温熔体黏度仪测量了Sn-xCu (x = 0.7, 1.5, 2)钎料熔体在不同温度下的黏度值, 发现在一定温度范围内钎料熔体的黏度值存在突变, 可划分为低温区和高温区. 在各温区内, 黏温关系很好地符合Arrhenius方程, 在此基础上讨论了液态钎料的结构特征和演变规律. 同时, 利用黏度值计算了液态Sn-xCu钎料在相应温度下的表面张力, 并通过Sn-xCu钎料在Cu基板上的润湿铺展实验对计算结果进行验证. 结果显示, 润湿角和扩展率的测试结果与表面张力的计算结果具有很好的一致性, 表明通过熔体黏度值来计算锡基二元无铅钎料合金表面张力并评估其润湿性能的方法是可行的. 关键词： Sn-Cu钎料 黏度 表面张力 润湿性     

退火温度对TiO_2纳米薄膜酒精气敏特性影响的研究(英文)

采用直流磁控溅射的方法在Al2O3陶瓷管、硅基片上溅射制备了二氧化钛(TiO2)纳米薄膜材料.将薄膜样品放入管式退火炉中分别在500℃, 700℃和1100℃温度下退火.由于退火温度的不同,薄膜的晶体结构、晶粒尺寸、晶向以及气敏特性都有所不同.利用X射线衍射(XRD)技术和薄膜气敏特性测试,分析了退火温度对薄膜气敏特性的影响.分析结果表明退火温度在500℃时,呈现锐钛矿结构,薄膜具有很好的选择性、很短的反应(恢复)时间.对TiO2薄膜表面进行修饰,发现此TiO2薄膜的最佳工作温度为370℃左右.薄膜的气敏机理也得到了讨论.     

基于光子计数的合作目标“量子”成像

在实验上研究了赝热光照明下, 基于光子计数模式的合作目标“量子”成像, 并给出理论模型和解释. 研究表明, 利用光子计数的单光子探测器代替以往光强度线性探测器作为桶探测器在“量子”成像中同样适用. 实验发现, 合 作目标的反射信号可穿透弱散射介质实现成像, 该技术在减小光学成像透镜孔径方面具有潜在的应用价值. 对比了基于强度关联成像和压缩感知算法的“量子”成像结果, 并得出实用性结论. 本文的方案为“量子”成像的实际应用提供了新方法.     

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.     

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.     

Microstructural evolution of SiC joints soldered using Zn–Al filler metals with the assistance of ultrasound

SiC ceramics were successfully soldered with the assistance of ultrasound. Two kinds of filler metals, namely non-eutectic Zn–5Al–3Cu and eutectic Zn–5Al alloys, were used. The effects of ultrasonic action on the microstructure and mechanical properties of the soldered joints were investigated. The results showed that ultrasound could promote the wetting and bonding between the SiC ceramic and filler metals within tens of seconds. For the Zn–5Al–3Cu solder, a fully grain-refined structure in the bond layer was obtained as the ultrasonic action time increased. This may lead to a substantial enhancement in the strength of the soldered joints. For the Zn–5Al solder, the shear strength of the soldered joints was only ∼102 MPa when the ultrasonic action time was shorter, and fractures occurred in the brittle lamellar eutectic phases in the center of the bond layer. With increasing ultrasonic action time, the lamellar eutectic phase in the bond layer of SiC joints could be completely transformed to a fine non-lamellar eutectic structure. Meanwhile, the grains in the bond layer were obviously refined. Those results led to the remarkable enhancement of the shear strength of the joints (∼138 MPa) using the Zn–5Al solder, which had approached that enhancement using the Zn–5Al–3Cu solder. The enhanced mechanical properties of the joints were attributed to the significant refinement of the grains and the change in the eutectic structure in the bond layer. Prolonged enhanced heterogeneous nucleation triggered by ultrasonic cavitation is the predominant refinement mechanism of the bond metals of the SiC joints.     

Polymer‐filler derived ceramics with low shrinkage using PCS/SiC/Al mixture

Active Al and inert SiC powders were dispersed in the polycarbosilane to manufacture SiC ceramic composites by a new process of active‐filler‐controlled pyrolysis of polymer. 40 wt% of active Al fillers, 40 wt% of inert SiC fillers and 20 wt% of PCS, were homogenized. The samples were obtained by pyrolysis at 1100 °C for different soaking time. The results showed that due to the incorporation of active Al fillers, formation of crystallite phases such as Al₄C₃, Al₄Si₃ and AlN occured due to the of reaction of Al particles with the polymer decomposition products and the reactive nitrogen atmosphere. The microstructural and mechanical characterization results of the composites are presented in the paper. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Control of polarity and defects in the growth of AlN films on Si (111) surfaces by inserting an Al interlayer

We discuss the role of the Al interlayer in the suppression of pinhole formations and also look at the polarity transition of the AlN layers from N-polarity to Al-polarity when this Al interlayer is present. The AlN layers were grown by molecular beam epitaxy on an AlN nucleation layer. A thin Al interlayer was deposited on the initial nucleated AlN layer after the nitridation of the Al-soaked Si (111) substrates. The AlN layer with an Al interlayer showed a relatively smooth surface with a reduced density of pinholes compared with the AlN layer grown without an Al interlayer. In addition, the AlN layer with an Al interlayer showed some stacking faults in the interface between the Si substrate and the A1N layer. We also identify the polarity change of the AlN layer after the insertion of a thin Al interlayer from N-polarity to Al-polarity by chemical etching. A simple model is constructed to explain the polarity change and the pinhole suppression due to the Al interlayer.     

High‐Strength Pressure‐Free Bonding Using Cu and Ni‐Sn Nanoparticles

High‐strength pressure‐free bonding is investigated using Cu nanoparticles as an alternative to conventional solders. Focus is placed on the morphology of Ni‐Sn intermetallic nanoparticles, an additive to a paste of Cu nanoparticles, for improvement of sinterability. The shear strength increases from 23.2 (Cu nanoparticles only) to 31.8 MPa, when 10 wt% of the newly synthesized 15‐nm Ni₃Sn₂ nanocubes is mixed with the Cu nanoparticle paste. This is the first example of the use of base metal nanoparticles under pressure‐free conditions to achieve the bonding strength of an ordinary Pb‐free solder (Sn‐Ag‐Cu). The addition of smaller Ni₃Sn₂ nanocubes 8 nm in size or irregularly shaped Ni₃Sn₂ nanoparticles (25.0 MPa) results in a limited increase in shear strength (26.6 MPa), while the addition of micrometer‐sized Ni₃Sn₂ particles results in a decrease in shear strength (21.5 MPa). The effects of the size and shape of the added Ni₃Sn₂ particles on the shear strength are discussed based on SEM observation of the sintered layers.     

铜-铝扩散焊及拉伸的分子动力学模拟

采用分子动力学方法模拟了铜-铝扩散焊过程，分析了理想平面铜-铝试件(001)晶面间扩散焊的过渡层厚度，并利用径向分布、键对分析方法分析了在不同的降温速率下过渡层的结构变化.降温速率大时，过渡层保持原有无序结构，降温速率小时，过渡层从无序结构向面心立方结构转变.还对扩散焊后的铜-铝试件进行了拉伸模拟，并与尺寸大小相近的单晶铜和单晶铝的拉伸模拟结果进行比较.结果发现焊接后的强度比单晶铝和单晶铜的强度都要小，最大应变值也小.     

Epitaxial growth of Al on Si(1 1 1) with Cu buffer layers

The structure of thin Al films grown on Si(1 1 1) with thin Cu buffer layers has been investigated using synchrotron radiation photoemission spectroscopy. A thin Cu(1 1 1) layer between the Si(1 1 1) substrate and an Al film may enhance quantum well effects in the Al film significantly. The strength of quantum well effects has been investigated qualitatively with respect to the thickness of the Cu buffer layer and to the Al film thickness. Deposition of Cu on Si(1 1 1)7 × 7 leads to formation of a disordered silicide layer in an initial regime before a well-ordered Cu(1 1 1) film is formed after deposition of the equivalent of 6 layers of Cu. In the regime below 6 layers of Cu the disorder is transferred to Al layers subsequently grown on top. The initial growth of up to 8 layers of Al on a well-ordered Si/Cu(1 1 1) layer leads to a disordered film due to the lattice mismatch between the two metals. When the Cu buffer layer and the Al over-layer are above 6 and 8 layers, respectively the Al film shows sharp low energy electron diffraction patterns and very sharp quantum well peaks in the valence band spectra signalling good epitaxial growth.     

Microstructure evolution and grain refinement of ultrasonic-assisted soldering joint by using Ni foam reinforced Sn composite solder

In this investigation, ultrasonic-assisted soldering at 260 °C in air produced high strength and high melting point Cu connections in 60 s using Ni foam reinforced Sn composite solder. Systematically examined were the microstructure, grain morphology, and shear strength of connections made with various porosities of Ni foam composite solders. Results shown that Ni foams as strengthening phases could reinforce Sn solder effectively. The addition of Ni foam accelerated the metallurgical reaction due to great amount of liquid/solid interfaces, and refined the intermetallic compounds (IMCs) grains by ultrasonic cavitation. The joints had different IMCs by using Ni foam with different porosity. Layered (Cu,Ni)₆Sn₅ and (Ni,Cu)₃Sn₄ phases both existed in Cu/Ni60-Sn/Cu joint while only (Cu,Ni)₆Sn₅ IMCs grew in Cu/Ni98-Sn/Cu joint. As ultrasonic time increasing, Ni skeletons were dissolved and the IMCs were peeled off from substrates and broken into small particles. And then, the IMCs gradually dissociated into refined particles and distributed homogeneously in the whole soldering seam under cavitation effects. Herein, the Cu/Ni60-Sn/Cu joint ultrasonically soldered for 60 s exhibited the highest shear strength of 86.9 MPa, as well as a high melting point about 800 ℃ for the solder seam composed of Ni skeletons and Ni-Cu-Sn IMCs. The characterization indicated that the shearing failure mainly occurred in the interlayer of the soldering seam. The homogeneous distributed granular IMCs and Ni skeletons hindered the crack propagation and improved the strength of Cu alloy joints.