Strong bonding of infrared brazed α2-Ti3Al and Ti–6Al–4V using Ti–Cu–Ni fillers

Infrared dissimilar brazing of α₂-Ti₃Al and Ti–6Al–4V using Ti–15Cu–25Ni and Ti–15Cu–15Ni filler metals has been performed in this study. The brazed joint consists primarily of Ti-rich and Ti₂Ni phases, and there is no interfacial phase among the braze alloy, α₂-Ti₃Al and Ti–6Al–4V substrates. The existence of the Ti₂Ni intermetallic compound is detrimental to the bonding strength of the joint. The amount of Ti₂Ni decreases with increasing brazing temperature and/or time due to the depletion of Ni content from the braze alloy into the Ti–6Al–4V substrate during brazing. The shear strength of the brazed joint free of the blocky Ti₂Ni phase is comparable with that of the α₂-Ti₃Al substrate, and strong bonding can thus be obtained.     

Joint between MoSi2 and 316L stainless steel surfaces and its interfacial mechanical properties

In this study, we proposed a new method using the spark plasma sintering technique to join ceramics to alloys. MoSi₂ and 316L stainless steel were chosen as sample materials and can be welded well with graded interlayers. We found that dense uniformed joints were achieved because of the comparable coefficient of thermal expansion of the interlayers. Furthermore, such a compatibility between the graded interlayers prevented MoSi₂ with low toughness from the occurrence of microcracks resulted from the residual stresses formed during cooling of the joint.     

The analysis of residual stress in glass-to-metal seals for solar receiver tube

The solar receiver tube is a key component in the parabolic trough solar thermal power system. Breakage of glass-to-metal sealing is main cause for damages of receivers in existing power plants. The residual stresses that are generated during the cooling process of the seal can decrease the seal strength and induce the breakage of the glass-to-metal sealing. Residual stresses were simulated by finite element software ANSYS and measured experimentally by photoelastic techniques. In order to lower the seal failure probability, the effects of the component dimensions were analyzed using finite element method. The simulation results agreed with the measurement results. The dangerous tensile stresses occur not only at the glass–metal interface but also on the outer surface of glass tube near the sealing area. When the depth of metal embedded into glass increases, the magnitude of residual stress decreases and the sealing strength will increase. The results of this study have important implications on the optimization of seal configuration in the solar receiver tubes.     

The effects of welding parameters on the weldability of different materials using brazing alloy fillers

The objectives of the study were to investigate the microwelding conditions related to diffusion mechanism and elemental migration metallurgical and microscopy investigation, and to establish the fundamental corrosion mechanism on the properties of small welding and brazing areas that consist different materials. This study focuses on the weldability of Ti /Ni using microspot brazing technology by selection of brazing condition current, 2, 2.5, 3, 3.5 and 4 kA, voltage 2 V, load 60 N and welding time 25–50 ms, this welding condition effective on brazing temperature optimization this condition. Ti and Ni were selected as base metals. Four types of metal fillers were used as filler foils, sandwiched between Ti/Ni. First type of metal fillers was, 65Ni–35Cu foil, melting point 846 °C; the second was, 71Ag–28Cu–1Mg foil, melting point 775 °C; the third was, 80Ag–18Cu–2Ti foil, melting point 782 °C; and fourthly was, 73Ni–18Cr–9Si foil, melting point 917 °C. The electrode tip face chosen was circuitous in form. All brazed joint were made by microspot brazing method. Brazing was done under normal atmospheric condition.     

Hybrid CFRP/titanium bolted joints: Performance assessment and application to a spacecraft payload adaptor

This paper presents an experimental investigation of the mechanical response and the industrial manufacturability of CFRP–titanium hybrid laminates using the example of a spacecraft payload adaptor. The local hybridization with metal within a bolted joint region of composite laminates is proven to be an effective method of increasing the mechanical joint efficiency of highly loaded bolted joints. High-strength titanium foils are locally embedded into the composite laminate by means of ply substitution techniques, thus avoiding any local laminate thickening and providing for a local laminate with high bearing and shear capabilities. An extensive sample and component test program has been performed evaluating the impact of different design parameters and load conditions. The verification of the hybrid technique’s processability, inspectability and compatibility with a standard industrial fibre placement process has been successfully demonstrated through the manufacturing of a spacecraft payload adaptor featuring diverse applications of the hybridization technique.     

Evaluation Metrics for the Rating and Optimization of Snap-fits

Current snap-fit design guides recommend sizing snap-fit features on the basis of insertion force and allowable strain during assembly. Retention force information in such guides is often inaccurate, although this is considered to be the primary attribute of the snap-fit after assembly. The authors contend that these (insertion force, allowable strain, retention force) are not the only critical performance criteria for snap-fit features. Designers have to contend with several other constraints and design requirements. Additional performance metrics for snap-fit features are proposed by drawing upon considerable experience with plastic part design issues. Locking ratio, dimensional and volumetric retention force, consideration of the characteristic dimension of the joint and snap-fit, feature stiffness, required over-insertion and consideration of snap-fit strength relative to part strength are proposed to supplement currently used metrics for evaluating and rating snap-fit designs. The applicability of these metrics is illustrated with real-life examples, and their merits and demerits discussed. A chart of achievable locking ratios for different snap-fit topologies is presented for use as a design tool for the initial selection of snap-fit topologies. Its use as a rational basis for selection and optimization of snap-fits is suggested. Adoption of proposed metrics will allow designers to better quantify, and thereby optimize the performance of, snap-fit features. These ideas will be built upon in the future, and used as a basis for a comprehensive snap-fit selection and detailed design tool.     

Lap joint formed by friction stir spot welding between SiC and magnesium alloy containing aluminum

A lap joint between plates of SiC and AZX612-magnesium alloy containing aluminum was formed by friction stir spot welding using a drilling machine. The joint interface was analyzed by scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. Aluminum from the AZX612-magnesium alloy segregated along the joint interface suggesting that SiC and AZX612-magnesium alloy could be strongly joined by friction stir spot welding due to the formation of aluminum compounds. SiC and A1050-aluminum alloy plates were joined by friction stir spot welding and a tensile-shear test was performed. At 245 N, the lap joint fractured in the SiC matrix rather than the joint interface. These results confirmed that SiC and A1050-aluminum can be strongly joined due to the formation of aluminum compounds.     

AlN陶瓷的应用及其表面金属化

ＡｌＮ陶瓷由于其优良的导热性能，良好的高频性能及与ＢｅＯ相比无毒性，是一种很有潜力的微波功率器件用材料。ＡｌＮ陶瓷的许多应用都涉及到了陶瓷表面金属化技术及与金属接合技术，本文对ＡｌＮ陶瓷的应用、ＡｌＮ陶瓷表面金属化及其与金属接合技术的现状及发展进行了评述。     

Einflüsse auf die mechanischen Eigenschaften lasergelöteter Mischverbindungen aus Stahl und Aluminium

Influences on the Mechanical Properties of Laser Brazed Hybrid Joining of Steel and Aluminium Within the scope of a fundamental research project, a laser brazing process has been developed, enabling the joining of aluminium to steel sheet metal. By applying zinc‐based solders, melting the edges of the aluminium sheets can be reduced to a minimum compared to concurring joining processes. This leads to an excellent joining strength, with tearing in the aluminium base metal as shown by tensile tests. Moreover, the joined material can be formed into hollow parts, with few limitations. There is a great potential for applying this process, for example in car production, resulting from, among other things, high process automation possibilities.     

面向二十一世纪 建立新的工艺观念──从JWRJ更名改组谈起

本文介绍了日本大阪大学焊接研究所改名为连接及焊接研究所并调整研究体制的情况．面向二十一世纪,连接及焊接研究应建立“闭环制造和维修工艺过程”的新观念和与之相适应的研究体制．