熔炼时间对稀土单晶合金坩埚界面反应的影响

为了实现稀土单晶高温合金中稀土含量的稳定控制,明确稀土元素在熔炼过程中参与的坩埚界面反应机理,研究了熔炼时间对含Y高温合金CMSX-4与Al2O3陶瓷坩埚在真空感应熔炼过程中的界面反应和稀土Y收得率的影响。实验结果表明：随着熔炼时间的延长界面反应加剧,熔炼过程中Y首先与Al2O3陶瓷基体发生反应生成Y2O3,生成的Y2O3会继续与Al2O3发生反应生成Y、Al原子比不同的铝酸钇反应层,最终坩埚表面形成的界面反应产物由外层的YAlO3、内层的Y3Al5O12(Y3Al2(AlO4)3) 以及附着的高温合金组成。熔炼10~30min时合金中稀土Y收得量为41.023、4.566和5.368ppm。     

搅拌针对FSSW-B接头界面组织与力学性能的影响

铝/镁异种金属复合结构在结构轻量化领域具有极大的应用价值。采用新型搅拌摩擦点焊-钎焊技术(friction stir spot welding-brazing,FSSW-B)对铝/镁异种金属进行搭接点焊,同时与搅拌摩擦钎焊(friction stir spot brazing,FSSB)工艺进行对比,研究焊接工具中搅拌针的存在对接头界面组织与力学性能的影响。FSSW-B接头界面中间层分为明显上下2个部分,上层界面主要为MgZn₂相,下层界面主要为Mg₇Zn₃相;FSSB接头主要为MgZn₂相。接头的断裂模式主要为界面剥离断裂,由于搅拌针的存在,出现了眉状断裂模式。搅拌针的存在提高了接头的抗拉剪性能与疲劳性能,FSSW-B接头的最大抗拉剪力为7600 N,疲劳极限为3366.6 N;搅拌针使抗拉剪性能提升了53.5%,使疲劳性能提升了11.4%;FSSW-B中搅拌针的存在增加了接头疲劳性能的分散性。     

单晶UBM在电子封装微互连中的研究进展

3D封装是未来电子封装制造技术领域的重要发展方向,3D封装中微凸点的尺寸将急剧降低,此时,芯片凸点下金属层(UBM)可能仅包含几个甚至单个晶粒。因此,UBM的晶体取向对界面金属间化合物(IMC)的形核和生长过程将具有显著影响,而界面IMC的特性会直接影响到凸点微/纳尺度互连的可靠性。因此,以单晶作为UBM研究界面物质的传输与IMC的生长规律,具有重要的理论和应用价值。本文对近年来以单晶Cu、Ni和Ag作为UBM焊点的界面反应进行综合分析,总结了单晶UBM上特殊形貌IMC晶粒的形成条件、界面IMC与单晶基体的位向关系、IMC的生长动力学过程、柯肯达尔空洞的形成规律、单晶UBM上IMC的晶体取向调控方法及晶体取向对无铅焊点力学性能和可靠性的影响,为评价单晶UBM凸点的力学性能和可靠性及提供指导。     

The liquid–liquid flow dynamics and droplet formation in a modified step T-junction microchannel

The droplet generation mechanism in the asymmetrically enhanced step T-junction remains unknown, especially for the transition stage from dripping to jetting regimes. In this work, the droplet generation mechanism was systematically investigated in a modified step T-junction by modulating a large flowrate range and altering different interfacial tensions. We found that under different fluid regimes, both the capillary number and flow rate ratio of continuous and dispersed phase showcase completely different impacts over droplet generation. In dripping regime, the interfacial tension, which was controlled by changing the surfactant concentration, dominated the formation mechanism when the surfactant concentration was found below micelle concentration. In jetting regime, our experimental results showed that the influence of the surfactant concentration on the size of generated droplets was rather negligible while the flow rate ratio of continuous and dispersed phase indeed determined such a parameter. In the dripping-jetting transition stage, an increase of droplet size was observed despite the increase of continuous phase flow. After reaching a peak, the droplet dimension started to decrease with the increase of continuous phase flow as expected. To the best for our knowledge, it is the first study to report generation mechanism in modified step T-junction from dripping to jetting regimes.     

Ternary fluid lattice Boltzmann simulation of dynamic interfacial tension induced by mixing inside microdroplets

A ternary fluid color-gradient lattice Boltzmann model is proposed to investigate the effect of mixing-induced dynamic interfacial tension on the diffusive mixing of two fluids inside microdroplets moving in a third continuous phase through a baffled channel. The diffusion coefficient of binary mixtures and dynamic interfacial tension in this model can be directly defined and independently adjusted. The simulation results show that the dynamic interfacial tension between miscible binary fluids at interfaces with ambient phase would lead to the motion of the interface and redistribution of solutes inside the droplet during mixing. The larger initial interfacial tension gradient would improve mixing efficiency at early stages by promoting faster solute flow. The present model can be easily applied to quantitatively characterize the mixing behavior inside droplets in the practical processes involving the dynamic interfacial tension phenomenon and inspire new designs for mixing intensification.     

表/界面调控策略在氢/氧反应电极中的研究进展

高效的非贵金属基电催化剂对于提升氢气析出反应（HER）、氧气析出反应（OER）、氧气还原反应（ORR）等电催化反应的整体效率、促进能源转换技术的发展及应用起着至关重要的作用。近年来,对现有的电催化剂进行表/界面调控以诱导其产生新的理化性质,从而提高催化活性的研究受到了广泛的关注。本文综述了近年来利用形貌尺寸调控、缺陷调控、杂原子掺杂、异质结结构等表/界面调控策略在设计非贵金属基电催化剂方面的研究进展,揭示了催化材料体系改性对优化和提升催化性能的关键特性。从催化剂制备、先进表征手段、理论计算、应用性评价等方面展望了非贵金属基电催化剂在实际应用中存在的挑战和未来的研究方向,为实现清洁能源的大规模应用提供参考。     

On the association between poly(vinyl alcohol) and sodium dodecyl sulfate and its effect on liquid–liquid interfacial tension: A mathematical model

Association between poly(vinyl alcohol-co-vinyl acetate) copolymer (PVA) and sodium dodecyl sulfate (SDS) was studied experimentally and theoretically. It was found that, for the ethyl acetate-aqueous phase interface in which PVA was previously adsorbed, the interfacial tension (γ) increases abruptly to a maximum and then exhibits a relatively mild decay with the addition of SDS to the aqueous phase. The theoretical results indicate that vinyl acetate (VAc) segments determine γ. However, for relatively low concentrations of SDS (C_SDS), this latter plays a major role because through its association with the VAc segments it modulates the extent to which PVA is adsorbed at the interface, indirectly determining the value of γ. As C_SDS approaches to the CMC value for SDS, its influence on γ decreases because SDS tends to self-assembly rather than associates with VAc. These model predictions are consistent with experimental findings reported in the literature.     

部分地铁车辆车体涂膜修补工作浅析

根据实际情况和具体问题,介绍了杭州部分地铁车辆车体涂膜修补工作。针对现场施工环境、3种色漆品种、局部色漆遮盖力、色差、流挂等问题,逐一给出了相应的解决方案和色漆调制配比,具有一定实用价值。     

Ionic liquid recovery alternatives in ionic liquid‐based three‐phase partitioning (ILTPP)

Ionic liquid‐based three‐phase partitioning (ILTPP) is a promising technique to recover high‐added value proteins at the liquid–liquid interface. Its economic and environmental performance highly depends on the net ionic liquid consumption. Alternatives to maximize the fraction of ionic liquid that can be recycled are studied. It is demonstrated that the addition of extra salt, previously proposed in literature, has a very limited effect on ionic liquid recovery for relatively high protein concentrations in the feed stream, and that it may even lead to an increase of the ionic liquid losses under certain conditions. However, small additions of salt are shown to be effective and profitable from an economic point of view. Vacuum evaporation is shown to allow for the complete ionic liquid and salt recovery, reinforcing the sustainability and viability of ILTPP processes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3577–3586, 2014