面向多功能非贵金属电催化剂的构筑和微尺度解析

相对于贵金属电催化剂制作成本高、地球储量稀少、电化学稳定性低等缺点,制备廉价、能量转换效率高、使用寿命长、环境友好的非贵金属电催化剂是推动能源存储和转换技术快速发展的重要途径.根据电催化过程中电催化析氢反应(Hydrogen Evolution Reaction,HER)、电催化析氧反应(Oxygen Evolution Reaction,OER)及氧还原反应(Oxygen Reduction Reaction,ORR)这三个重要反应类型,概述了水裂解和燃料电池的电化学反应机制,同时归纳了单功能电催化剂、双功能电催化剂、多功能电催化剂及其他电化学材料的设计与制备方法、相互关系和各自功能特点.借助先进的电子显微技术,如扫描电子显微镜、原子力扫描电子显微镜、透射电子显微镜、X射线能谱仪、电子能量损失谱仪等对其微观结构进行表征,重点对其表面形貌、结构、内部成分、元素分布等相关信息进行解析.从提供更丰富的缺陷空位、潜在活性位点、优化界面相互作用、增大电化学比表面积、形成协同效应等方面,分析其在降低成本的同时,提高电催化剂的电导率、增强稳定性的相关机理,以期为非贵金属电催化剂的研究和推广应用提供新策略.     

《评价材料的高分辨电子显微方法》

材料的性能取决于其组织结构，尤其取决于材料的显微结构。因此，直接观察和研究材料显微结构对于新材料的研制和开发、材料性能的改进以及材料可靠性的评价是十分重要的。 此书是一本关于高分辨电子显微方法原理、实验技术、在材料中的应用以及相关边缘技术的书。书中介绍了高分辨电子显微方应关系，给出了像计算的具体步骤；叙述了高分辨电子显微像的种类及其具体的拍摄方法；强调了获得最佳拍摄条件的重要性，讨论了最佳条件拍摄的注意事项以及试样厚度与聚焦量差等对像衬度的影响。书中用较大篇幅介绍了该方法在材料评价中的应用。叙述…     

电子显微术在原位金属基复合材料界面研究中的应用

原位金属基复合材料的增强颗粒是在基体中原位生成,因而增强颗粒和基体间不存在界面反应,两者间为直接的原子结合.界面对原位金属基复合材料的性能有着重要的影响.本文综述了扫描电子显微镜、普通透射电子显微镜、高分辨电子显微镜和电子能量损伤谱仪等现代电子显微技术在原位金属基复合材料界面研究中的应用及部分研究结果.利用现代电子显微技术和先进的实验方法在原子尺度上对界面的精细结构、结合方式、界面缺陷、界面稳定性及其影响因素等进行研究,从而在较深的层次上认识原位金属基复合材料的界面,对在该领域做进一步研究探讨起到促进作用.     

固体氧化物燃料电池/电解池金属连接体涂层研究进展

可逆固体氧化物池(SOC)既可作为燃料电池(SOFC)发电,又可用作电解池(SOEC)制氢或合成气,用于清洁能源转换和存储。涂层制备技术对SOC电堆的发展尤为重要。本研究对SOC在不同操作模式下的工作环境进行了分析,对SOC电堆连接体可用的合金材料、涂层材料和涂层制备技术进行了综述。     

腐蚀电化学阻抗谱等效电路解析完备性研究

随着使用电化学阻抗谱方法研究腐蚀过程的工作日益增多,腐蚀电化学阻抗谱解析技术逐渐成为腐蚀科学家需要掌握的重要研究工具之一。近年来,电化学阻抗谱方法研究的腐蚀体系越来越复杂,不仅腐蚀环境和金属状态复杂化,且形成于金属表面界面膜层的种类也越来越多,导致简单电化学体系的阻抗谱等效电路解析方法越来越难以满足复杂腐蚀体系解析建模的要求。与动力学解析方法相比,模拟等效电路的解析方法因其简单直观而易于理解,应用范围日益扩展。但其固有的解析过程不严谨、不规范等不足,导致腐蚀过程等效电路模型缺陷增加和学术价值下降。为此,在多年研究腐蚀电化学阻抗谱等效电路解析方法的基础上,本文分析了电化学阻抗谱等效电路解析方法在腐蚀研究中的应用现状,探讨了等效电路方法解析腐蚀过程的优点和不足,以及提高这一解析方法学术价值的必要性和可行途径,以期建立严谨规范的腐蚀电化学阻抗谱等效电路模型解析路线,以适应复杂腐蚀过程的模型化研究需求,为腐蚀科学工作者提供一种高效实用的腐蚀电化学阻抗谱解析工具。     

新型镁基双离子电池面世

来自中国科学院深圳先进技术研究院等单位的研究人员,成功研发出了一种基于不溶性有机负极材料的新型镁基双离子电池(Mg-DIB)。相关研究成果发表于国际顶级能源材料期刊《能源存储材料》上。近年来,锂离子电池已广泛应用于消费类电子设备、新能源汽车及储能等领域。但是,锂资源储量有限且分布不均,难以满足未来社会对大规模储能的低成本要求。镁离子电池由于具有高容量、储量丰富等优势,在大规模储能领域具有良好的应用前景。“然而,金属镁负极在有机电解液中易发生钝化,导致镁离子不能可逆沉积/溶解,此外尚缺乏可逆脱嵌镁离子的正极材料,使得镁电的发展受到制约。”论文通信作者之一、中科院深圳先进技术研究院研究员唐永炳说。     

前驱体体系pH值对LiFePO4/C正极材料性能的影响

采用溶胶-凝胶法制备了LiFePO4/C正极材料.采用X射线衍射(XRD)、扫描电镜(SEM)和电化学手段对材料进行了结构表征和性能测试.研究了其前驱体体系pH值对材料性能的影响.结果表明:当前驱体体系pH值为8.4时,LiFePO4/C正极材料具有最佳的电化学性能.在0.1C倍率下充放电,磷酸铁锂首次放电比容量为16...     

AZ31合金用于镁二次电池负极材料的电化学性能

采用扣式电池循环伏安测试(CV)、充放电测试和扫描电子显微(SEM)技术,研究AZ31合金与工业纯镁(99.95%)作为镁二次电池负极材料时的电化学性能和镁在电极表面的沉积形貌。结果表明:作为镁二次电池的负极材料,AZ31合金与工业纯镁相比,其镁的溶解-沉积的过电位稍高,初始循环过程的库仑效率略低,但长期循环的库仑效率稳定,并能有效抑制枝晶镁的形成,且其长期循环性能优于工业纯镁的。     

铁、镍基合金在Na_2SO_4-NaCl熔盐中腐蚀和稀土元素的作用

<正> 本工作应用现代电化学理论和实验技术,对各种以燃油、煤等矿物燃料作为能源的动力装置如(航空、航用、陆用及工业用)燃气轮机、电站锅炉和其它能量转换系统在高温燃气环境中,由于熔融或半熔融态沉积物(主要是Na_2SO_4)的作用而遭受的加速氧化破坏热腐蚀问题进行了较深入的研究。运用各种电化学测试方法,实现了对多种合金和涂层在800℃、75%(Na、K)_2SO_4     

金属多孔材料制备技术研究进展

传统的金属多孔材料的制备技术主要是粉末冶金和铸造、沉积技术.随着新材料、新技术的不断出现,金属多孔材料的制备已从最初的粉末冶金技术发展为自组装、流体沉积、电化学腐蚀、共晶定向凝固以及SHS等各种先进技术.本文重点阐述金属多孔材料制备技术的国内外研究现状和一些新的发展趋势.     

先进的电子断层扫描技术在材料科学中的发展——基于透射电子显微镜和扫描透射电子显微镜(英文)

介绍了基于透射电子显微镜和扫描透射电子显微镜的电子断层扫描技术在材料科学领域的最新进展。详细地描述各种电子断层扫描的类型:基于透射电子显微镜的断层扫描技术包括明场断层扫描、暗场断层扫描、弱束暗场断层扫描、环形暗场断层扫描和能量过滤断层扫描;基于扫描透射电子显微镜的断层扫描技术包括高角环形暗场断层扫描、环形暗场断层扫描,非共格明场断层扫描、电子能量损失谱断层扫描和X射线能谱断层扫描。报道了优化的倾转系列,比如双轴倾转、同轴倾转、锥形倾转以及等斜率倾转等。总结了先进的重构算法包括离散迭代重构技术、压缩传感算法以及等斜率算法。最后,提出了电子断层扫描技术在材料科学中的发展趋势。     

Microstructure and properties of low friction TiC---C nanocomposite coatings deposited by magnetron sputtering

The objective of nanocomposite coatings combining hard and lubricant phases is the development of advanced multi-functional protective thin films showing abrasion resistance, and simultaneously, low friction. Up to now, no clear relation between constitution, microstructural properties and performance of such nanocomposite coatings based on dry lubricants like carbon or MoS₂ has been evaluated. Deposition techniques, constitution, properties and performance of magnetron-sputtered nanocomposite coatings in the TiC---C system are presented. The Vickers hardness could be optimized to values of polycrystalline TiC thin films, and at the same time, low friction coefficients against steel, similar to diamond-like amorphous carbon, could be realized. The mechanical properties and the tribological behavior of these thin films are related to the chemical composition and the microstructure of these advanced materials, characterized by electron microprobe analysis, Auger electron spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and high resolution transmission electron microscopy.     

Boundaries and interfaces in ultrafine grain composites

The present study was motivated by two questions. First, what are the characteristics of grain and phase boundaries in a nanostructured material containing multiple phases? Second, what is the influence of these interfaces on mechanical behavior? Accordingly, a three-constituent Al 5083/B₄C ultrafine grain (UFG) composite, consisting of a coarse grain (CG) phase (1–2 μm), an UFG phase (100–200 nm) and B₄C particles (∼0.7 μm), was selected for study. Interest in this particular Al 5083/B₄C system stems from its hierarchical architecture, which comprises multiple scales, as well as from a reported yield strength of 1145 MPa. The associated grain boundaries (GB) and interfaces were investigated by transmission electron microscopy (TEM), high-resolution TEM, energy dispersive X-ray spectroscopy and electron energy loss spectroscopy methods. The role of high/low-angle GB, equilibrium and non-equilibrium GB within and between the CG and UFG regions, twin boundaries, twist transition boundaries and impurity segregation at GB in strengthening mechanisms is discussed.     

Corrosion Resistance and Electrochemical Behaviour of Amorphous Ni84.9Cr7.4Si4.2Fe3.5 Alloy in Alkaline and Acidic Solutions

In this work, the corrosion behaviours of the amorphous Ni_84.9Cr_7.4Si_4.2Fe_3.5 alloy and its crystalline counterpart are studied in acidic, neutral, and alkaline solutions by scanning electron microscopy, electrochemical impedance spectroscopy, and potentiodynamic and potentiostatic polarization tests. X-ray photoelectron spectroscopy and scanning Kelvin probe are employed to characterize the alloy surface. The results show that the amorphous Ni_84.9Cr_7.4Si_4.2Fe_3.5 alloy presents a better corrosion resistance compared to its crystalline counterpart, which is attributed to the uniform energy distribution of the atoms on the amorphous alloy surface, and this presents as a uniform electric potential map to effectively suppress the occurrence of the corrosion cell reaction.     

Electrocatalytic behaviour of NiBi coatings for hydrogen evolution reaction in alkaline medium

The nickel-bismuth binary coatings with various chemical compositions were galvanostatically deposited on the copper electrode in view of their possible applications as electrocatalytic materials for the hydrogen evolution reaction (HER) in alkaline solution. The HER activity of coatings was tested with the help of potentiodynamic measurements and electrochemical impedance spectroscopy (EIS) technique. The electrochemical characterization was achieved by the means of cyclic voltammetry (CV). The surface morphology and surface composition of coatings were determined with scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). The potentiodynamic measurements show that, the binary coatings decrease the hydrogen over potential and increase the current density values for HER. The EIS analysis confirms, the charge transfer resistances decrease and the double layer capacitance values increase for binary coatings. The EDX results in sign that the composition of binary coating changes by using coating bath. The Cu/NiBi-2 coating (Ni²⁺/Bi³⁺ is 99.71:0.29 molar ratio) is the best suitable cathode composition for the HER in alkaline media under these experimental conditions.     

Surface modification of polymer fibre by the new atmospheric pressure cold plasma jet

A new cold plasma jet has been developed for surface modification of materials at atmospheric pressure. This new cold plasma jet generator is composed of two concentric cylindrical all-metal tube electrodes. The argon is fed into the inner-grounded electrode, the outer electrode is connected to the high-voltage power supply and covered with a layer of dielectric, and then a stable cold plasma jet is formed and blown out into air. The plasma gas temperature is only 25–30 °C. Preliminary results are presented on the modification of polypropylene (PP) and polyethylene terephthalate (PET) fibres by this cold plasma jet. The water contact angle of these materials is found to decrease after plasma treatment and it will recover a little in two months. The chemical changes on the surface of polymers are studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) is used to study the changes in surface feature of polymers due to plasma treatment. The hydrophilicity and surface structure of these materials after plasma treatment are discussed. The results show that such a plasma jet is effective.     

Electrochemical behaviour and structure of rust formed on Si- and Al-bearing steel after atmospheric exposure

The corrosion resistance of Si- and Al-bearing steel was estimated by atmospheric exposure test, and the structure of the rust was examined by EPMA (electroprobe X-ray microanalysis) and TEM (transmission electron microscopy) analysis. Moreover, the electrochemical behaviour of rust was investigated by EIS (electrochemical impedance spectroscopy).The Si- and Al-bearing steel exhibited excellent corrosion resistance in the exposure test as compared with carbon steel (SM). EPMA and TEM analysis showed that Si and Al mainly existed in nanoscale iron complex oxides in the inner rust formed on this steel. The Al K spectrum of the rust exhibited a peak that was the same as that of Al₂O₃ in the EPMA and TEM-EELS (electron energy loss spectroscopy) analysis. This result suggests that Al was present in the complex oxides as Al³⁺. In the same way, Si was identified as being in an intermediate state in the complex oxides of the inner rust.EIS measurement of the exposure test samples revealed much higher rust resistance (R_rust) and corrosion reaction resistance (R_t) of Si- and Al-bearing steel compared to that of SM. Finally, it was found that nanoscale complex iron oxides formed in the inner rust of Si- and Al-bearing steel, resulting in increased R_rust and R_t, and corrosion suppression.     

The effect of solution temperature and pH on corrosion performance and morphology of nanoceramic‐based conversion thin film

In the present study, a nanoceramic hexafluorozirconic acid was used as an eco‐friendly conversion coating, which is free of the conventional phosphate salts. The effect of practical parameters on morphology and corrosion resistance of the coating was studied. Anti‐corrosion behavior of the nanoceramic‐based conversion coating on cold rolled steel substrates was evaluated at different solution pH and temperatures, utilizing the electrochemical impedance spectroscopy and direct current polarization. Moreover, the morphology of thin films was studied using field emission scanning electron microscopy (FE‐SEM). The results revealed that the conversion thin films formed at a dipping temperature of 20 °C and pH 4.5 showed best anti‐corrosion performance. SEM images indicated that increasing solution temperature resulted in micro‐cracks creation and lack of consistency on the surface of the conversion coating. Moreover, the morphological structure changed with increasing pH value.     

先进材料与异种材料电子束焊接研究进展

电子束焊接是近年来飞速进步、蓬勃发展的一种先进连接技术，随着技术工艺的日益成熟，其在工业领域的竞争力也日渐增强，已为工业部门所广泛接受.文中综述了电子束焊接在高温钛合金、高温合金、难熔金属、金属间化合物等先进材料与各类互相固溶的、难以互溶的异种材料连接方面的研究现状，对国内外在焊接缺陷控制、焊接工艺优化、焊接机理研究等方面取得的典型研究成果进行了简要介绍，并从中概括总结了先进材料与异种材料电子束焊接的具体问题，归纳阐述了先进材料与异种材料电子束焊接中所采用的能量控制与冶金调控等特色技术方法.