碳和石墨烯对磷酸锰锂材料性能的影响

在采用溶剂热法制备磷酸锰锂的基础上,以蔗糖和石墨烯为碳源,制备了裂解碳和石墨烯含量不同的磷酸锰锂/碳/石墨烯复合材料,研究了裂解碳和石墨烯对材料性能的影响。采用扫描电镜（SEM）和透射电镜（TEM）对材料的形貌进行了表征。裂解碳包覆可以提高LiMnPO₄纳米片表面的电子导电性,对于材料性能的改善起到主要的作用;石墨烯可以提高纳米片之间的电子和离子导电性,改善材料的电化学性能。电化学测试表明,当裂解碳含量为4%、石墨烯含量为2%时,LiMnPO₄电极具有较好的电化学性能,在0.5C下的放电比容量为139.1 mAh·g^-1,循环100次后,容量保持率为93.6%。与添加单一碳和单一石墨烯的LiMnPO₄电极相比,该电极在0.5C下的放电比容量分别提高了35.0%和48.6%。     

Coating of Sol Particles for Membrane Applications

For improving chemical and thermal stability of γ-Al₂O₃ membranes boehmite (AlOOH) sol-particles are coated with Zr⁴⁺-species with two techniques. These techniques are heterogeneous precipitation (HP-method) and “surface-reaction-followed-by-polycondensation” (SRPC-method). A continuous coating layer is formed at relative low Zr⁴⁺-concentration, about one monolayer coverage of boehmite particles, and with the HP-method. For large concentrations and for the SRPC-method small particles (order 1 nm) of Zr⁴⁺-species are formed on the surface of the boehmite particles. After drying and calcination up to 1000°C no continuous layer of a zirconia phase could be detected for all samples. However the thermal stability of the porous structure is improved. Phase transitions of alumina occur at temperatures of 1100°C and the porous structure of the membrane material is then destabilized.     

Characterization of chromate conversion coating on AA7075‐T6 aluminum alloy

Chromate conversion coatings (CCCs) on AA7075‐T6 were characterized using scanning electron microscopy, focused ion beam sectioning and scanning transmission electron microscopy with nano‐electron dispersive spectroscopy line profiling. The thickness and composition of the CCC was different at different locations on the heterogeneous microstructure of AA7075‐T6. The coating formed on the matrix phase was much thicker than that formed on the coarse Al–Cu–Mg, Al–Fe–Cu and Mg–Si intermetallic particles. Nano‐electron dispersive spectroscopy line profiling indicated that the coating on the Al–Fe–Cu particles was similar to the CCC formed on the phase matrix, primarily a chromium oxide. However, the coatings on the Al–Cu–Mg and Mg–Si particles were mixed Al/Mg/Cr oxide and Mg oxide, respectively. The growth of CCC followed a linear‐logarithmic kinetic rate law. The observations of this study support the sol‐gel model of CCC formation. Copyright © 2004 John Wiley & Sons, Ltd.     

超疏水涂层表面粗糙结构对防覆冰性能的影响

结冰给交通、电力输送和航空等领域带来极大的安全隐患,研究防覆冰技术具有重要的应用价值。目前最具前景的防冰方法是涂层防冰,本文介绍了疏水涂层的构建方法,阐述了涂层疏水性和疏冰性之间的关系;重点论证了涂层表面粗糙结构对其防覆冰性能的影响,指出防覆冰涂层研发中存在的问题,并对该领域的发展趋势进行了分析和展望。     

Growth of cedar-like Au nanoparticles coating on an etched stainless steel wire and its application for selective solid-phase microextraction

A novel cedar-like Au nanoparticles (AuNPs) coating was fabricated on an etched stainless steel (SS) wire by direct chemical deposition and used as an efficient and unbreakable solid phase microextraction (SPME) fiber. The etched SS wire offers a rough surface structure for subsequent growth of AuNPs in chloroauric acid solution. As a result, the uniform cedar-like AuNPs coating with larger surface area was tightly attached to the etched SS wire substrate. The AuNPs coated etched SS fiber (AuNPs/SS) was examined for SPME of ultraviolet (UV) filters, phthalate esters and aromatic hydrocarbons coupled to high-performance liquid chromatography with UV detection. The fabricated fiber exclusively exhibited excellent extraction efficiency and selectivity for some aromatic hydrocarbons. Influential parameters of extraction and desorption time, temperature, stirring rate and ionic strength were investigated and optimized. The limits of detection ranged from 0.008 μg L⁻¹ to 0.037 μg L⁻¹. The single fiber repeatability varied from 3.90% to 4.50% and the fiber-to-fiber reproducibility ranged from 5.15% to 6.87%. The recovery of aromatic hydrocarbons in real water samples spiked at 2.0 μg L⁻¹ and 20 μg L⁻¹ ranged from 94.38% to 106.2% with the relative standard deviations below 6.44%. Furthermore the growth of the cedar-like AuNPs coating can be performed in a highly reproducible manner. This fabricated fiber exhibits good stability and withstands at least 200 extraction and desorption replicates.     

Fe3O4磁性纳米粒子的超声包金及其表征

超声条件下, 在乙醇分散的3-氨丙基三乙氧基硅烷(APTES)功能化的磁性Fe₃O₄纳米粒子和四氯合金酸的混合溶液中滴加柠檬酸钠, 成功地制备了磁性Fe₃O₄/Au复合纳米粒子. 采用X射线粉末衍射仪(XRD)、紫外吸收可见光谱(UV-Vis)、带有电子能谱仪(EDS)的扫描电子显微镜(SEM)、透射电子显微镜(TEM)、光电子能谱(XPS)、超导量子干涉仪(SQUID)等方法, 对复合粒子的形态、结构、组成以及磁学性质进行了表征. 结果表明: 在此条件下制得的复合粒子粒径在30 nm左右, 室温下磁化强度可达63 emu/g.     

Protective Properties of Zinc-Rich Coatings: An Impedance Method Estimate

The impedance of zinc-rich polymer coatings on steel in a 3-% NaCl solution is studied. The electrochemical behavior of the electrode is satisfactorily described by an equivalent circuit that contains a constant-phase element, which reflects fractal properties of the zinc surface in the binder. From the results of calculations of the circuit elements for metal-rich electrodes with different zinc contents computed are fractions of the active area of the surface of the coating and its fractal dimensionality.     

AlF3包覆LiNi0.45Mn0.45Co0.10O2锂离子电池正极材料的结构表征和 电化学性能研究

通过共沉淀与固相反应法制备层状的LiNi0.45Mn0.45Co0.10O2, 并利用X射线衍射(XRD)和电子扫描显微镜(SEM)测定材料的结构和形貌. 在2.5～4.5 V范围内, 以0.1 C (28 mA•g－1)放电, LiNi0.45Mn0.45Co0.10O2正极材料的起始放电容量达到167.2 mAh•g－1, 但循环性能较差. 当采用AlF3包覆后, 材料的循环性能得到明显改善. 利用电化学阻抗谱(EIS)技术探索AlF3包覆对正极材料的电化学性能改善机理, 实验结果表明: AlF3包覆层能够阻止电解液对正极材料的溶解和侵蚀, 稳定其层状结构, 同时降低了电极界面阻抗. 因此AlF3包覆技术是一种改善LiNi0.45Mn0.45Co0.10O2材料电化学性能的有效方法和工具.     

Interfacial bonding mechanism and bonding strength of AlTiCrN coating by cathodic arc ion plating

AlTiCrN coating was prepared on the surface of YT14 tungsten carbide cutting tools by cathodic arc ion plating with Ti, Al and Cr as targets. The surface morphologies, interface energy spectrum, phase and elements' binding energy of the coatings were observed with SEM, EDS, XRD and XPS, respectively, and bonding strength of the coating interface was measured with scratch tester. The results show that the phases of AlTiCrN coating are mainly composed of AlN, CrN and TiN, the crystal plane of (111) has a strong preferred orientation. The concentrations of Al, Ti, Cr, N in the coating are higher than those in the substrate, showing the gradient diffusion distribution at the bonding interface, while C atoms of the substrate have diffused into the lattices of TiN, AlN and CrN to form an obvious interdiffusion layer, and the average bonding strength of coating interface is 57.65 N. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Mn2+ on the chrome‐free colored Ti/Zr‐based conversion coating on 6063 aluminum alloy

The conversion coating with golden color and improved corrosion resistance had been prepared by adding Mn²⁺ in the Ti/Zr conversion coating solution. Comparing with that of conversion coating without Mn²⁺, the optimal treatment time of this conversion coating was much shorter and the corrosion resistance was obviously improved. The effect of Mn²⁺ on the formation of golden Ti/Zr conversion coating was thoroughly investigated by means of energy dispersive X‐ray spectroscopy, SEM, XPS, and Raman and electrochemical workstation. The results showed that the conversion coating had a double‐layer structure: the outer layer consisted of the metal‐organic complex and the inner layer was mainly made up of Na₃AlF₆. Mn²⁺ was oxidized into MnOOH in solution and precipitated on the substrate surface which provided the nucleus to Na₃AlF₆ crystal and accelerated Na₃AlF₆ crystal formation and also made the microstructure of conversion coating change to the cubic. The mechanism of the formation of the conversion coating can be deemed as nucleation, growth of Na₃AlF₆ crystal, and formation of metal‐organic complex. Copyright © 2015 John Wiley & Sons, Ltd.