氮、氧杂质对V40Ti26Cr26Fe8 合金化学成分、微观组织和贮氢性能的影响

采用X射线衍射、扫描电子显微镜、光学显微镜和压力-成分-温度（PCT）等手段研究了氮、氧杂质对V-Ti-Cr-Fe合金微区化学成分、微观结构和贮氢能力的协同影响。V₄₀Ti₂₆Cr₂₆Fe₈合金的贮氢能力随着氮、氧杂质含量的增加而明显降低,主要作用机理如下：氧在V基合金中的溶解抑制了二氢化物相的形成,导致氢容量的降低（主要效应）,而氮与钛结合形成了新的富氮钛相,导致了主相成分的变化和晶格参数的减小（二次效应）。     

Ni-B-C对La0.94Mg0.06Ni3.49Co0.73Mn0.12Al0.20储氢合金电化学性能的影响研究

为提高新型AB₃型储氢合金La_0.94Mg_0.06Ni_3.49Co_0.73Mn_0.12Al_0.20的电化学性能,将球磨法制备的Ni-B-C粉末按不同重量比添加到合金中。采用X-射线粉末衍射仪(XRD)和扫描电子显微镜(SEM)分析合金的相结构和表面形貌,添加Ni-B-C粉末后,合金相结构没有变化,仍由LaNi₅相和La₂Ni₇相两个相组成,但合金表面出现了细小颗粒。添加Ni-B-C粉末后,合金电极的最大放电容量和放电容量保持率均提高。当添加重量百分比为10%的Ni-B-C粉末后,电极的最大放电容量从346 mAh/g增加到363 mAh/g,50个循环后的放电容量保持率从70%提高到77%,交换电流密度I₀与极限电流密度I_L分别为106 mA/g和987 mA/g。动电位极化测试表明,电极的抗腐蚀能力也有所增强。研究结果表明,Ni-B-C可以提高AB₃型储氢合金的综合电化学性能。     

Effect of sintering on microstructure and mechanical properties of nano-TiO2 dispersed Al65Cu20Ti15 amorphous/nanocrystalline matrix composite

Mechanically alloyed Al₆₅Cu₂₀Ti₁₅ amorphous alloy powder with or without 10 wt% nano-TiO₂ dispersion was consolidated by isothermal spark plasma sintering in the range 200–500 °C with pressure up to 50 MPa. Selected samples were separately cold compacted with 50 MPa pressure and sintered at 500 °C using controlled atmosphere resistance and microwave heating furnaces. Phase and microstructural evolution at appropriate stages of mechanical alloying/blending and sintering was monitored by X-ray diffraction and scanning and transmission electron microscopy. Measurement and comparison of relevant properties (density/porosity, microhardness and yield strength) of the sintered compacts suggest that spark plasma sintering is the most appropriate technique for developing nano-TiO₂ dispersed amorphous/nanocrystalline Al₆₅Cu₂₀Ti₁₅ matrix composite for structural application.     

Enhancement of Ti-Cr-V BCC alloys on the dehydrogenation kinetics of Li-Mg-N-H hydrogen storage materials

The hydrogen storage properties of a Li-Mg-N-H material doped by a 4 mol.% Ti₃Cr₃V₄ body centre cubic (BCC) alloy hydride and prepared with a ball-milling method were investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Sievert’s technology test. The results show that the Ti₃Cr₃V₄ BCC alloy hydride/Li-Mg-N-H composite has good reversible hydrogen storage properties. The dehydrogenation kinetics of the Li-Mg-N-H system can be greatly improved by doping the Ti₃Cr₃V₄ BCC alloy hydride. The composite desorbed 4.1 wt.% hydrogen in the first 60 min at 473 K under 0.1 MPa pressure, but when without the BCC alloy addition, only 3.0 wt.% hydrogen was desorbed under the same dehydrogenation condition. It can be deduced that the Ti₃Cr₃V₄ BCC alloy uniformly distributed in the Li-Mg-N-H substrate could decrease the activating energy of hydrogen molecules to H atoms and increase H diffusion paths in the composite, enhancing the dehydrogenation kinetics of the Li-Mg-N-H system.     

Magnetoelectric CoFe2O4/Pb(Zr0.53Ti0.47)O3 composite thin films of 2-2 type structure derived by a sol-gel process

CoFe₂O₄/Pb(Zr_0.53Ti_0.47)O₃ (CFO/PZT) magnetoelectric composite thin films of 2-2 type structure have been prepared onto Pt/Ti/SiO₂/Si substrate by a sol-gel process and spin coating technique. The optimal annealing process of composite thin films was determined by using X-ray diffraction (XRD) and differential scanning calorimetry (DSC). It is found that the amount of the citric acid and concentration of CFO starting precursor solution have great impact on morphologies of composite thin films. Subsequent scanning electron microscopy (SEM) investigations show that the prepared thin films exhibit good morphologies and compact structure, and cross-sectional micrographs clearly display a multilayered nanostructure of multilayered thin films. The purpose of this work is to determine the optimal annealing processes of composite thin films and to prepare magnetoelectric composite thin films with good microstructure. It is shown that the films exhibit both good magnetic and ferroelectric properties, as well as a magnetoelectric effect.     

反应等离子喷涂 Al2O3-TiB2-Al 复相涂层的反应机理

目的在铝合金表面制备Al2O3-TiB2-Al复合涂层,研究Al,TiO2,B2O3在等离子喷涂中的反应机理。方法采用反应等离子喷涂技术在铝合金表面制备复合涂层,应用扫描电镜与X射线衍射技术测试复合涂层的物相组成和显微组织,并通过燃烧波淬熄试验分析等离子喷涂产物。结果机械球磨可以有效降低粉末发生反应的活化能,等离子喷涂最佳飞行距离范围为150~200 mm。结论喷涂粉末在飞行过程中发生反应,经历了预热、熔化、分解、团聚等过程,验证了最终引燃发生燃烧化学反应的机理。     

溅射功率对La-Ti/WS2 复合薄膜高温摩擦学行为的影响

高温条件下WS₂易于氧化生成WO3,导致WS₂固体润滑薄膜的摩擦学性能受到较大影响。为改善WS₂固体润滑薄膜在高温条件下的摩擦学性能,采用非平衡磁控溅射技术制备了共掺杂La-Ti/WS₂复合薄膜,研究了靶功率对磁控溅射La-Ti/WS₂复合薄膜结构和高温摩擦学性能的影响。利用扫描电镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪和X射线光电子能谱仪(XPS)分析了薄膜微观形貌、成分、力学性能、微观结构。利用高温摩擦磨损试验机研究了复合薄膜的高温摩擦学性能。结果表明,高温环境下,靶功率为20W时La-Ti/WS₂复合薄膜表现出优异的摩擦学性能。此时,复合薄膜H/E值最大,摩擦系数最小,平均为0.012,磨损率最低为1.56×10^-8mm³/N·m,这主要归因于高温下摩擦界面产生的稀土氧化物,促使La-Ti/WS₂复合薄膜的摩擦磨损机制发生了改变,使得WS₂在高温受破坏的情...     

NiFe1 . 98Nd0 . 02O4-Fe 双层吸波涂层设计及制备

目的制备高性能NiFe1.98Nd0.02O4-Fe双层吸波涂层。方法采用溶胶凝胶自燃烧法制备钕掺杂NiFe1.98Nd0.02O4。借助X射线衍射仪、扫描电镜和矢量网络分析仪对NiFe1.98Nd0.02O4和羰基铁的结构、形貌、电磁参数进行测试分析。采用遗传算法对NiFe1.98Nd0.02O4-羰基铁双层涂层的厚度进行优化设计。结果以环氧树脂为基体,以羰基铁和NiFe1.98Nd0.02O4为吸波剂的双层吸波涂层具备较好的吸波性能,厚度约1 mm,反射率在9.25~11.35 GHz范围内均小于-10 dB。结论 NiFe1.98Nd0.02O4层和羰基铁层在吸波性能上有很好的互补性,理论优化结果和实验结果相同。     

不同纳米WS2含量Ni-P-Ti N-WS_(2)复合化学镀层的制备及其摩擦学性能EI北大核心CSCD

Ni-P-TiN化学复合镀层具有比Ni-P镀层更高的硬度和耐磨性,但其表面粗糙度大,与对偶件之间的摩擦因数高,应用潜力受到限制。通过在化学镀液中添加不同用量的纳米WS_(2)颗粒和固定用量的TiN颗粒,在低碳钢表面制备Ni-P-TiN-WS_(2)复合镀层。采用X射线能谱仪(EDS)、扫描电子显微镜(SEM)和X射线衍射仪(XRD)对镀层的化学成分(质量分数)、表面形貌及微观结构进行表征,并利用球盘式摩擦磨损试验机测试复合镀层的摩擦磨损性能。结果表明:纳米WS_(2)颗粒与纳米TiN颗粒的共沉积可使镀层表面更加致密、平整。随着镀液中纳米WS_(2)用量的增加,复合镀层的硬度先减小后增大,与氮化硅陶瓷球的摩擦因数则先升后降,磨损率显著下降,耐磨性增强。镀液中纳米WS_(2)粉末的用量为2.5 g/L时复合镀层的摩擦学性能最佳。纳米WS_(2)颗粒的加入及用量优化可显著改善复合镀层的综合性能,可为发展高耐磨低摩擦因数的先进涂层提供借鉴。     

In situ nanostructured ceramic matrix composite coating prepared by reactive plasma spraying micro-sized Al-Fe2O3 composite powders

In situ nanostructured ceramic matrix composite coating was prepared by reactive plasma spraying micro-sized Al-Fe₂O₃ composite powders. The microstructure of the composite coating was characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, respectively. The results indicated that the composite coating exhibited dense and crack-free microstructure with a number of spherical α-Fe and γ-Al₂O₃ nano-grains embedded within equiaxed and columnar FeAl₂O₄ nano-grains matrix. The composite coating showed markedly higher toughness and wear resistance than the conventional Al₂O₃ coating.     

Improvement of the hydrogen storage properties and electrochemical characteristics of Ti0.85VFe0.15 alloy by Ce substitution

The effect of Ce substitution for Ti on the microstructure, hydrogen absorption characteristics and electrochemical properties of Ti_0.85−xCe_xVFe_0.15 (x = 0, 0.02 and 0.05) is studied in detail. In the Ti-V-Fe series, the composition Ti_0.85VFe_0.15 which crystallizes in single phase BCC structure shows the highest hydrogen storage capacity of 3.7 wt%. In the present study, the effect of Ce addition (2 and 5 at%) on the hydrogen absorption properties of Ti_0.85VFe_0.15 has been investigated by X-ray diffraction, electron probe microanalysis (EPMA) and pressure-composition isotherm studies. The hydrogen absorption capacity is found to be higher for the Ce substituted alloys. The alloys Ti_0.85VFe_0.15, Ti_0.83Ce_0.02VFe_0.15 and Ti_0.80Ce_0.05VFe_0.15 show maximum hydrogen storage capacities of 3.7, 4.02 and 3.92 wt%, respectively. Kinetic studies show that the hydrogen absorption is quite fast for all the three alloys and they reach near saturation value in about 120 s. Electrochemical studies of the Ce (2 at%) substituted alloy, Ti_0.83Ce_0.02VFe_0.15 show higher electrocatalytic activity for the hydrogen electrode reactions as compared to Ce-free parent compound, Ti_0.85VFe_0.15.     

Preparation and characterization of electro-spun RuO2-Ag2O composite nanowires for electrochemical capacitors

We synthesized RuO₂-Ag₂O composite nanowires by means of an electrospinning method and investigated the capacitance, high-rate performance, and cycle number dependence of the composite nanowire electrodes. In order to synthesize optimum RuO₂-Ag₂O composite nanowires, the relative mole ratio of Ag precursor to Ru precursor varied from ∼0.1 to ∼0.3. X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and high-resolution transmission electron microscopy results show that crystalline RuO₂-Ag₂O composite nanowires (∼40-70 nm in diameter) are formed upon calcinations. Cyclic voltammetry results show that among the samples, the RuO₂-Ag₂O composite nanowires fabricated with the mole ratio of ∼0.2 give the highest capacitance, excellent high-rate performance, and excellent retention of capacity (∼97%).     

Characteristics of N-doped TiO2 nanotube arrays by N2-plasma for visible light-driven photocatalysis

N-doped TiO₂ nanotube arrays were prepared by electrochemical anode oxidation of Ti foil followed by treatment with N₂-plasma and subsequent annealed under Ar atmosphere. The morphologies, composition and optical properties of N-doped TiO₂ nanotube arrays were characterized using field-emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction spectrometer (XRD), Photoluminescence (PL) and UV-vis diffusion reflection spectroscopy (UV-vis DRS). Methylene blue (MB) solution was utilized as the degradation model to evaluate the photocatalytic activity of the samples under visible light irradiation. The results suggested N₂-plasma treatment created doping of nitrogen onto the surface of photoelectrodes successfully and the N-doped TiO₂ nanotube arrays display a significantly enhancement of the photocatalytic activity comparing with the pure TiO₂ nanotube arrays under the visible light irradiation.     

Microwave ECR plasma CVD of cubic Y2O3 coatings and their characterization

Yttrium oxide (Y₂O₃) thin films are deposited by microwave electron cyclotron resonance (ECR) plasma assisted metal organic chemical vapour deposition (MOCVD) process at a substrate temperature of 350 °C using indigenously developed metal organic precursors (2,2,6,6-tetra methyl-3,5-heptane dionate) yttrium, commonly known as Y(thd)₃ synthesized by ultrasound method. The deposited coatings are characterized by X-ray photoelectron spectroscopy, glancing angle X-ray diffraction, scanning electron microscopy, EDS and infrared spectroscopy. The characterization results indicate that it is possible to deposit non-porous coatings with excellent uniformity of a single phase cubic Y₂O₃ on various substrates by this process at reasonably low substrate temperature that is desirable in various manufacturing processes.     

Synthesis and microwave absorbing properties of polyaniline/MnFe2O4 nanocomposite

Conductive polyaniline (PANi)-manganese ferrite (MnFe₂O₄) nanocomposites with core-shell structure were synthesized by in situ polymerization in the presence of dodecyl benzene sulfonic acid (DBSA) as the surfactant and dopant and ammonium persulfate (APS) as the oxidant. The structure and magnetic properties of manganese ferrite nanoparticles were measured by using powder X-ray diffraction (XRD) and vibrating sample magnetometer (VSM), respectively. Its morphology, microstructure and DC conductivity of the nanocomposite were characterized by scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and four-wire-technique, respectively. The microwave absorbing properties of the nanocomposite powders dispersing in resin acrylic coating with the coating thickness of 1_.4 mm were investigated by using vector network analyzers in the frequency range of 8-12 GHz. A minimum reflection loss of −15.3 dB was observed at 10.4 GHz.     

Investigation on microstructure and mechanical properties of diffusion bonded Al/Mg2Si metal matrix composite using copper interlayer

Diffusion bonding of Al/Mg₂Si metal matrix composite (MMC) using Cu interlayer at optimal bonding temperature of 540 °C for various bonding durations was investigated. This metal matrix composite (MMC) containing 15% Mg₂Si particles was produced by in situ technique. Specific diffusion bonding process was introduced as a low vacuum technique. The composition and microstructure of the joined areas were examined by X-ray diffraction (XRD) and scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (EDS). Microhardness and shear tests were conducted to the samples to evaluate the effect of bonding duration on weldability. Several different diffusion layers exist at the bond region depending on the bonding duration. The shear strength of joints increased with bonding duration due to elimination of CuAl₂ brittle diffusion layer.     

Formation, properties and microstructure of amorphous/crystalline composite Ag20Cu30Ti50 alloy using miscibility gap

The aim of the work was to produce the amorphous/crystalline composite with uniform distribution of fine crystalline soft phase. Silver–copper–titanium Ag₂₀Cu₃₀Ti₅₀ alloy was prepared using 99.95 wt% Ag, 99.95 wt% Cu, 99.95 wt% Ti that were arc-melted in argon atmosphere. Then the alloy was melt spun on a copper wheel with linear velocity of 33 m/s. Investigation of the microstructure for both arc-melt massive sample and melt-spun ribbons was performed with use of scanning electron microscope (SEM) with EDS, light microscope (LM) and X-ray diffraction. The thermal stability was evaluated by differential scanning calorimetry (DSC). The properties such as Young modulus and Vickers hardness number before and after crystallization of the amorphous matrix were measured with use of nanoindenter. The microstructure was investigated by transmission electron microscope (TEM). It was found, that the alloy has a tendency for separation within the liquid state due to the miscibility gap which resulted in segregation into Ti–Cu–Ag matrix and Ag-base spherical particles after arc-melting. During rapid cooling through the melt spinning the Ag₂₀Cu₃₀Ti₅₀ alloy formed an amorphous/crystalline composite of fcc silver-rich spherical particles within the amorphous Ti–Cu–Ag matrix.     

Preparation and microwave absorbency of Fe/epoxy and FeNi3/epoxy composites

The focus of this study was placed on the lightness of microwave absorbing effective metal/epoxy composites. For such a focus, high aspect ratio of flake iron powder and high absorbing FeNi₃ were prepared. The iron powder particle size was reduced significantly through wet milling, comparing to dry milling. The FeNi₃ alloy powders were synthesized by mechanical alloying (MA); then, the particle size was reduced through wet milling. The iron powder and FeNi₃ alloy were characterized by scanning electron microscopy (SEM) and X-ray diffraction. SEM of the metal particles showed the flake and small structure by wet milling. The microwave absorbing effectiveness of metal/epoxy composite was affected by the structure, loading and dispersion of metal materials. The polyvinylpyrrolidone (PVP) plays an important role in suspending metal powders in wet milling to reduce powder size. Besides, the PVP will be a coupling agent in inhibiting the aggregation and enhancing the interfacial interaction between metal and epoxy. Results suggested that after the above manufacturing process, the microwave absorbency was enhanced substantially. Composite films of Fe/epoxy and FeNi₃/epoxy 1.6 mm in thickness possessed a microwave absorbency above 10 dB at 9.2-15.2 GHz and 13.1-16.2 GHz, respectively.     

Microstructure and hydrogen storage properties of Mg-Sn nanocomposite by mechanical milling

To improve the hydrogen storage properties, the composition and microstructure of Mg-Sn alloys were modified through fabricating Mg/Mg₂Sn nanocomposite by mechanical alloying. The microstructures were characterized by X-ray diffraction and scanning electron microscopy. It is found that Mg₂Sn instead of Mg(Sn) solid solution is preferably formed during milling process. Although Mg₂Sn is not a hydriding phase, the in situ formed nanosized Mg₂Sn facilitates hydrogen absorption/desorption of Mg by forming Mg/Mg₂Sn nanocomposite. The mechanically milled Mg-5 at.% Sn nanocomposite exhibits slightly elevated plateau pressure and destabilized thermodynamics due to the introduction of large amount of interface energy in Mg/Mg₂Sn nanocomposite.     

P110钢在CO2／H2S环境中的适用性研究

采用高温高压实验设备辅以失重法,研究了CO2／H2S腐蚀环境中P110钢的腐蚀性能,用SEM、EDS和XRD等分析了腐蚀产物．分别用电化学充氢及NACE TM0177A法对P110钢进行耐氢损伤试验．结果表明,虽然P110钢在试验环境中的均匀腐蚀速率很小,未发生点蚀,但随着充氢量的增加,强度、伸长率及断面收缩率均降低．...