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51.
The effect of vanadium (V) addition on the mechanical properties of a Cr Ni Mo Cu Ti stainless steel was studied and its influence on microstructural changes was also investigated. Results indicate that the structure of the solution treated specimens mainly comprises of austenite martensite, and adding V leads to the formation of a considerable amount of ferrite. Under this condition, austenite phase is not mechanically stable, and transforms to martensite by plastic deformation. The addition of 05% - 10% (in mass percent) of V increases the hardness and the strength of the 80% cold rolled and aged steel, without any effect on ductility. Improvement in mechanical properties is presumably attributed to the formation of a small amount of ferrite in the primary structure, and the formation of certain precipitates is accelerated by the addition of V during aging. By contrast, excessive V decreases the strength and ductility simultaneously. This is due to the strong effect of ferrite formation compared to the beneficial effect of precipitation. The loss of ductility caused by adding higher amount of V is due to the formation of ferrite phases which in turn are suitable nucleation sites for crack propagation. 相似文献
52.
质子交换膜(PEM)作为全钒液流电池(VRFB)的核心组件之一,应当解决成本高昂、合成过程复杂等问题,并具备高质子传导率、低钒离子渗透率、高机械强度和优异化学稳定性等关键性能。本文基于四甲基双酚芴单体通过缩聚反应合成了一系列聚芴醚酮化合物PFEKs,再利用溴代反应将苯甲基功能化为溴甲基,接着通过4-羟基苯磺酸钠的SN2亲核取代制得了一系列不同离子交换容量的磺化聚芴醚酮聚合物(SPFEKs)。通过溶液浇铸法成膜并酸化,得到一系列新型低成本PEMs。该合成路线的原料来源广泛,价格低廉,不涉及危险的磺化反应,易于工业放大。所得膜都具有良好的机械性能和氧化稳定性,其中SPFEK-40膜具有较高的质子传导率及离子选择性、较低的钒离子渗透率及面电阻,综合性能优异。以SPFEK-40膜组装的VRFB在电流密度为80 mA/cm2时的能量效率(EE)为88.2%,高于以Nafion 212膜组装的VRFB的84.8%。此外,以SPFEK-40膜组装的VRFB在30次循环后放电容量仅衰减至84.3%,远高于以Nafion 212膜组装的VRFB的66.1%。 相似文献
53.
Svetlana G. Yakubova Guzalia R. Abilova Elvira G. Tazeeva Yulia Y. Borisova Dmitry V. Milordov Nikolay A. Mironov 《Petroleum Science and Technology》2018,36(16):1319-1324
Features of the content and distribution of vanadium and vanadyl porphyrins in the fractions of resins, which were obtained by separation using column chromatography on silica, have been studied on heavy sulfurous oils of various deposits of the Volga–Ural basin (Russia). The difference of the vanadium and vanadyl porphyrin contents in the fractions of oils of various production complexes has been shown. Features of structural–group composition and predominant types of vanadyl porphyrins in the fractions of resins have been determined. 相似文献
54.
本实验采用一种简单、低成本有效的溶胶-凝胶法制备了热致变色钨掺杂二氧化钒薄膜。首先将乙酰丙酮氧钒和氯化钨置于甲醇溶液中反应制备出前驱体,然后将前驱物旋涂在衬底基材上。最后在氩气氛围中、600 ℃进行退火。同时,对所制备的二氧化钒薄膜进行了XRD、XPS、SEM、UV和WCA等表征和测试。结果表明,钨掺杂二氧化钒薄膜颗粒尺寸范围从30~150 nm,薄膜的表面展现出优异的亲水性,其静态水接触角为12°。根据光学测试,钨掺杂VO2薄膜表现出优异的光学性能与可见光调节效率(Tlum,s = 80.75%,Tlum,m = 79.24%)和优良的太阳能调节效率(ΔTsol = 9.10%,Tsol,s = 81.40%,Tsol,m= 72.30%)。VO2薄膜相变表现出可适用的相变温度:在钨掺杂摩尔量为2%时,其相变温度为32 ℃。 相似文献
55.
在氮气气氛下,采用低温焙烧的方法对含砷铜烟尘中的砷进行选择性分离,研究了温度、氮气流量和焙烧时间的变化对砷挥发率的影响,用X射线衍射分析、差热-差重分析等方法研究了含砷铜烟尘中砷的挥发规律,并分析了砷挥发过程的动力学。结果表明,含砷铜烟尘中砷的选择性分离应在低温下进行,避免高温下Zn、Pb挥发损失和As_2O_3生成难挥发的砷酸盐。在250℃,氮气流量300mL/min、焙烧120min的条件下,砷的挥发率为95.68%,渣中砷的含量为0.79%,其他有价金属基本不挥发,实现了砷与其他有价金属的选择性分离,砷以初级As_2O_3产品回收,纯度为96.85%。动力学研究表明,在一定范围内,砷的低温选择性挥发过程符合收缩核模型,其表观活化能为19.71kJ/mol,该过程受内扩散控制。 相似文献
56.
《Journal of Nuclear Science and Technology》2013,50(3):242-249
A neutronics benchmark experiment on vanadium, which is a low activation fusion reactor material, was conducted by using the D-T neutron source facility of FNS/JAERI. Neutron spectra, dosimetry reaction rates, γ-ray spectra and γ-ray heating rates were measured in a vanadium experimental assembly. Benchmark tests for four evaluated nuclear data files were performed by analyzing the experiment. As a result, the following problems were pointed out in view of accuracy of fusion reactor designs. (1) JENDL-FF and JENDL-3.2: Total cross section should be reexamined especially at ~2keV. (2) ENDF/B-VI: Double differential cross sections for 14 MeV neutrons should be revised because of the isotropic angular distribution for continuum neutron emission. Gamma-ray production cross sections are too small and discrete γ-ray peaks are not represented clearly. (3) EFF-3: Gamma-ray production cross sections are too large. 相似文献
57.
In this paper, titanium dioxide (TiO2) nanoparticles were employed as catalysts towards V2+/V3+ redox couple of vanadium redox flow battery (VRFB). The effect of TiO2 phase on the electrocatalytic performance for negative couple was systematically investigated. The electrochemical properties of TiO2 with different phase were assessed via cyclic voltammetry and electrochemical impedance spectroscopy by using AB as conductive agent. Obtained from the results, anatase TiO2 (α‐TiO2) exhibits superior electrocatalytic activity to rutile TiO2 (γ‐TiO2). The VRFB cell performs well at discharge capacity, voltage efficiency, and energy efficiency by employing α‐TiO2‐modified negative electrode with current density varying between 50 and 100 mA cm?2. The discharge capacity of α‐TiO2‐modified cell with vanadium ion concentration of 1.6 M comes up to 113.5 mA h at 100 mA cm?2 current density, which is increased by 39.1 mA h after modification for negative electrode. Moreover, the corresponding energy efficiency increases by 7.5% after modification of α‐TiO2. Experimental results show that TiO2 is an ideal catalyst for VRFB. Moreover, α‐TiO2 demonstrates superior electrocatalytic performance to γ‐TiO2 towards V2+/V3+ reaction. 相似文献
58.
59.
Yuan Qiang Li Naoto Hirosaki Rong-Jun Xie Mamoru Mitomo 《Science and Technology of Advanced Materials》2007,8(7-8):607
The crystal and electronic structures, as well as the luminescence properties of Sr2Al2−xSi1+xO7−xNx:Eu2+ are reported. First-principles calculations energetically confirm that the Al and Si atoms are in partial ordering in the 2a and 4e sites in Sr2Al2SiO7. In addition, the band structure calculation shows that Sr2Al2SiO7 has an indirect band gap with an energy gap of about 4.07 eV, which is in good agreement with the experimental data (5.3 eV) obtained from the diffuse reflection spectrum. The crystal structure of Sr2Al2SiO7 can be modified by Si–N substitution for Al–O in the lattice with a maximum solubility of about x=0.6. The average bond length of EuSr-(O,N) slightly increases although the lattice parameters decrease with the incorporation of Si–N in Sr2Al2SiO7:Eu2+. Under excitation in the visible spectral region, Sr2Al2−xSi1+xO7−xNx:Eu2+ emits blue to yellow light with a broad emission band in the range of 480–570 nm, varying with both the Eu concentration and the x value. The red shift of the emission band of Eu2+ is associated with an increase in the crystal-field splitting and the covalency, which arise from the incorporation of nitrogen as well as the energy transfer between the Eu ions at high Eu concentrations. Moreover, the Eu ions have a strong effect on both the concentration quenching and the thermal quenching in Sr2Al2−xSi1+xO7−xNx. The temperature dependence of photoluminescence indicates that Sr2Al2−xSi1+xO7−xNx:Eu2+ shows strong thermal quenching due to the dominant nonradiative process at room temperature. 相似文献
60.