极端电场环境激励下的VO2相变性能研究与应用

为揭示VXOY薄膜场致相变规律,推广钒氧化物应用于卫星控制系统,指导氧化钒规模制备,将磁控溅射法和真空退火工艺相结合,在Al2O3陶瓷基片上制备出VXOY薄膜,降低了实验对仪器精度的要求,提高了实验的成功率。对基片进行磁控溅射镀膜,在管式炉中进一步氧化处理生成表面均匀的V2O5,然后进行高温退火处理,对不同退火条件下的生成的薄膜进行了XRD表征。测得了电场激励下VXOY薄膜的相变现象,验证了电场激励下焦耳热并非薄膜相变的主导因素;总结了不同组分下VXOY薄膜的相变规律,研究了不同V6O13含量对VO2薄膜临界相变电压的影响规律,可指导VXOY薄膜应用于微纳卫星等极端环境下的设备控制系统。     

Effective adsorption of As(V) and V(V) ions from water samples using 2,4-dinitrophenylhydrazine functionalized sodium dodecyl sulfate-coated magnetite nanoparticles

In this study, 2,4-DNPH coated magnetite was used for removal of As(V) and V(V) ions from aqueous solution. The synthesized nanoparticles were characterized by XRD analysis, FT-IR, SEM, and SEM-EDXS measurement. The size of the nanoparticles according to SEM was obtained as around 20–35 nm. Equilibrium isotherm data showed that the Langmuir–Freundlich model was in a good agreement with the experimental data according to high correlation coefficient. The maximum adsorption capacities of As(V) and V(V) on adsorbent were 338.4 and 266.8 mg g^?1, respectively. Kinetic study showed that the fractal like-PSO model was appropriate to describe the adsorption process. The optimum pH was obtained to be 7 and 5 for As(V) and V(V) ions, respectively.     

Benchmark Experiment on Vanadium with D-T Neutrons and Validation of Evaluated Nuclear Data Libraries by Analysis of the Experiment

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.     

Cyclic metallurgical process for extracting V and Cr from vanadium slag: Part II. Separation and recovery of Cr from vanadium precipitated solution

Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO₃ and leaching with Na₂CO₃ was investigated. The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO₃ into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5, adjusting the pH to 3.0 and stirring for 180 min at 30 °C. Then, the precipitates were leached with hot Na₂CO₃ solution to obtain leaching solution containing Na₂CrO₄ and leaching residue containing PbCO₃. The leaching efficiency of Cr reaches 96.43% by adding the precipitates into 0.5 mol/L Na₂CO₃ solution with the mass ratio of liquid to solid (L/S) of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70 °C. After filtration, leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na₂CrO₄ approaches the saturation. Finally, the product of Na₂CrO₄·4H₂O is obtained by evaporation and crystallization of leaching solution.     

用Shedlovsky方法求解298.15K时硫酸氧钒离子对解离常数

采用电导法测定了水溶液中298.15 K时VOSO4·n H2O(s)的电导率,通过Origin数据拟合求出极限摩尔电导;采用改进的Ostwald稀释定律和改进的Davies方程求解活度系数,进而求得溶液的真实离子强度;采用Shedlovsky方法求解硫酸氧钒离子对的解离常数。经过数据处理得到了298.15 K时硫酸氧钒极限摩尔电导率Λ0为209.205 020 9S·dm2/mol,硫酸氧钒离子对的解离常数Kd为0.001 756 218,进而可以研究其他相关热力学性质。     

水热法制备纳米二氧化钒粉体

以五氧化二钒和无水亚硫酸钠为原料,采用水热法制备纳米VO2粉体。系统地探讨了p H、填充度、反应温度、无水亚硫酸钠用量对VO2产品制备工艺的影响,采用化学法、X射线衍射仪(XRD)、扫瞄电子显微镜(SEM)和差示热扫描仪(DSC)对产品的价态、物相、形貌进行了分析。结果表明,在p H=3、填充度为0.7、物质的量比为n(V2O5)∶n(Na2SO3)=1∶1.2、温度250℃下水热反应24 h,所得到的初产品经氢氧化钠溶液纯化1 h后,质量分数达到98.5%,总产率为85.4%。产品为纯度高的B相VO2,经800℃热处理2 h后由B相转变为M相,热处理后产品的相变点为69.0℃。     

离子色谱法测定三氧化铬中氯离子和硫酸根含量

建立了离子色谱法分析测定三氧化铬中氯离子和硫酸根含量的方法。选用水合肼作为还原剂,将铬酸根还原成氢氧化铬沉淀,分离除去后,以5.0 mmol/L Na_2CO_3/1.0 mmol/L NaHCO_3为淋洗液,流速为1.0 m L/min的条件下分离测定。在0.1~20.0μg/m L的范围内,氯离子线性方程为y=0.300 3x+0.051 5,相关系数为0.999 7,检出限为0.016μg/m L;硫酸根线性方程为y=0.177 2x-0.000 5,相关系数为0.999 9,检出限为0.029μg/m L。经过方法学考察,精密度和稳定性试验,相对标准偏差结果均5%,样品中氯离子和硫酸根的回收率在81.4%~101.8%。     

Electron beam braze-welding of vanadium alloy to stainless steel with electroplated Cu/Ag coatings

Cracks may easily occur in the fusion weld between vanadium alloys and stainless steel due to the brittle intermetallics and welding stress.The high vacuum electron beam braze-welding has been successfully used to join vanadium alloy(V-5Cr-5Ti) to stainless steel(HR-2) with electroplated Cu and Ag coating.To investigate the effects of electroplated coating on the weldability,the joint appearance,the microstructure and the mechanical properties of the joints have been thoroughly analyzed.The results show that the joint surface configuration was good and root reinforcement was full and smooth.A reaction zone(RZ) was gained on the interface between the VSCrSTi alloy and HR-2 stainless steel base metals.The width of reaction zone at the top of the joint was up to 0.65 mm,wider than that in the bottom of the joint(0.46 mm).The reaction zone consisted of considerably smaller dendritic structures with an average grain size of less than 10 μm.Element Ag and Cu almost enriched the interface between V-5Cr-5Ti alloy substrate and RZ,serving as a physical barrier which decreases or avoids the formation of intermetallics.The maximum tensile strength of vanadium alloy/stainless steel dissimilar alloy joint was more than 300 MPa.The joint was defects free.