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Jianguang Yuan Jinting Chen Haixiang Huang Yujie Lv Bogu Liu Zhongyu Li Bao Zhang Wei Lv Ying Wu 《自然科学进展(英文版)》2021,31(4):521-526
As two important members of complex hydrides,Mg(BH4)2 and Na BH4 have a high gravimetric capacity (14.9 and10.8 wt%,respectively).In this study,the Mg(BH4)2 was synthesized by the ion exchange method.Afterwards,the Mg(BH4)2 and Na BH4 composites with different amounts (30,40 and 50 wt%) of NdF3 were prepared by mechanical milling.Effects of the Nd F3 on the microstructural evolution and ... 相似文献
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Fabrication of Fe–TiC–Al2O3 composites on the surface of steel using a TiO2–Al–C–Fe combustion reaction induced by gas tungsten arc cladding
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The aim of the present study was to fabricate Fe–TiC–Al2O3 composites on the surface of medium carbon steel. For this purpose, TiO2–3C and 3TiO2–4Al–3C–xFe (0 ≤ x ≤ 4.6 by mole) mixtures were pre-placed on the surface of a medium carbon steel plate. The mixtures and substrate were then melted using a gas tungsten arc cladding process. The results show that the martensite forms in the layer produced by the TiO2–3C mixture. However, ferrite–Fe3C–TiC phases are the main phases in the microstructure of the clad layer produced by the 3TiO2–4Al–3C mixture. The addition of Fe to the TiO2–4Al–3C reactants with the content from 0 to 20wt% increases the volume fraction of particles, and a composite containing approximately 9vol% TiC and Al2O3 particles forms. This composite substantially improves the substrate hardness. The mechanism by which Fe particles enhance the TiC + Al2O3 volume fraction in the composite is determined. 相似文献
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《山东师范大学学报(自然科学版)》2004,19(4):37-39
用硝酸镍和十二烷基苯磺酸钠在乙醇溶剂中进行溶剂热反应,制得了碱式硝酸镍纳米管,做出了该化合物的TG和DTG曲线,并采用积分法中的Coats-Redfern法和微分法中的Achar法,对其热分解过程的非等温动力学数据进行处理,得到了热分解反应的动力学参数和最可儿反应机理函数. 相似文献
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Microstructure and mechanical properties of Nb–Mo–ZrB2 composites prepared by hot-pressing sintering
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Nb–Mo–ZrB2 composites (V(Nb)/V(Mo)=1) with 15vol% or 30vol% of ZrB2 were fabricated by hot-pressing sintering at 2000℃. The phases, microstructure, and mechanical properties were then investigated. The composites contain Nb-Mo solid solution (denoted as (Nb, Mo)ss hereafter), ZrB, MoB, and NbB phases. Compressive strength test results suggest that the strength of Nb–Mo–ZrB2 composites increases with increasing ZrB2 content; Nb–Mo–30vol%ZrB2 had the highest compressive strength (1905.1 MPa). The improvement in the compressive strength of the Nb–Mo–ZrB2 composites is mainly attributed to the secondary phase strengthening of the stiffer ZrB phase, solid-solution strengthening of the (Nb, Mo)ss matrix as well as fine-grain strengthening. The fracture toughness decreases with increasing ZrB2 content. Finally, the fracture modes of the Nb–Mo–ZrB2 composites are also discussed in detail. 相似文献
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福州大学学报 《福州大学学报(自然科学版)》1999,27(Z1):1999-38
研究了Ni(SAA)2 -2 配合物对K2S2 O8 氧化鲁米诺产生强的化学发光反应. 以水杨酸为配位体时, Ni( Ⅱ) 的检出限为103μg/L, 工作曲线响应浓度范围在1 ~100 μg/m L. 测定20μg/LNi( Ⅱ) 浓度RSD 为2-1 % . 配合物化学发光法检测在线镀镍件洗涤排放废水中微量镍可获得满意结果. 相似文献
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The effects of SiO2 content on the preparation process and metallurgical properties of acid oxidized pellets, including compressive strength, reduction, and softening–melting behaviors, were systematically investigated.Mineralogical structures, elemental distribution, and pore size distribution were varied to analyze the mechanism of the effects.The results show that with an increase in SiO2 content from 3.51 wt%to 7.18 wt%, compressive strength decreases from 3150 N/pellet to 2100 N/pellet and reducibility decreases from 76.5% to 71.4%.The microstructure showed that pellets with high SiO2 content contained more magnetite in the mineralogical structures.Additionally, some liquid phases appeared, which hindered the continuous crystallization of hematite.Also, the softening–melting properties of the pellets clearly deteriorated as the SiO2 content increased.With increasing SiO2 content, the temperature range of the softening–melting zone decreased, and the maximum differential pressure and the comprehensive permeability index increased significantly.When acid oxidized pellets are used as the raw materials for blast furnace smelting, it should be combined with high basicity sinters to improve the softening–melting behaviors of the comprehensive charge. 相似文献
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采用水热法合成了一例由Anderson型铬钼酸构筑的有机无机杂化材料:(H3O)3{Cu2(H2O)2(4-ptz)4[Cr(OH)6Mo6O18]}.用单晶X射线测定其晶体结构,该晶体属三斜晶系,空间群P-1.晶胞参数a=1.351 2(3)nm,b=1.353 3(3)nm,c=1.619 8(3)nm,α=68.64(3)°,β=68.64(3)°,γ=64.75(3)°.V=2.466(8)nm3,Z=2,Mr=1 822.44,Dc=2.454g/cm3,F(000)=1 770,μ=2.642mm-1,全矩阵最小二乘法修正至R=0.062 1,wR=0.167 6.化合物由质子化的水和二维层{Cu2(H2O)2(4-ptz)4[Cr(OH)6Mo6O18]}3nn-构成. 相似文献
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Reaction condition optimization and kinetic investigation of roasting zinc oxide ore using (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>SO<Subscript>4</Subscript>
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An orthogonal test was used to optimize the reaction conditions of roasting zinc oxide ore using (NH4)2SO4. The optimized reaction conditions are defined as an (NH4)2SO4/zinc molar ratio of 1.4:1, a roasting temperature of 440°C, and a thermostatic time of 60 min. The molar ratio of (NH4)2SO4/zinc is the most predominant factor and the roasting temperature is the second significant factor that governs the zinc extraction. Thermogravimetric–differential thermal analysis was used for (NH4)2SO4 and zinc mixed in a molar ratio of 1.4:1 at the heating rates of 5, 10, 15, and 20 K·min-1. Two strong endothermic peaks indicate that the complex chemical reactions occur at approximately 290°C and 400°C. XRD analysis was employed to examine the transformations of mineral phases during roasting process. Kinetic parameters, including reaction apparent activation energy, reaction order, and frequency factor, were calculated by the Doyle–Ozawa and Kissinger methods. Corresponding to the two endothermic peaks, the kinetic equations were obtained. 相似文献
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Preparation and radar-absorbing properties of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/TiO<Subscript>2</Subscript>/Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/Yb<Subscript>2</Subscript>O<Subscript>3</Subscript> composite powder
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Yi-fan Zhang Zhen Ji Ke Chen Cheng-chang Jia Shan-wu Yang Meng-ya Wang 《矿物冶金与材料学报》2017,24(2):216-221
Al2O3/TiO2/Fe2O3/Yb2O3 composite powder was synthesized via the sol-gel method. The structure, morphology, and radar-absorption properties of the composite powder were characterized by transmission electron microscopy, X-ray diffraction analysis and RF impedance analysis. The results show that two types of particles exist in the composite powder. One is irregular flakes (100-200 nm) and the other is spherical Al2O3 particles (smaller than 80 nm). Electromagnetic wave attenuation is mostly achieved by dielectric loss. The maximum value of the dissipation factor reaches 0.76 (at 15.68 GHz) in the frequency range of 2-18 GHz. The electromagnetic absorption of waves covers 2-18 GHz with the matching thicknesses of 1.5-4.5 mm. The absorption peak shifts to the lower-frequency area with increasing matching thickness. The effective absorption band covers the frequency range of 2.16-9.76 GHz, and the maximum absorption peak reaches -20.18 dB with a matching thickness of 3.5 mm at a frequency of 3.52 GHz. 相似文献
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QU Xiaosheng LI Jie WANG Zhiyong WANG Cunxin 《武汉大学学报:自然科学英文版》2007,12(3):511-514
A coordination complex was synthesized from NiCl2 and dipeptide glycylglycine(GG). It was characterized by element analysis, NMR and TG methods, and then was determined to be Ni(C4HsN2O3)2Cl2. Using an isoperibolic reaction calorimeter, the standard molar enthalpy of formation of Ni(GG)2Cl2(solid) has been determined to be -(1 674.66±2.02) kJ · mol^-1 at 298.15 K. 相似文献
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Long-Biao Zhu Da-yang Chen Xin-xin Wu Qing-dong Zhong Yu-fa Qi Li-yi Shi 《矿物冶金与材料学报》2011,18(5):600-605
Silver in the form of AgNO3 was added to ZnO-based varistor ceramics prepared by the solid-state reaction method. The effects of AgNO3 on both the microstructure and electrical properties of the varistors were studied in detail. The optimum addition amount
of AgNO3 in ZnO-based varistors was also determined. The mechanism for grain growth inhibition by silver doping was also proposed.
The results indicate that the varistor threshold voltage increases substantially along with the AgNO3 content increasing from 0 to 1.5mol%. Also, the introduction of AgNO3 can depress the mean grain size of ZnO, which is mainly responsible for the threshold voltage. Furthermore, the addition
of AgNO3 results in a slight decrease of donor density and a more severe fall in the density of interface states, which cause a decline
in barrier height and an increase in the depletion layer. 相似文献
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To enhance the microwave absorption performance of silicon carbide nanowires (SiCNWs), SiO2 nanoshells with a thickness of approximately 2 nm and Fe3O4 nanoparticles were grown on the surface of SiCNWs to form SiC@SiO2@Fe3O4 hybrids. The microwave absorption performance of the SiC@SiO2@Fe3O4 hybrids with different thicknesses was investigated in the frequency range from 2 to 18 GHz using a free-space antenna-based system. The results indicate that SiC@SiO2@Fe3O4 hybrids exhibit improved microwave absorption. In particular, in the case of an SiC@SiO2 to iron(Ⅲ) acetylacetonate mass ratio of 1:3, the microwave absorption with an absorber of 2-mm thickness exhibited a minimum reflection loss of -39.58 dB at 12.24 GHz. With respect to the enhanced microwave absorption mechanism, the Fe3O4 nanoparticles coated on SiC@SiO2 nanowires are proposed to balance the permeability and permittivity of the materials, contributing to the microwave attenuation. 相似文献
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Mineral-phase evolution and sintering behavior of MO-SiO2-Al2O3-B2O3 (M=Ca,Ba) glass-ceramics by low-temperature liquid-phase sintering
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In this work, network former SiO2 and network intermediate Al2O3 were introduced into typical low-melting binary compositions CaO·B2O3, CaO·2B2O3, and BaO·B2O3 via an aqueous solid-state suspension milling route. Accordingly, multiple-phase aluminosilicate glass-ceramics were directly obtained via liquid-phase sintering at temperatures below 950℃. On the basis of liquid-phase sintering theory, mineral-phase evolutions and glass-phase formations were systematically investigated in a wide MO-SiO2-Al2O3-B2O3 (M=Ca, Ba) composition range. The results indicate that major mineral phases of the aluminosilicate glass-ceramics are Al20B4O36, CaAl2Si2O8, and BaAl2Si2O8 and that the glass-ceramic materials are characterized by dense microstructures and excellent dielectric properties. 相似文献
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Guo-qiang Liu Xi Wang Ya-jie Gao Lei Wen Guang-yin Liu Jian-jie Zheng Peng Cen Ying Li 《矿物冶金与材料学报》2012,19(5):457-460
Spinel compounds LiNi0.5Mn1.3Ti0.2O4 (LNMTO) and Li4Ti5O12 (LTO) were synthesized by different methods. The particle sizes of LNMTO and LTO are 0.5–2 and 0.5–0.8 μm, respectively.
The LNMTO/LTO cell exhibits better electrochemical properties at both a low current rate of 0.2C and a high current rate of
1C. When the specific capacity was determined based on the mass of the LNMTO cathode, the LNMTO/LTO cell delivered 137 mA·h·g−1 at 0.2C and 118.2 mA·h·g−1 at 1C, and the corresponding capacity retentions after 30 cycles are 88.5% and 92.4%, respectively. 相似文献
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XIONG ZhengYe ZHANG ChunXiang TANG Qiang 《科学通报(英文版)》2007,52(13):1776-1779
This paper reports the thermoluminescence (TL) characteristics of lithium borate activated by Cu, Ag and P. The glow curves and spectra of thermoluminescence were measured, and the thermoluminescence response as a function of the absorbed dose and the fading behavior were studied. The results indicate that TL of this material has a low fading and wide linear dose response (10^-4-10^3 Gy). 相似文献
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A comparative study of the dissolution kinetics of galena ore in binary solutions of FeCl3/HCl and H2O2/HCl has been undertaken. The dissolution kinetics of the galena was found to depend on leachant concentration, reaction temperature,
stirring speed, solid-to-liquid ratio, and particle diameter. The dissolution rate of galena ore increases with the increase
of leachant concentration, reaction temperature, and stirring speed, while it decreases with the increase of solid-to-liquid
ratio and particle diameter. The activation energy (E
a) of 26.5 kJ/mol was obtained for galena ore dissolution in 0.3 M FeCl3/8.06 M HCl, and it suggests the surface diffusion model for the leaching reaction, while the E
a value of 40.6 kJ/mol was obtained for its dissolution in 8.06 M H2O2/8.06 M HCl, which suggests the surface chemical reaction model for the leaching reaction. Furthermore, the linear relationship
between rate constants and the reciprocal of particle radius supports the fact that dissolution is controlled by the surface
reaction in the two cases. Finally, the rate of reaction based on the reaction-controlled process has been described by a
semiempirical mathematical model. The Arrhenius and reaction constants of 11.023 s−1, 1.25×104 and 3.65×102 s−1, 8.02×106 were calculated for the 0.3 M FeCl3/8.06 M HCl and 8.06 M H2O2/8.06 M HCl binary solutions, respectively. 相似文献
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Electrical conductivity optimization of the Na3AlF6-Al2O3-Sm2O3 molten salts system for Al-Sm intermediate binary alloy production
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Chun-fa Liao Yun-fen Jiao Xu Wang Bo-qing Cai Qiang-chao Sun Hao Tang 《矿物冶金与材料学报》2017,24(9):1034-1042
Metal Sm has been widely used in making Al-Sm magnet alloy materials. Conventional distillation technology to produce Sm has the disadvantages of low productivity, high costs, and pollution generation. The objective of this study was to develop a molten salt electrolyte system to produce Al-Sm alloy directly, with focus on the electrical conductivity and optimal operating conditions to minimize the energy consumption. The continuously varying cell constant (CVCC) technique was used to measure the conductivity for the Na3AlF6-AlF3-LiF-MgF2-Al2O3-Sm2O3 electrolysis medium in the temperature range from 905 to 1055℃. The temperature (t) and the addition of Al2O3 (W(Al2O3)), Sm2O3 (W(Sm2O3)), and a combination of Al2O3 and Sm2O3 into the basic fluoride system were examined with respect to their effects on the conductivity (κ) and activation energy. The experimental results showed that the molten electrolyte conductivity increases with increasing temperature (t) and decreases with the addition of Al2O3 or Sm2O3 or both. We concluded that the optimal operation conditions for Al-Sm intermediate alloy production in the Na3AlF6-AlF3-LiF-MgF2-Al2O3-Sm2O3 system are W(Al2O3) + W(Sm2O3)=3wt%, W(Al2O3):W(Sm2O3)=7:3, and a temperature of 965 to 995℃, which results in satisfactory conductivity, low fluoride evaporation losses, and low energy consumption. 相似文献