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International Journal of Minerals,Metallurgy and Materials 2022年第10期29卷 1873-1881页

作者： Heng Zheng Oday Daghagheleh Thomas Wolfinger Bernd Taferner Johannes Schenk Runsheng Xu Chair of Ferrous Metallurgy Montanuniversitaet LeobenFranz-Josef-Straβe 188700LeobenAustria K1-MET GmbH Stahlstraße 144020 LinzAustria The State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China

The influence of different pre-oxidation temperatures and pre-oxidation degrees on the reduction and fluidization behaviors of magnetite-based iron ore was investigated in a hydrogen-induced fluidized bed.The raw magnetite-based iron ore was pre-oxidized at 800 and1000℃ for a certain time to reach a partly oxidation and deeply oxidation state.The structure and morphology of the reduced particles were analyzed via optical microscope and scanning electron microscopy(SEM).The reaction kinetic mechanism was determined based on the double-logarithm analysis.The results indicate that the materials with higher oxidation temperature and wider particle size range show better fluidization behaviors.The lower oxidation temperature is more beneficial for the reduction rate,especially in the later reduction stage.The pre-oxidation degree shows no obvious influence on the fluidization and reduction behaviors.Based on the kinetic analysis,the reduction progress can be divided into three stages.The reduction mechanism was discussed combing the surface morphology and phase structure.

关键词： magnetite-based iron ore prior oxidation fluidization behavior kinetic analysis hydrogen reduction

Synthesis and Characterization of Ultra-fine Cr_2O_3 from hydrogen reduction of K_2CrO_4

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Journal of Wuhan University of Technology(Materials Science) 2008年第2期23卷 181-183页

作者： BAI Yulan XU Hongbin ZHANG Yi LI Zuohu Key Laboratory of Green Process and Engineering Institute of Process Engineering Chinese Academy of Sciences Beijing 100080 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China

As a part of the green process for manufacturing chromium compounds, two steps are involved in the synthesis of ultra-fine Cr2O3 powders： the first is the hydrogen reduction of K2CrO4 into intermediate trivalent （Cr^3＋） or tetravalent （Cr^4＋） chromium compounds; the second is the decomposing of the intermediate into Cr2O3 by heat treating. The intermediate is well characterized by means of SEM, XRD, and XPS. The possible reaction mechanism of the process is analyzed.

关键词： hydrogen reduction ultra-fine chromic oxide potassium chromate green process

The effect of hydrogen reduction of α-MnO_(2) on formaldehyde oxidation: The roles of oxygen vacancies

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Chinese Chemical Letters 2023年第3期34卷 171-174页

作者： Liping Zhou Chunying Wang Yaobin Li Xiaofeng Liu Hua Deng Wenpo Shan Hong He College of Resources and Environmental Sciences Fujian Agriculture and Forestry UniversityFuzhou 350002China Center for Excellence in Regional Atmospheric Environment Key Laboratory of Urban Pollutant ConversionInstitute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China Zhejiang Key Laboratory of Urban Environmental Processes and Pollution Control Ningbo Urban Environment Observation and Research StationInstitute of Urban EnvironmentChinese Academy of SciencesNingbo 315800China State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China

A series of α-MnO_(2) catalysts with various Mn valence states were treated by hydrogen reduction for different periods of time. Their catalytic capacity for formaldehyde(HCHO) oxidation was evaluated. The results indicated that hydrogen reduction dramatically improves the catalytic performance of α-MnO_(2) in HCHO oxidation. The α-MnO_(2) sample reduced by hydrogen for 2 h possessed superior activity and could completely oxidize 150 ppm HCHO to CO_(2) and H_(2)O at 70℃. Multiple characterization results illustrated that hydrogen reduction contributed to the production of more oxygen vacancies. The oxygen vacancies on the catalyst surface enhanced the adsorption, activation and mobility of O_(2) molecules, and thereby enhanced HCHO catalytic oxidation. This study provides novel insight into the design of outstanding MnO_x catalysts for HCHO oxidation at low temperature.

关键词： hydrogen reduction α-MnO_(2) Formaldehyde oxidation Oxygen vacancies

Preparation of spherical ultrafine copper powder via hydrogen reduction-densification of Mg(OH)_2-coated Cu_2O powder

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International Journal of Minerals,Metallurgy and Materials 2012年第11期19卷 1063-1068页

作者： Yue-jun Wang Kang-gen Zhou School of Metallurgical Science and Engineering Central South UniversityChangsha 410083China

A novel process was developed to produce spherical copper powder for multilayer ceramic capacitors （MLCC）. Spherical ultrafine cuprous oxide （Cu20） powder was prepared by glucose reduction of Cu（OH）2. The Cu20 particles were coated by Mg（OH）2 and reduced to metallic copper particles. At last, the copper particles were densified by high-temperature heat treatment. The products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, tap density, and thermogravimetry （TG）. It is found that the shape and size distribution of the copper powder are determined by the Cu20 powder and the copper particles do not agglomerate during high-temperature heat treatment because of the existence of Mg（OH）2 coating. After densification at high temperature, the particle tap density increases from 3.30 to 4.18 g/cm3 and the initial oxidation temperature rises from 125 to 150~C.

关键词： ceramic capacitors multilayers copper powder hydrogen reduction densification

Kinetics of hydrogen reduction and the influence of gas composition on hot- rolled steel scale after temper rolling

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Baosteel Technical Research 2014年第4期8卷 48-52页

作者： GUAN Chuang LI Jun TAN Ning ZHANG Shuguang School of Materials Science and Engineering Shanghai Jiaotong University Research Institute Baoshan Iron & Steel Co.Ltd.

For replacing the presently employed pickling method with a more environmentally friendly descaling method, hydrogen reduction of oxide scale formed during hot rolling was studied at 800℃ under a varied atmosphere. The hydrogen level and water vapor content in the reducing atmosphere were found to influence the reduction rate wherein increasing hydrogen level as well as decreasing water vapor content resulted in faster oxide reduction. The reduction reaction substantially obeyed a parabolic rate law. Oxide scale of a usual thickness （approximately 7 micrometer） could be reduced almost completely in an atmosphere of 20 vol. % hydrogen with a water vapor content corresponding to a -40℃ dew point at 800℃. When lowering the hydrogen level to 10% and increasing the water vapor content to a 10℃ dew point,quite a large extent of the oxide scale was retained,which might be attributable to the formation of an outermost dense layer of pure iron at the early stage of reduction.

关键词： oxide scale hydrogen reduction pickling

Effect of Y_(2)O_(3)doping on preparation ultrafine/nano-tungsten powder and refinement mechanism

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Tungsten 2023年第4期5卷 539-547页

作者： Dong-Dong Lv Yu Sun Jian-Bo Zhang Sheng-Da Guo Bai-Xiong Liu Faculty of Materials Metallurgy and Chemistry Jiangxi University of Science and TechnologyGanzhou341000China Jiangxi Advanced Copper Industry Research Institute Yingtan335000China Naional Rare Earh Functional Material Innovation Center Jiangxi Universiy of Science and TechnologyGanzhou341000China Engineering Research Center of Tungsten Resources High-Efficiency Development and Application Technology of the Ministry of Education Jiangxi University of Science and TechnologyGanzhou341000China

In this study,ultrafine/nano W-Y_(2)O_(3)composite powders were synthesized by spray drying,roasting and two-step hydrogen reduction using ammonium metatungstate and yttrium nitrate as raw materials.The mechanism of the influence of Y_(2)O_(3)on the growth of WO_(2.72)and the particle refinement of tungsten powder is discussed.The effect of Y_(2)O_(3)particles on the reduction behavior of tungsten powder was investigated using scanning electron microscopy to study the near surface morphology and X-ray diffraction for phase ID(composition)and crystal structural changes for the reduced powders at each step.The results show that the doping of 0.3 wt.%Y_(2)O_(3)can significantly increase the aspect ratio of WO_(2.72)in the first step of hydrogen reduction.Moreover,Y_(2)O_(3)can effectively inhibit the growth of tungsten particles in the hydrogen reduction process.Therefore,The Y_(2)O_(3)-doped tungsten powders have finer particles and a narrower particle size distribution range than the undoped powders.The average particle diameter of 0.3 wt.%Y_(2)O_(3)doping tungsten powder was in the range of 90-120 nm.

关键词： Tungsten powder hydrogen reduction Yttrium oxide

Study on hydrogen adsorption on WO_(3)(001) surface by density functional theory calculation

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钨科技(英文) 2023年第4期5卷 558-569页

作者： Ping-Guo Jiang Xiang-Biao Yu Yi-Yu Xiao Su Zhao Wang-Jun Peng School of Materials Science and Engineering Shanghai Dianji UniversityShanghai200240China School of Metallurgy and Chemistry Engineering Jiangxi University of Science and TechnologyGanzhou341000China

hydrogen reduction of tungsten oxide is currently the most widely used technology to produce metal tungsten for its simplicity and pollution-free nature.The computer simulation is a powerful tool for exploring the mechanism of hydrogen reduction of tungsten oxide from a microscopic view.The density functional theory(DFT) is applied to investigate the adsorption characteristic of hydrogen molecule on the surface and inside the lattice of WO_(3).The adsorption energy of hydrogen on the WO_(3)(001) surface is 66.56 kJ.mol^(-1) which is larger than the adsorption energy of hydrogen molecule inside the lattice of WO3 which indicates that once the hydrogen diffuses inside the lattice,it is easier to adsorb on the O atom to break W-O bond.And The diffusion process of a hydrogen molecule from the WO-terminated WO_(3)(001) surface to the inside of the WO_(3) lattice and hydrogen molecule adsorption inside the lattice was investigated.The activation energy of hydrogen molecule diffusion from the surface down to the first interstitial and diffusion from the first interstitial down to the second interstitial is 195.41 and 172.81 kJ·mol^(-1),respectively.The controlling step of hydrogen reduction of tungsten oxide may be the hydrogen molecule diffusion inside the oxides lattice through the interstitial.

关键词： WO_(3) hydrogen reduction DFT

Effects of Al contents on microstructure and properties of hot-dip Zn-Al alloy coatings on hydrogen reduced hot-rolled steel without acid pickling

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Journal of Iron and Steel Research(International) 2017年第10期24卷 1032-1040页

作者： Zhi-feng Li Yong-quan He Guang-ming Cao Jun-jian Tang Xiang-jun Zhang Zhen-yu Liu State Key Laboratory of Rolling and Automation Northeastern University School of Mechatronics Engineering Zhengzhou University of Aeronautics

A new hot-dip galvanizing method was employed on hot-rolled low carbon steel.The effects of Al contents on microstructure,micro-hardness and corrosion resistance of Zn-Al alloy coatings were systematically investigated.Phase composition,microstructure and element distribution in Zn-Al alloy coatings were analyzed using X-ray diffraction（XRD）and electron probe micro analysis（EPMA）,respectively.It is found that Al content（0.6-6.0 wt.%）in galvanizing zinc affects surface quality and adhesion between coatings and matrix in the newly developed method.In addition,with increasing Al content,micro-hardness significantly increased due to the increase in Zn-Al eutectoid phases.Potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）also revealed that increase in Al plays a noticeable role in improving the corrosion resistance of Zn-Al alloy coatings.

关键词： Hot-rolled steel strip hydrogen reduction Eutectoid structure Micro-hardnessCorrosion resistance Zn-Al alloy coating

Effect of rare earth element cerium on preparation of tungsten powders

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Journal of Rare Earths 2015年第5期33卷 561-566页

作者：何文谭敦强李亚蕾杨欣陆磊陆德平 School of Materials Science and Engineering Nanchang University Institute of Applied Physics Jiangxi Academy of Sciences

Tungsten powders and Ce doped powders were prepared by hydrogen reduction combined with the liquid-solid doping method. The phase composition, particle size and powder morphology of Ce doped tungsten powders were analyzed by X-ray diffrac-tion, scanning electron microscopy and transmission electron microscopy, respectively. The results indicated that 10000 ppm Ce doped tungsten oxide powders were consisted of WO3 phase and Ce4W9O33 phase. The hydrogen reduction of Ce doped tungsten powders was basically accomplished at 800 oC for 3 h. The size of Ce doped W powders was remarkably decreased compared to the undoped W powders. The phase of Ce4W9O33 was reduced to Ce2 （WO4）3 phase and Ce2W2O9 phase during the process of hydrogen reduction. Moreover, Ce2 （WO4）3 phase and Ce2W2O9 phase were observed form their morphologies, where the doping content of Ce was more than 100 ppm. The ternary phase embedding into W particles was assigned to Ce2 （WO4）3, while the ternary phase distrib-uting among W particles corresponded to Ce2W2O9. The phase of Ce2 （WO4）3 might be the nucleus of W particles and increase the number of the nucleus. And the particles of Ce2W2O9 covered WO2 particles and might inhibit the growth of W particles. These two reasons resulted in the decrease of the size of Ce doped W particles. Uniform fine W powders were fabricated with the doping content of Ce more than 100 ppm.

关键词： cerium tungsten oxide hydrogen reduction tungsten powders rare earths

A study on comprehensive recycling of waste diamond tools

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Rare Metals 2012年第1期31卷 88-91页

作者： Wang, Limin Zhang, Guocheng Ma, Fei General Research Institute for Nonferrous Metals Beijing 100088 China General Research Institute for Powder Metals Advanced Materials Co. Ltd Beijing 101407 China

This article puts forward a new method of recycling materials in diamond tools comprehensively and efficiently by means of analyzing and summarizing various methods of recycling waste diamond tools. After the waste diamond tools were decomposed in a mixed acid, metals contained in it went into solution in their ionic forms, while diamond and tungsten carbide particles formed into residues to be reclaimed. The amounts of metal ions in the leaching solution were adjusted according to the contents of metals in the diamond tools; then, the leaching solution was co-precipitated using oxalic acid as precipitation agent, and ammonia water was added to adjust the pH value of the oxalic acid. Under the right conditions, the comprehensive precipitation rate of metals reached above 98%. Finally, ultrafine pre-alloy powder was obtained by hydrogen reduction of oxalate.

关键词： diamond tools leaching co-precipitation hydrogen reduction