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A review of late-stage tungsten fuzz growth

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tungsten 2022年第3期4卷 184-193页

作者： Jacob A.R.Wright Department of Materials Science and Metallurgy University of CambridgeCambridgeCB30FSUK

tungsten will be used as the plasma-facing divertor material in the International Thermonuclear Experimental Reactor(ITER)fusion reactor.Under high temperatures and high ion fluxes,a‘fuzz’nanostructure forms on the tungsten surface with dramatically different properties and could contaminate the plasma.Although simulations and experimental observations have provided understanding of the initial fuzz formation process,there is debate over whether tungsten or helium migration is rate-limiting during late-stage growth,and the mechanisms by which tungsten and helium migrations occur.Here,the proposed mechanisms are considered in turn.It is concluded that tungsten migration occurs by adatom diffusion along the fuzz surface.Continual helium migration through the porous fuzz to the tungsten bulk is also required for fuzz growth,for continued bubble growth and rupture.Helium likely migrates due to ballistic penetration,although diffusion may contribute.It is difficult to determine the limiting process,which may switch from helium penetration to tungsten adatom diffusion above a threshold flux.Areas for further research to clarify the mechanisms are then considered.A greater understanding of the fuzz formation mechanism is key to the successful design of plasma-facing tungsten components,and may have applications in forming porous tungsten catalysts.

关键词： tungsten tungsten fuzz Plasma-material interactions Fusion reactors

tungsten nanoparticle-strengthened copper composite prepared by a sol–gel method and in-situ reaction

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International Journal of Minerals,Metallurgy and Materials 2019年第11期26卷 1477-1483页

作者： Tian-xing Lu Cun-guang Chen Zhi-meng Guo Pei Li Ming-xing Guo Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

tungsten nanoparticle-strengthened Cu composites were prepared from nanopowder synthesized by a sol–gel method and in-situ hydrogen reduction.The tungsten particles in the Cu matrix were well-dispersed with an average size of approximately 100–200 nm.The addition of nanosized W particles remarkably improves the mechanical properties,while the electrical conductivity did not substantially decrease.The Cu–W composite with 6 wt%W has the most comprehensive properties with an ultimate strength of 310 MPa,yield strength of 238 MPa,hardness of HV 108 and electrical conductivity of 90%IACS.The enhanced mechanical property and only a small loss of electrical conductivity demonstrate the potential of this new strategy to prepare W nanoparticle-strengthened Cu composites.

关键词： copper composites second phase strengthening tungsten sol–gel method

tungsten carbide coatings with different binders prepared by low power plasma spray system

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中国有色金属学会会刊：英文版 2004年第Z1期14卷 77-82页

作者： GAO Yang M.F.Morks FU Ying-qing Materials and Technology Institute Dalian Maritime University Dalian 116026 China Materials and Technology Institute Dalian Maritime University Dalian 116026 China Central Metallurgical Research and Development Institute P.O. Box 87 Helwan El-Tibben Cairo Egypt Materials and Technology Institute Dalian Maritime University Dalian 116026 China

Thermal spraying of cermet coatings is widely used for protection of machining parts against wear and corrosion. These coatings consist of WC particles in metal binders such as Co, Cr and Ni. Three kinds of WC powders with different metal binders (Co, NiCr and CoCr) were sprayed by low power plasma spray system on Al-Si-Cu alloy substrate. Fundamental aspects of sprayed cermet coatings, including (i) the effects of binder type on the coating structure, (ii) the hardness and (iii) the microstructure, were investigated. All cermet coatings have the same phase structure such as WC and W2 C. However, the intensities of these phases are different in each coating, mainly due to the difference in solidification rate in each case. Moreover, the hardness measurements are found to be different in each coating. The results show that, binder type has a significant effect on the physical and mechanical properties of the sprayed coatings.

关键词： tungsten carbide binders aluminum alloy substrate hardness microstructure

Investigation of electropolishing characteristics of tungsten in ecofriendly sodium hydroxide aqueous solution

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Advances in Manufacturing 2020年第3期8卷 265-278页

作者： Wei Han Feng-Zhou Fang Centre of Micro/Nano manufacturing Technology(MNMTDublin) University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China

In this study,an eco-friendly electrolyte for electropolishing tungsten and the minimum material removal depth on the electropolished tungsten surface are investigated using an electrochemical etching method.Using a concentrated acid electrolyte,the polarization curve and current density transient are observed.For a NaOH electrolyte,the effects of interelectrode gap and electrolyte concentration on electropolishing are investigated.The differences in electropolishing characteristics are compared among different electrolyte types.Microholes are etched on the electropolished tungsten surface to determine the minimum material removal depth on the tungsten surface.Experimental results indicate the color effect due to a change in the thickness of the oxide film on the tungsten surface after electropolishing with a concentrated acid electrolyte.The surface roughness decreases with the interelectrode gap width owing to the increased current density when using the NaOH electrolyte.However,the electropolishing effect is less prominent with a significantly smaller gap because the generated bubbles are unable to escape from the narrow working gap in time.A material removal depth of less than 10 nm is achieved on the tungsten surface in an area of diameter 300 lm,using the electrochemical etching method.

关键词： Electropolishing NaOH solution Surface roughness tungsten Etching

tungsten ELECTRODES CONTAINING THREE TYPES OF RARE EARTH OXIDES

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中国有色金属学会会刊：英文版 1999年第1期9卷 38-41页

作者： Nie, Zuoren Zhou, Meiling Chen, Ying Fan, Xiaowu Zhang, Jiuxing Zuo, Tieyong Beijing Polytechnic Univ Beijing China

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关键词： rare earth oxides tungsten electrode welding rim Y 2O 3+La 2O 3+CeO 2

tungsten and arsenic substance flow analysis of a hydrometallurgical process for tungsten extracting from wolframite

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tungsten 2021年第3期3卷 348-360页

作者： Yuan-Lin Chen Xue-Yi Guo Qin-Meng Wang Qing-Hua Tian Shao-Bo Huang Jin-Xiang Zhang School of Metallurgy and Environment Central South UniversityChangsha 410083China Changsha Research Institute of Mining and Metallurgy Co.LTD Changsha 410012China Ganzhou Nonferrous Metallurgy Research Institute Ganzhou 341000China

In this study,the metabolism of a hydrometallurgical process for tungsten extracting from wolframite was studied through substance flow analysis.The mass balance accounts,substance flow charts of tungsten and arsenic were established to evaluate the metabolism efficiency of the investigated system.The results showed that,the total tungsten resource efficiency of the system was 97.56%,and the tungsten recovery of unit process autoclaved alkali leaching,ion exchange,Mo removing,concentration and crystallization was 98.16%,98.94%,99.71%,99.89%,respectively.Meanwhile,for extracting 1 ton of tungsten into the qualified ammonium paratungstate,10.0414 kg of arsenic was carried into the system,with the generation of 7.2801 kg of arsenic in alkali leaching residue,1.5067 kg of tungsten in arsenic waste residue,and 1.2312 kg of tungsten in Mo residue.Besides,7.9 g of arsenic was discharged into nature environment with waste water,15.5 g of arsenic was entrained into the final APT.The distribution and transformation behaviors of arsenic during production were analyzed through phases change analysis,and some recommendations for improving the resource efficiency of tungsten and pollution control during production were also proposed based on the substance flow analysis in this study.

关键词： tungsten Arsenic Substance flow analysis Resource efficiency Pollution control

Modeling tungsten response under helium plasma irradiation:a review

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Plasma Science and Technology 2022年第12期24卷 68-83页

作者：杨章灿凡俊逸 Department of Nuclear Engineering and Technology School of Energy and Power EngineeringHuazhong University of Science and TechnologyWuhan 430074People's Republic of China

tungsten,a leading candidate for plasma-facing materials(PFM) in future fusion devices,will be exposed to high-flux low-energy helium plasma under the anticipated fusion operation conditions.In the past two decades,experiments have revealed that exposure to helium plasma strongly modifies the surface morphology and hence the sputtering,thermal and other properties of tungsten,posing a serious danger to the performance and lifetime of tungsten and the steadystate operation of plasma.In this article,we provide a review of modeling and simulation efforts on the long-term evolution of helium bubbles,surface morphology,and property changes of tungsten exposed to low-energy helium plasma.The current gap and outstanding challenges to establish a predictive modeling capability for dynamic evolution of PFM are discussed.

关键词： plasma-surface interactions tungsten helium plasma surface evolution modeling and simulations

Kinetic Monte Carlo code development and application on the formation of hydrogen-vacancy clusters in tungsten

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Science China(Physics,Mechanics & Astronomy) 2019年第1期62卷 83-89页

作者： Chao Meng JianNan Hao Ke Xu Li-Fang Wang XiaoLin Shu Shuo Jin Guang-Hong Lu Department of Physics Beihang University Beijing Key Laboratory of Advanced Nuclear Materials & Physics Beihang University

We have developed an object kinetic Monte Carlo(OKMC)code and simulated hydrogen-vacancy clustering behavior and dependence on temperature and hydrogen-vacancy ratio in tungsten.For each of the temperatures we simulated from 300 K to1000 K,H_nV clusters with smaller n form before those with larger n.The elevating temperature leads to a decrease in hydrogen vacancies:H_(10)V and H_9V clusters dominate at 300 K and 600 K,whereas H_5V,H_6V,and H_7V clusters dominate when the temperature reaches 1000 K.Furthermore,only H_nV clusters with smaller n formed when a lower hydrogen-vacancy ratio was used due to insufficient availability of hydrogen atoms to occupy vacancies.The results suggest hydrogen emission occurs very rarely at lower temperatures,while higher temperatures facilitate the dissociation of hydrogen from H_nV clusters.

关键词： tungsten hydrogen vacancy KMC

Effect of Ni Interlayer on Cavitation Erosion Resistance of NiTi Cladding by tungsten Inert Gas(TIG)Surfacing Process

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Acta Metallurgica Sinica(English Letters) 2020年第3期33卷 415-424页

作者： Zhen-Ping Shi Zheng-Bin Wang Ji-Qiang Wang Yan-Xin Qiao Huai-Ning Chen Tian-Ying Xiong Yu-Gui Zheng CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212003China

The NiTi cladding with/without Ni interlayer was prepared on stainless steel(SS) by tungsten inert gas(TIG) surfacing process,aiming at achieving good cavitation erosion resistance.The ranking according to the cavitation erosion resistance is NiTi plate> NiTi-Ni-TIG cladding> NiTi-TIG cladding> SS.The better cavitation erosion resistance of NiTi-TIG and NiTi-Ni-TIG claddings than SS substrate is due to their higher micro-hardness and superelasticity.Furthermore,the existence of Ni interlayer can decrease the amount of brittle intermetallic compounds,such as Fe2 Ti,and inhibit the crack generation,which results in the higher cavitation erosion resistance of NiTi-Ni-TIG compared with NiTi-TIG cladding.Thus,the cavitation erosion resistance of NiTi cladding prepared by TIG surfacing process can be improved by employing Ni interlayer.

关键词： Cavitation erosion NiTi Cladding tungsten inert gas surfacing process Ni interlayer