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Jet formation and penetration performance of a double-layer charge liner with chemically-deposited tungsten as the inner liner 被引量:2
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作者 Bihui Hong Wenbin Li +2 位作者 Yiming Li Zhiwei Guo Binyou Yan 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第3期374-385,共12页
This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double... This paper proposes a type of double-layer charge liner fabricated using chemical vapor deposition(CVD)that has tungsten as its inner liner.The feasibility of this design was evaluated through penetration tests.Double-layer charge liners were fabricated by using CVD to deposit tungsten layers on the inner surfaces of pure T2 copper liners.The microstructures of the tungsten layers were analyzed using a scanning electron microscope(SEM).The feasibility analysis was carried out by pulsed X-rays,slug-retrieval test and static penetration tests.The shaped charge jet forming and penetration law of inner tungsten-coated double-layer liner were studied by numerical simulation method.The results showed that the double-layer liners could form well-shaped jets.The errors between the X-ray test results and the numerical results were within 11.07%.A slug-retrieval test was found that the retrieved slug was similar to a numerically simulated slug.Compared with the traditional pure copper shaped charge jet,the penetration depth of the double-layer shaped charge liner increased by 11.4% and>10.8% respectively.In summary,the test results are good,and the numerical simulation is in good agreement with the test,which verified the feasibility of using the CVD method to fabricate double-layer charge liners with a high-density and high-strength refractory metal as the inner liner. 展开更多
关键词 Shaped charge Chemical vapor deposition tungsten Double-layer charge liner X-ray PENETRATION
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Trace elements in magmatic and hydrothermal quartz:Implications on the genesis of the Xingluokeng Tungsten Deposit,South China
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作者 Qing-Qing Zhang You-Wei Chen Jian-Feng Gao 《Acta Geochimica》 EI CAS CSCD 2024年第3期441-458,共18页
The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South China.The Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,and... The Xingluokeng deposit is the largest gran-ite-related tungsten deposit within the Wuyi metallogenic belt in South China.The Xingluokeng intrusion primarily consists of porphyritic biotite granite,biotite granite,andfine-grained granite.The deposit is represented by veinlet-disseminated mineralization with K-feldspathization and biotitization,alongside quartz-vein mineralization with gre-isenization and sericitization.This study investigates in-situ analyses of quartz compositions from both the intrusion and hydrothermal veinlets and veins.Trace element correlations indicate that trivalent Al^(3+)and Fe^(3+)replace Si^(4+)within the quartz lattice,with monovalent cations(such as Li^(+),Na^(+),and K^(+))primarily serving as charge compensators.Low Ge/Al ratios(<0.013)of quartz from granites suggest a mag-matic origin.The low Al/Ti and Ge/Ti ratios,accompanied by high Ti contents in quartz,suggest that the porphyritic biotite granite and biotite granite are characterized by rela-tively low levels of differentiation and high crystallization temperatures.In contrast,thefine-grained granite exhibits a higher degree of fractionation,lower crystallization tem-peratures,and a closer association with tungsten miner-alization.Ti contents in quartz from quartz veins indicate Qz-Ⅰformed at temperatures above 400°C,while Qz-Ⅱto Qz-Ⅴformed at temperatures below 350°C.Variations in different generations of quartz,as indicated by Al content and(Al+Fe)/(Li+Na+K)ratio,suggest that Qz-Ⅰprecipi-tated from a less acidicfluid with a stable pH,whereas Qz-Ⅱto Qz-Ⅴoriginated from a more acidicfluid with notable pH variations.Consequently,alkaline alteration and acidic alteration supplied the essential Ca and Fe for the precipita-tion of scheelite and wolframite,respectively,highlighting a critical mechanism in tungsten mineralization at the Xin-gluokeng deposit. 展开更多
关键词 QUARTZ Xingluokeng tungsten deposit Trace elements South China
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Simulation of tungsten impurity transport by DIVIMP under different divertor magnetic configurations on HL-3
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作者 Qingrui ZHOU Yanjie ZHANG +5 位作者 Chaofeng SANG Jiaxian LI Guoyao ZHENG Yilin WANG Yihan WU Dezhen WANG 《Plasma Science and Technology》 SCIE EI CAS CSCD 2024年第10期29-38,共10页
Tungsten(W)accumulation in the core,depending on W generation and transport in the edge region,is a severe issue in fusion reactors.Compared to standard divertors(SDs),snowflake divertors(SFDs)can effectively suppress... Tungsten(W)accumulation in the core,depending on W generation and transport in the edge region,is a severe issue in fusion reactors.Compared to standard divertors(SDs),snowflake divertors(SFDs)can effectively suppress the heat flux,while the impact of magnetic configurations on W core accumulation remains unclear.In this study,the kinetic code DIVIMP combined with the SOLPS-ITER code is applied to investigate the effects of divertor magnetic configurations(SD versus SFD)on W accumulation during neon injection in HL-3.It is found that the W concentration in the core of the SFD is significantly higher than that of the SD with similar total W erosion flux.The reasons for this are:(1)W impurities in the core of the SFD mainly originate from the inner divertor,which has a short leg,and the source is close to the divertor entrance and upstream separatrix.Furthermore,the W ionization source(S_(W0))is much stronger,especially near the divertor entrance.(2)The region overlap of S_(W0)and F_(W,TOT)pointing upstream promote W accumulation in the core.Moreover,the influence of W source locations at the inner target on W transport in the SFD is investigated.Tungsten impurity in the core is mainly contributed by target erosion in the common flux region(CFR)away from the strike point.This is attributed to the fact that the W source at this location enhances the ionization source above the W ion stagnation point,which sequentially increases W penetration.Therefore,the suppression of far SOL inner target erosion can effectively prevent W impurities from accumulating in the core. 展开更多
关键词 snowflake divertor neon seeding tungsten transport DIVIMP HL-3
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Preparation of Spherical Tungsten Particles Assisted by Hydrothermal Method
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作者 GUO Jiawang WEN Xiaoqiang +2 位作者 WU Ying XU Jianbing ZHOU Jieying 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第6期1457-1462,共6页
We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction process.In hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical te... We presented a strategy to prepare spherical tungsten powder by the combination of hydrothermal method and H2reduction process.In hydrothermal process,the micelle of tetraethylammonium bromide(TEAB)act as spherical templates for the deposition of tungsten oxide,whereas the excessive TEAB inhibit the formation of spherical tungsten oxide due to the dense molecular layer of TEAB on the tungsten oxide particles.Citric acid(CA)can control the formation rate and structure of the tungsten oxide when its concentration is more than 0.2 mol/L,because of its ability to coordinate with tungsten atoms.The synergistic effect of TEAB and CA facilitates the formation of spherical tungsten oxide with nanorod crown.After being treated by H_(2)at 600 and 650℃,the tungsten oxide particles are reduced to tungsten particles,which maintain the spherical structure of tungsten oxide and have porous structure. 展开更多
关键词 spherical tungsten particles spherical tungsten oxide hydrothermal method citric acid tetraethylammonium bromide
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Sol-gel-based porous Ti-doped tungsten oxide films for high-performance dual-band electrochromic smart windows 被引量:1
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作者 Qiancheng Meng Sheng Cao +6 位作者 Juquan Guo Qingke Wang Ke Wang Tao Yang Ruosheng Zeng Jialong Zhao Bingsuo Zou 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第2期137-143,I0004,共8页
Dual-band electrochromic smart windows(DESWs)with independent control of the transmittance of near-infrared and visible light show great potential in the application of smart and energy-saving buildings.The current st... Dual-band electrochromic smart windows(DESWs)with independent control of the transmittance of near-infrared and visible light show great potential in the application of smart and energy-saving buildings.The current strategy for building DESWs is to screen materials for composite or prepare plasmonic nanocrystal films.These rigorous preparation processes seriously limit the further development of DESWs.Herein,we report a facile and effective sol-gel strategy using a foaming agent to achieve porous Ti-doped tungsten oxide film for the high performance of DESWs.The introduction of foaming agent polyvinylpyrrolidone during the film preparation can increase the specific surface area and free carrier concentration of the films and enhance their independent regulation ability of near-infrared electrochromism.As a result,the optimal film shows excellent dual-band electrochromic properties,including high optical modulation(84.9%at 633 nm and 90.3%at 1200 nm),high coloration efficiency(114.9 cm^(2) C^(-1) at 633 nm and 420.3 cm^(2) C^(-1) at 1200 nm),quick switching time,excellent bistability,and good cycle stability(the transmittance modulation losses at 633 and 1200 nm were 11%and 3.5%respectively after 1000 cycles).A demonstrated DESW fabricated by the sol-gel film showed effective management of heat and light of sunlight.This study represents a significant advance in the preparation of dual-band electrochromic films,which will shed new light on advancing electrochromic technology for future energy-saving smart buildings. 展开更多
关键词 ELECTROCHROMISM tungsten oxide Smart windows Sol-gel method Dual-band absorption
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Cerium-tungsten oxides supported on activated red mud for the selective catalytic reduction of NO_(x) 被引量:1
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作者 Qiuzhun Chen Dong Wang +7 位作者 Chuan Gao Bin Wang Shengli Niu Gaiju Zhao Yue Peng Junhua Li Chunmei Lu John Crittenden 《Green Energy & Environment》 SCIE EI CSCD 2023年第1期173-182,共10页
Activated red mud(RM)has been proved to be a promising base material for the selective catalysis reduction(SCR)of NOx.The inherent low reducibility and acidity limited its low-temperature activity.In this work,molybde... Activated red mud(RM)has been proved to be a promising base material for the selective catalysis reduction(SCR)of NOx.The inherent low reducibility and acidity limited its low-temperature activity.In this work,molybdenum oxide,tungsten oxide,and cerium oxide were used to reconfigure the redox sites and acid sites of red mud based catalyst.When activated red mud was reconfigured by cerium-tungsten oxide(Ce-W@RM),the NOx conversion kept above 90%at 219-480℃.The existence of Ce^(3+)/Ce^(4+) redox electron pairs provided more surface adsorbed oxygen(O_(α)) and served as a redox cycle.Positive interactions between Ce,W species and Fe oxide in red mud occurred,which led to the formation of unsaturated chemical bond and promoted the activation of adsorbed NH_(3) species.WO_(3) and Ce_(2)(WO_(4))_(3)(formed by solid-state reaction between Ce and W species)could provide more Brønsted acid sites(W-O modes of WO_(3),W=O or W-O-W modes of Ce_(2)(WO_(4))_(3)).CeO_(2) species could provide more Lewis acid sites.The Langmuir-Hinshelwood(L-H)routes and Eley-Rideal(E-R)routes occurred in the low-temperature SCR reaction on the Ce-W@RM surface.NH_(4)^(+) species on Brønsted acid sites,NH_(3) species on Lewis acid sites,bidentate nitrate and bridging nitrate species were key active intermediates species. 展开更多
关键词 Air pollution control NOx Selective catalytic reduction CERIUM tungsten
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Tungsten combustion in impact initiated W-Al composite based on W(Al) super-saturated solid solution 被引量:1
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作者 Kong-xun Zhao Xiao-hong Zhang +5 位作者 Xiao-ran Gu Yu Tang Shun Li Yi-cong Ye Li'an Zhu Shu-xin Bai 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2023年第7期112-120,共9页
Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into ... Element W can effectively improve the density of energetic structural materials. However, W is an inert element and does not combust in air. To change the reaction characteristics of W, 60 at.% Al was introduced into W through mechanical alloying. XRD analysis shows that after 50 h of ball milling, the diffraction peak of Al completely disappears and W(Al60) super-saturated solid solution powder is obtained. Further observation by HAADF and HRTEM reveals that the W(Al60) super-saturated solid solution powder is a mixture of solid solution and amorphous phase. Based on the good thermal stability of W(Al60) alloy powder below 1000℃, W(Al60)-Al composite was synthesized by hot pressing process.Impact initiation experiments suggest that the W(Al60)-Al composite has excellent reaction characteristics, and multiple types of tungsten oxides are detected in the reaction products, showing that the modified W is combustible in air. Due to the combustion of tungsten, the energy release rate of the W(Al60)-Al composite at speed of 1362 m/s reaches 2.71 kJ/g. 展开更多
关键词 tungsten combustion Reactive materials Super-saturated solid solution Shock-induced reactions WeAl composite
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Giant saturation absorption of tungsten trioxide film prepared based on the seedless layer hydrothermal method 被引量:1
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作者 马晓光 胡芳珍 +4 位作者 陈希 王艺盟 郝晓剑 顾敏 张启明 《Chinese Physics B》 SCIE EI CAS CSCD 2023年第3期286-290,共5页
Nonlinear materials have gained wide interest as saturable absorbers and pulse compression for pulsed laser applications due to their unique optical properties.This work investigates the third-order nonlinear phenomen... Nonlinear materials have gained wide interest as saturable absorbers and pulse compression for pulsed laser applications due to their unique optical properties.This work investigates the third-order nonlinear phenomenon of tungsten trioxide(WO_(3))thin films.The giant nonlinear absorption and nonlinear refractive index of WO_(3)thin films were characterized by Z-scan method at 800 nm.We experimentally observed the giant saturable absorption(SA)and nonlinear refractive index of WO_(3)thin films prepared by the seedless layer hydrothermal method,with SA coefficient being as high as-2.59×105cm·GW^(-1).The SA coefficient is at least one order of magnitude larger than those of the conventional semiconductors.The nonlinear refractive index n_(2)of WO_(3)film has been observed for the first time in recent studies and the corresponding coefficient can be up to 1.793 cm^(2)·GW^(-1).The large third-order nonlinear optical(NLO)response enables WO_(3)thin films to be promising candidates for optoelectronic and photonic applications in the near-infrared domain. 展开更多
关键词 tungsten trioxide Z-SCAN saturable absorption
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Plasma synthesis of various polymorphs of tungsten trioxide nanoparticles using gliding electric discharge in humid air:characterization and photocatalytic properties
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作者 Romaric L SEUTCHA Georges KAMGANG-YOUBI +4 位作者 Elie ACAYANKA Valeria VERMILE François DEVRED Eric M GAIGNEAUX Samuel LAMINSI 《Plasma Science and Technology》 SCIE EI CAS CSCD 2023年第12期72-82,共11页
A gliding electric arc(glidarc)discharge generates a low-temperature plasma at atmospheric pressure.When the discharge occurs in humid air as the feed gas,the chemistry of a glidarc plasma consists of in situ formatio... A gliding electric arc(glidarc)discharge generates a low-temperature plasma at atmospheric pressure.When the discharge occurs in humid air as the feed gas,the chemistry of a glidarc plasma consists of in situ formation of HO°and NO°as the primary chemical species.Tungsten trioxide(WO_(3))nanoparticles were successfully prepared by exposure of a liquid precursor to glidarc plasma.The WO_(3)samples were calcined at three different temperatures(300℃,500℃and 800℃),resulting in different pure polymorphs:γ-WO_(3)(at 300℃),β-WO_(3)(at 500℃)andα-WO_(3)(at 800℃)according to x-ray diffraction analysis.The identification of WO_(3)compounds was also confirmed by attenuated total reflection Fourier transform infrared spectroscopy analysis.Increase in the calcination temperature of WO_(3)induced a decrease in its specific surface area according to Brunauer–Emmett–Teller nitrogen physisorption analysis.The UV-visible results showed that the absorption bands of plasma-WO_(3)samples were more intense than those of WO_(3)samples obtained by a precipitation route,a classical method used for comparison.Consequently,this parameter can improve the photocatalytic properties of WO_(3)under visible light.The photodegradation(in sunlight conditions)of gentian violet,chosen as a model pollutant,confirmed the photocatalytic properties of plasma-WO_(3)samples.This novel synthesis method has great potential to improve the efficiency of advanced tungsten trioxide-based functional material preparation,as well as in pollution-reducing and energy-saving tungsten extractive metallurgy. 展开更多
关键词 plasma glidarc tungsten trioxide plasma-synthesis NANOPARTICLES PHOTOCATALYST
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Crushing Mechanism of Spherical Tungsten Alloy Fragments Penetrate Thick Steel Plate Target
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作者 WAN Mingming BAI Rong +3 位作者 SHANG Zaifei WANG Yanli LIANG Jiayi LI Xue 《Journal of Wuhan University of Technology(Materials Science)》 SCIE EI CAS CSCD 2023年第2期445-450,共6页
Against protection requirements for high-speed fragments on the ground weapons,we carried out the research work of crushing mechanism at different impact speeds ofφ8.7 mm spherical tungsten alloy,the penetration to 6... Against protection requirements for high-speed fragments on the ground weapons,we carried out the research work of crushing mechanism at different impact speeds ofφ8.7 mm spherical tungsten alloy,the penetration to 603 armor steel was completed by 20 mm ballistic gun,and the ANSYS/LS-DYNA software was used to complete the numerical calculation of the penetration.We find that there are different crushing mechanisms of spherical tungsten alloy with different speeds and low speed,the crushing mechanism of fragment is mainly controlled by overall plastic deformation,shearing stripping,and squeezing at a high pressure and a high speed.The crushing mechanism will have a spallation phenomenon in addition to the crushing mechanism under high pressure. 展开更多
关键词 spherical tungsten alloy experimental research numerical simulation crushing mechanism high pressure affected zone spallation zone
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Exciting News from Indentations onto Silicon, Copper, and Tungsten
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作者 Gerd Kaupp 《Journal of Applied Mathematics and Physics》 2023年第12期4042-4078,共37页
Indentations onto crystalline silicon and copper with various indenter geometries, loading forces at room temperature belong to the widest interests in the field, because of the physical detection of structural phase ... Indentations onto crystalline silicon and copper with various indenter geometries, loading forces at room temperature belong to the widest interests in the field, because of the physical detection of structural phase transitions. By using the mathematically deduced F<sub>N</sub>h<sup>3/2 </sup>relation for conical and pyramidal indentations we have a toolbox for deciding between faked and experimental loading curves. Four printed silicon indentation loading curves (labelled with 292 K, 260 K, 240 K and 210 K) proved to be faked and not experimental. This is problematic for the AI (artificial intelligence) that will probably not be able to sort faked data out by itself but must be told to do so. High risks arise, when published faked indentation reports remain unidentified and unreported for the mechanics engineers by reading, or via AI. For example, when AI recommends a faked quality such as “no phase changes” of a technical material that is therefore used, it might break down due to an actually present low force, low transition energy phase-change. This paper thus installed a tool box for the distinction of experimental and faked loading curves of indentations. We found experimental and faked loading curves of the same research group with overall 14 authoring co-workers in three publications where valid and faked ones were next to each other and I can thus only report on the experimental ones. The comparison of Si and Cu with W at 20-fold higher physical hardness shows its enormous influence to the energies of phase transition and of their transition energies. Thus, the commonly preferred ISO14577-ASTM hardness values HISO (these violate the energy law and are simulated!) leads to almost blind characterization and use of mechanically stressed technical materials (e.g. airplanes, windmills, bridges, etc). The reasons are carefully detected and reported to disprove that the coincidence or very close coincidence of all of the published loading curves from 150 K to 298 K are constructed but not experimental. A tool-box for distinction of experimental from faked indentation loading curves (simulations must be indicated) is established in view of protecting the AI from faked data, which it might not be able by itself to sort them out, so that technical materials with wrongly attributed mechanical properties might lead to catastrophic accidents such as all of us know of. There is also the risk that false theories might lead to discourage the design of important research projects or for not getting them granted. This might for example hamper or ill-fame new low temperature indentation projects. The various hints for identifying faked claims are thus presented in great detail. The low-temperature instrumental indentations onto silicon have been faked in two consecutive publications and their reporting in the third one, so that these are not available for the calculation of activation energies. Conversely, the same research group published an indentation loading curve of copper as taken at 150 K that could be tested for its validity with the therefore created tools of validity tests. The physical algebraic calculations provided the epochal detection of two highly exothermic phase transitions of copper that created two polymorphs with negative standard energy content. This is world-wide the second case and the first one far above the 77 K of liquid nitrogen. Its existence poses completely new thoughts for physics chemistry and perhaps techniques but all of them are open and unprepared for our comprehension. The first chemical reactions might be in-situ photolysis and the phase transitions can be calculated from experimental curves. But several further reported low temperature indentation loading curves of silicon were tested for their experimental reality. And the results are compared to new analyses with genuine room temperature results. A lot is to be learned from the differences at room and low temperature. 展开更多
关键词 Phase-Transition-Onset and -Energy Indentation of Silicone COPPER Copper Nanoparticles tungsten with Polymorphs Low-Temperature Indentations Detection of Faked Loading Curves Protection of AI from False Advices Risk of Catastrophic Crashes Physical Hardness Exothermic Copper-Transitions Algebraic Calculations Negative-Standard-Energy Polymorphs
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Evaluation of ultra-fine grained tungsten under transient high heat flux by high-intensity pulsed ion beam 被引量:2
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作者 谈军 周张健 +4 位作者 朱小鹏 郭双全 屈丹丹 雷明凯 葛昌纯 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2012年第5期1081-1085,共5页
Pure tungsten, oxide dispersion strengthened tungsten and carbide dispersion strengthened tungsten were fabricated by high-energy ball milling and spark plasma sintering process. In order to evaluate the properties of... Pure tungsten, oxide dispersion strengthened tungsten and carbide dispersion strengthened tungsten were fabricated by high-energy ball milling and spark plasma sintering process. In order to evaluate the properties of the tungsten alloys under transient high heat flues, four tungsten samples with different grain sizes were tested by high-intensity pulsed ion beam with a heat flux as high as 160 MW/(m^2·s^-1/2). Compared with the commercial tungsten, the surface modification of the oxide dispersion strengthened tungsten by high-intensity pulsed ion beam is completely different. The oxide dispersion strengthened tungsten shows inferior thermal shock response due to the low melting point second phase of Ti and Y2O3, which results in the surface melting, boiling bubbles and cracking. While the carbide dispersion strengthened tungsten shows better thermal shock response than the commercial tungsten. 展开更多
关键词 tungsten tungsten alloy ultra-fine grain surface effects thermal shock transient high heat flux
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A Preliminary Review of Metallogenic Regularity of Tungsten Deposits in China 被引量:8
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作者 SHENG Jifu LIU Lijun +5 位作者 WANG Denghong CHEN Zhenghui YING Lijuan HUANG Fan WANG Jiahuan ZENG Le 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第4期1359-1374,共16页
Tungsten ore resources are abundant in China with relatively complete types of deposits. Skarn type and quartz vein type deposits are dominated in the tungsten resources, whereas quartz vein type wolframite deposits a... Tungsten ore resources are abundant in China with relatively complete types of deposits. Skarn type and quartz vein type deposits are dominated in the tungsten resources, whereas quartz vein type wolframite deposits are most important in terms of exploitation and utilization. Skarn type tungsten deposits are concentratedly distributed in the central Nanling region, such as South Hunan, South Anhui and the eastern Qinling region, while quartz vein type tungsten deposits occur mainly in South China, such as West Fujian, South Jiangxi, North Guangdong and South Hunan. The most important metallogenic epoch of tungsten is the Mesozoic, while the metallogenic tectonic setting is featured by an intracontinental environment after orogeny with sever tectonic movements, deep-seated faults and frequent magmatic activities, especially Mesozoic granitoids closely related to tungsten-tin mineralization. 22 metallogenic series of ore deposits characterized by or significantly related to tungsten were defined based on precise statistic information of 1199 tungsten mining areas and thorough the summary of metallogenic regularities. Based on studies of the metallogenic regularity of tungsten deposits, skarn type (or greisen type), quartz vein type and massif-type of tungsten deposits are thought to be the key prediction types. 65 tungsten-forming belts and 22 key ore concentration areas were ascertained and a distribution map of tungsten-forming belts of China was compiled, which provided a theoretical basis for evaluation and prediction of potential tungsten resources. 展开更多
关键词 tungsten resources characteristics types of tungsten deposit tungsten-forming belt metallogenic regularity
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Fabrication and characterization of tungsten-containing mesoporous silica for heterogeneous oxidative desulfurization 被引量:7
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作者 张铭 朱文帅 +5 位作者 李宏平 荀苏杭 李猛 李亚男 魏延臣 李华明 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第6期971-978,共8页
A series of functional,tungsten-containing mesoporous silica materials(W-SiO2) have been fabricated directly from an ionic liquid that contained imidazole and polyoxometalate,which acted as mesoporous template and m... A series of functional,tungsten-containing mesoporous silica materials(W-SiO2) have been fabricated directly from an ionic liquid that contained imidazole and polyoxometalate,which acted as mesoporous template and metal source respectively.These materials were then characterized through X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman spectroscopy,Fourier transform infrared spectra(FTIR),diffuse reflectance spectra(DRS),and N2 adsorption-desorption,which were found to contain tungsten species that were effectively dispersed throughout the structure.The as-prepared materials W-SiO2 were also found to possess a mesoporous structure.The pore diameters of the respective sample W-SiO2-20 determined from the TEM images ranged from 2 to 4 nm,which was close to the average pore size determined from the nitrogen desorption isotherm(2.9 nm).The materials were evaluated as catalysts for the heterogeneous oxidative desulfurization of dibenzothiophene(DBT),which is able to achieve deep desulfurization within 40 min under the optimal conditions(Catalyst(W-SiO2-20)= 0.01 g,temperature = 60℃,oxidant(H2O2)= 20 μL).For the removal of different organic sulfur compounds within oil,the ability of the catalyst(W-SiO2-20) under the same conditions to remove sulfur compounds decreased in the order:4,6-dimethyldibenzothiophene Dibenzothiophene Benzothiophene 1-dodecanethiol.Additionally,they did not require organic solvents as an extractant in the heterogeneous oxidative desulfurization process.After seven separate catalytic cycles,the desulfurization efficiency was still as high as 90.3%.From the gas chromatography-mass spectrometer analysis,DBT was entirely oxidized to its corresponding sulfone DBTO2 after reaction.A mechanism for the heterogeneous desulfurization reaction was proposed. 展开更多
关键词 Heterogeneous oxidative desulfurization tungsten species Mesoporous silica One-pot synthesis ORGANOSULFUR
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CUTTING FORCES IN HIGH SPEED TAPPING CAST IRON BY TUNGSTEN CARBIDE TAPS 被引量:7
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作者 张晓辉 刘钢 +4 位作者 陈明 胡祖光 励政伟 许辉 祝新发 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2007年第2期94-99,共6页
The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the paramet... The engineblock production lines need high speed tapping with tungsten carbide taps. In the tapping process, the machining precision and the tool life of taps are directly influenced by tapping forces. And the parameter optimization of tap structures is also correlated with the variation of tapping forces. Therefore, the study of tapping forces is necessary in developing new style taps. Several experiments about some novel carbide taps are performed on a vertical machining center by a Kistler dynamometer system in blind tapping both gray cast iron and ductile cast iron. And the variations of tapping forces are analyzed in tapping-in and tapping-out periods. It indicates that cutting forces hardly vary with the tap wear in tapping cast iron. Contrarily, tapping forces are closely correlated with the holding method. Besides, it also depends on the helix angle, the flute numbers and the plasticity of the work material to some extent. 展开更多
关键词 tungsten carbide tap cast iron high speed tapping tapping force
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Decomposition laws of tungsten prices fluctuation since 1900 and its applications 被引量:3
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作者 朱灏 何杭飞 +2 位作者 王昶 张晶 朱学红 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第9期2807-2816,共10页
Tungsten current price was transformed yearly to its constant price since 1900, which is roughly decomposed into four components as trend, cycle, impact and random. The core prices, consisting of the trend and the cyc... Tungsten current price was transformed yearly to its constant price since 1900, which is roughly decomposed into four components as trend, cycle, impact and random. The core prices, consisting of the trend and the cycle, present regularities that a long-run cycle is embedded within two major cycles, and major cycle is composed of low-price period and high-price period, along with the rapid rise into a tower, and along with deep down into next trough; three sharply upward shocks occur by the events in a tower. Fluctuations in prices trend to slow cycles and expand the bands. It can be expected that tungsten price will highly stand over 17 a, and is is a advice that reducing production and restricting export maybe maintain a high price level. 展开更多
关键词 tungsten PRICE cycle trend impact fixed price strategy management
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Separation of macro amounts of tungsten and molybdenum by precipitation with ferrous salt 被引量:13
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作者 赵中伟 曹才放 陈星宇 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2011年第12期2758-2763,共6页
In order to develop a low-cost approach for separating macro amounts of Mo and W, the effects of parameters on the separation using FeSO4 as precipitation reagent were studied. The results show that the optimum reacti... In order to develop a low-cost approach for separating macro amounts of Mo and W, the effects of parameters on the separation using FeSO4 as precipitation reagent were studied. The results show that the optimum reaction temperature is 10 °C, and the separation factor does not further improve after a reaction time of 7 h. Moreover, slow dropping speed of the precipitation reagent is beneficial for improving the separation efficiency. When the H+/W molar ratio is below 1/1, the addition of acid to a neutral solution is favorable to the separation. For the solution with an ammonium concentration below 3 mol/L, the separation factor is high due to the high W-precipitation rate. Furthermore, the method is also effective when it is applied to industrial solution containing some other impurities. All these indicate the ferrous salts have great potential for removing W from Mo on a commercial scale. 展开更多
关键词 tungsten MOLYBDENUM selective precipitation ferrous sulfate
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Tungsten/steel diffusion bonding using Cu/W-Ni/Ni multi-interlayer 被引量:4
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作者 杨宗辉 沈以赴 +1 位作者 王志阳 成家林 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第8期2554-2558,共5页
Diffusion bonding between tungsten and 0Cr13Al stainless steel using a Cu/90W-10Ni powder mixtures/Ni multi-interlayer was carried out in vacuum at 1150 °C with a pressure of 5 MPa for 60 min. The microstructures... Diffusion bonding between tungsten and 0Cr13Al stainless steel using a Cu/90W-10Ni powder mixtures/Ni multi-interlayer was carried out in vacuum at 1150 °C with a pressure of 5 MPa for 60 min. The microstructures, composition distribution and fracture characteristics of the joint were studied by SEM and EDS. Joint properties were evaluated by shear experiments and thermal shock tests. The results showed that the joints comprised tungsten/Cu-Ni sub-layer/W-Ni composites sub-layer/Ni sub-layer/0Cr13Al stainless steel. The W-Ni composites sub-layer with a homogeneous and dense microstructure was formed by solid phase sintering of 90W-10Ni powder mixtures. Sound bonding between tungsten base material and W-Ni composites sub-layer was realized based on transient liquid phase (TLP) diffusion bonding mechanism. Joints fractured at bonding zone of W-Ni composites sub-layer and Ni sub-layer during shear testing, and the average strength was 256 MPa. Thermal shock tests showed that joints could withstood 60 thermal cycles quenching from 700 °C to room temperature. 展开更多
关键词 tungsten diffusion bonding SINTERING INTERLAYER
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FABRICATION OF DLC COATED COBALT-CEMENTED TUNGSTEN CARBIDE MICRO-DRILLS AND THEIR CUTTING PERFORMANCE 被引量:4
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作者 马玉平 陈明 +1 位作者 向道辉 孙方宏 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2007年第2期89-93,共5页
In machining the particle reinforced aluminum based composite material with high Si content using the cobalt-cemented tungsten carbide micro cutting tools, diamond like carbon (DLC) films are deposited on cobalt-cem... In machining the particle reinforced aluminum based composite material with high Si content using the cobalt-cemented tungsten carbide micro cutting tools, diamond like carbon (DLC) films are deposited on cobalt-cemented tungsten carbide micro-drills with two-step pretreatment method. Characteristics of DLC coated tools are investigated in bias-enhanced HFCVD system with the optimized hot filament arrangement. The optimization deposition technology is obtained and the wear mechanism of cutting tools is analyzed. The drilling performance of DLC coated tools is verified by the experiments of cutting particle reinforced aluminum based composite material (Si 15% in volume) compared with uncoated ones. Experimental results show that the two-step pretreatment method is appropriate for complex shaped cemented carbide substrates and ensures the good adhesive strength between the diamond film and the substrate. The cutting performance of DLC coated tool is enhanced 10 times when machining the Si particle reinforced aluminum based metal matrix composite compared with that of uncoated ones under the same cutting conditions. 展开更多
关键词 DLC film bias-enhanced HFCVD cobalt-cemented tungsten carbide cutting tool micro-drilling cutting performance
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Tungsten carbide-reduced graphene oxide intercalation compound as co-catalyst for methanol oxidation 被引量:3
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作者 施梅勤 章文天 +2 位作者 李影影 褚有群 马淳安 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第11期1851-1859,共9页
Highly dispersed tungsten carbide(WC) nanoparticles(NPs) sandwiched between few-layer reduced graphene oxide(RGO) have been successfully synthesized by using thiourea as an anchoring and inducing reagent.The met... Highly dispersed tungsten carbide(WC) nanoparticles(NPs) sandwiched between few-layer reduced graphene oxide(RGO) have been successfully synthesized by using thiourea as an anchoring and inducing reagent.The metatungstate ion,[H2W(12)O(40)]^6-,is assembled on thiourea-modified graphene oxide(GO) by an impregnation method.The WC NPs,with a mean diameter of 1.5 nm,are obtained through a process whereby ammonium metatungstate first turns to WS2,which then forms an intercalation compound with RGO before growing,in situ,to WC NPs.The Pt/WC-RGO electrocatalysts are fabricated by a microwave-assisted method.The intimate contacts between Pt,WC,and RGO are confirmed by X-ray diffraction,scanning electron microscope,transmission electron microscope,and Raman spectroscopy.For methanol oxidation,the Pt/WC-RGO electrocatalyst exhibited an electrochemical surface area value of 246.1 m^2/g Pt and a peak current density of1364.7 mA/mg Pt,which are,respectively,3.66 and 4.77 times greater than those of commercial Pt/C electrocatalyst(67.2 m^2/g Pt,286.0 mA/mg Pt).The excellent CO-poisoning resistance and long-term stability of the electrocatalyst are also evidenced by CO stripping,chronoamperometry,and accelerated durability testing.Because Pt/WC-RGO has higher catalytic activity compared with that of commercial Pt/C,as a result of its intercalated structure and synergistic effect,less Pt will be required for the same performance,which in turn will reduce the cost of the fuel cell.The present method is facile,efficient,and scalable for mass production of the nanomaterials. 展开更多
关键词 tungsten carbide-reduced graphene oxide Intercalation compound THIOUREA ANCHORING Methanol oxidation
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