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Molecular dynamics simulation on diffusion properties of Pb-Mg alloy

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Science China(Technological Sciences) 2010年第9期53卷 2328-2332页

作者： LIU YuanYuan,JIA GuoBin & YANG Bin national engineering laboratory of vacuum metallurgy,Kunming University of Science and Technology,Kunming 650093,China national engineering laboratory of vacuum metallurgy Kunming University of Science and Technology Kunming China

A new method to calculate mutual-diffusion coefficients of the binary alloy has been proposed in this report.At first self-diffusion coefficient of the constituent element was calculated using molecular dynamics method,thermodynamic factor of the alloy was got with the NRTL (non-random-two-liquid) equation,then mutual-diffusion coefficient was obtained with Darken formula.Using this method the mutual-diffusion coefficient of Pb-Mg alloy with different Pb content was calculated.The calculated values were compared with the available experimental ones and the reason of the maximal mutual-diffusion coefficient appearing at 33.3 at.%Pb was discussed.Partial pair correlation function and partial coordination number were calculated to analyze the effect of the melt structure on mutual-diffusion coefficient.

关键词： molecular dynamics NRTL (non-random-two-liquid) equation diffusion coefficient partial pair correlation function

Kinetics of iron removal from metallurgical grade silicon with pressure leaching

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Rare Metals 2011年第6期30卷 688-694页

作者： YU Zhanliang XIE Keqiang MA Wenhui ZHOU Yang XIE Gang DAI Yongnian national engineering laboratory for vacuum metallurgy Kunming University of Science and Technology Kunming 650093 China Technology Center of Yunnan metallurgy Group Co. Kunming 650031 China Kunming metallurgy Research Institute Kunming 650031 China

In this paper, the kinetics of pressure leaching for purification of metallurgical grade silicon with hydrochloric acid was investigated. The effects of particle size, temperature, total pressure, and concentration of hydrochloric acid on the kinetics and mechanism of iron removal were studied. It was found that the reaction kinetic model followed the shrinking core model, and the apparent activation energy of the leaching reaction was 46.908 kJ/mol. And the apparent reaction order of iron removal with pressure leaching was 0.899. The kinetic equation was obtained and the mathematical model of iron removal from metallurgical grade silicon （MG-Si） was given as follows：The values calculated from the equation were consistent with the experimental results.

关键词： metallurgical physics and chemistry kinetics pressure leaching metallurgical grade silicon iron removal

Recycling of spent lithium-ion batteries to resynthesize high-performance cathode materials for sodium-ion storage

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Tungsten 2024年第3期6卷 574-584页

作者： Hai-Qiang Gong Xing-Yuan Wang Long Ye Bao Zhang Xing Ou national engineering laboratory for High-Efficiency Recovery of Refractory Nonferrous Metals School of Metallurgy and Environment Central South University

The spent lithium-ion batteries recovery has been brought into focus widely for its environmental imperatives and potential profits from the metal components,such as lithium,cobalt,nickel and manganese.However,the weaker pollution and fewer profits of LiMn2O4cathode dispel the enthusiasm and responsibility of industry companies.Thus,a simplified and efncient method to regenerate the sodium-ion cathode materials and separate Li from spent LiMn2O4materials for the profit improvement is proposed.In detail,adjusting the parameters of carbothermal reduction process appropriately,the LiMn2O4spinel structure is destroyed within a short period time and transformed into simple metal oxide.As anticipated,nearly 95 wt.%lithium can be obtained and recovered during the water leaching,while 99 wt.% of manganese can be extracted in acid solution.Noted that the leaching residue can return to the carbothermic reduction,leading to a closed-loop economic recycling process.The regenerated Na0.67Ni0.3Mn0.7O2cathode displays excellent electrochemical performance with superior cycling stability(the initial capacity reaches 95.9 mAh·g-1,and the retention rate reached 98.3% after 100 cycles at 1 C).The delicate strategy of sodium-ion cathode material regenerated from spent LiMn2O4aims to realize lithium separation and material utilization of manganese simultaneously,providing the instructive suggestion to rise up the recycling profits of spent batteries.

关键词： Manganese Spent battery LiMn 2 O 4 cathode Recycling Regenerated Na 0.67 Ni 0.3 Mn 0.7 O 2 Sodium-ion storage

Effect of crystal morphology of ultrahigh-nickel cathode materials on high temperature electrochemical stability of lithium ion batteries

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Journal of Energy Chemistry 2024年第1期88卷 327-335,I0008页

作者： Bi Luo Hui Li Haoyu Qi Yun Liu Chuanbo Zheng Weitong Du Jiafeng Zhang Lai Chen School of metallurgy engineering Jiangsu University of Science and TechnologyZhangjiagang 215600JiangsuChina national engineering laboratory for High-Efficiency Recovery of Refractory Nonferrous Metals School of Metallurgy and EnvironmentCentral South UniversityChangsha 410083HunanChina School of Materials Science and engineering Beijing Key Laboratory of Environmental Science and EngineeringBeijing Institute of TechnologyBeijing 100081China

Higher nickel content endows Ni-rich cathode materials LiNi_(x)Co_yMn_(1-x-y)O_(2)(x>0.6)with higher specific capacity and high energy density,which is regarded as the most promising cathode materials for Li-ion batteries.However,the deterioration of structural stability hinders its practical application,especially under harsh working conditions such as high-temperature cycling.Given these circumstances,it becomes particularly critical to clarify the impact of the crystal morphology on the structure and high-temperature performance as for the ultrahigh-nickel cathodes.Herein,we conducted a comprehensive comparison in terms of microstructure,high-temperature long-cycle phase evolution,and high-temperature electrochemical stability,revealing the differences and the working mechanisms among polycrystalline(PC),single-crystalline(SC)and Al doped SC ultrahigh-nickel materials.The results show that the PC sample suffers a severe irreversible phase transition along with the appearance of microcracks,resulting a serious decay of both average voltage and the energy density.While the Al doped SC sample exhibits superior cycling stability with intact layered structure.In-situ XRD and intraparticle structural evolution characterization reveal that Al doping can significantly alleviate the irreversible phase transition,thus inhibiting microcracks generation and enabling enhanced structure.Specifically,it exhibits excellent cycling performance in pouch-type full-cell with a high capacity retention of 91.8%after 500 cycles at 55℃.This work promotes the fundamental understanding on the correlation between the crystalline morphology and high-temperature electrochemical stability and provides a guide for optimization the Ni-rich cathode materials.

关键词： Single-crystalline Ultrahigh-nickel cathode High-temperature performance Phase evolution

Crosslinked solubilizer enables nitrate-enriched carbonate polymer electrolytes for stable,high-voltage lithium metal batteries

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Science Bulletin 2024年第2期69卷 209-217页

作者： Chuyang Jing Kuan Dai Dong Liu Wenran Wang Libao Chen Chunxiao Zhang Weifeng Wei State Key laboratory of Powder metallurgy Central South UniversityChangsha 410083China College of Materials and Chemical engineering Hunan Institute of EngineeringXiangtan 411104China

High-voltage lithium metal batteries(LMBs)have been considered promising next-generation highenergy-density batteries.However,commercial carbonate electrolytes can scarcely be employed in LMBs owing to their poor compatibility with metallic lithium.N,N-dimethylacrylamide(DMAA)-a crosslinkable solubilizer with a high Gutmann donor number-is employed to facilitate the dissolution of insoluble lithium nitrate(LiNO3)in carbonate-based electrolytes and to form gel polymer electrolytes(GPEs)through in situ polymerization.The Lit solvation structure of the GPEs is regulated using LiNO3 and DMAA,which suppresses the decomposition of LiPFe and facilitates the formation of an inorganic-rich solid electrolyte interface.Consequently,the Coulombic efficiency(CE)of the LillCu cell assembled with a GPE increases to 98.5%at room temperature,and the high-voltage LillNCM622 cell achieves a capacity retention of 80.1%with a high CE of 99.5%after 400 cycles.The bifunctional polymer electrolytes are anticipated to pave the way for next-generation high-voltage LMBs.

关键词： Crosslinked solubilizer Lithium nitrate Carbonate electrolytes Gel polymer electrolytes Lithium metal batteries

Developing Core-Shell Nano-Structures in FeCrAl-ODS Ferritic Alloys with the Co-Addition of Ni and Zr

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 364-372页

作者： Wenquan Ding Jieli Ma Yong Jiang Yiren Wang Huiqun Liu Key laboratory for Nonferrous Materials of Ministry of Education School of Materials Science and EngineeringCentral South UniversityChangsha410083China national Key laboratory for Powder metallurgy Central South UniversityChangsha410083China

A new Ni+Zr co-alloyed FeCrAl-ODS(oxide-dispersion-strengthened)ferritic alloy was fabricated by ball-milling and hot-isostatic-pressing.Using electron microscopy and atom probe tomography,the dispersive formation of high density core-shelled nano-particles of various sizes was confirmed with a common B2-NiAl shell.Among which,median-sized nano-particles(20-50 nm)typically have an Y_(4)Al_(2)O_(9)nano-core of<~20 nm,ultra-fine nano-particles(<~20)nm have an Y_(4)Zr_(3)O_(12)nano-core of<~10 nm,and larger-sized nano-particles(50-100 nm)incorporate an ultra-fine Y_(4)Al_(2)O_(9)nano-core and a few ultra-fine Y_(4)Zr_(3)O_(12)nano-oxides.All these nano-phases were highly coherent with the ferritic matrix.No large Y--Al-O nano-oxides were formed.The total number density of ultra-fine nano-particles was estimated as~2×10^(23)m^(-3)with a mean size of 6.3 nm only,and accordingly,the new alloy achieved an excellent combination of strength and ductility at high temperatures.

关键词： FeCrAl Oxide-dispersion-strengthened(ODS)alloy Mechanical alloying Nano-oxides Core-shell

Recent Advances in Asymmetric Structural Composites for Excellent Electromagnetic Interference Shielding: A Review

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Chinese Journal of Polymer Science 2024年第6期42卷 693-710页

作者： Ying Zhou Bai Xue Lan Xie Chang-Mei Wu Qiang Zheng Department of Polymer Materials and engineering College of Materials and Metallurgy Guizhou University national engineering Research Center for Compounding and Modification of Polymer Materials National and Local Joint Engineering Research Center for Functional Polymer Membrane Materials and Membrane Processes State Key laboratory of Public Big Data Guizhou University Department of Polymer Science and engineering Zhejiang University

Since electromagnetic pollution is detrimental to human health and the environment, numerous efforts have been successively made to achieve excellent electromagnetic interference shielding effectiveness(EMI SE) via designing the hierarchical structures for electromagnetic interference(EMI) shielding polymer composites. Among the plentiful structures, the asymmetric structures are currently a hot spot, principally categorizing into multi-layered, porous, fibrous, and segregated asymmetric structures, which endows the high EMI shielding performance for polymer composites incorporated with magnetic, conductive, and/or dielectric micro/nano-fillers, due to the “absorption-reflection-reabsorption” shielding mechanism. Therefore, this review provides the retrospection and summary of the efforts with respect to abundant asymmetric structures and multifunctional micro/nano-fillers for enhancing EMI shielding properties, which is conducive to the booming development of polymeric EMI shielding materials for the promising prospect in modern electronics and 5-generation(5G) technology.

关键词： Asymmetric structure Microano functional filler Polymer composite Electromagnetic interference shielding

Luminescence and magnetic properties of bifunctional nanoparticles composited by nitrogen-doped graphene quantum dots and gadolinium

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Journal of Rare Earths 2024年第4期42卷 716-723页

作者： Wanli Zhang Hao Zhou Meigui Ou Donghao Sun Chunlin Yang College of Materials and metallurgy University of GuizhouGuiyang550025China national Local Co-construction engineering laboratory for High Performance Metal Structure Material and Manufacture Technology Guiyang550025 China College of Chemistry and Materials engineering Guiyang UniversityGuiyang550003China

In this paper,nitrogen-doped graphene quantum dots(N-GQDs)were combined with gadolinium ions(Gd^(3+))by a surface modification to obtain magneto-optical dual-functional N-GQDs/Gd^(3+)nanoparticles.The morphology of obtained composite was characterized by field emission scanning electron microscopy and transmission electron microscopy.Luminescence and magnetic properties were measured by a fluorescence spectrophotometer and a vibrating sample magnetometer,respectively.Results indicate that well-dispersed spherical N-GQDs/Gd^(3+)nanoparticles have an average diameter of 7 nm.N-doping significantly increases the luminesce nce of particles with an optimal luminescence intensity at 20℃and pH=9.X-ray photoelectron spectroscopy results indicate that the N-doping introduces pyrrolic N as an electron donor,enhancing fluorescence by increasing the surface electron cloud density of N-GQDs.In addition,density functional theory calculation results reveal that N-doping reduces the band gap of NGQDs/Gd^(3+),enabling electronic transitions to higher energy levels and generating more activation sites,thereby enhancing luminescence.Compared to N-GQDs/Gd^(3+)prepared at 20℃,the saturated magnetization of particles prepared at 40℃is 0.85 emu/g,indicating a better magnetic response.The above results suggest that bifunctional nanomaterials N-GQDs/Gd^(3+)with excellent optical properties and magnetism can be better used for fluorescence and magnetic resonance imaging.

关键词： Nitrogen-doped graphenequantum dots Gadolinium Luminescence Magnetism Rare earths

A Hf-doped dual-phase high-entropy alloy: phase evolution and wear features

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Rare Metals 2024年第1期43卷 324-333页

作者： Hao Ren Rui-Run Chen Xue-Feng Gao Tong Liu Gang Qin Yu-Lung Chiu Shi-Ping Wu Jing-Jie Guo national Key laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of TechnologyHarbin 150001China School of metallurgy and Materials University of BirminghamEdgbastonBirmingham B152TTUK

Initially defined high entropy alloys(HEAs)usually exhibit a single-phase solid-solution structure.However,two and/or more types of phases in HE As possibly induce the desired microstructure features,which contribute to improving the wear properties of HE As.Here,we prepare a series of(AlCoCrFeNi)_(100-x)Hf_(x)(x=0,2,4and 6;at%) HEAs and concern their phase compositions,micro structures and wear properties.Hf leads to the formation of(Ni,Co)_(2)Hf-type Laves phase and tailors the microstructure from a body-centered cubic(BCC) singlephase structure to a hypoeutectic structure.An increased hardness from~HV 512.3 to~HV 734.1 is due to solid-solution strengthening,grain refinement strengthening and precipitated phase strengthening.And a few oxides(Al_(2)O_(3)+Cr_(2)O_(3)) caused by the wear heating contribute to an 85.5% decrease in wear rate of the HEA system from6.71×10^(-5) to 0.97×10^(-5) m^(3)·N^(-1)·m^(-1).In addition,Hf addition changes the wear mechanism from abrasive wear,mild oxidative wear and adhesive wear to oxidative wear and adhesive wear.

关键词： High entropy alloy Laves phase Hardness Wear mechanism