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Microscale shaping and rounding of ridge arrays and star pattern features on nickel mould via electrochemical polishing

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Advances in Manufacturing 2024年第2期12卷 207-226页

作者： Sana Zaki Nan Zhang Michael D.Gilchrist School of mechanical and materials engineering University College DublinBelfieldDublin 4Ireland

High quality micro mould tools are critical for ensuring defect-free production of micro injection moulded *** demoulding stage of the micro injection moulding can adversely affect the surface integrity due to friction,adhesion and thermal stresses between the metallic mould and polymeric replicated *** the present work,we propose the use of precision electropolishing(EP)as a shaping and polishing process to control the draft angle and fillet radius of micro features in order to ease *** defects that occur in replicated polymer parts include cracks,burrs and distorted features.A nickel mould having multiple linear ridges and star shape patterns was designed for the present investigation to have characteristic dimensions ranging from 10μm to 150μm and with various aspect ratios to study the effect of electropolishing on modifying the shape of micro features and surface morphology.A transient 2D computational analysis has been conducted to anticipate the effect of shaping on the Ni mould after electrochemical polishing with non-uniform material removal rates,based on the distribution of current *** experimental results indicate that after shaping using EP,the draft angle of star-patterns and linear patterns can be effectively increased by approximately 3.6°,while the fillet radius increases by up to 5.0μ*** controlling the electropolishing process,the surface roughness can be maintained under 50 *** work uses a green and environmental friendly nickel sulfamate electrolyte which can be effective for shaping of nickel micro features without causing any surface deposition.

关键词： Micro feature shaping and electropolishing Micro mould tools Green electrolyte Demoulding micro patterns

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Nickel Sulfide Modified NiCu Nanoalloy with Excellent Oxygen Evolution Reaction Properties Prepared through Electrospinning and Heat Treatment

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Journal of Wuhan University of Technology(materials Science) 2024年第2期39卷 320-326页

作者：李涛凌帅 ZHONG Shujie LOU Qiongyue Department of materials engineering School of Mechanical EngineeringChengdu UniversityChengdu 610106China

Ni^(2+)/Cu^(2+)/SO_(4)^(2-)/polyvinyl alcohol precursor fibers with uniform diameters were prepared through ***-based composite nanoalloys containing Ni,Cu,and S were prepared through heat treatment in an Ar *** experimental results show that the main components of the prepared nanoalloys are NiCu,Ni_(3)S_(2),Ni,and *** nanoalloys exhibit fine grain sizes about 200-500 nm,which can increase with increasing heat treatment *** test results show that the nickel sulfidemodified NiCu nanoalloy composites exhibit excellent oxygen evolution reaction properties,and the oxygen evolution reaction properties gradually improve with the increasing heat treatment *** sample prepared at 1 000℃ for 40 min show a low overpotential of 423 mV and a small Tafel slope of 134 mV·dec^(-1) at a current density of 10 mA·cm^(-2).

关键词： NiCu nanoalloy Ni_(3)S_(2) structure transformation oxygen evolution reaction

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Twinning aspects and their efficient roles in wrought Mg alloys:A comprehensive review

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Journal of Magnesium and Alloys 2024年第6期12卷 2201-2230页

作者： S.S.A.Shah Manping Liu Azim Khan Farooq Ahmad M.R.Abdullah Xingquan Zhang Shiwei Xu Zhen Peng School of materials Science and engineering Jiangsu UniversityZhenjiang 212013China School of mechanical engineering Anhui University of TechnologyMáanshan 243002China college of mechanical and Vehicle engineering Hunan UniversityChangsha 410082China

Twinning is widely recognized as an effective and cost-efficient method for controlling the microstructure and properties of wrought magnesium(Mg)***,twins play a crucial role in initiating dynamic recrystallization(DRX),while twin regions experience rapid recrystallization during static recrystallization(SRX).The activation of twinning can lead to changes in lattice orientation,significantly impacting the final texture in Mg *** active roles of twinning are influenced by various factors during the activation process,and the mobility of twin boundaries(TB)can be amplified by stress effects,dislocation interactions,and thermal ***,annealing treatments that involve proper segregation or precipitation on TBs serve to stabilize them,restraining their *** such as segregation may also alter the twinning propensity in Magnesium-rare earth(Mg-RE)***{10-11}contraction twins(CT)and{10-11}-{10-12}double twins(DT)can promote dynamic recrystallization(DRX),they also pose a risk as potential sources of voids and ***,understanding the nucleation and growth mechanisms of twinning is crucial,and these aspects are briefly reviewed in this *** the factors mentioned above,this article summarizes the recent research progress in this field,shedding light on advancements in recent eras.©2024 Chongqing *** services provided by Elsevier *** behalf of KeAi Communications ***.

关键词： Mg alloys Twinning Recrystallization Texture mechanical properties

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Temperature-jump tensile tests to induce optimized TRIP/TWIP effect in a metastable austenitic stainless steel

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International Journal of Minerals,Metallurgy and materials 2024年第9期31卷 2025-2036页

作者： Mohammad Javad Sohrabi Hamed Mirzadeh Saeed Sadeghpour Abdol Reza Geranmayeh Reza Mahmudi School of Metallurgy and materials engineering College of EngineeringUniversity of Tehran14395-515TehranIran Centre for Advanced Steels Research Materials and Mechanical EngineeringUniversity of Oulu90014 OuluFinland

In the present work,plastic deformation mechanisms were initially tailored by adjusting the deformation temperature in the range of 0 to 200℃ in AISI 304L austenitic stainless steel,aiming to optimize the strength-ductility *** was shown that the combined twinning-induced plasticity(TWIP)/transformation-induced plasticity(TRIP)effects and a wider strain range for the TRIP effect up to higher strains by adjusting the deformation temperature are good strategies to improve the strength-ductility synergy of this metastable stainless *** this regard,by consideration of the observed temperature-dependency of plastic deformation,the controlled sequence of TWIP and TRIP effects for archiving superior strength-ductility trade-off was intended by the pre-designed temperature jump tensile ***,the optimum tensile toughness of 846 MJ/m^(3) and total elongation to 133% were obtained by this strategy via exploiting the advantages of the TWIP effect at 100℃ and the TRIP effect at 25℃ at the later stages of the ***,a deformation-temperature-transformation(DTT)diagram was developed for this metastable ***,based on work-hardening analysis,it was found that the main phenomenon constraining further improvement in the ductility and strengthening was the yielding of the deformation-induced α′-martensite.

关键词： metastable stainless steels transformation-induced plasticity twinning-induced plasticity stacking fault energy mechanical properties

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Electron-microscopical visualization on the interfacial and crystallographic structures of lithium metal anode

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Chinese Chemical Letters 2024年第6期35卷 26-37页

作者： Jiale Zheng Mei Chen Huadong Yuan Jianmin Luo Yao Wang Jianwei Nai Xinyong Tao Yujing Liu college of materials Science and engineering Zhejiang University of TechnologyHangzhou 310014China college of mechanical and Energy engineering Zhejiang University of Science and TechnologyHangzhou 310014China

Lithium(Li)metal anodes(LMAs)have garnered significant attention as a potential solution for developing high-energy density batteries,given their theoretical specific capacity and redox ***,safety concerns and internal cycling stability issues originated from uncontrollable Li dendrite growth have impeded the practical application of *** the interface between Li metal and electrolyte is a crucial process that offers valuable insights into the characteristics and regularity of primary circular *** illustrate the intrinsic characteristic of Li metal batteries(LMBs)in spatial and temporal,it is imperative to employ electron microscopes to characterize the structural components distribution of Li with atomic *** paper summarizes the progress in the characterization and analysis of the interfaces in LMBs with electron microscopes based on the principles of electron-matter ***,future trends and the potential of electron microscopes are also discussed to advance our understanding of LMBs.

关键词： Li metal anode Electron microscopy Visualization High-resolution Battery

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Durable K-ion batteries with 100% capacity retention up to 40,000 cycles

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Carbon Energy 2024年第5期6卷 201-212页

作者： Xianlu Lu Zhao Liang Zhi Fang Dongdong Zhang Yapeng Zheng Qiao Liu Dingfa Fu Jie Teng Weiyou Yang Institute of Micro/Nano materials and Devices Ningbo University of TechnologyNingboZhejiangChina college of materials Science and engineering Hunan UniversityChangshaChina college of mechanical and Vehicle engineering Hunan UniversityChangshaChina

Currently,the major challenge in terms of research on K-ion batteries is to ensure that they possess satisfactory cycle stability and specific capacity,especially in terms of the intrinsically sluggish kinetics induced by the large radius of K+***,we explore high-performance K-ion half/full batteries with high rate capability,high specific capacity,and extremely durable cycle stability based on carbon nanosheets with tailored N dopants,which can alleviate the change of volume,increase electronic conductivity,and enhance the K+ion *** as-assembled K-ion half-batteries show an excellent rate capability of 468 mA h g^(−1) at 100 mA g^(−1),which is superior to those of most carbon materials reported to ***,the as-assembled half-cells have an outstanding life span,running 40,000 cycles over 8 months with a specific capacity retention of 100%at a high current density of 2000 mA g^(−1),and the target full cells deliver a high reversible specific capacity of 146 mA h g^(−1) after 2000 cycles over 2 months,with a specific capacity retention of 113%at a high current density of 500 mA g^(−1),both of which are state of the art in the field of K-ion *** study might provide some insights into and potential avenues for exploration of advanced K-ion batteries with durable stability for practical applications.

关键词： carbon nanosheet cycle stability K-ion batteries rate performance specific capacity

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Fine structure and facet analyses of tunnel-structured FeOOH nanocrystals

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Progress in Natural Science:materials International 2024年第1期34卷 172-177页

作者： Xuemei Zeng Yanshuai Li Wenjun Song Yun Li Dewu Yin Yifei Yuan Kun He college of Chemistry and materials engineering Wenzhou University

The development of energy storage systems in the future relies on identifying suitable target materials and synthesizing target materials with controllable physicochemical properties to unlock their electrochemical contributions. Based on the structure-property-performance relationship established in materials science, it is crucial to determine the fine structure of key functional materials. Among these materials, tunnel-structured β-FeOOH is widely studied due to its low-cost, decent performance and environmental friendliness; yet, its fine structure in terms of the atomic framework and surface configuration has not been well understood. In this work, we successfully synthesized β-FeOOH nanorods and analyzed their crystallographic features via transmission electron microscopy(TEM). By combining ultramicrotome and aberration-corrected scanning TEM with atomic resolution,we first experimentally revealed the structural details of β-FeOOH featuring 1 × 1 tunnels and 2 × 2 tunnels along the c-axis([001]), the same as the nanorod growth direction. The dominant exposed facets of β-FeOOH nanorods were further revealed to be {010}. Such fine structural elucidation unveils the long-existing mystery in this material system, which is expected to contribute to structural/compositional engineering toward functionality optimization in the near future.

关键词： β-FeOOH tunnel Anisotropic growth Atomic resolution Nanorod Energy storage

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Numerical simulation on the multiphase flow and reoxidation of the molten steel in a two-strand tundish during ladle change

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International Journal of Minerals,Metallurgy and materials 2024年第7期31卷 1540-1553页

作者： Jingcheng Wang Zhentong Liu Wei Chen Hongliang Chen Lifeng Zhang School of mechanical engineering Yanshan UniversityQinhuangdao 066004China School of materials Science and engineering Tianjin UniversityTianjin 300350China School of mechanical and materials engineering North China University of TechnologyBeijing 100144China

A 3D mathematical model was proposed to investigate the molten steel–slag–air multiphase flow in a two-strand slab continuous casting(CC)tundish during ladle *** study focused on the exposure of the molten steel and the subsequent reoxidation *** exposure of the molten steel was calculated using the coupled realizable k–εmodel and volume of fluid(VOF)*** diffusion of dissolved oxygen was determined by solving the user-defined scalar(UDS)***,the user-defined function(UDF)was used to describe the source term in the UDS equation and determine the oxidation rate and oxidation *** effect of the refilling speed on the molten steel exposure and dissolved oxygen content was also *** the refilling speed during ladle change reduced the refilling time and the exposure duration of the molten ***,the elevated refilling speed enlarged the slag eyes and increased the average dissolved oxygen content within the tundish,thereby exacerbating the reoxidation *** addition,the time required for the molten steel with a high dissolved oxygen content to exit the tundish varied with the refilling *** the inlet speed was 3.0 m·s^(-1)during ladle change,the molten steel with a high dissolved oxygen content exited the outlet in a short period,reaching a maximum dissolved oxygen content of 0.000525wt%.Conversely,when the inlet speed was 1.8 m·s^(-1),the maximum dissolved oxygen content was 0.000382wt%.The refilling speed during the ladle change process must be appropriately decreased to minimize reoxidation effects and enhance the steel product quality.

关键词： tundish ladle change reoxidation multiphase flow numerical simulation

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Crystalline-amorphous M@MN_x(M=Co,Fe,Ni)encapsulated in nitrogen-doped carbon for enhanced efficient and durable hydrogen evolution reaction

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Rare Metals 2024年第4期43卷 1547-1556页

作者： Yang Yang Xiao-Chuan Duan Shao-Hui Guo Xian-Ming Zhang college of materials Science and engineering College of ChemistryKey Laboratory of Interface Science and Engineering in Advanced MaterialsTaiyuan University of TechnologyYuci030600China

Developing earth-abundant electrocatalysts for hydrogen evolution reaction(HER)is important for the sustainable energy ***,efficient and stable heterocatalysts consisting of crystalline-amorphous M@MN_(x)(M=Co,Fe,Ni)encapsulated in N-doped carbon layers supported with N-doped graphene sheets(denoted as M@MN_(x)@NC-NG)are synthesized by facile hydrothermal reaction and nitridation *** the nitriding process,metal ions in M(tzbc)_2(H_(2)O)_4(tzbc=4-(1H-1,2,4-triazol-1-yl)benzoic acid)complexes are reduced to crystalline M cores,accompanied by the formation of amorphous MN_(x)shells;the tzbc ligands are insitu carbonized to form outermost N-doped carbon(NC)layers that connect with inner MN_(x)via M-N-C motifs inherited from the complex precursors and inhibit the transition of MN_(x)from amorphous to crystalline *** Co@CoN_(x)@NC-NG catalyst exhibits excellent HER activity with small overpotentials of 45 and 64 mV at a cathode current density of 10 mA·cm^(-2)and low Tafel slopes of 40 and 85 mV·dec^(-1)in 0.5 mol·L^(-1)H_(2)SO_4 and1.0 mol·L^(-1)KOH electrolytes,*** Co@CoN_(x)@NC-NG retains 97%of the initial overpotential after 100,000 s in both acidic and alkaline *** outstanding HER performance originates from the crystalline-amorphous Co@CoN_(x)that redistributes electrons around the heterointerfaces,facilitating the conversion process of H^(+)/H_(2)O to hydrogen and thereby promoting HER *** outermost NC layers serve as the armor of Co@CoN_(x),and graphene nanosheets act as carriers of egg-like Co@CoN_(x)@NC and conduction paths for electron shuttles,ensuring stable and continuous electrocatalytic hydrogen production.

关键词： Hydrogen evolution reaction Electrocatalysts Iron group metals Heterojunction Crystalline-amorphous structure

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Prediction of liquid circulation flow rate in RH degasser:improvement of decarburization at low atmospheric pressure

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Journal of Iron and Steel Research(International) 2024年第7期31卷 1661-1667页

作者： Gu-jun Chen Sheng-ping He college of materials Science and engineering Yangtze Normal UniversityChongqing 400044China college of materials Science and engineering Chongqing UniversityChongqing 400044China

The two-fluid model coupled with population balance model was used for simulating the gas-liquid flow in the Ruhrstahl-Heraeus(RH)*** predicted circulation flow rate was compared with that measured from a water model experiment to validate the mathematical ***,influence of snorkel immersion depth on liquid circulation flow rate was numerically investigated under an atmospheric pressure of 101 and 84 kPa,*** result indicates that the circulation flow rate of the RH degasser in the high-altitude area was severely reduced because of the decrease in atmospheric ***,increasing the snorkel immersion depth from 0.5 to 0.7 m can compensate for the decrease in atmospheric *** test result indicates that decarburization rate is significantly enhanced by increasing the snorkel immersion *** optimization,the percentage of heats with a final carbon content less than 0.002 wt.%is significantly increased from 22.0%to 96.4%.

关键词： RH degasser Two-fluid model Population balance model-Circulation flow rate Decarburization Snorkel immersion depth

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