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Effects of process parameters on nonaqueous gelcasting for copper powder

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International Journal of Minerals,Metallurgy and Materials 2016年第5期23卷 542-547页

作者： Karima Bekouche Zhao-li Wang Cheng-Chang Jia Bo-wen Liu Yi Tang Institute of Advanced Materials and Technology University of Science and Technology Beijing

An approach to fabricate sintered copper with high green strength and high sintered density using nonaqueous gelcasting technol- ogy is presented in this study. The effects of various gelcasting processing parameters such as monomer content, monomer/crosslinker ratio, initiator content, dispersant dosage, and temperature on the flexural strength of dried green bodies and the relative density of sintered bodies were studied to obtain better microstructures and properties. The appropriate process parameters obtained for copper gelcasting are as follows monomer content, 20vol%-30vol% （based on the total volume of reagents）; monomer/crosslinker ratio, 10：1 to 20：1; initiator content, 3vol%-4vol% （based on the volume of the monomer）; dispersant dosage, 1.5wt%-2.5wt% （based on the mass of the copper powder）; and reaction temperature, 65-75℃.

关键词： copper powder gelcasting monomer process parameters flexural strength density

Experimental Investigation on the Vapor Chambers with Sintered copper powder Wick

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Journal of Thermal Science 2021年第6期30卷 1938-1950页

作者： HUANG Dou JIA Li WU Hong AAKER Olav Beijing Key Laboratory of Flow and Heat Transfer of Phase Changing in Micro and Small Scale School of MechanicalElectronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China Faculty of Engineering 0stfold University CollegeBox700N-1757Norway

High power electronics units generate high-density heat flux,which poses a significant threat to the reliability of these *** vapor chamber(VC)has a very high heat transfer rate and has a wide range of applications in the heat dissipation of electronic *** with sintered copper powder wicks sized as irregular shape copper powder 50μm(I-50μm),I-75μm,I-110μm,I-150μm were studied in this *** effect of liquid filling ratio was *** results indicated that the thermal resistance of all VCs decreased with the increase of heating *** capillary performance of wick was the dominant factor for the heat transfer performance of VCs with different kinds of wick.A capillary performance factor was proposed to evaluate the capillary performance of *** capillary performance factor of VC with the wick of I-75μm was much higher than that of the other types of VC in this *** heat source surface temperature of VCs could be affected by filling ratio and wick ***,it should be insensitive to the filling ratio when a better capillary performance factor was *** the same heating area and similar structure,the maximum heat flux density of the VC would decrease as the height of vapor cavity decreased.

关键词： vapor chamber copper powder capillary performance heat transfer performance thermal resistance

DYNAMIC COMPACTION OF PURE copper powder USING PULSED MAGNETIC FORCE

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Acta Metallurgica Sinica(English Letters) 2007年第4期20卷 277-283页

作者： H.P. Yu C.F. Li National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of Technology Harbin 150001 China

The compaction of pure Cu powder was carried out through a series of experiments using dynamic magnetic pulse compaction, and the effects of process parameters, such as discharge energy and compacting direction, on the homogeneity and the compaction density of compacted specimens were presented and discussed. The results indicated that the compaction density of specimens increased with the augment of discharge voltage and time. During unidirectional compaction, there was a density gradient along the loading direction in the compacted specimen, and the minimum compaction density was localized to the center of the bottom of the specimen. The larger the aspect ratio of a powder body, the higher the compaction density of the compacted specimen. And high conductivity drivers were beneficial to the increase of the compaction density. The iterative and the double direction compaction were efficient means to manufacture the homogeneous and high-density powder parts.

关键词： magnetic pulse compaction copper powder compaction density electromagnetic forming

Direct electroreduction of solid cuprous chloride to copper powder in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid

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Science China Chemistry 2014年第3期57卷 397-401页

作者： ZHANG QiBo HUA YiXin WANG Rui Key Laboratory of Ionic Liquids Metallurgy Faculty of Metallurgical and Energy Engineering Kunming University of Science and Technology

Direct electroreduction of solid cuprous chloride to prepare copper powder in a"neutral"ambient-temperature ionic liquid,1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid(BMIMBF4)was *** voltammetry of the CuCl powder in a Pt-powder cavity microelectrode exhibited that solid CuCl can be electrochemical reduced in the ionic *** of the salt powder filled Mo-cavity electrode(current collector)in the ionic liquid further demonstrated the conversion of chloride to metal inside the cavity,as confirmed by scanning electron microscopy,energy-dispersive X-ray,and X-ray diffraction spectra.

关键词： ionic liquid copper powder electroreduction Pt-powder cavity microelectrode

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

Sintering microstructure and properties of copper powder prepared by electrolyzation and atomization

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Journal of Central South University 2021年第7期28卷 1966-1977页

作者： LI Pei CHEN Cun-guang QIN Qian LU Tian-xing SHAO Yan-ru YANG Fang HAO Jun-jie GUO Zhi-meng 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 Innovation Group of Marine Engineering Materials and Corrosion Control Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai 519000China

The almost completely dense copper was prepared by ultrafine copper powder prepared with both methods of electrolysis and novel water-gas atomization through cold isostatic pressing(CIP)and sintering under atmospheric *** copper powder possesses the higher sintering driving force,thereby promoting shrinkage and densification during the sintering *** grain size of sintered samples by electrolytic copper powder is smaller than that prepared by the atomized copper powder,and the twin crystals are particularly prone to forming in the former sintered microstructure due to the raw powder with low oxygen content and high residual stress originating from the CIP *** relative density of samples by electrolytic and atomized powder at 1000℃ sintering temperature achieves 99.3%and 97.4%,respectively,significantly higher than that of the powder metallurgy copper parts reported in the ***,the ultimate tensile strength and yield strength of samples by both kinds of copper powder are approximately similar,while the elongation of the sintered sample by the electrolytic powder(60%)is apparently higher than the atomized powder(44%).The superior performance of samples fabricated by electrolytic powder is inferred from the full density and low oxygen level for there is no cuprous oxide in the grain boundaries.

关键词： copper powder electrolyzation gas-water combined atomization sintered microstructure property

Comparison between oxide-reduced and water-atomized copper powders used in making sintered wicks of heat pipe

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China Particuology 2007年第3期5卷 220-224页

作者： Liu-Ho Chiu Chang-Hui Wu Pee-Yew Lee Department of Materials Engineering Tatung University Taipei 10451 Taiwan China Institute of Materials Engineering Taiwan Ocean University Keelung Taiwan China

Oxide-reduced copper powder can be produced efficiently at low cost. The volume shrinkage, porosity, maximum pore size, permeability and thermal conductivity of wicks sintered from two oxide-reduced （OR） powders were compared with one from water-atomized （WA） powder. The green specimens were sintered at temperatures from 800 to 1000 ℃ in a tube furnace under a reduction stream of 10% hydrogen and 90% argon. The results show that the property variations of OR - 100 and WA wicks due to porosity changes have a similar tendency and range. Nine hundred degree celsius is a recommended sintering temperature for producing ideal wicks for use in heat pipes. A smaller maximum pore size can be obtained by increasing the green density.2007 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V.

关键词： Sintered wick copper powder Porous property Oxide-reduced powder

DEM simulation and characterization of copper and iron powders fabricated by ball milling

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Particuology 2024年第11期94卷 96-108页

作者： Khulan Uranchimeg Battsetseg Jargalsaikhan Lee Sang Eui Heekyu Choi Graduate School of Material Science Engineering Changwon National UniversityChangwonGyoungnam641-773Republic of Korea Citi University Ulaanbaatar 14201Mongolia Department of Mechatronics Convergence Engineering College of Future ConvergenceChangwon National UniversityChangwonGyoungnam641-773Republic of Korea Graduate School of Convergence on Culture Technology Changwon National UniversityChangwonGyoungnam641-773Republic of Korea Research Institute of Future Convergence Changwon National UniversityChangwonGyoungnam641-773Republic of Korea

In this study,the particle morphology,and size changes in copper and iron powders were investigated by using a high-energy ball mill under the same experimental *** particle sizes and morphologies of the powders were examined using a particle size analyzer and scanning electron microscopy(SEM).We also used the discrete element method(DEM)to analyze the ball impaction and the shear energy during the ball milling *** was discovered that the quantity of milling balls and rotational speed had a major impact on energy dissipation through heat and plastic deformation as well as milling *** characteristic(particle morphology and size)of the iron and copper powder were differently changed under the same experimental conditions,shear energy,and ball *** the particle sizes of copper and iron powder were compared under the same experimental conditions,the copper particle size increased from 21.6μm to 280μm,resulting in particle agglomeration,while the iron powder particle size decreased from 154μm to 4.35μm.

关键词： copper powder Iron powder Ball size Particle morphology Particle size

Comparison between Oxide-reduced and Water-atomized copper powders Used in Sintered Wicks of Heat Pipe

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Comparison between Oxide-reduced and Water-atomized Copper P...