• 한국재료학회지
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• 제30권2호
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• pp.93-98
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• 2020

Effective control of the heat generated from electronics and semiconductor devices requires a high thermal conductivity and a low thermal expansion coefficient appropriate for devices or modules. A method of reducing the thermal expansion coefficient of Cu has been suggested wherein a ceramic filler having a low thermal expansion coefficient is applied to Cu, which has high thermal conductivity. In this study, using pressureless sintering rather than costly pressure sintering, a polymer solution synthesis method was used to make nano-sized Cu powder for application to Cu matrix with an AlN filler. Due to the low sinterability, the sintered Cu prepared from commercial Cu powder included large pores inside the sintered bodies. A sintered Cu body with Zn, as a liquid phase sintering agent, was prepared by the polymer solution synthesis method for exclusion of pores, which affect thermal conductivity and thermal expansion. The pressureless sintered Cu bodies including Zn showed higher thermal conductivity (180 W/m·K) and lower thermal expansion coefficient (15.8×10^-6/℃) than did the monolithic synthesized Cu sintered body.

• 한국분말재료학회지
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• 제9권5호
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• pp.329-335
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• 2002

Recently, the fabrication process of the W-Cu nanocomposite powders has been studied to improve the sinterability through the mechanical alloying and reduction of W and Cu oxide mixtures. In this study. the W-Cu composites were produced by mechanochemical process (MCP) using $WO_3-CuO$ mixtures with two different milling types of low and high energy, respectively. These ball-milled mixtures were reduced in $H_2$ atmosphere. The ball-milled and reduced powders were analyzed through XRD, SEM and TEM. The fine W-Cu powder could be obtained by the high energy ball-milling (HM) compared with the large Cu-cored structure powder by the low energy ball-milling (LM). After the HM for 20h, the W grain size of the reduced W-Cu powder was about 20-30 nm.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2001년도 추계학술강연 및 발표대회
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• pp.16-16
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• 2001

• 한국분말재료학회지
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• 제10권4호
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• pp.270-274
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• 2003

Recently, the fabrication process of W-Cu nanocomposite powders has been researched to improve the sinterability by mechanochemical process (MCP), which consists of ball milling and hydrogen-reduction with W- and Cu-oxide mixture. However, there are many control variables in this process because the W oxides are hydrogen-reduced via several reduction stages at high temperature over 80$0^{\circ}C$ with susceptive reduction conditions. In this experiment, the W-15 wt%Cu nanocomposite powder was fabricated with the ball-milling and hydrogen-reduction process using W and CuO powder. The microstructure of the fabricated W-Cu nanocomposite powder was homogeneously composed of the fine W particles embedded in the Cu matrix. In the sintering process, the solid state sintering was certainly observed around 85$0^{\circ}C$ at the heating rate of 1$0^{\circ}C$/min. It is considered that the solid state sintering at low temperature range should occur as a result of the sintering of Cu phase between aggregates. The specimen was fully densified over 98% for theoretical density at 120$0^{\circ}C$ for 1 h with the heating rate of 1$0^{\circ}C$/min.

• 한국환경보건학회지
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• 제13권1호
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• pp.67-71
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• 1987

This study was intended to investigate the content of Cu, Mn, Zn in the dried milk powders except infant formula milkpowder from January to March, 1986. The content of the trace metals was determined by Atomic Absorption Spectrophotometry. The results were as follows: 1. Averages of Cu, Mn, Zn in the total samples were Cu, 0.3043 ppm Mn, 0.5101 ppm Zn, 26.006 ppm. 2. Averages and ranges of Cu, Mn, Zu in the whole milk powder were Cu, 0.2483, 0.216 - 0.48 Mn, 0.552 ppm, 0.336 - 0.732 ppm Zn, 28.961 ppm, 7.5 - 51.9 ppm. 3. Averages and ranges of Cu, Mn, Zn in the skim milk powder were Cu, 0.4095 ppm, 0.3 - 0.54 ppm Mn, 0.6907 ppm, 0.348 - 0.84 ppm Zn, 38.381 ppm, 30.6 - 55.2 ppm. 4. Averages and ranges of Cu, Mn, Zn in the modified milk powder were Cu, 0.3459 ppm, 0.12 0.948 ppm Mn, 0.2414 ppm, 0.096 - 0.348 ppm Zn, 7.752 ppm, 1.2 - 17.002 ppm. 5. It showed the highest amount of Cu, Mn, Zu in the skim milk powder group than in the other group and the lowest amount of Cu in the whole milk powder group and Mn, Zn in the modified milk group.

• 한국분말재료학회지
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• 제26권5호
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• pp.410-414
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• 2019

The hydrogen reduction behavior of the $CuO-SCo_3O_4$ powder mixture for the synthesis of the homogeneous Cu-15at%Co composite powder has been investigated. The composite powder is prepared by ball milling the oxide powders, followed by a hydrogen reduction process. The reduction behavior of the ball-milled powder mixture is analyzed by X-ray diffraction (XRD) and temperature-programmed reduction at different heating rates in an Ar-10%H2 atmosphere. The scanning electron microscopy and XRD results reveal that the hydrogen-reduced powder mixture is composed of fine agglomerates of nanosized Cu and Co particles. The hydrogen reduction kinetics is studied by determining the degree of peak shift as a function of the heating rate. The activation energies for the reduction of the oxide powders estimated from the slopes of the Kissinger plots are 58.1 kJ/mol and 65.8 kJ/mol, depending on the reduction reaction: CuO to Cu and $SCo_3O_4$ to Co, respectively. The measured temperature and activation energy for the reduction of $SCo_3O_4$ are explained on the basis of the effect of pre-reduced Cu particles.

• 한국분말재료학회지
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• 제21권3호
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• pp.229-234
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• 2014

This study manufactured a CIG-based composite coating layer utilizing a new warm spray process, and a mixed powder of Cu-20at.%Ga and Cu-20at.%In. In order to obtain the mixed powder with desired composition, the Cu-20at.%Ga and Cu-20at.%In powders were mixed with a 7:1 ratio. The mixed powder had an average particle size of $35.4{\mu}m$. Through the utilization of a warm spray process, a CIG-based composite coating layer of $180{\mu}m$ thickness could be manufactured on a pure Al matrix. To analyze the microstructure and phase, the warm sprayed coating layer underwent XRD, SEM/EDS and EMPA analyses. In addition, to improve the physical properties of the coating layer, an annealing heat treatment was conducted at temperatures of $200^{\circ}C$, $400^{\circ}C$ and $600^{\circ}C$ for 1 hour each. The microstructure analysis identified ${\alpha}$-Cu, $Cu_4In$ and $Cu_3Ga$ phases in the early mixed powder, while $Cu_4In$ disappeared, and additional $Cu_9In_4$ and $Cu_9Ga_4$ phases were identified in the warm sprayed coating layer. Porosity after annealing heat treatment reduced from 0.75% (warm sprayed coating layer) to 0.6% (after $600^{\circ}C/1hr$. heat treatment), and hardness reduced from 288 Hv to 190 Hv. No significant phase changes were found after annealing heat treatment.

• 한국분말재료학회지
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• 제10권5호
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• pp.337-343
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• 2003

Nanostructured Cu-$Al_2O_3$ composite powders were synthesized by thermochemical process. The synthesis procedures are 1) preparation of precursor powder by spray drying of solution made from water-soluble copper and aluminum nitrates, 2) air heat treatments to evaporate volatile components in the precursor powder and synthesis of nano-structured CuO + $Al_2O_3$, and 3) CuO reduction by hydrogen into pure Cu. The suggested procedures stimulated the formation of the gamma-$Al_2O_3$, and different alumina formation behaviors appeared with various heat treating temperatures. The mean particle size of the final Cu/$Al_2O_3$ composite powders produced was 20 nm, and the electrical conductivity and hardness in the hot-extruded bulk were competitive with Cu/$Al_2O_3$ composite by the conventional internal oxidation process.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.761-762
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• 2006

W-Cu alloy was very useful material for a heat sink, high electric contact and EDM electrode. Powder injection molding (PIM) is the optimum manufacturing technology to provide W-Cu components with low-cost and high-volume. We used various compositions of tungsten coated copper powders (W-Cu with 10 to 80 wt-% of copper) to manufacture W-Cu components by PIM. The optimum mixing, injection molding, debinding and sintering conditions to provide the high performance W-Cu components were investigated. The thermal and mechanical properties of W-Cu parts by PIM were measured. Finally, we can verify the high performance of W-Cu components by PIM with the tungsten coated copper.

• 한국분말재료학회지
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• 제5권2호
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• pp.145-153
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• 1998

W-Cu alloy is attractive to thermal managing materials in microelectronic devices because of its good thermal properties. The metal injection molding (MIM) of W-Cu systems can satisfy the need for mass production of the complex shaped W-Cu parts in semiconductor devices. In this study, the application of MIM process of the mechanically alloyed (MA) W-Cu composite powders, which had higher sinterability were investigated. The MA W-Cu powders and reduction treated (RT) powders were injected by using of the multicomponent binder system. The multi-stage debinding cycles were adopted in $N_2$ and $H_2$ atmosphere. The isostatic repressing treatment was carried out in order to improve the relative density of brown parts. The brown part of RT W-Cu composite powder sintered at 110$0^{\circ}C$ had shown the higher sinterability compared to that of MA powder. The relative sintered density of all specimens increased to 96% by sintering at 120$0^{\circ}C$ for 1 hour. The relationship between green density and the sintering behavior of MA W-Cu composite powder was analyzed and discussed on the basis of the nanostructured characteristics of the MA W-Cu composite powder.