Microhomogeneity and Sintering of W-Cu Composite Powders Produced by Hydrogen Reduction

Lee, J.S.; Kim, T.H.

doi:10.4028/www.scientific.net/ssp.25-26.143

Cited by 16 publications

(6 citation statements)

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“…Figure 2 shows the thermo-gravimetric(TG) results of the ball-milled WO 3 and CuO powder mixture. It can be seen that, with increasing temperature, the weight losses of the powder mixture show stepwise behavior approximately divided into three plateau regions, which is basically in accordance with previous investigation [4]. The reduction reaction of CuO to Cu mainly occurs at the temperature around 250 °C and almost completes below 300 °C.…”

Section: Resultssupporting

confidence: 90%

“…The enhancement of densification has been accomplished by forming fine W-Cu composite powder through mechanical alloying of the elemental powders or hydrogen reduction of W and Cu oxides [3,4]. The formation of fine W-Cu composite powder contributes to densification through enhancing particle re-arrangement process and/or increasing solubility of W in Cu during liquid phase sintering.…”

Section: Introductionmentioning

confidence: 99%

“…However, the occurrence of remarkable grain growth of W in very fine W-Cu powders may imply that there exists a certain relationship between W and Cu. In terms of morphology of W-Cu composite powders, although the formation of micro-homogeneously mixed W-Cu composite powder was reported [4], there is still ambiguity. Moreover, the formation mechanism of the W-Cu composite powder has not been investigated, yet.…”

Section: Introductionmentioning

confidence: 99%

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Reduction Behavior of W and Cu Oxides Powder Mixture

Lee¹,

Noh²,

Kim³

et al. 2008

SSP

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The reduction behavior of WO3 and CuO powder mixture has been studied by using thermo-gravimetric(TG), X-ray diffraction, and scanning electron microscopic analyses. The powder mixture was manufactured by ball-milling. It was found that W coated W-Cu composite powders were formed when reducing the powder mixture under hydrogen atmosphere. The following reduction steps are suggested as a mechanism for the formation of W coated W-Cu composite powders: with increasing temperature, Cu is initially reduced from CuO and the reduction reactions of WO3 to WO2 via WO2.9 and WO2.72 are followed. The gas phase WO2(OH)2 is formed by the reaction of the WO2 and water vapor, and then WO2(OH)2 diffuses toward Cu surface and deposits on it as W by reducing reaction with environmental hydrogen gas. The formation mechanism of W coated W-Cu composite powders involving the gas phase transportation reaction has been confirmed by the model experiment conducted by using Cu plate and WO3 powder.

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Section: Resultssupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Reduction Behavior of W and Cu Oxides Powder Mixture

Lee¹,

Noh²,

Kim³

et al. 2008

SSP

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“…Hence, many researches have been carried out on the development of synthesis methods for nano metal powders, such as sol-gel, co-precipiation, and mechanical alloying (MA) [2,3]. Recently, Lee and his co-workers reported on the successful fabrications of nano metal alloy and composite powders by hydrogen reduction of ball-milled metal oxide nanopowders [4,5]. In spite of the processing advantage, however, thermal process of hydrogen reduction inevitably accompanies grain growth during the process at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Nano Metal Powder by Electrochemical Reduction of Iron Oxides

Seong

Lee

2007

MSF

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Synthesis of iron nanopowder by room-temperature electrochemical reduction process of α-Fe2O3 nanopowder was investigated in terms of phase evolution and microstructure. As process variables, reduction time and applied voltage were changed in the range of 1~20 h and 30~40 V, respectively. From XRD analyses, it was found that volume of Fe phase increased with increasing reduction time and applied voltage, respectively. The crystallite size of Fe phase in all powder samples was less than 30 nm, implying that particle growth was inhibited by the reaction at room temperature. Based on the distinct equilibrium shape of crystalline particle, phase composition of nanoparticles was identified by TEM observation.

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“…W-Cu pseudo-alloy possesses potential for applications such as a contact of high power electricity and heat sink of micro-electronic package because of its high electrical and thermal conductivities and low thermal expansion coefficient [1,2]. Moreover, W-Cu pseudo-alloy has been focused as one of promising materials for a shaped charge liner in military field, due to its high density and excellent elongation in high strain rate [3,4].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of Microstructural Homogeneity of W-Cu Pseudo-Alloy by Adding W-Cu Composite Powder in Infiltration Process

Hong¹,

Choi²,

Lee³

et al. 2007

MSF

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An infiltration technique using W-Cu composite powder has been developed to enhance microstructural uniformity of W-Cu pseudo-alloy. W-Cu composite powder, manufactured by reduction from WO3 and CuO powder mixtures, were blended with W powder and then cold isostatically pressed into a cylindrical bar under 150 MPa. The pressed samples were pre-sintered at 1300 oC for 1 hour under hydrogen to make a skeleton structure. This skeleton structure was more homogeneous than that formed by using W and Cu powder mixtures. The skeleton structures were infiltrated with Cu under hydrogen atmosphere. The infiltrated W-Cu pseudo-alloy showed homogeneous microstructure without Cu rich region.

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Microhomogeneity and Sintering of W-Cu Composite Powders Produced by Hydrogen Reduction

Cited by 16 publications

References 0 publications

Reduction Behavior of W and Cu Oxides Powder Mixture

Reduction Behavior of W and Cu Oxides Powder Mixture

Synthesis of Nano Metal Powder by Electrochemical Reduction of Iron Oxides

Enhancement of Microstructural Homogeneity of W-Cu Pseudo-Alloy by Adding W-Cu Composite Powder in Infiltration Process

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