• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.826-827
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• 2006

Copper infiltration is demonstrated as a viable solution to achieve higher mechanical properties by filling the interconnected porosities of a ferrous structure with copper infiltrant. This paper will present the results of a design of experiments study based on the selected processing variables in the copper infiltration process. The variables are the following: Infiltrating temperatures, infiltrating time at pre-heat zone and hot zone, the green density of iron part, the migration of copper into the iron part at different processing conditions. The results show the flexibility of the infiltration process to attain certain mechanical properties by changing the processing conditions.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.922-923
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• 2006

Thermal management is one of the critical aspects in the design of highly integrated microelectronic devices. The reliability of electronic components is limited not only to operating temperature but also by the thermal stresses caused during the operation. The need for higher power densities calls for use of advanced heat spreader materials. A copper diamond composite has been developed with high thermal conductivity $(\lambda)$ and tailorable coefficient of thermal expansion (CTE). Copper diamond composites are processed via gas pressure assisted infiltration with different copper alloys. Emphasis has been placed on the addition of trace elements in deisgning the copper alloys to facilitate a compromise between thermal conductivity and mechanical adhesion. The interfaces between the alloy and the diamond are related to the thermal properties of these copper composites.

• 한국어병학회지
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• 제30권2호
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• pp.115-134
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• 2017

A total number of 668 apparently healthy fish were obtained from farm to study the effect of two heavy metals (Copper and Mercury) on histopathology of liver, kidney, spleen, gills and muscles also residues in muscles. The $LC_{50}$/96 hr. of Cu and Hg were estimated and fish exposed to 1/2 $LC_{50}$ for 7 days and for 1/10 $LC_{50}$ for 8 weeks from each product separately. Histopathological findings in acute and chronic mercuric chloride toxicity revealed degeneration and necrosis in the glomeruli, interstitium tissue and epithelium lining renal tubules. The tubular epithelium became necrotic at several places. Eosinophilic hyaline droplets is exist in the cytoplasm of the necrosed cells. Degenerative changes and hyperactivity in melanomachrophage center was seen in the spleen together with some necrotic areas. Necrosis and aggregation of melanomachrophage were seen in the hepatic cells, Hepatic cells showed vacuolar degeneration in the hepatic cells. Gills showed loss in the lamellae of the filaments associated with edema, inflammatory cells infiltration and haemorrhages in the arch. The sarcoplasm of the bundles of the skeletal muscle showed granular degeneration and focal inflammatory cells infiltration between the hyalinized bundles. Mercury residues obtained from these studies in the acute toxicity were 0.22 ppm/gm in the 2nd day, 0.411 ppm/gm in the $5^{th}$ day ended with 0.96 ppm/gm in the $7^{th}$ day. In chronic toxicity it was 1.1320, 1.7140, 2.3620 and 3.5640 ppm/gm respectively from the $2^{nd}$ to the $8^{th}$ week of exposure. In acute and chronic copper toxicity, there was degenerative changes in renal tubules. Melanophores aggregation in the wall of the blood vessels of the spleen and depletion of some of the melanophores in the melanomachrophage were seen together with necrosis in some areas. Congested Mvs (Micro vessels) and vacuolation of hepatocytes were observed. Some areas of hemorrhage and melanophores vacuolar degeneration in the liver were seen. There was mitosis in some areas with displesia of hepatopancreatic cells and eosinophilic granular cells aggregation. Zymogen granules disappeared and there were dyplastic hepatocytes. Congestion in the blood vessels of the gill filaments, associated with massive number of granular eosinophilic cells infiltration were seen in the base of the filaments. There were sever vacuolization and hyalinization in the skeletal muscle bundles. Detection of residues of copper sulfate revealed increase of the amount of copper measured in ppm/gm comparing to the normal control starting from 0.60 ppm/g in the $2^{nd}$ day, 0.67 ppm/g in the $5^{th}$ day and 0.67 ppm/g in the $7^{th}$ day. Result obtained in chronic copper sulfate toxicity revealed gradual increase of the amount of copper which ranged from 0.18 ppm/g at the $2^{nd}$ week to 0.21 ppm/g in the $8^{th}$ week of exposure.

• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.399-405
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• 2020

Hollow copper oxide/multi-walled carbon nanotubes (CuO/MWCNT) composites were fabricated via an optimized infiltration-reduction-oxidation method, which is more facile and easy to control. The crystalline structure and morphology were characterized by X-ray diffraction (XRD), and transmission electron microscopy (TEM). The as-prepared CuO/MWCNT composites deliver an initial capacity of 612.3 mAh·g^-1 and with 80% capacity retention (488.2 mAh·g^-1) after 100 cycles at a current rate of 0.2 A·g^-1. The enhanced electrochemical performance is ascribed to the better electrical conductivity of MWCNT, the hollow structure of CuO particles, and the flexible structure of the CuO/MWCNT composites.

• Advanced Composite Materials
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• 제18권4호
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• pp.381-394
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• 2009

The kinetics of centrifugal infiltration of fibrous tubular preform is built theoretically, and simulations are conducted to study the effects of various casting conditions on infiltration kinetics and macrosegregation by combining with the energy, mass and kinetic equations. A similarity way is used to simplify the one-dimensional model and the parameter is ascertained by an iterative method. The results indicate that the increase of superheat, initial preform temperature, porosity tends to enlarge the remelting region and decrease copper solute concentration at the infiltration front. Higher angular velocity leads to smaller remelting region and solute concentration at the tip. The pressure in the infiltrated region increase significantly when the angular velocity is much higher, which requires a stronger preform. It is observed that the pressure distribution is mainly determined by the angular velocity, and the macrosegregation in the centrifugal casting is greatly dependent on the superheat of inlet metal matrix, initial temperature and porosity of the preform, and the angular velocity.

• 한국주조공학회지
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• 제23권5호
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• pp.244-250
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• 2003

The aim of this study is fabricating of composite filler metal (CFM) by a combination of selective laser sintering (SLS) of stainless steel powders (RapidSteel $2.0^{TM}$ and liquid phase infiltration of Ag-28 wt.%Cu alloy. Porous stainless steel body with inter-connected pore channels was fabricated by SLS, binder decomposing and densification processes. By the direct contact infiltration, the narrow inter-particle channels of the porous body were completely filled with the Ag-28 wt.%Cu alloy infiltrant. During infiltration, the dissolved elements of Fe, Ni and Cr from the porous body were solved into copper solid solution phases, which consist of eutectic structure of composite metal matrix. The S10C/CFM/S10C joints, which have narrow clearance gaps between them up to 10 micrometers, were joined successfully by self-feeding of filler metal from the matrix of CFM. The CFM kept its original thickness and microstructure after brazing. The tensile strength of brazed specimen was higher than 30 kgf/$mm^2$ and showed a typical ductile fracture mode in the CFM.

• 한국분말재료학회지
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• 제26권2호
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• pp.112-118
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• 2019

Infiltration is a popular technique used to produce valve seat rings and guides to create dense parts. In order to develop valve seat material with a good thermal conductivity and thermal expansion coefficient, Cu-infiltrated properties of sintered Fe-Co-M(M=Mo,Cr) alloy systems are studied. It is shown that the copper network that forms inside the steel alloy skeleton during infiltration enhances the thermal conductivity and thermal expansion coefficient of the steel alloy composite. The hard phase of the CoMoCr and the network precipitated FeCrC phase are distributed homogeneously as the infiltrated Cu phase increases. The increase in hardness of the alloy composite due to the increase of the Co, Ni, Cr, and Cu contents in Fe matrix by the infiltrated Cu amount increases. Using infiltration, the thermal conductivity and thermal expansion coefficient were increased to 29.5 W/mK and $15.9um/m^{\circ}C$, respectively, for tempered alloy composite.

• 대한수의학회지
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• 제23권1호
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• pp.69-79
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• 1983

The present studs was undertaken to observe the histopathological changes on the cardiac and skeletal muscles, and liver of rabbits fed a commercial ration, either alone or with supplements of Zinc (3,000mg/kg. of diet, as sulfate), Copper (1,500mg/kg. of diet, as sulfate), Linoleic acid (3% of diet), Zinc with Linoleic acid and Copper with Linoleic acid. In the skeletal muscle, light microscopic changes observed were cloudy swelling, hyaline degeneration, atrophy, fragmentation and coagulative necrosis of muscle fibers, and proliferation of fibroblasts and infiltration of mononuclear cells. Especially, in rabbits fed with supplements of Zinc with Linoleic acid and Copper with Linoleic acid, calcification with muscle fibers progressing to necrosis were often observed. In the myocardium, loss of muscle fibers with necrosis and vacuolization, hyaline degeneration, hemorrhage and congestion were observed. In the liver, congestion and necrosis of hepatocytes, and centrilobular necrosis were observed. Differences of histological changes among the experimental groups was not marked.

• Journal of the Korean Wood Science and Technology
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• 제43권1호
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• pp.112-121
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• 2015

국내에서 사용되고 있는 가압주입 처리용 구리 붕소 아졸화합물계의 목재 방부제 Copper Azole (CuAz)의 목재내 주입량별 부후 특성을 조사하였다. 여러 가지 주입량으로 CuAz-2 방부제를 가압주입한 시편을 이용하여 갈색부후균인 부후개떡버섯에 의한 방부효력시험을 실시한 후 질량감소율을 측정하였다. 또한, CuAz-2 처리 시편을 부후개떡 버섯으로 부후시킨 후 광학현미경과 전자현미경으로 부후 특성을 관찰하였다. 그 결과, 부후개떡버섯에 의한 무처리재는 40% 이상의 질량감소율을 보여주었고 실내 부후에 의한 CuAz-2 약제의 방부효력을 나타내는 값은 $1.79{\sim}3.32kg/m^3$이었다. CuAz-2의 주입량에 따라 횡단면, 방사단면, 접선단면에서의 목재조직은 무처리 시편과 비교하여 부후 정도가 다르게 나타났다. 횡단면에서는 조재와 만재부분에서 수직수지구, 방사조직의 부후가 많이 관찰되었고, 방사단면에서는 방사가도관, 방사유세포, 벽공 부분이 부후되어 파괴되었고, 접선단면에서는 방사조직, 수평수지구가 심하게 부후되었다. 따라서 본 연구에서 주입량에 따른 부후 현상이 크게 차이가 난 점 등을 고려하여, 현재의 CuAz-2 주입량에 대한 적정성 검토가 국내 환경에 대해서 이루어져야 할 것으로 생각된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1994년도 추계학술대회 논문집
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• pp.169-175
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• 1994

This study attempts to develop a process which can produce three-dimensional shapes of metals directly from CAD data. Prototypes made from metals, can not only be used to test the mecchanical properties of the product, but also potentially become the actual die or product itself. The test-device of the process has been designed and manufactured. The laser scanning method using a scanning path schedule composed of circle and arc elements, scanning speed variation method and dwell method have been developed, which resist warping phenomenon and increase the adhesiveness between the layers. For the production of prototypes with pure iron powder, the optimal values of the principal process parameters have been determined, through which cross-shaped and twisted clover-shaped prototypes have been fabricated. In order to improve the strength of the prototype, the experimental studies of solid-phase sintering, and copper infiltration have been done.