• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.301-301
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• 2003

In current study, Nanocomposites are reinforced with carbon nanofiber, carbon nanotube and SiC, etc. Since the nano reinforcements have the excellent mechanical, thermal and electrical properties compared with that of existing composites, it has lately attracted considerable attention in the various areas. Cu have been widely used as signal transmission materials for electrical electronic components owing to its high electrical conductivity. However, it's size have been limited to small ones due to its poor mechanical properties. Until now, strengthening of the copper alloy was obtained either by the solid solution and precipitation hardening by adding alloy elements or the work hardening by deformation process. Adding the alloy elements lead to reduction of electrical conductivity. In this aspect, if carbon nanofiber is used as reinforcement which have outstanding mechanical strength and electric conductivity, it is possible to develope Cu matrix nanocomposite having almost no loss of electric conductivity. It is expected to be innovative in electric conducting material market. The unidirectional alignment of carbon nanofiber is the most challenging task developing the cooer matrix composites of high strength and electric conductivity. In this study, the unidirectional alignment of carbon nanofibers which is used reinforced material are controlled by drawing process and align mechanism as well as optimized drawing process parameter are verified via numerical analysis. The materials used in this study were pure copper and the nanofibers of 150nm in diameter and of 10∼20$\mu\textrm{m}$ in length. The materials have been tested and the tensile strength was 75MPa with the elongation of 44% for the copper. it is assumed that carbon nanofiber behave like porous elasto-plastic materials. Compaction test was conducted to obtain constitutive properties of carbon nanofiber Optimal parameter for drawing process was obtained by analytical and numerical analysis considering the various drawing angles, reduction areas, friction coefficient, etc. The lower drawing angles and lower reduction areas provides the less rupture of co tube is noticed during the drawing process and the better alignment of carbon nanofiber is obtained.

• 한국환경보건학회지
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• 제19권2호
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• pp.46-54
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• 1993

This study was carried out on the stabilized/solidified treatment for the reducing leachability of hazardous heavy metals copper, lead, chromium and cadmium in the hazardous sludge which treated to be unleached heavy metals by sodium diethyl dithiocarbamate. Cement matrix was analyzed for the leachability of 24 hrs and dynamic leaching test, structure and the optimum condition for the stabilization and solidification of the hazardous sludge. In 28 days of curing time the unconfined compressive strength was 21.5 kg/cm$^2$ at the ratio of portland cement (0.5)+fly ash (0.25) and 23.5 kg/cmz at the ratio of portland cement (0.5)+fly ash (0.25) + cake (0.25). High concentration of Pb, Cr and Cd in the sea water and Cu in the distilled water were leached at the dynamic leaching test. The concentration of leaching heavy metals for specimens which were tested 24 hrs were found low leachability with decreasing pH of leachant. According to dynamic leaching test, the low level of copper, lead, cadmium and chromium were leached in the cement matrix with sodium diethyl dithiocarbamate. But the effective diffusion coefficient of unleached cement matrix which was treated sodium diethyl dithiocarbamate was decreased above 2 times than that of cement matrix. The relation of leachant renewal period (Y) and cumulative fraction ion leached (X) was the following regression equations. Solidification with unleached agent. Y$_{Cu}$ = 1413752X + 247, Y$_{Pb}$ = 223501IX + 214, Y$_{Cr}$ = 8310601X - 472, Y$_{Cd}$ = 168787X + 1061 The structure of' solidified matrix with X-ray diffraction analysis was composed more Ca(OH)$_2$, Si, Mg(OH)$_2$ and Al in the unleached cement matrix than those in cement matrix.

• 한국재료학회지
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• 제28권12호
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• pp.691-695
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• 2018

In this study, we investigate the recycling of aluminum-based metal matrix composites(AMCs) embedded with SiC particulates. The microstructure of the AMCs is characterized by X-ray diffraction and scanning electron microscopy. The possibility of recycling the composite scrap is attempted from the melted alloy and SiC particulates by re-melting, holding and solidification in crucibles. The recovery percentage of the matrix alloy is calculated after a number of holding times, 0, 5, 10, 15, 20, 25 and 30 minutes and for different particulate sizes and weight fractions in the Al matrix. The results show that the recovery percentage of the matrix alloy, as well as the time required for maximum recovery of the matrix, is dependent on the size and weight fraction of SiC particulates. In addition, the percentage recovery increases with particulate size but drops with the particulate fraction in the matrix. The time to reach maximum recovery falls rapidly with an increase in particulate size and fraction.

• 한국재료학회지
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• 제11권5호
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• pp.398-404
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• 2001

SiC 보강재 표면에 도금된 Cu금속층이 Al/SiC복합재료의 젖음성에 미치는 영향을 검토하였다. 보강재에 대한 금속층의 도금은 무전해도금법을 이용하였으며, Al/SiC 복합재료의 제조는 텅스텐 발열체 진공로의$ 670^{\circ}C$~$900^{\circ}C$에서 제조하여 보강재와 기지간의 접촉부위를 촬영하여 젖음성을 측정하였다 젖음성 측정 결과 보강재에 도금된 Cu층은 젖음성을 향상시켰고, 젖음성의 개선은 보강재에 도금된 금속층과 기지간의 반응에 의해 계면에너지를 변화시킴으로서 나타난 결과이며. 반응을 통한 산화피막의 배제도 영향을 미친 것으로 판단된다

• 열처리공학회지
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• 제37권2호
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• pp.79-85
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• 2024

The effects of annealing heat treatment and the addition of Cu element on the shape memory effect of the NiTi-based alloy were investigated by analyzing differential scanning calorimeter results and characterizing recovery rate through 3D scanning after Vickers hardness test. Through 3D scanning of impressions after Vickers hardness test, the strain recovery rates for specimens without annealing treatment and annealed specimens at 400, 450, and 500℃ were measured as 45.96%, 46.76%, 52.37%, and 43.57%, respectively. This is because as the annealing temperature increases, both B19' and NiTi₂ phases, which can impede martensitic transformation, are incorporated within the NiTi matrix. Particularly, additional phase transformation from R-phase to B19' observed in specimens annealed at 400 and 450℃ significantly contributes to the improvement in strain recovery rates. Additionally, the results regarding the Cu element content indicate that when the total content of Ni and Cu is below 49.6 at.%, the precipitation of fine B19' and NiTi₂ phases within the matrix can greatly influence the transformation enthalpy and temperature range, resulting in relatively lower strain recovery rates in NiTi alloys with a small amount of Cu element produced in this study.

• 대한의용생체공학회:의공학회지
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• 제24권3호
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• pp.203-208
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• 2003

인듐함량에 따른 Au-Pt-Cu 삼원계합금의 미세조직 및 기계적 특성을 광학현미경, 시차주사열분석기, SEM, XRD, EPMA 그리고 미소경도계를 이용하여 조사하였다. 인듐함량이 0.5 wt% 인 Au-Pt-Cu-0.5In 사원계 합금을 온도범위 150~95$0^{\circ}C$에서 열처리한 결과 55$0^{\circ}C$/3O분 열처리한 시료의 경도 값이 가장 높게 나타났고, 55$0^{\circ}C$에서 시효시간을 증가시킴에 따라 30분에서 최고 경도치에 도달된 후 거의 일정하게 유지되었다 또한, 55$0^{\circ}C$에서 30분 동안 시효 처리한 Au-Pt-Cu 삼원계합금의 미세조직은 인듐 함량이 증가함에 따라 결정립이 미세화 되었다. XRD, EPMA을 이용하여 Au-Pt-Cu-In 사원계 합금에 존재하는 석출상을 분석한 결과 모상은 fcc구조를 갖는 Au-Pt-Cu 고용체, 석출상은 Ll$_2$구조를 갖는InPt$_3$ 석출물로 판명되었다. 이러한 연구결과로부터 인듐 함량에 따른 Au-Pt-Cu-In 합금의 경도증가는 결정립 미세화에 의한 강화 효과와 InPt$_3$ 형태의 석출물에 의한 석출강화 효과에 기인하는 것으로 해석된다.

• 한국분말재료학회지
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• 제17권6호
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• pp.477-481
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• 2010

Cu-Sn based alloys were manufactured by gas atomization spray casting route in order to achieve a fine scale microstructure and a high tensile strength. The spray cast Cu-10Sn-2Ni-0.2Si alloy had an equiaxed grain microstructure, with no formation of brittle ${\delta}-Cu_{41}Sn_{11}$ phase. Aging treatment promoted the precipitation of finely distributed particles corresponding to ${\delta}-Ni_2Si$ intermetallic phase throughout the $\alpha$-(CuSn) matrix. The cold-rolled Cu-Sn-Ni-Si alloy had a very high tensile strength of 1200 MPa and an elongation of 5%. Subsequent aging treatment at $450^{\circ}C$ for 1h slightly reduced the tensile strength to 700 MPa and remarkably increased the elongation up to 30%. This result has been explained by coarsening the precipitates due to over aging and reducing the dislocation density due to annealing effects.

• 한국재료학회지
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• 제9권6호
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• pp.569-576
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• 1999

In this study, the effect of the microstructural evolution on the electrical of Cu-Ag microcomposite was investigated. The nature of interfaces between silver filaments and Cu matrix may have pronounced effects on the physical properties of Cu-Ag filamentary microcomposites, little is known about these interfaces. In heavily drawn Cu-Ag filamentary microcomposities, the microstructure is too fine and the interfacial area is too large to maintsin a stable internal dislocation structure because of closely spaced filaments. Rather, most dislocations are thought to be gradually absorbed at the interfaces as the draw ratio increases. The mechanical and electrical properties of Cu-Ag filamentary microcomposites wires were also examined and correlated with the microstructural change caused by thermomechanical treatments. The study on the electrical conductivity combined to resistivity in Cu-Ag filamentary microcomposites and the rapid increase of the electrical conductivity at high annealing temperatures is mainly caused by the dissolution and coarsening of silver filaments. The relatively low ratio of the resistivities is mainly caused by the dissolution and coarsening of silver filaments. The relatively low ratio of the resistivities at 295K($\rho$\ulcorner/$\rho$\ulcorner) in as-drawn Cu-Ag microcomposites can also be explained by the contribution of the interface scattering.

• 분석과학
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• 제31권6호
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• pp.240-246
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• 2018

본 연구에서는 GD-MS를 활용하여 원소 별 함량이 다른 세 종류의 알루미늄 매질의 표준 시료를 분석하였다. 13 종의 원소(Mg, Si, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Ga, Sn, Pb)에 대해 검량 곡선을 작성하고 그 기울기를 RSF(Relative sensitivity reference)로 확립하였다. 검량 곡선은 X축을 IBR(Ion beam ratio)로, Y축을 표준 시료의 인증 값으로 작성하였다. 검량 곡선의 정밀도와 직선성을 평가하기 위해 RSD(Relative standard deviation)와 결정 계수를 계산하였다. 그 결과 모든 원소의 RSD는 10 %이내로 높은 정밀도를 나타냈다. 바나듐, 니켈 그리고 갈륨 원소를 제외한 대부분의 원소들은 결정 계수가 0.99 이상으로 1에 가까운 값을 얻어 직선성이 우수했다. 바나듐, 니켈 그리고 갈륨 원소는 결정 계수가 0.90~0.95 범위로 비교적 낮은 직선성을 나타냈으며, 이는 좁은 농도 범위로 인한 오차로 판단된다. 바나듐, 니켈 그리고 갈륨 원소는 결정 계수는 낮지만 각각의 표준 시료 RSF와 기울기로 확립한 표준RSF(Standard-RSF)가 비슷하여 정량 분석을 위한 RSF로 활용 가능할 것으로 판단된다. 다른 매질의 시료에 표준RSF(Al matrix)를 적용 가능 여부와 실제 표준 값에 대한 오차를 확인하기 위해서 철 매질(Fe matrix)의 표준 시료를 분석하여 검증하였다. 구리 원소를 제외한 6 종(Al, Si, V, Cr, Mn, Ni) 원소의 오차율은 약 30 %로 나타났으며, 구리 원소는 측정을 방해하는 불순물 화합물의 영향으로 오차율이 크게 나타난 것으로 판단된다. 일반적으로 동위원소$^{63}Cu$는 $^{54}Fe^{2+}-^{36}Ar$ 간섭을 받고 $^{65}Cu$는 $^{56}Fe-Al^{3+}$간섭을 받는다. 이를 분해하기 위해서는 8000 이상의 분해능이 필요하다. 하지만, 높은 분해능은 이온의 투과도를 낮추기 때문에 미량원소 분석에 어려움이 있다. 구리 원소를 제외한 알루미늄 외 5종의 원소에 대해서는 비교적 적은 오차로 정량 분석이 가능한 것으로 확인되었다.

• 수산해양기술연구
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• 제53권2호
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• pp.204-209
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• 2017

In order to use PUR/CuO Composites as the sealing materials for ships equipment, this research has been performed. PUR/CuO composites are produced by using ultrasonic waves. The increase of CuO leads to increase in the tensile strength and shore hardness. The cumulative wear volume shows a tendency to increase in proportional to sliding distance. As the CuO particles of these composites indicated, the friction coefficient was slightly increased. The major failure mechanisms were lapping layers, deformation of matrix, plowing, debonding of particles and microcracking by scanning electric microscopy photograph of the wear tested surface.