• 동력기계공학회지
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• 제10권3호
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• pp.58-66
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• 2006

The effect of bath composition, plating condition and plating rate on the magnetic properties of electroless Ni-Cu-P deposits were investigated. With increasing $CuSO_4$ concentration in the bath, plating rate increased, while the Br value of deposits decreased Sharply. Plating rate increased up to 34% with the addition of 200ppm of NaF and 0.8ppm of Thiourea to the bath. Plating reaction had been ceased by the increase of pH above 11.3, bath temperature higher than $90^{\circ}C$ and under $70^{\circ}C$. The Br value of deposit was uniform with various concentration of complexing agent (Sodium citrate, Ethylenediamine) in the bath. The Br value of deposit was almost equal to that found by the addition of stabilizer(Thiourea) and accelerator(NaF). The Br value of deposit was uniform in plating time(120 min) and heat treatment temperature(below $200^{\circ}C$), and were confirmed to have adequate bath stability for practical use.

• 한국재료학회지
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• 제11권4호
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• pp.300-304
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• 2001

Al-Cu-Mn 주조합금의 피로성질에 미치는 Cd 첨가의 영향을 저주기 및 고주기 피로시험을 통하여 조사하였다. Cd 첨가량이 증가함에 따라 피로수명이 증가하였으며, 인장강도도 증가하였다. 고주기 피로시험결과 피로강도는 115MPa이었으며 피로비는 0.31이었다. 피로시험 결과 균열이 표면에서 발생하여 입계를 따라 전파되었는데 이러한 입계파괴는 입계를 따라 존재하는 무석출대의 영향으로 생각된다. 인장강도값은 Cd이 첨가되지 않았을 경우 330MPa이었으나 0.15%의 Cd이 첨가됨으로써 401MPa 까지 증가되었다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.495-496
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• 2008

The magnetic characteristics of Mg-Zn ferrite that was fired at $1150^{\circ}C$ for 1hour and sintered at $1250^{\circ}C$ for 3hours was examined. The composition ratio of the ferrite was changed after sintering. In that case the composition ratio of ${Fe_2}{O_3}$ was increased but that of CuO was decreased. When the addition quantity of CuO was 3.8 mole%, it's shrinkage rate had maximum value. Magnetic permeability was decreased as the addition rate of CuO was increased and MgO was decreased. When the composition rate of CuO was 2.3 mol% and MgO was 10.9 mol%, the firing density had maximum value. In case that CuO was 2.8mol% and MgO was 10.4mol%, PL had minimum value.

• 한국재료학회지
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• 제16권4호
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• pp.257-263
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• 2006

We have investigated the effect of silver added to Cu films on the microstructure evolution, resistivity, surface morphology, stress relaxation temperature, and adhesion properties of Cu(Ag) alloy thin films deposited on Mo glue layer upon annealing. In addition, pure Cu films deposited on Mo has been annealed and compared. The results show that the silver in Cu(Ag) thin films control the grain growth through the coarsening of its precipitates upon annealing at $300^{\circ}C{\sim}600^{\circ}C$ and the grain growth of Cu reveals the activation energy of 0.22 eV, approximately one third of activation energy for diffusion of Ag dopant along the grain boundaries in Cu matrix (0.75 eV). This indicates that the grain growth can be controlled by Ag diffusion along the grain boundaries. In addition, the grain growth can be a major contributor to the decreased resistivity of Cu(Ag) alloy thin films at the temperature of $300^{\circ}C{\sim}500^{\circ}C$, and decreases the resistivity of Cu(Ag) thin films to $1.96{\mu}{\Omega}-cm$ after annealing at $600^{\circ}C$. Furthermore, the addition of Ag increases the stress relaxation temperature of Cu(Ag) thin films, and thus leading to the enhanced resistance to the void formation, which starts at $300^{\circ}C$ in the pure Cu thin films. Moreover, Cu(Ag) thin films shows the increased adhesion properties, possibly resulting from the Ag segregating to the interface. Consequently, the Cu(Ag) thin films can be used as a metallization of advanced TFT-LCDs.

• 한국분말재료학회지
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• 제18권1호
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• pp.24-28
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• 2011

Effect of Cu content on microstructural and magnetic properties of a $(Nd_{26.06},Dy_{6.51})Fe_{bal.}$ $Cu_xB_{0.97}$(wt.%), (x = 0.2, 0.3, 0.4, 0.5) strip-cast was studied. The average inter-lamellar spacing in the free surface and wheel side of the strip cast increased as the Cu content increases. The grain uniformity, the grain alignment, and (00L) texture of the strip cast increased with Cu contents up to 0.4 wt.%. These microstructural changes were attributed to the decrease of the effective cooling rate of the melted alloy caused by the decrease of the melting temperature of resulting from Cu addition. Coercivity and remanence were increased because of the grain alignment and (00L) texture improvement with Cu contents up to 0.4 wt.%.

• 한국초전도ㆍ저온공학회논문지
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• 제25권2호
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• pp.5-9
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• 2023

The effect of La_0.7Sr_0.3MnO₃ (LSMO) addition on the superconducting property of Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O_10+δ ((Bi, Pb)-2223) polycrystalline samples was studied. LSMO (0.3 wt.% to 2.0 wt.%) added (Bi, Pb)-2223 samples were prepared by using a solid-state reaction method. The XRD analyses show that as the LSMO addition increases, the volume fraction of the Bi-2223 phase is gradually decreased. The critical temperature (T_c) exhibits a gradual decrease with a single transition as the LSMO amount increases up to 1.0 wt.%, but a further addition of LSMO induces an abrupt decrease of T_c with a dual transition. The analyses on the local structure of the CuO₂ plane from the X-ray absorption fine structure (EXAFS) measurements showed that for the samples with low concentration of LSMO up to 1.0 wt.%, the Cu-O bond length and the CuO₂ plane ordering do not degrade from the values of pure (Bi, Pb)-2223, while they get worsen with a further increase of LSMO addition. These results open up the possibility of LSMO as artificial pinning centers of the (Bi, Pb)-2223 system for power application.

• 한국주조공학회지
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• 제30권5호
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• pp.161-166
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• 2010

In this examination, the effect of Sr addition and holding time on microstructure of Al-10.5wt%Si-2wt%Cu secondary die-casting alloy was investigated. Degree of undercooling was improved with increasing the Sr content in this alloy. Up to 0.02wt%Sr addition, acicular and lamellar eutectic structure was observed in the microstructure. Meanwhile, the eutectic Si was modified toward the fine fibrous form by increasing Sr content with more than 0.03wt% and holding time of the melt. The well- modified alloys showed decreased eutectic silicon size from 3.25 ${\mu}m$ to less than 0.8 ${\mu}m$. From these results, the optimal strontium content and holding time were identified on the Al-10.5wt%Si-2wt%Cu secondary die-casting alloy.

• 대한금속재료학회지
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• 제48권3호
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• pp.248-255
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• 2010

The effect of various alloying elements and melt treatment on the microstructural control of Al-Sn metallic bearing alloy was investigated. The thickness of tin film crystallized around primary aluminum decreased with the addition of 5% Cu in Al-Sn alloy, with tin particles being reduced in size by intervening the Ostwald ripening. With the addition of Si in Al-10%Sn alloy, the tin particles were crystallized with eutectic silicon, resulting in uniform distribution of tin particles. With the addition of Cu and Si in Al-Sn alloy, both the tensile strength and yield strength increased, with the increasing rate of yield strength being less than that of tensile strength. Although the Al-10%Sn-7%Si alloy has similar tensile strength compared with Al-10%Sn-5%Cu, the former showed superior abrasion resistance, resulting from preventing the tin particles from movement to the abrasion surface.

• 동력기계공학회지
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• 제12권3호
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• pp.72-77
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• 2008

This study was investigated to know the effect of Cu addition on austempered ductile cast iron at various temperatures and times. Test results showed that the volume fraction of retained austenite and the carbon contents of retained austenite showed the greatest value at $400^{\circ}C$. Also, in case of specimens having more Cu contents, the volume fraction of retained austenite and the carbon contents of retained austenite showed the lower value. After austempering treatment, tensile strength and Impact value increased, but elongation decreased. With increasing austempering treatment temperature, tensile strength, elongation, and impact value decreased. In case of specimen having more Cu contents, tensile strength showed the higher value, but elongation showed the lower value. Damping capacity was decreased by austempering treatment and was not affected on austempering temperature and time. In case of specimen having more Cu contents, damping capacity showed the higher value.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제48권4호
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• pp.221-225
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• 1999

This paper shows the parameters to affect the critical characteristic of YBaCuO superconducting bulk fabricated by MPMG (Melt Powdered Melt Growth)process. In order to investigate proper processing variables, the effect of the holding time at the melting temperature and that of the slow cooling time in $O_2\; ambient\; on\; the\; J_c$ were experimented. And then with the above obtained heat treatment conditions, the effects of addition of $Y_2BaCuO_5\; and\; Ag\; on\; the\; J_c$ were also investigated. A proper slow cooling time yields phase transformation from Tetragonal $(YBa_2Cu_3O_6)$ to Orthorhombic $(YBa_2Cu_3O_7)$ during an annealing time in $O_2$. Ag addition plays a role in increasing the $T_c\; and\; the J_c$, but the magnetization decreases. The $J_c$ and the magnetization increase with addition of Y211. $J_c$ of the sample added Ag 10wt% is superiorover 3000 G. Proper holding time, slow cooling time and amount of impurity addition are important parameters in fabricating the YBaCuO bulk by MPMG process with high $J_c$.