• Fire Science and Engineering
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• v.15 no.1
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• pp.108-115
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• 2001

In this paper, we analyzed the properties change of electric wire when the thermal stress was applied to 600V grade polyvinyl chloride insulated wire (IV). In the structure analysis, normal wire has the properties of direction on the surface, but in case of deteriorated wire at above $400^{\circ}c$, it formed the carbide, the crack and the crystal. The surface composition rate of normal wire was Cu : 100%, but the section composition of the deteriorated wire at $800^{\circ}c$ showed Cu : 78.89%, O : 21.11%. In result of analyzing the differential scanning calory of copper wire, the new reaction peak was observed on the deteriorated wire at above $700^{\circ}c$. In case of the deteriorated wire as $150^{\circ}c$ at the differential thermal analysis, an endothermic reaction appeared at $264^{\circ}c$ lower than the reactive point of normal wire. The occupation rate of oxygen according to the deterioration of copper wire is about 20% at $500^{\circ}c$.

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.683-686
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• 2011

The effect of welding material such as welding wires and materials for contact tip on the contact tip wear was investigated. Two types welding wires such as solid and flux cored wire and a variety of contact tips made of Cu-P, Cu-Cr(0.25%), Cu-Cr(1%) and Cu-Cr-Zr were employed for the comparison of wear resistance. It was found that the wear resistance of contact tips materials was Cu-Cr-Zr, Cu-Cr(1%), Cu-Cr(0.25%), Cu-P in order while the solid wire had a better wear resistance than flux cored wire.

• Korean Journal of Materials Research
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• v.12 no.12
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• pp.941-946
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• 2002

Both Cu and Cu-oxide nanopowders have great potential as conductive paste, solid lubricant, effective catalysts and super conducting materials because of their unique properties compared with those of commercial micro-sized ones. In this study, Cu and Cu-oxide nanopowders were prepared by Pulsed Wire Evaporation (PWE) method which has been very useful for producing nanometer-sized metal, alloy and ceramic powders. In this process, the metal wire is explosively converted into ultrafine particles under high electric pulse current (between $10^4$ and $10^{ 6}$ $A/mm^2$) within a micro second time. To prevent full oxidations of Cu powder, the surface of powder has been slightly passivated with thin CuO layer. X-ray diffraction analysis has shown that pure Cu nanopowders were obtained at $N_2$ atmosphere. As the oxygen partial pressure increased in $N_2$ atmosphere, the gradual phase transformation occurred from Cu to $Cu_2$O and finally CuO nanopowders. The spherical Cu nanopowders had a uniform size distribution of about 100nm in diameter. The Cu-oxide nanopowders were less than 70nm with sphere-like shape and their mean particle size was 54nm. Smaller size of Cu-oxide nanopowders compared with that of the Cu nanopowders results from the secondary explosion of Cu nanopowders at oxygen atmosphere. Thin passivated oxygen layer on the Cu surface has been proved by XPS and HRPD.

• Journal of Powder Materials
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• v.17 no.4
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• pp.270-275
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• 2010

Ethylene glycol-based Cu nanofluids were prepared by pulsed wire evaporation (PWE) method. The structural properties of Cu nanoparticles were studied by X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM). The average diameter and Brunauer Emmett Teller (BET) surface area of Cu nanoparticles were about 100 nm and $7.46\;m^2/g$, respectively. The thermal conductivity and viscosity of copper nanofluid were measured as functions of Cu concentration and temperature. As the volume fraction of Cu nanoparticles increased, both the enhanced ratios of thermal conductivity and viscosity of Cu nanofluids increased. As the temperature increased, the enhanced ratio of thermal conductivity increased, but that ratio of viscosity decreased.

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.34-36
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• 2005

Copper wire bonding is an alternative interconnection technology that serves as a viable and cost saving alternative to gold wire bonding. In this paper, ultrasonic wedge bonding with $25{\mu}m$ copper wire on Au/Ni/Cu metallization of a PCB substrate was performed at ambient temperature. The central composite design of experiment (DOE) approach was applied to optimize the copper wire wedge bonding process parameters. After that, pull test of the wedge bond was performed to study the bond strength and to find the optimum bonding parameters. SEM was used to observe the cross section of the wedge bond. The pull test results show good performance of the wedge bond. Additionally, DOE results gave the optimized parameter for both the first bond and the second bond. Cross section analysis shows a continuous interconnection between the copper wire and Au/Ni/Cu metallization. The diffusion of Cu into the Au layer was also observed.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.1
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• pp.78-85
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• 1999

Burning characteristics of solid propellants embedded with four kinds of metal wires(Ag, Cu, Al, Ni-Cr wire) were studied with varying wire diameters(O.10.8 mm) lot N-5 propellant. It was found that the order of the burning rate increment ratio($r_w$/$r_sb$) was Ag wire > Cu wire > Al wire> Ni-Cr wire which was the same as the order of the magnitude of thermal diffusivity. The burning rate increment ratio($r_w$/$r_sb$) of N-5 propellant was less than that of composite Propellant because of the difference of adiabatic flame temperature and flame structure. When Ag, Cu and Al wire having high thermal diffusivity were embedded in N-5 propellant, the plateau and mesa characteristics of the double base propellant were disappeared, but not disappeared in the case of propellant embedded with Ni-Cr wire due to its poor thermal conductivity.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.05a
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• pp.432-434
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• 2009

Metal nano-wire arrays on Cu-coated seed layers were fabricated by aqueous solution method using sulfate bath at room temperature. The seed layers were coated on Anodic aluminum oxide (AAO) bottom substrates by electrochemical deposition technique, length and diameter of metal nano-wires were dominated by controlling the deposition parameters, such as deposition potential and time, electrolyte temperature. Anodic aluminum oxide (AAO) was used as a template to prepare highly ordered Ni, Fe, Co and Cu multilayer magnetic nano-wire arrays. This template was fabricated with two-step anodizing method, using dissimilar solutions for Al anodizing. The pore of anodic aluminum oxide templates were perfectly hexagonal arranged pore domains. The ordered Ni, Fe, Co and Cu systems nano-wire arrays were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and Vibrating Sample Magnetometer (VSM). The ordered Ni, Fe, Co and Cu systems nano-wires had different preferred orientation. In addition, these nano-wires showed different magnetization properties under the electrodepositing conditions.

• Journal of Powder Materials
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• v.11 no.1
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• pp.60-68
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• 2004

Pulsed wire evaporation (PWE) method is known as the promising production-technique for nanopowders. In this study, we developed and modified the previous single wire explosion equipment to the simultaneous two-wire explosion one for the fabrication of alloy or mixture of nano metallic powder. First of all, both the theoretical and empirical background of pulsed wire explosion of single wire were summarized, and compared with our experimental results for Cu and Al single wlre explosion. After then, the simultaneous wire evaporation equipment was designed, constructed, and tested. The current and voltage behavior were well matched between the calculated ones from the circuit equations, and the experimental results from simultaneous explosion of Cu and Al wire.

• Journal of the Korean Ceramic Society
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• v.27 no.3
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• pp.355-360
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• 1990

One of the possible ways to make a flexible wire of high-Tc superconductiong ceramics is the extrusion of a mixture slurry of superconducting powder with an appropriate polymer binder. The fabrication procedure for $YBa_2Cu_3O_{7-{\delta}}$ superconducting coils with this plastic mass is described. The major factors limiting the formation of extruded wire are the binder content, powder size, and entrapped gas in the mixture slurries. The optimum content of binder for both good flexbility and strength of wire was estimated to be 30wt%. The finer the powder size is, the more homogeneous structure the extruded wire has. The vacuum degassing before extrusion was necessary to remove the entrapped gas in as-extruded wire. The formability of wire depends greatly on the wire radius and binder content. After burning out the binder and the successive sintering, the contacts between the superconducting grains could be made. The resistivity vs. temperature behavior measured in the final wire showed the transition temperature of 90K with narrow transition width. However, the critical current densities of these wires are much lower in comparison to those of conventional bulk specimens.

• Progress in Superconductivity and Cryogenics
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• v.24 no.3
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• pp.30-34
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• 2022

Effects of electron beam (EB) irradiation on the mechanical strength of Cu (conducting sheath) and Nb (diffusion barrier) of Cu/Nb/MgB₂ superconducting was investigated. Wire- and tape-type Cu/Nb/MgB₂ samples were irradiated at E-beam energy of 2.5 MeV and 5 mA and a maximum E-beam dose was 5×10¹⁷ e/m². The hardness value of Cu and Nb region was measured by the Vickers micro-hardness method. In the case of the wire sample, the hardness of Cu and Nb increased proportionally as the dose was increased up to 5×10¹⁷ e/m², whereas in the case of the tape sample, the hardness increased up to a dose of 0.5×10¹⁷ e/m², and decreased slightly 5×10¹⁷ e/m². The hardness increase of Cu and Nb is believed to be due to the decrease of the deformability of Cu and Nb due to the defects formed inside the materials by E-beam irradiation.