• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.257-260
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• 2005

Graphite reinforced conductive polymer composites were fabricated by the compression molding technique. Graphite powder was mixed with an phenol resin to impart electrical property in composites. The ratio and particle size of graphite powder were varied to investigate electrical conductivity of cured composites. In this study, graphite reinforced conductive polymer composites with high filler loadings(>66wt.%) were manufactured to accomplish high electrical conductivity. With increasing the loading ratio of graphite powder, the electrical conductivity and flexural strength increased. However. above 80wt.% filler loadings, flexural strength decreased due to lack of resin. Regardless of graphite particle size, electrical conductivity wasn’t varied. On the other hand, with decreasing particle size, flexural strength increased due to high specific surface area.

• Journal of the Korean Society for Heat Treatment
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• v.20 no.6
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• pp.318-322
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• 2007

The high electrical conductivity Cu-0.15% Sn alloys containing various P contents, and the high conductivity and high strength Cu-0.1% Sn-0.1%Ag alloys with various Mg/P additions were fabricated and their mechanical properties and electrical conductivity were investigated. The electrical conductivity was generally decreased as the P content was increased where as the hardness and strength was shown to increase. When Mg was added to P-containing Cu alloys, the detrimental effect of P on the conductivity was significantly reduced, and TEM observations indicated that the formation of $Mg_3P_2$ phase is responsible for this result.

• Design & Manufacturing
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• v.6 no.1
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• pp.95-100
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• 2012

In this study, a novel Cu composite sheet with embedded high electric conduction path was developed as another alternative for the interconnect materials possessing high electrical conductivity as well as high strength. The Cu composite sheet was fabricated by forming Ag conduction paths not within the interior but on the surface of a high strength Cu substrate by damascene electroplating process. As a result, the electrical conductivity increased by 40% thanks to mesh type Ag conduction paths, while the ultimate tensile strength decreased by 20%. The interfacial fracture resistance of Cu composite sheet prepared by damascene electroplating increased by above 50 times compared to Cu composite sheet by conventional electroplating. For feasibility test for practical application, a leadframe for LED module was manufactured by a progressive blanking and piercing processes, and the blanked surface profile was evaluated as a function of the volume fraction of Ag conduction paths. As Ag conduction path became finer, pressing formability improved.

• Journal of Powder Materials
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• v.28 no.3
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• pp.253-258
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• 2021

There is increasing demand for the development of a new material with high strength, high stiffness, and good electrical conductivity that can be used for high-voltage direct current cables. In this study, we develop aluminum-based composites containing C₆₀ fullerenes, carbon nanotubes, or graphene using a powder metallurgical route and evaluate their strength, stiffness, coefficient of thermal expansion, and electrical conductivity. By optimizing the process conditions, a material with a tensile strength of 800 MPa, an elastic modulus of 90 GPa, and an electrical conductivity of 40% IACS is obtained, which may replace iron-core cables. Furthermore, by designing the type and volume fraction of the reinforcement, a material with a tensile strength of 380 MPa, elastic modulus of 80 GPa, and electrical conductivity of 54% IACS is obtained, which may compete with AA 6201 aluminum alloys for use in all-aluminum conductor cables.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.248-251
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• 2005

Graphite reinforced conductive polymer composites for PEMFC bipolar plates were fabricated by the compression molding technique. Graphite powder was mixed with an phenol resin to impart electrical property in composites. In this study, conductive polymer composites with high filler $loadings(>60wt.\%)$ were manufactured to accomplish high electrical conductivity above 100S/cm. The level of compaction is important because graphite powder increase electrical conductivity of composites by direct physical contact between particles. The optimum molding pressure according to filler was proposed experimentally. Various tests(electrical conductivity, flexural strength, compressive strength, leach test, etc) were carried out to verify the performance of fabricated composites for PEMFC bipolar plates. Fabricated composites have good electrical conductivity and mechanical strength. The results of leach test and contact angle measurement showed similar characteristics compared with commercial bipolar plates.

• Korean Journal of Materials Research
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• v.20 no.2
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• pp.60-64
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• 2010

This study looked at high performance copper-based alloys as LED lead frame materials with higher electrical-conductivity and the maintenance of superior tensile strength. This study investigated the effects on the tensile strength, electrical conductivity, thermal softening, size and distribution of the precipitation phases when Cr was added in Cu-Fe alloy in order to satisfy characteristics for LED Lead Frame material. Strips of the alloys were produced by casting and then properly treated to achieve a thickness of 0.25 mm by hot-rolling, scalping, and cold-rolling; mechanical properties such as tensile strength, hardness and electrical-conductivity were determined and compared. To determine precipitates in alloy that affect hardness and electrical-conductivity, electron microscope testing was also performed. Cr showed the effect of precipitation hardened with a $Cr_3Si$ precipitation phase. As a result of this experiment, appropriate aging temperature and time have been determined and we have developed a copper-based alloy with high tensile strength and electrical-conductivity. This alloy has the possibility for use as a substitution material for the LED Lead Frame of Cu alloy.

• Composites Research
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• v.19 no.2
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• pp.7-12
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• 2006

Graphite particle/carbon fiber hybrid conductive polymer composites were fabricated by the compression molding technique. Graphite particles were mixed with an epoxy resin to impart the electrical conductivity in the composite materials. In this study, graphite reinforced conductive polymer composites with high filler loadings were manufactured to accomplish high electrical conductivity above 100S/cm. Graphite particles were the main filler to increase the electrical conductivity of composites by direct contact between graphite particles. While high filler loadings are needed to attain good electrical conductivity, the composites becomes brittle. So carbon fiber was added to compensate weakened mechanical property. With increasing the carbon fiber loading ratio, the electrical conductivity gradually decreased because non-conducting regions were generated in the carbon fiber cluster among carbon fibers, while the flexural strength increased. In the case of carbon fiber 20wt.% of the total system, the electrical conductivity decreased 27%, whereas the flexural strength increased 12%.

• Journal of the Korean Society for Heat Treatment
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• v.32 no.3
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• pp.107-112
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• 2019

In order to investigate the effect of plastic deformation and annealing process parameters on strength and electrical conductivity of Cu-Fe alloys, Cu-10wt%Fe, Cu-15wt%Fe alloys were drawn up to ${\eta}=4$ and annealed in the temperature range of $300^{\circ}C$ to $700^{\circ}C$, followed by measurements of tensile strength and electric conductivity. As draw strain increases, tensile strength increases while electrical conductivity decreases. These observations result from reduction of dislocation density and decrease in Fe fiber spacing. Raising annealing temperature brought about decrease of tensile strength and increase of electrical conductivity up to $500^{\circ}C$, being followed by decreasing above $500^{\circ}C$. Such results are thought to be caused by decrease of dislocation density below $500^{\circ}C$ and rapid solubility increase of Fe in Cu above $500^{\circ}C$. For the purpose of obtaining both high strength and high conductivity, annealing process should be incorporated just prior to reaching to final draw strain. For Cu-10wt%Fe alloy, the tensile strength 706.9 MPa and the electrical conductivity 54.34%IACS were obtained through the processes of drawing up to ${\eta}=3$, annealing at $500^{\circ}C$ for 1 hour and additional drawing up to total strain of ${\eta}=4$.

• Journal of the Korean Society for Heat Treatment
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• v.14 no.1
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• pp.17-21
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• 2001

The effects of Cr content above its solubility limit and thermomechanical treatment on tensile strength and electrical conductivity of Cu-Cr alloys were studied to obtain optimum Cr content exhibiting a high tensile strength without degradation of electrical conductivity. The increase in Cr content above the solubility limit increased tensile strength of Cu-Cr alloys without deterioration of the electrical conductivity. The electrical conductivity was not affected by cold rolling. The electrical conductivity of a Cu-3.5%Cr alloy subjected to cold rolling ${\rightarrow}$ aging treatment ($450^{\circ}C{\times}1hr$) ${\rightarrow}$ cold rolling was equal to that of the alloy subjected to cold rolling ${\rightarrow}$ aging treatment. However, the tensile strength of the alloy subjected to the former thermomechanical treatment was superior to that of the alloy subjected to the latter thermomechanical treatment at all the deformation degrees.

• Journal of The Korean Astronomical Society
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• v.8 no.1
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• pp.29-34
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• 1975

Solar electrical conductivity has been calculated, making use of Yun and Wyller's formulation. The computed results arc presented in a tabulated form as functions of temperature and pressure for given magnetic field strengths. The results of the calculation show that the magnetic field does not play any important role in characterizing the electrical conductivity of the ionized gas when the gas pressure is relatively high (e.g., $P{\geq}10^4\;dynes/cm^2$). However, when the gas pressure is low (e.g., $P{\leq}10\;dynes/cm^2$), the magnetic field becomes very effective even if its field strength is quite small (e.g., $B{\leq}0.01$ gauss). It is also found that, except for lower temperature region (e.g., $T{\leq}10^{4^{\circ}}K$), there is a certain linear relationship in a log- log graph between the pressure and the critical magnetic field strength, which is defined as a field strength capable of reducing the non-magnetic component of the electrical conductivity by 20%.