• Korean Journal of Materials Research
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• v.11 no.5
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• pp.398-404
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• 2001

Effects of coating treatment of metallic Cu film on SiC for Al/SiC composite were studied. The Copper was deposited on SiC by electroless plating method. Al/sic composite was fabricated at temperature range of $670^{\circ}C$ to 90$0^{\circ}C$ under vacuum atmosphere. The wetting behavior of Al/SiC composite were analysed by SEM and XRD. The coating treatment on SiC improved wettability of Al melt on SiC considerably comparing to the non coated SiC. This improved wettability seems strongly concerned to the increase of chemical reactivity between coated layer and Al matrix. The improvement of wettability of Al melt on the Cu coated SiC was closely related to in the initial stage of reaction. The metallic film played an important role in reducing the interfacial free energy and breaking down the aluminum oxide film through the reaction with Al melt. The wetting behavior of the as-received SiC with Al melt was not uniform, indicated by the contact angles from less than $97^{\circ}$to more than $97^{\circ}$.

• 한국초전도학회:학술대회논문집
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• v.12
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• pp.62-62
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• 2002

• Korean Journal of Materials Research
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• v.28 no.12
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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.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.28 no.1
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• pp.21-27
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• 2018

Synthesis of ferromagnetic composite materials for the $Cu-BaFe_{12}O_{19}$ system by mechanical alloying (MA) has been investigated at room temperature. A mixture of copper and barium ferrite with a weight ratio of $Cu:BaFe_{12}O_{19}=4:1$, 3 : 2, 2 : 3 and 1 : 4 was used. It is found that $Cu-BaFe_{12}O_{19}$ composite powders in which $BaFe_{12}O_{19}$ is dispersed in copper matrix are successfully produced by mechanical alloying of $BaFe_{12}O_{19}$ with Cu for 80 min. in all composition. The change in X-ray diffraction patterns and magnetic properties reflects the details for the formation of ferromagnetic metal matrix composite of pure Cu and $BaFe_{12}O_{19}$ during mechanical alloying. Magnetization of $Cu-BaFe_{12}O_{19}$ composite powders gradually increases with increasing the amounts of barium ferrite, whereas coercive force of MA powders gradually decreases due to the refinement of barium ferrite powders with ball milling. However, it can be seen that the coercivity of $Cu-BaFe_{12}O_{19}$ MA composite powders with a weight ratio of $Cu:BaFe_{12}O_{19}=4:1$ and 3 : 2 ball-milled for 80 min. is still high value of 1400 Oe and 1450 Oe, respectively suggesting that the refinement of barium ferrite powders during ball milling process tend to be suppressed due to the ductile copper.

• Progress in Superconductivity
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• v.4 no.1
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• pp.80-85
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• 2002

In order to disseminate the IEC international standard of RRR measurement of Cu／Nb／-Ti composite superconductors, a measuring system was developed at KRISS. The system consisted of helium reservoir, base plate, thermometer, voltmeter and current source. The helium reservoir and base plate provided a stable temperature of a range from 4.2 K to 300 K and the voltmeter measured several order of $mutextrm{V}$ on specimen for obtaining RRR of the Cu／Nb-Ti composite superconductor. Three specimens of the Cu／Nb-Ti composite superconductors were measured using this system for characterizing their RRR. The resistance-temperature curves ortho specimens showed 10／sup -6／ to 10／sup -5／ Ohms near transition temperature and 10／sup -4／ to 10／sup -3／ Ohms at 293 K. The RRR values of the specimens were 145, 71 and 140, respectively.

• Journal of Welding and Joining
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• v.15 no.6
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• pp.96-104
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• 1997

The present study was aimed to correlate the microstructure and the hardness as well as the wear resistance of the metal-ceramic particulated composite layer on the pure Al plate. The composite layers were constructed by the addition of TiC particles on the surface of Al-Cu alloyed layers by PTA overlaying process. Initially, the Al-Cu alloyed layers were achieved by the deposition of Al-(25 ~ 48%) Cu alloys on the pure Al plate by TIG process. It was revealed that TiC particles were uniformly dispersed without any reaction with matrix in the composite layer. The volume fraction of TiC particles (TiC V F) increased from 12% to 55% with increasing the number of pass of composite layer. Hardnesses of (Al-48%Cu + TiC (3&4layers)) composite layer were Hv450 and Hv560, respectively, due to the increase of TiC V/F. Hardnesses of (Al-Cu + TiC) composite layers decreased gradually with insreasing temperature from 100$^{\circ}$C to 400$^{\circ}$C, and hardnesses at 400$^{\circ}$C were then reached to 1/5 - 1/10 of room temperature hardness depending on the construction of composite layers. The Specific wear of (Al + Tic) layer and Al-48%Cu alloyed layer decreased to 1/10 of the of pure Al, while the specific wear of (Al-48%Cu + TiC (4 layers)) composite layer exhibited 1/15 of that of steel such as SS400 and STS304.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1057-1058
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• 2006

The preparation of $Ti_{50}Cu_{28}Ni_{15}Sn_7$ metallic glass composite powders was accomplished by the mechanical alloying of a pure Ti, Cu, Ni, Sn and carbon nanotube (CNT) powder mixture after 8 h milling. In the ball-milled composites, the initial CNT particles were dissolved in the Ti-based alloy glassy matrix. The bulk metallic glass composite was successfully prepared by vacuum hot pressing the as-milled CNT/$Ti_{50}Cu_{28}Ni_{15}Sn_7$ metallic glass composite powders. A significant hardness increase with the CNT additions was observed for the consolidated composite compacts.

• Journal of Korea Foundry Society
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• v.13 no.1
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• pp.42-49
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• 1993

Conventional manufacturing process for cast iron-babbitt metal composite is complicate and bimetallic bonding by centrifugal casting is also difficult because their melting point is largely different and nonmetallic inclusion exists on outer shell. This study is aiming to simplify multistage process by adding Cu-powder as insert metals during cast iron solidification. The variables on fabrication of composite pipe are mold rotating speed and inner surface temperature of outer metal. The optimum temperature range for fusion bonding between cast iron and Cu-layer was $1100^{\circ}C-1140^{\circ}C$ in case of mold rotating speed was 700rpm. When the inner surface of Cu-layer was at $900^{\circ}C$, the value of interfacial hardness between Cu-layer and babbitt metal were higher than Cu-matrix by forming diffusion layer, interfacial products between Cu-layer and babbitt metal are proved to be $Cu_6Sn_5({\eta})$by XRD.

• Journal of Korea Foundry Society
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• v.17 no.5
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• pp.480-487
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• 1997

Particle reinforced metal matrix composites(MMCs) via a centrifugal spray-cast deposition(CSD) process were fabricated by injecting second phase particles($Al_2O_3$<40${\mu}m$, W<17.3${\mu}m$) into copper melt on the atomizing disc. Compositing modes were investigated by combining microstructures and mathematical modeling between Cu droplets and the reinforced particles injected. The $Cu/W_P$ powders were shown that the W particles penetrate and get embedded in the Cu droplets. It is considered that the W particles composite preferentially in Cu melt on the atomizing disc. On the other hand, the $Al_2O_3$, particles did not penetrate into the Cu droplets on the atomizing disc but get attached in surface of Cu droplets during the flight. It is considered that the compositing may be attained in the flight distance which the relative velocity between Cu droplet and $Al_2O_3$, particle is maximum. The microstructure of the $Cu/W_P$ and the $Cu/(Al_2O_3)_p$ composite preform was strongly influenced by compositing modes of droplets, and after subsequent deposition it was comprised as it is called the dispersed type and the cell type of microstructure, respectively.

• Transactions of Materials Processing
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• v.15 no.5 s.86
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• pp.360-365
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• 2006

Carbon nanotubes (CNTs) have been the subject of intensive studies for applications in the fields of nano technologies in recent years due to their superior mechanical, electric, optical and electronic properties. Because of their exceptionally small diameters (${\appros}\;several\;nm$) as well as their high Young's modulus (${\appros}1\;TPa$), tensile strength (${\appros}\;200\;GPa$) and high elongation (10-30%) in addition to a high chemical stability, CNTs are attractive reinforcement materials for light weight and high strength metal matrix composites. Although extensive researches have been performed on the electrical, mechanical and functional properties of CNTs, there are not many successful results on the mechanical properties of CNT dispersed nanocomposites. In this paper, we applied equal channel angular pressing for consolidation of CNT/Cu powder mixtures. We also investigated the hardness and microstructures of CNT/Cu nanocomposites used experimental for metal matrix composites.