• Journal of Korea Foundry Society
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• v.14 no.5
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• pp.455-463
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• 1994

Aluminum matrix composites reinforced by fine steel wires were fabricated by squeeze casting process. Preforms made of fine steel wires were prepared with different surface conditions, namely uncoated(TN), carbo-nitriding treated(TT), and brass coated(TA). Squeeze casting were performed under the pressure of $1500kg/cm^2$ for 3min. during solidification, and pouring temp. of the melt being $750^{\circ}C$ and the steel mold being preheated at $250^{\circ}C$. Microstructural characteristics were evaluated, particularly concerned with the effect of the surface conditions of the preforms. The results obtained from this study are like these. TN specimens show partially non-wetted regions, due to easy formation of oxides on the surface of the fine steel wires. TT specimens show no interfacial reaction between the steel wires and the aluminum alloy matrix, possibly due to the formation of carbo-nitrided zone on the surface of the steel wires. TA specimens show excellent wettabillity between the reinforced steel wires and the aluminum alloy matrix and very thin interfacial zone is formed between them. During the solution hardening treatment of TA specimens, thickness of the interfacial reaction zones were increased with the solution treating time. TA specimens show typical ductile fracture in tensile test, but TT specimens show brittle fracture possibly due to the formation of the brittle hard surface on the steel wires during carbo-nitriding treatments. TA specimens which were reinforced with 40 vol.% of the fine steel wires exhibit high tensile strength of $77.1kgf/mm^2$ and impact value of $8.1kgf-m/cm^2$.

• Analytical Science and Technology
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• v.7 no.2
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• pp.155-164
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• 1994

A conventional Grimm-type glow discharge source was constructed and applied to radio-frequency(13.56MHz) discharge for metal and ceramic analysis. We investigated the emission spectrum for aluminium and aluminium oxide and the influence of discharge operating paramaters including argon pressure, rf-power and DC-bias voltages at the sample-side electrode. Scanning Electron Microscope(SEM) also was used to investigate the effect of rf-sputtering on the microstructure formation of the aluminium oxide. Linear analytical calibration curves were constructed for Manganese and zinc element in samples of low alloy steel(BAS 401-405) and brass(NIST 1108-1117).

• Journal of Powder Materials
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• v.20 no.1
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• pp.33-36
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• 2013

A bulk metallic glass-forming alloy, $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ metallic glass powders was used for good commercial availability and good formability in supercooled liquid region. In this study, the Ni-based metallic glass was synthesized using by high pressure gas atomized metallic glass powders. In order to create a bulk metallic glass sample, the $Ni_{59}Zr_{20}Ti_{16}Si_2Sn_3$ metallic glass powders with ball-milled Ni-based amorphous powder with 40%vol brass powder and Cu powder for 20 hours. The composite specimens were prepared by Spark Plasma Sintering for the precursor. The SPS was performed at supercooled liquid region of Ni-based metallic glass. The amorphous structure of the final sample was characterized by SEM, X-ray diffraction and DSC analysis.

• Transactions of Materials Processing
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• v.22 no.2
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• pp.80-85
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• 2013

The surface integrity of micro-machined products affects the performance of products significantly. Micro-burrs resulting from micro-cutting degrades the surface quality. Therefore it is desired to eliminate them completely and many studies have been undertaken for this purpose. In this study, micro-end-milling was carried out on nickel alloy and brass materials commercially used for light guide plate mold in 3-D optical devices. After completing this micro-machining, the burr heights were measured with a microscope. Then, deburring was done on the machined edges using the MR jet polishing method. A jet angle of $0^{\circ}$ and deburring times of 1, 3, and 5 min. were chosen. It was found that burrs were completely eliminated after 5 min of MR fluid jet polishing.

• Korean Journal of Materials Research
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• v.27 no.3
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• pp.172-178
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• 2017

The aim of this study is to consider the effect hydrogen on dezincification behavior of Cu-Zn alloys. The investigations include microstructural observations with scanning electron microscope and chemical composition analysis with energy dispersive spectrometer. The dezincification layer was found to occur in high pressure hydrogen atmosphere, not in air atmosphere. In addition, the layers penetrated into the inner side along the grain boundaries in the case of hydrogen condition. The shape of the dezincification layers was porous because of Zn dissolution from the ${\alpha}$ or ${\beta}$ phase. In the case of stress corrosion cracks formed in the Cu-Zn microstructure, the dezincification phenomenon with porous voids was also accompanied by grain boundary cracking.

• Journal of Conservation Science
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• v.36 no.3
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• pp.178-186
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• 2020

Verdigris is a traditional artificial pigment reported on old research papers and according to the methods mentioned in the literature, it is manufactured by the corrosion of copper or copper alloys using vinegar and by further scraping the generated rust. Since the Three Kingdoms Period, various household products with copper alloys, such as bronze and brass, have been used, and pigment analysis of these cultural heritage items has revealed the presence of tin, zinc, lead, and copper in green pigments. Based on these data, five types of verdigris were prepared from copper and copper alloys, and analyzed. the analysis results revealed a bluish green pigmentation, and the chromaticity, particle shape, and oil absorption quantity of each verdigris differed based on the type of copper alloy used in its preparation. The main components of verdigris are Cu, Sn, Zn and Pb, and their proportions depended on the type of copper alloy used during manufacturing. However, the main constituent mineral of the pigments is the same as 'hoganite[Cu(CH₃COO)₂·H₂O]', regardless of the copper alloy used. The result of accelerated weathering test for stability evaluation revealed that verdigris was discolored rapidly, thereby indicating that its stability was low, in particular, the pigments comprising lead presented relatively lower stability.

• Archives of design research
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• v.17 no.4
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• pp.241-250
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• 2004

In this research, the copper alloy plates C2200, C5210, C7701, C8113 were selected to make datum and to identify further usage of metal craft experimentation. For its experimentation, the general welding and TIG welding methods were researched; for 2nd experimentation, the Reticulation and Electroforming skill's differences in color and temperature were researched. With these methods 3 different kinds of works are introduced for sample studies. For this research, Dr. Lee, Dong-Woo who works in Poongsan Metal Co, supported 4 kinds of copper alloy metals. Which are Commercial bronze (Cu-Zn), Deoxidiged Copper(Cu-Sn-P), Nickel Silver (Cu-Ni-Zn), and White Bronze (Cu-Ni); they were applied partly and wholly by the method of Laminatin, Reticulation, Fusing, and Electroforming skills. In case of C2200, the brass, the A. C. TIG welding method is better under 2mm slight plate; the D.C. TIG welding is better upper 2mm plate; and 250~300$^{\circ}C$ is recommended for remain heat treatment. In case of C5210, not having Hydrogen in high temperature return period, doesn't need Oxygen in high temperature and hardening in comparative high temperature neither, it is good for welding. It contains Sn 2-9% ad P 0.03-0.4% generally; and in accordance with the growth rate of Sn contain amount, the harden temperature boundary become broad. In case of cold moment after welding, they are recommended that higher speed TIG welding, smaller melting site and less than 200$^{\circ}C$ for pre-heating temperature. In case of C7701, the 10-20% Ni, 15-30% Zn are widely used.. If it is upper 30% Zn, it become (${\alpha}+{\beta}$) system and adhesive power rate become lower, and the productivity become lower in low temperature but the productivity become higher in high temperature. Nickel Silver's resistance of electricity is well; and the heatproof and incorrodibility is good, too. Lastly, in case of C8113, good at persistence in salty and grind; high in strength of high temperature. In case of white brass, contain 10-30% Nickel and hardened in high temperature and become single phrase. For these reason, the crystallization particles easily become large, if the resistance become higher small amount of Pb, P, S separation rate become higher.

• Journal of Conservation Science
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• v.38 no.2
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• pp.133-143
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• 2022

In this study, we analyzed the rickshaw (Owned by the Daegu Modern History Museum) by measuring each material. The purpose of the study was to identify the materials in modern cultural assets that utilize a variety of materials in a complex way, and establish basic data for preservation and management. Using portable X-ray fluorescence analyzers (P-XRF), species identification, fiber identification, paint film analysis (microscope observation, SEM-EDS, FTIR) on metal, wood, fiber and paint was carried out. Brass, an alloy of Copper, Zinc and Iron, was measured in the metal parts. Further, wooden parts, such as Oak (Quercus acutissima), Japanese Cedar (Cryptomeria japonica), Bamboo (Bambusoideae). Torreya nucifera (Torreya spp.) were identified in the body. Fiber parts consisted mainly of cotton, but some parts were also made of leather. In terms of paint, rickshaws were applied with multiple layers, using cashew (synthetic paint used in place of lacquer). In sum, the rickshaw body part appeared to overlap with layers of fiber, metal (soild), paint, and colored (black, red) layer.

• Nuclear Engineering and Technology
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• v.2 no.3
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• pp.163-178
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• 1970

Deformation modes at room temperature and the interaction between slip lines and ${\gamma}$' precipitate particles in heat treated Rene 41 were studied by means of replica techniques in an electron microscope. The alloy had been deformed by compression after aging for times up to 9300 hr at 76$0^{\circ}C$ and 87$0^{\circ}C$. The slip structure observed was similar to that of o brass, i.e., consisting of single slip lines occurred on the｛111｝<110> system. The slip structure was also correlated with aging conditions. Slip lines appeared to pass through ${\gamma}$' particles, shearing them with the matrix even after a prolonged heat treatment. It was concluded on the basis of comparison with previously published data that ${\gamma}$' particles remain at least partially coherent with the matrix even in a greatly overaged condition.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1833-1836
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• 2008

Recently as the micro surface features become higher and diverse in their shapes, the releasing of the molded features becomes more crucial for manufacturing of the micro patterned products. The higher aspect ratio of the features or more complex shape of the features results in larger releasing force, elongation or cohesive failure of the features during the releasing. Another issue would be the uniformity of the released surface features after molding, especially for applications with large area surface. The micro patterned optical film, one of typical applications for micro surface features, consists of two layers, the thermoplastic base film and the micro formed UV resin layer. Therefore two interfaces are typically involved during the forming of this micro featured film; one is between the base film and the UV resin and another is between the resin and the pattern master. To improve the releasing of the molded surface features, the adhesive characteristic was investigated at these two interfaces. A PET film was used as a base film and two UV curable resins with different surface energy were prepared for different adhesiveness. Also the two different pattern masters were employed; one is made from brass-copper alloy and fabricated with PMMA. The adhesiveness at each interface was measured for some combinations of these base film, UV resins and the masters and the effect of this adhesiveness on the releasing was investigated.