• Smart Structures and Systems
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• v.4 no.2
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• pp.247-259
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• 2008

The potential use of Cu-based shape memory alloys (SMA) in retrofitting historical monuments is investigated in this paper. This study is part of the ongoing work conducted in Tunisia within the framework of the FP6 European Union project (WIND-CHIME) on the use of appropriate modern seismic protective systems in the conservation of Mediterranean historical buildings in earthquake-prone areas. The present investigation consists of a finite element simulation, as a preliminary to an experimental study where a cantilever masonry wall, representing a part of a historical monument, is subjected to monotonic and quasi-static cyclic loadings around a horizontal axis at the base level. The wall was retrofitted with an array of copper SMA wires with different cross-sectional areas. A new model is proposed for heat-treated copper SMAs and is validated based on published experimental results. A series of nonlinear finite element analyses are then performed on the wall for the purpose of assessing the SMA device retrofitting capabilities. Simulation results show an improvement of the wall response for the case of monotonic and quasi-static cyclic loadings.

• Corrosion Science and Technology
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• v.4 no.1
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• pp.19-22
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• 2005

Two Au-Ag-Cu-Pd dental casting alloys (Au:12% and 20%) used. The test solutions used 0.9 % NaCl solution (isotonic sodium chloride solution), 0.9 % NaCl solution containing 1 % lactic acid, and 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_2S$. The surface of two samples in three sample solutions was not natural discoloration during one year. The alloy containing 12 % gold was easily alloyed and the composition was uniform comparing with the alloy containing 20 % gold. The rest potentials have not a little effect after three months. The kinds of metals could not definitely from the oxidation and reduction waves of metal on the cyclic voltammograms. The dissolutions of gold and palladium were 12 % Au sample in the 0.9 % NaCl solution containing 1 % lactic acid and 0.1 mol $dm^{-3}$ $Na_{2}S$. The pH of solution had an affect on dissolution of copper, and sulfur ion had an affect on dissolution of silver. The copper dissolved amount from 20 % gold sample was about 26 times comparing with that of 12 % gold sample in the 0.9 % solution containing 1 % lactic acid. Corrosion products were silver chloride and copper chloride in NaCl solution, and silver sulfide and copper sulfide in NaCl solution containing $Na_{2}S$.

• Journal of Korea Foundry Society
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• v.11 no.4
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• pp.283-292
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• 1991

• Proceedings of the Materials Research Society of Korea Conference
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• 2000.11a
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• pp.143-143
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• 2000

• Corrosion Science and Technology
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• v.11 no.6
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• pp.263-269
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• 2012

Copper alloys are commonly applied to ship's propellers, pumps and valves which are serviced in seawater due to their good castability and corrosion resistance. In the environment of high flow velocity, however, erosion damage predominates over corrosion damage. In particular, the cavitation in seawater environment accelerates surface damage to copper alloys, resulting in degradation of products and economic losses and also threatening safety. The surface was coated with WC-27NiCr by high velocity oxygen fuel(HVOF) spraying technique to attain durability and cavitation resistance of copper alloys under high velocity/pressure flow. The cavitation test was performed for the WC-27NiCr coating deposited by HVOF in seawater at the amplitude of $30{\mu}m$ with seawater temperature. The cavitation at $15^{\circ}C$ caused exfoliation of the coating layer in 17.5 hours while that of $25^{\circ}C$ caused the exfoliation in 12.5 hours. When the temperature of seawater was elevated to $25^{\circ}C$ from $15^{\circ}C$, more damage was induced by over 160%. Although WC-27NiCr has good durability, corrosion resistance and eletrochemical stability, the cavitation damage rate of the coating layer could remarkably increase at the elevated temperatures under cavitation environments.

• Journal of Korea Foundry Society
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• v.32 no.1
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• pp.38-43
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• 2012

The effects of Mg and Cu amounts on the casting characteristics and tensile property of Al-Zn-Mg-Cu alloys were investigated for the development of high strength aluminium alloys for gravity mold casting. Increase of copper amounts in Al-6%Zn-3%Mgy% Cu alloys resulted in reduction of the fluidity of these alloys and had little effects on the tensile property of these alloys. Increase of magnesium amounts from 1.0wt% to 3.3wt% in Al-6%Zn-x%Mg-0.5%Cu alloys resulted in reduction of the elongation of these alloys from 12% to 3% and increase of the tensile strength of these alloys from 340MPa to 450MPa, but had little effects on the fluidity of these alloys.

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.38-55
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• 2019

The purpose of this study is to clarify the historical flow of baekdong alloy's usage according to the alloying materials mentioned in document records. For this purpose, we first overviewed the use of copper as a base material for white copper alloys and other types of copper alloys. Baekdong is an alloy of copper and other metals and is currently defined as an alloy of copper and nickel. However, depending on the research subjects and time of the scholars, baekdong may be defined as a metal with over a certain percentage of tin added to copper, or as an alloy of tin, zinc, and lead with copper. There is disagreement regarding the interpretation of this term. Baekdong, which started to appear in the literature of the Three Kingdoms Period, has been steadily seen through the Goryeo and Chosun Dynasties to the modern period. It has been used in various ways, according to each age and culture, from the symbol of the office to trading goods, daily life goods, and money. In the literature, baekdong's alloying material is not only copper and nickel, which are currently defined as alloys, but it is the same in that copper is used as the base metal of the alloy, although it varies slightly from generation to generation. In addition to copper, tin, zeolite, and emerald, zinc and lead also appeared. It was found that baekdong, which means alloy, and baekdong, which means white metal, were mixed. Nickel, which is the alloy material of baekdong as it is currently defined, is a metal with a relatively high discovery time and is widely used as a material for modern industrial fields. Nickel was introduced into Korea at the end of the Joseon Dynasty, but its use is not known in detail. In this study, we examined the acceptance and use of nickel-based baekdong in articles of modern newspapers and in statistical data. Based on the experience of craftsmen, we estimated the period when nickel-based alloys were used in crafts. Material is a direct factor in the development and deterioration of technology, and the development of technology is the basis for the changing of civilizations and cultures. In this context, this study was to investigate baekdong with the material of alloys as a starting point.

• Journal of Conservation Science
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• v.36 no.3
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• pp.162-177
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• 2020

Research was conducted to characterize the copper production and smelting process with 11 copper smelting by-products (copper slag and copper crucible) excavated from the NA and LA areas at the Gwanbuk-ri archeological site in Buyeo. Scanning electron microscopy-energy dispersive spectroscopy, wavelength dispersive X-ray fluorescence, X-ray diffraction, and Raman microspectroscopy were employed in the analysis. The research results reveal that the copper slag from Gwanbuk-ri contained silicate oxide, magnetite, fayalite, and delafossite, which are typical characteristics of crucible slag and refined slag. The outward appearance and microstructure of the slag were grouped as follows: 1. glassy matrix + Cu prill, 2. glassy matrix + Cu prill + magnetite, 3. silicate mineral matrix + Cu prill, 4. crystalline (delafossite and magnetite) + amorphous (Cu prill), 5. magnetite + fayalite, and 6. slag from slag. The copper slags from Guanbuk-ri were found to contain residues of impurities such as SiO₂, Al₂O₃, CaO, SO₄, P₂O₅, Ag₂O, and Sb₂O₃ in their microstructure, and, in some cases, it was confirmed that copper, tin and lead are alloys. These results indicate that refining of intermediate copper(including impurities) and refining of alloys of copper(including impurities) - tin and refining of copper(including impurities) - tin - lead took place during the copper production process at Gwanbuk-ri, Buyeo.

• Journal of Electrochemical Science and Technology
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• v.3 no.3
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• pp.95-115
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• 2012

Although indium (In) is not an abundant element, the use of indium is expected to grow, especially as applied to copper-indium-(gallium)-selenide (CI(G)S) solar cells. In future when CIGS solar cells will be used extensively, the available amount of indium could be a limiting factor, unless a synthetic technique of efficiently utilizing the element is developed. Current vacuum techniques inherently produce a significant loss of In during the synthetic process, while electrodeposition exploits nearly 100% of the In, with little loss of the material. Thus, an electrochemical process will be the method of choice to produce alloys of In once the proper conditions are designed. In this review, we examine the electrochemical processes of electrodeposition in the synthesis of indium alloys. We focus on the conditions under which alloys are electrodeposited and on the factors that can affect the composition or properties of alloys. The knowledge is to facilitate the development of electrochemical means of efficiently using this relatively rare element to synthesize valuable materials, for applications such as solar cells and light-emitting devices.

• 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.