• Restorative Dentistry and Endodontics
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• 제19권1호
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• pp.1-26
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• 1994

The purpose of this study was to investigate the dissolution components during corrosion of amalgams and to identify surface corrosion products in the modified Fusayama artificial saliva. Four type of amalgam alloys were used: low copper lathe cut amalgam alloy (Cavex 68), low copper spherical amalgam alloy (Caulk Spherical Alloy), high copper admixed amalgam alloy (Dispersalloy) and high copper single composition amalgam alloy (Tytin). Each amalgam alloy and Hg were triturated according to the manufacturer's direction by means of mechanical amalgamator (Capmaster, S.S.White), and then the triturated mass was inserted into the cylindrical metal mold which was 10mm in diameter and 2.0mm in height and condensed with compression of 150kg/$cm^2$ using oil pressor. The specimens were removed from the mold and stored at room temperature for 7 days and cleansed with distiled water for 30 minutes in an ultrasonic cleaner. The specimens were immersed in the modified Fusayama artificial saliva for the periods of 1 month, 3 months and 6 months. The amounts of Hg, Cu, Sn and Zn dissolved from each amalgam specimen immersed in the artificial saliva for the periods of 1 month, 3 months and 6 months were measured using Inductivity Coupled Plasma Atomic Emission Spectrometry (ICPQ-1000, Shimadzu, Japan) and amount of Ag dissolved from amalgam specimen was measured using Atomic Absorption Spectrophotometry (Atomic Absorption/Flame emission spectrophotometer M-670, Shimadzu, Japan). A surface corrosion products of specimens were analysed using Electron Spectroscopy Chemical Analyser (ESCA PHI-558, PERKIN ELMER, U.S.A.). The secondary image and back scattered image of corroded surface of specimens was observed under the SEM, and the corroded surface of specimens was analysed with the EDX. The following results were obtained. 1. The dissolution amount of Cu was the most in high copper admixed amalgam(Dispersalloy) and the least in high copper single composition amalgam(Tytin). 2. Sn and Zn were dissolved during all the experiment periods, and dissolution amounts were decreased as the time elapsed. 3. Initial surface corrosion products were ZnO and SnO. 4. Corrosion of ${\gamma}$ and ${\gamma}_2$ phase in low copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in low copper spherical amalgam(Caulk Sperical Alloy). 5. Corrosion of ${\gamma}$ and $\eta$' phase in high copper amalgams was observed and Ag-Cu eutectic alloy phase was corroded in high copper admixed amalgam(Dispersalloy). 6. Sn-Cl was produced in the subsurface of low copper amalgams and high copper admixed amalgam.

• 한국재료학회지
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• 제22권11호
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• pp.581-586
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• 2012

The microstructure and mechanical properties of a copper alloy sheet processed by differential speed rolling (DSR) were investigated in detail. A copper alloy with thickness of 3 mm was rolled to a 50% reduction at ambient temperature without lubrication and with a differential speed ratio of 2.0:1. For comparison, conventional rolling (CR), in which the rolling speeds of the upper and lower rolls is 2.0 m/min, was also performed under the same rolling conditions. The shear strain of the sample processed by CR showed positive values at the positions of the upper roll side and negative values at the positions of the lower roll side. On the other hand, the sample processed by the DSR showed zero or positive shear strain values at all positions. However, the microstructure and mechanical properties of the as-rolled copper alloys did not show such significant differences between the CR and the DSR. The samples rolled by the CR and the DSR exhibited a typical deformation structure. In addition, the DSR processed samples showed a typical rolling texture in which {112}<111>, {011}<211> and {123}<634> components were developed at all positions. Therefore, it is concluded that the DSR was very effective for the introduction of a uniform microstructure throughout the thickness of the copper alloy.

• 대한치과기공학회지
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• 제24권1호
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• pp.65-71
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• 2002

This study was performed to observe the microhardness change of the surface and the bonding strength between the porcelain and alloy specimens in order to investigate the effects of appended indium, tin and copper on interfacial properties of Au-Pd-Ag alloys. The hardness of castings was measured with a micro-Vicker's hardness tester. The interfacial shear bonding strength between alloy specimen and fused porcelain was measured with a mechanical testing system(MTS 858.20). The microhardness of Au-Pd-Ag alloy was increased by adding indium and tin, but not increased by adding copper. The shear bonding strength of Au-Pd-Ag-Sn alloy and Au-Pd-Ag-Cu alloy showed 87MPa, 57MPa. The higher concentration of adding elements showed the higher shear bonding strength.

• 열처리공학회지
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• 제8권2호
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• pp.113-119
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• 1995

We have reported that an Fe-17wt%Mn alloy exhibits the highest damping capacity in the Fe-Mn binary system. In the present work, the effects of copper content on the damping capacity, atmospheric corrosion and mechanical properties were studied. The damping capacities were measured at room temperature for the air cooled Fe-17wt%Mn alloy having copper content from 0.1wt% to 1.1wt%. The damping capacity of the Fe-17wt %Mn alloy was decreased with increasing copper content. However, the addition of Copper was found to improve mechanical properties and atmospheric corrosion resistance. These mechanical properties were attributed to the formation of stress-induced martensite during tensile test.

• 수산해양기술연구
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• 제55권1호
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• pp.62-73
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• 2019

Recently, copper alloy netting has been proposed as a material for aquaculture facilities that can be set in harsh offshore environments. To design a cage made of copper alloy netting, it is necessary to calculate the flow of water through the netting and force of external sources on the netting. Therefore, this study measured and analyzed the current velocity reduction after passing through the netting and the hydrodynamic forces acting on the netting using copper alloy netting with nine solidity ratios. As a result of the reduction rate of the flow velocity through the netting, the flow reduction rate was increased as the solidity ratio of netting was increased. The flow reduction rate was also increased as the attack angle on the netting was decreased. In analyzing the resistance on the netting, we also discovered that resistance was increased with increase in the flow velocity and solidity ratio. An analysis of the hydrodynamic coefficient acting on the netting is shown that the drag coefficient tends to increase as the attack angle increases. We also analyzed the hydrodynamic coefficient according to the variation of the Reynolds number. When the drag coefficients acting on the netting were analyzed with the different Reynolds numbers, the Reynolds number increased from over 0.3 m/s to a relative constant. Finally, the copper alloy nettings had a smaller velocity reduction rate when comparing the flow velocity reduction rate between copper alloy nettings and nylon nettings.

• 한국분말재료학회지
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• 제5권4호
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• pp.329-333
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• 1998

Copper-10 wt. % tungsten alloyed powder was obtained by co-reduction of mixed tungsten-trioxide and copper oxide powders at 973 K for 7.2 Ks. In the alloy obtained by pressure-assisted sintering of this co-reduced powder, ultra fine tungsten particles (about 100nm) were dispersed uniformly in the copper matrix. At room temperature, the hardness of this alloy was Hv151 and the electrical conductivity was 85% IACS. After annealing at 1173 K for 3.6 Ks, the hardness and electrical conductivity were Hv147 and 84% IACS, respectively, and were same as before annealing. It was confirmed that the hardness and electrical conductivity of this alloy were hardly influenced by annealing condition since the microstructure of this alloy is highly stabilized.

• 한국어류학회지
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• 제29권1호
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• pp.41-51
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• 2017

어류양식용 가두리로서 동합금가두리망의 현장활용 가능성을 파악하기 위해 양식어류인 2년산 참돔을 동합금망과 합성섬유망에서 9개월 동안 각각 사육관리하면서 참돔에 미치는 양식생물학적 및 병리학적 영향을 조사하여 생물학적 안전성을 평가하였다. 동합금가두리망은 지름 25 m, 깊이 10 m의 규모로 제작하여 경남 통영시 욕지면 주변해역 연구교습어장에 설치하였다. 동합금가두리망과 합성섬유망에서 사육한 참돔의 생존율은 각각 99.75%와 99.70%로 유의한 차이는 나타나지 않았다. 일일체중성장률은 동합금가두리망과 합성섬유망에서 각각 2.13 g/day와 1.65 g/day로 동합금가두리망에서 사육한 참돔의 성장률이 빠른 것으로 나타났다. 혈액성분 분석에 따른 건강도 평가는 합성섬유망에 비해 동합금가두리망에서 양호한 것으로 나타났다. 가두리망 종류별 사육중인 참돔의 구리와 아연의 축적은 다른 기관에 비해 생식소에서 축적이 높게 나타났으며, 가용부분인 근육내 중금속 축적은 허용기준치에 비해 매우 낮았다. 또한 병원체 감염조사결과 동합금가두리망과 합성섬유망에서 기생충은 Microcotyle tai, 세균은 Vibrio alginolyticus 외 5종 등이 공통적으로 관찰되었으나, 동합금가두리망에서 Vibrio속의 세균 감염률에는 다소 차이를 보여 항균작용이 있을 것으로 예상된다. 따라서 동합금가두리망의 시스템안정성, 재활용가능성, 항균성 및 식품안전성 등을 고려할 때 어류양식용 가두리로 현장에서 활용이 가능할 것으로 여겨진다.

• 방사성폐기물학회지
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• 제21권1호
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• pp.1-8
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• 2023

The major concern in the deep geological disposal of spent nuclear fuels include sulfide-induced corrosion and stress corrosion cracking of copper canisters. Sulfur diffusion into copper canisters may induce copper embrittlement by causing Cu₂S particle formation along grain boundaries; these sulfide particles can act as crack initiation sites and eventually cause embrittlement. To prevent the formation of Cu₂S along grain boundaries and sulfur-induced copper embrittlement, copper alloys are designed in this study. Alloying elements that can act as chemical anchors to suppress sulfur diffusion and the formation of Cu₂S along grain boundaries are investigated based on the understanding of the microscopic mechanism of sulfur diffusion and Cu₂S precipitation along grain boundaries. Copper alloy ingots are experimentally manufactured to validate the alloying elements. Microstructural analysis using scanning electron microscopy with energy dispersive spectroscopy demonstrates that Cu₂S particles are not formed at grain boundaries but randomly distributed within grains in all the vacuum arc-melted Cu alloys (Cu-Si, Cu-Ag, and Cu-Zr). Further studies will be conducted to evaluate the mechanical and corrosion properties of the developed Cu alloys.

• 한국응용과학기술학회지
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• 제26권4호
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• pp.434-439
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• 2009

This paper is a new method for prevent. The particulate scale. stero-microscope were used for the scale removal experiment to improve mineralogical characteristics and the reduction of scales in heat pipe. Generally, the scale in the heat pipe consists of calcium carbonate minerals, such as calcite and aragonite which are precipitated by the reaction of Ca and $CO_2$ in the water. Copper alloy metal could eliminate the scale and prevent the production of scale in the heat pipe.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.523-524
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• 2006

The $TiB_2$ dispersion strengthened copper alloy was attracted as thermal and electrical functional material for the high mechanical strength, high thermal stability and good conductivity of $TiB_2$. In the present study, the focus is on the synthesis of $TiB_2$ dispersed copper alloy by spark plasma sintering process using copper oxide and titanium diboride as raw materials. The mechanical, thermal and electrical properties of sintered bodies were discussed with the sintering parameters, and developed microstructure and phase of sintered bodies.