• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.35-35
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• 1994

• Transactions of Materials Processing
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• v.7 no.5
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• pp.465-473
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• 1998

The effect of alloying elements of Ag-Cu-Zr-X brazing alloy on the microstructure and the bond strength of $Al_2O_3/Ni-Cr$ brazed steel joint was investigated. The reaction layer, $ZrO_2$ (a=5.146 ${\AA}$ , b=5.213 ${\AA}$ , c=5.311 ${\AA}$ )was formed at the interface of $Al_2O_3/Ni-Cr$ steel joint by the redox reaction between alumina and Zr. The addition of An and Al to the Ag-Cu-Zr brazing alloy gave rise to changes in the thickness of the reaction product layer and the morphology of the brazement. Sn caused the segregation of Zr was decreased b Al the $ZrO_2$ layer formed at the Ag-Cu-Zr-Al alloy was thinner than that of $ZrO_2$ formed at the Ag-Cu-Zr-An alloy. The fracture shear strength was strongly dependent on the microstructure of the brazement. Brazing with Ag-Cu-Zr-Sn alloy resulted in a better bond strength than with Ag-Cu-Zr or Ag-Cu-Zr-Al alloy.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.05a
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• pp.36-36
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• 1994

• International Journal of Railway
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• v.3 no.1
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• pp.19-27
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• 2010

In the present study, the electrical sliding wear and corrosion resistance of pure copper (Cu) and six age-hardened copper alloys (CuCr, CuZr, CuCrZr, CuNiSiCr, CuBe and CuBeNi) were investigated by a pin-on-disc tribometer and electrochemical measurement. Various copper-based alloys in the form of cylindrical pin were forced to slide against a counterface stainless steel disc in air under unlubricated condition at a sliding velocity of 31 km/h under normal load up to 20 N with and without electric current. The worn surface of and wear debris from the specimens were studied by scanning electron microscopy. Both mechanical wear and electrical arc erosion were the wear mechanisms for the alloys worn at 50 A. Owing to its good electrical conductivity, high wear and corrosion resistance, CuCrZr is a promising candidate as the overhead catenary material for electric traction systems.

• Transactions of Materials Processing
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• v.7 no.5
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• pp.481-488
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• 1998

The active metal brazing was applied to bond Alumina and Ni-Cr steel by Ag-Cu-Zr-Sn alloy and the interfacial microstructure and reaction mechanism were investigated. Polycrystalline monoclinic $ZrO_2$ with a very fine grain of 100-150 nm formed at the alumina grain boundary contacted with Zr segregation layer at the interface. The $ZrO_2$ layer containing the inclusions and cracks were developed at the boundary of inclusion/$ZrO_2$ due to the difference in specific volume. The development of $ZrO_2$ at the interface was successfully explained by the preferential penetration of $ZrO_2$ at the interface was successfully explained by the preferential penetration of Zr atoms a higher concentration of oxygen and a high diffusion rate of Al ions into molten brazing alloy.

• Progress in Superconductivity and Cryogenics
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• v.26 no.2
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• pp.24-30
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• 2024

Metal 3D printing is utilized in various industrial fields due to its advantages, such as fewer restrictions on production shape and reduced production time and cost. Existing research on 3D printing metal materials focused on changes in material properties depending on manufacturing conditions and was mainly conducted in a room temperature environment. In order to apply metal 3D printing products to cryogenic applications, research on the properties of materials in cryogenic environments is necessary but still insufficient. In this study, we evaluate the properties of stainless steel (STS) 316L and CuCr1Zr manufactured by Laser Powder Bed Fusion (LPBF) in a cryogenic environment. CuCr1Zr is a precipitation hardening alloy, and changes in material properties were compared by applying various heat treatment conditions. The mechanical properties of materials manufactured using the LBPF method are evaluated through tensile tests at room temperature and cryogenic temperature (77 K), and the thermal properties are evaluated by deriving the thermal conductivity of CuCr1Zr according to various heat treatment conditions. In a cryogenic environment, the mechanical strength of STS 316L and CuCr1Zr increased by about 150% compared to room temperature, and the thermal conductivity of CuCr1Zr after heat treatment increased by about 6 to 10 times compared to before heat treatment at 40 K.

• Journal of Power System Engineering
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• v.6 no.4
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• pp.49-55
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• 2002

In this paper, the elevated temperature tensile properties and short-time creep rupture characteristics were investigated for the friction welded joints of dissimilar materials, Cu-1%Cr-0.5%Zr and STS316L. The joining tests on Cu-1%Cr-0.5%Zr/STS316L by friction welding were performed, and optimum joining conditions of the friction welded joints were determined. The characteristics of the elevated temperature tensile strength, hardness, fractographs were examined, and the creep rupture characteristics for the optimum welded joints were investigated under uniaxal static load at 300, 400 and $500^{\circ}C$.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.05a
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• pp.78-78
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• 2002

• Proceedings of the KAIS Fall Conference
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• 2011.05b
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• pp.683-686
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• 2011

The effect of welding material such as welding wires and materials for contact tip on the contact tip wear was investigated. Two types welding wires such as solid and flux cored wire and a variety of contact tips made of Cu-P, Cu-Cr(0.25%), Cu-Cr(1%) and Cu-Cr-Zr were employed for the comparison of wear resistance. It was found that the wear resistance of contact tips materials was Cu-Cr-Zr, Cu-Cr(1%), Cu-Cr(0.25%), Cu-P in order while the solid wire had a better wear resistance than flux cored wire.

• Transactions of Materials Processing
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• v.8 no.3
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• pp.327-327
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• 1999

The oxidation behavior of 60%Cu-40%Zn brass haying small amounts of Zr, Cr, Mg, Al, and Si was studied between 873 and 1043 K in air. The alloying element of Mg was harmful, while other alloying elements were beneficial to oxidation resistance. Particularly, the simultaneous addition of Al and Si decreased the oxidation rate drastically. During oxidation, Zr formed ZrO₂, Cr formed CuCr₂O₄, Mg formed MgO, Al formed A1₂CuO₄, and Si formed amorphous SiO₂. These oxides were incorporated in the oxide scale composed predominantly of ZnO. The oxide scales formed on all the tested alloyswere prone to cracking, wrinkling, and spallation.