• Journal of the Korean institute of surface engineering
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• v.44 no.1
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• pp.1-6
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• 2011

A NiW functional alloy plating was investigated as variables of metal ion concentration, complexing agent, temperature, pH and applied current density. Even if numerous studies on reaction mechanism of NiW induced codeposition were carried out during couples of decade, it has not been acceptable reaction mechanism. This study was focused on the effect of the plating variables on the alloy composition in the NiW alloy plating. Applied current density could control mainly the alloy composition rather than other plating variables. It has also been confirmed that the functional alloy plating such as layered or gradient plating was possible by controlling applied current density.

• 한국전기화학회:학술대회논문집
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• 2003.07a
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• pp.83-88
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• 2003

PtRu alloy and $PtRu-WO_3$ nanocomposite thin-film electrodes for methanol electrooxidation were fabricated by means of a sputtering method. The structural and electrochemical properties of well-defined PtRu alloy thin-film electrodes were characterized using X-ray diffraction, Rutherford backscattering spectroscopy. X-ray photoelectron spectroscopy, and electrochemical measurements. The alloy thin-film electrodes were classified as follows: Pt-based and Ru-based alloy structure. Based on structural and electrochemical understanding of the PtRu alloy thin-film electrodes, the well-controlled physical and (electro)chemical properties of $PtRu-WO_3$, showed superior specific current to that of a nanosized PtRu alloy catalyst, The homogeneous dispersion of alloy catalyst and well-formed nanophase structure would lead to an excellent catalytic electrode reaction for high-performance fuel cells. In addition, the enhanced catalytic activity in nanocomposite electrode was found to be closely related to proton transfer in tungsten oxide using in-situ electrochemical transmittance measurement.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1934-1937
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• 1999

A copper-tungsten sintered alloy(Cu-W) has been friction-welded to a tough pitch copper (Cu) in order to investigate friction weldability. The tensile strength of the friction welded joint was increased up to 87% of the Cu base metal under the condition of friction time 1.0 see, friction pressure 40MPa and upset pressure 100MPa, upset time 5.0 sec. And it is related to upset pressure rather than friction time. Mixed layer was formed in the Cu adjacent weld interface and W particles which were included in mixed layer could induce fracture in the Cu adjacent to the weld interface. Thickness of mixed layer was reduced as upset pressure increase.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2172-2178
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• 1997

Development of diamond wheel with fine grains and multi-pore structures were newely attempted. Wheels, that are employed for ultra precision and high performance grinding of difficult-to materials such as tungsten carbide alloy using tool and die materials, must have both performances to remove tool marks efficiently and to contact elastically with curved surfaces. Diamond grains were bonded firmly by a melamine resin to prevent the decrease of machining efficiency due to grain sinking within the bond materials. Also, highly foamed structures were developed to increase the flexibility of the wheel, and to induce active self-sharpening by increasing contact pressure between the wheel and work surfaces. In this paper, melamine-bonded diamond wheels are trial manufactured, then the forming method of wheels are suggested, and the grinding characteristics of wheels are also illustrated.

• Journal of the Korean Society for Precision Engineering
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• v.12 no.7
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• pp.178-188
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• 1995

A study on the temperature distribution of tungsten carbide alloy steel(WC-Co) in surface grinding was conducted to improve the surface finish and to find optimum grinding conditions which would lead to efficient grinding operation by theoretical finite element method analysis and experimental test of workpiece under various conditions. Based on the comparixion of test results and FEM analysis data, it is concluded that the FEM computer simulation of heat transfer is useful in predicting the temperature distribution of test material that the increase of temperature is more infuleneced by the grinding depth than the grinding speed. And that the grinding energy flux of dey grinding is 4 to 6 time greater than wet grinding regardless of grinding speed and finally that the heat transfer does not take place in depth deeper than 3mm from the grinding surface.

• Journal of Ceramic Processing Research
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• v.13 no.spc2
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• pp.363-367
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• 2012

DLC (diamond liked carbon) coating of the tungsten carbide (WC) alloy core surface for molding a glass aspheric lens improves the quality of glass lens and the molding core and is characterized by high hardness, high elasticity, abrasion resistance and chemical stability. In this study, the effect of DLC coating of a thin film by means of the filtered AIP (arc ion plating) technique was examined on Ra and shape of the coated surface. Roughness before and after DLC coating was measured and the result showed that the roughness was improved after coating as compared to before coating. It was observed that DLC coating of the WC alloy core surface for molding had an effect on improving the roughness and shape of the core surface. It is considered that this will have an effect on improving abrasion resistance and the service life of the core surface.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1998.04b
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• pp.19-19
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• 1998

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2000.11a
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• pp.43-43
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• 2000

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.10a
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• pp.27-27
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• 1997

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.10a
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• pp.28-28
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• 1997