• Journal of the Korean Ceramic Society
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• v.33 no.12
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• pp.1421-1425
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• 1996

Sintered Si3N4 and Inconel composed of Ni(58-63%) Cr(21-25%) Al(1-17%) Mn(<1%) fe(balance) were pressurelessly joined by using Ag-Cu-Ti brazing filler metal at 950℃ and 1200℃ under N2 gas atmosphere of 1atm and their interfacial structures were investigated. In case that the reaction temperature was low as 950℃ its interfacial structure was "Inconel metal/Ti-rich phase layer/brazing filler metal layer/Si3N4 " Ti used as reactive metal existed in between inconel steel and brazing metal and moved to the interface of between brazing filler metal nd Si3N4 according as reaction temperature increased up to 1200℃. The interfacial structure of inconel steel-Si3N4 reacted at 1200℃ was ' inconel metal/Ni-rich phase layer containing of Fe. Cr and Si/Cu-rich phase layer containing of Mn and Si/Si3N4 " Cr Mn, Ni and Fe diffused to the interface of between brazing filler metal and Si3N4 and reacted with Si3N4 The most reactive components of ingredients of inconel metal were Cr and Mn. On the other hand Ti added as reactive components to Ag-Cu eutectic segregated into Ni-rich phase layer,.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.11 s.254
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• pp.1376-1383
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• 2006

Densification behavior of various metal and ceramic powders was investigated under cold compaction. The Cap model was proposed by using the parameters involved in the yield function for sintered metal powder and volumetric strain evolution under cold isostatic pressing. The parameters for ceramic powder can also be obtained from experimental data under triaxial compression. The Cap model was implemented into a finite element program (ABAQUS) to compare with experimental data for densification behavior of various metal and ceramic powders under cold compaction. The agreement between finite element calculations from the Cap model and experimental data is very good for metal and ceramic powder under cold compaction.

• Journal of the Korean Ceramic Society
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• v.32 no.2
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• pp.257-269
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• 1995

The TiC-Co/Al reaction-sintered products were prepared by the infiltration of various Co/Al metal mixture into the preform, and their microstructure, phases, and mechanical properties were investigated. With increasing the atomic ratio of Co/Al, tiC grain shape was changed from spherical to platelet particles, and the grain size increased. The crystalline phases found in the liquid matrix formed by the infiltration of Co/Al metal mixture were determined to be Al5Co2 and AlCo by EDS and XRD, and the two crystalline phases were located dominantly between TiC grains, when the Co/Al atomic ratio was lower than an unity. There was a tendency that the density, bending strength and fracture toughness increase with Co/Al atomic ratio until the infiltrated metal was 100% Co. The maximum value was achieved by the composition containing 100% Co infiltrated metal. The Vickers hardness decreased as Co/Al atomic ratio increased.

• Journal of the Korean Ceramic Society
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• v.22 no.6
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• pp.58-70
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• 1985

The bond strength of metal to ceramic sealing in Mo-Mn metallizing was investigated by examining the effects of flux composition in alumina ceramics particle size of molybdenum metal powder wet hydrogen atmosphere and temperature in metallizing. The maximum bond strength was obtained when the glass phase filled almost all the microstructural cavities around the interfacial area with few micropores. Such a favorable microstrcutre waas formed and maximum bond strength was observed between 130$0^{\circ}C$. Also the metal to ceramic bond strength was increased using finer molybdenum metal powder than coarse powder. When content of $SiO_2$ in the flux of alumina ceramics was constant metal to ceramic bond strength was improved with increasing the ratio of CaO to MgO in the flux.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1128-1129
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• 2006

Currently Chemical Mechanical Planarization (CMP) has become an essential step in the overall semiconductor wafer fabrication technology. Especially the CMP pad conditioner, one of the diamond tools, is required to have strong diamond cohesion. Strong cohesion between diamond and metal matrix prevents macro scratch on the wafer during CMP Process. Typically the diamond tool has been manufactured by sintered, brazed and electro-plated methods. In this paper, some results will be reported of cohesion between diamond and metal matrix of the diamond tools prepared by three different manufacturing methods. The cohesion force of brazed diamond tool is found stronger than the others. This cohesion force is increased in reverse proportion to the contact area of diamond and metal matrix. The brazed diamond tool has a strong chemical combination of the interlayer composed of Cr in metal matrix and C in diamond, which enhance the interfacial cohesion strength between diamonds and metal matrix.

• Archives of Metallurgy and Materials
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• v.67 no.4
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• pp.1517-1520
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• 2022

Recently, 3D printing processes have been used to manufacture metal powder filters with manufacturing complex-shape. In this study, metal powder filters of various shapes were manufactured using the metal extrusion additive manufacturing (MEAM) process, which is used to manufacture three-dimensional structures by extruding a filament consisting of a metal powder and a binder. Firstly, filaments were prepared by appropriately mixing SUS316 powder with sizes ranging from 7.5 ㎛ to 50 ㎛ and a binder. These filaments were extruded at temperatures of 100℃ to 160℃ depending on the type of filament being manufactured, to form three types of cylindrical filter. Specimens were sintered in a high vacuum atmosphere furnace at 850℃ to 1050℃ for 1 hour after debinding. The specimens were analyzed for permeability using a capillary flow porometer, porosity was determined by applying Archimedes' law and microstructure was observed using SEM.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 1997.04a
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• pp.13-13
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• 1997

• Journal of Magnetics
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• v.7 no.2
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• pp.29-39
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• 2002

The initial NiCuZn synthetic ferrite were acquired from thermally decomposing the metal nitrates $Fe(NO_3)_39H_2O, Zn(NO_3)_26H_2O, Ni(NO_3)_26H_2O, and Cu(NO_3)_23H_2O$ at $150^circ{C}$ for 24 hours, and then we calcined the synthetic powder at $500^circ{C}$, pulverized each of those for 3, 6, 9, 12, and 15 hours in a steel ball mill, sintered each at $700^circ{C}$ to $1,000^circ{C}$ for 1 hour, and thus studied their microstructures and electromagnetic properties. We could make the initial specimens chemically bonded in liquidity at a low-temperature $150^circ{C}$, by using the low melting points less than $200^circ{C}$ of the metal nitrates instead of the mechanical ball-mill pulverization, then narrow a distance between the particles into a molecular one, and thus lower the reaction point of sintering by at least $200^circ{C}$ to $300^circ{C}$. Their initial permeability was 50 to 400 and their maximum magnetic induction density and coercive force, 2,400 G and 0.3 Oe to 0.5 Oe respectively, which was similar to those of NiZnCu ferrite synthesized in the conventional process. In the graph of initial permeability by frequencies, a $180^circ{C}$ rotation of the magnetic domains which appears in a broad band of micro-wave before and after the resonance frequency, could be perceived.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.8
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• pp.100-105
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• 1999

This work analyses the effects of electrical conductivities of dielectric and cobalt amount on output parameters such as metal removal rate and the surface roughness value of cemented carbides cut by wire electrical discharge machining(W-EDM). Especially, the cracking behaviour of W-EDM machined surface and optimal machining condition of three kinds of cemented carbides, which have different chemical composition of tungsten carbide and cobalt are also tested. Experimental result shows that increases in cobalt content and electrical conductivity of the dielectric affect the metal removal rate and substantially worsen the final surface quality as a greater quantity of solidified metal deposits on the eroded surface.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.179-180
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• 2006

Densification behavior of various metal and ceramic powder was investigated under cold compaction. The Cap model was proposed based on the parameters obtained from axial and radial deformation of sintered metal powder compacts under uniaxial compression and volumetric strain evolution. For ceramic powder, the parameters were obtained from deformation of green powder compacts under triaxial compression. The Cap model was implemented into a finite element program (ABAQUS) to compare with experimental data for densification behavior of various metal and ceramic powder under cold compaction.