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정승부 成均館大學校 科學技術硏究所 1996 論文集 Vol.47 No.2
Reaction diffusion and formation of Ni_3AL phase with L1_2 structure has been studied at temperature from 1423 to 1573K using the diffusion couple of (Ni-40.5at%Al)/(Ni-15at%Al) and (Ni-49.2at%Al)/(Nickel). The layer growth of Ni_3-Al phase in the annealed diffusion couple was measured by optical microscope and electron probe microanalyzer(EPMA). The layer growth of Ni_3Al phase in this experimental temperature range was controlled by the volume diffusion mechanism. The rate of layer growth of Ni_3-Al phase was found to be closely related to the composition of NiAl phase. The activation energy for layer growth of Ni_3Al phase was calculated to be 127kJ/mol.
전자현미경 In-Situ 관찰방법을 이용한 황동의 절삭성평가
정승부,임옥동,안성욱,Jung, Seung-Boo,Lim, Ok-Dong,An, Seong-Uk 한국현미경학회 1994 Applied microscopy Vol.24 No.3
In order to elucidate the machinability of lead brass, orthogonal machining experiment was conducted in SEM(Scanning Electron Microscope) equipped with a micro-machining device at a cutting speed of $7{\mu}m/s$ for brass containing 0.2 to 3wt% Pb. The microfactors (i.e., shear angle, contact length between chip and tool) were determined by in-situ observations. Machinability of brass containing lead is discussed in terms of the microfactors and the cutting resistant force tested by lathe cutting. The dynamic behavior of the chip formation of lead brass during the machining process was examined: The chips of lead brass form as a shear angle type. The shear angle increases with the content of lead in (6:4) brass. The pronounced effect of lead on the contact length between chip and tool was observed above 1% Pb. The cutting resistant force tested by lathe decreases remarkably with the lead content in brass. The observed microfactors are in close relation to the tested resistant force in macromachining.
WC-Co/Cu/SM45C강접합에 미세조직 및 접합강도에 미치는 냉각속도의 영향
정승부,양훈모 대한용접접합학회 1999 대한용접·접합학회지 Vol.17 No.2
The interfacial microstructure and bond strength were examined for WC-Co/Cu/SM45C steel join using a nickel-plated copper in vacuum at 1323K for 0.6ks∼3.6ks. After bonding, microstructure in bonding interface was observed by OM(Optical Microscopy), SEM(Scanning Electron Microscopy) and EPMA(Eelectron Probe Micro Analyzer). The oil cooling was carried out at 353K, the cooling rate in air and furnace was 22K/s and 4.4K/s. respectively. It was found that dendritic widths increased with the content of cobalt and bonding times at 1323K. As a whole, bond strength values at the same bonding condition decreased in this order: WC-13wt.%Co/SM45Csteel. WC-8wt.%Co/SM45Csteel and WC-4wt.%Co/SM45Csteel. The bond strength of WC-13wt.%Co/S45C steel joint in oil cooling was 273MPa. This value was greatly higher than those of 125MPa in furnace cooling and 93MPa in air cooling at 1323K for 0.6ks. The bond strength values were found to be closely associated with the content of cobalt in WC-Co and cooling rate.
Ni-NiAl 확산대에서 $Ni_3Al$ 상의 형성과 반응확산
정승부 대한용접접합학회 1997 대한용접·접합학회지 Vol.15 No.3
Reaction diffusion and formation of $Ni_3Al$phase with $L1_2$ structure have been studied in temperature range of 1432K to 1573K using the diffusion couple of (Ni-40, 5at%Al)/(Ni-14, 1at%Al) and (Ni-49, 2at%Al)/ (Nickel). The layer growth of Ni$_{3}$Al pyhase in the annealed diffusion couple was measured by optical microscope and electron probe microanalyzer (EPMA). The layer growth of $Ni_3Al$phase in diffusion zone obeyed the parabolic law without any indication of grain boundary effects. The layer growth of $Ni_3Al$phase in temperature range of 1423K to 1573K was mainly controlled by the volume diffusion mechanism. The rate of layer growth of $Ni_3Al$phase was found to be colsely related to the composition of intermetallic compound NiAl phase. The activation energy for layer growth of $Ni_3Al$phase was calculated to be 127kJ/mol.
액상확산접합부 생성상의 생성 및 성장 거동에 관한 연구
김대업,정승부 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.10
The formation, growth and disappearance behaviors of microconstituents in the bonded region of Ni-base single superalloy, CMSX-2 during transient liquid phase (TLP) bonding was investigated employing MBF-80 insert metal. TLP-bonding was carried out at 1373∼1548 K for 0∼19.6 ks in vacuum of 4 mPa. The (100) orientation of each test specimen was always aligned perpendicular to the bonding interface. Borides were formed in the bonded layer during TLP-bonding operation. In the early stage of bonding, base metal dissolution process, small and lots of microconstituents come into being, and the microconstituents combine and grew as the bonding temperature increased and the holding time was increased. The amount of microconstituents in the bonded layer after isothermal solidification was decreased with the holding time. The microconstituents in the bonded layer disappeared at the bonding condition of 1523 K×1.8 ks.