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은(Ag)계 활성금속을 사용한 질화 알미늄(AlN)과 Cu의 브레이징
허대,김대훈,천병선,Huh, D.,Kim, D.H.,Chun, B.S. 대한용접접합학회 1995 대한용접·접합학회지 Vol.13 No.3
Aluminium nitride(AlN) is currently under investigation as potential candidate for replacing alumium oxide(Al$_{2}$ $O_{3}$) as a substrate material for for electronic circuit packaging. Brazing of aluminium nitride(AlN) to Cu with Ag base active alloy containing Ti has been investigated in vacuum. Binary Ag$_{98}$ $Ti_{2}$(AT) and ternary At-1wt.%Al(ATA), AT-1wt.%Ni(ATN), AT-1wt.% Mn(ATM) alloys showed good wettability to AlN and led to the development of strong bond between brate alloy and AlN ceramic. The reaction between AlN and the melted brazing alloys resulted in the formation of continuous TiN layers at the AlN side iterface. This reaction layer was found to increase by increase by increasing brazing time and temperature for all filler metals. The bond strength, measured by 4-point bend test, was increased with bonding temperature and showed maximum value and then decreased with temperature. It might be concluded that optimum thickness of the reaction layer was existed for maximum bond strength. The joint brazed at 900.deg.C for 1800sec using binary AT alloy fractured at the maximum load of 35kgf which is the highest value measured in this work. The failure of this joint was initiated at the interface between AlN and TiN layer and then proceeded alternately through the interior of the reaction layer and AlN ceramic itself.
윤승채,팜쾅,천병선,이홍로,김형섭,Yoon, Seung-Chae,Quang, Pham,Chun, Byong-Sun,Lee, Hong-Ro,Kim, Hyoung-Seop 한국분말야금학회 2006 한국분말재료학회지 (KPMI) Vol.13 No.6
Nanostructured metallic materials are synthesized by bottom-up processing which starts with powders for assembling bulk materials or top-down processing starting with a bulk solid. A representative bottom-up and top-down paths for bulk nanostructured/ultrafine grained metallic materials are powder consolidation and severe plastic deformation (SPD) methods, respectively. In this study, the bottom-up powder and top-down SPD approaches were combined in order to achieve both full density and grain refinement without grain growth, which were considered as a bottle neck of the bottom-up method using conventional powder metallurgy of compaction and sintering. For the powder consolidation, equal channel angular pressing (ECAP), one of the most promising method in SPD, was used. The ECAP processing associated with stress developments was investigated. ECAP for powder consolidation were numerically analyzed using the finite element method (FEM) in conjunction with pressure and shear stress.
임계상대밀도 모델을 이용한 분말 등통로각압축 공정시 분말 치밀화 거동
복천희,유지훈,윤승채,김택수,천병선,김형섭,Bok, Cheon-Hee,Yoo, Ji-Hoon,Yoon, Seung-Chae,Kim, Taek-Soo,Chun, Byong-Sun,Kim, Hyoung-Seop 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.5
In this study, bottom-up powder processing and top-down severe plastic deformation processing approaches were combined in order to achieve both full density and grain refinement with least grain growth. The numerical modeling of the powder process requires the appropriate constitutive model for densification of the powder materials. The present research investigates the effect of representative powder yield function of the Shima-Oyane model and the critical relative density model. It was found that the critical relative density model is better than the Shima-Oyane model for powder densification behavior, especially for initial stage.
가스분무공정을 이용한 (AgSbTe<sub>2</sub>)<sub>15</sub>(GeTe)<sub>85</sub> 열전분말의 제조 및 특성평가
김효섭,이진규,구자명,천병선,홍순직,Kim, Hyo-Seob,Lee, Jin-Kyu,Koo, Jar-Myung,Chun, Byong-Sun,Hong, Soon-Jik 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.5
In this study, p-type $(AgSbTe_2)_{15}(GeTe)_{85}$: TAGS-85 compound powders were prepared by gas atomization process, and then their microstructures and mechanical properties were investigated. The fabricated powders were of spherical shape, had clean surface, and illustrated fine microstructure and homogeneous $AgSbTe_2$ + GeTe solid solution. Powder X-ray diffraction results revealed that the crystal structure of the TAGS-85 sample was single rhombohedral GeTe phase, which with a space group $R_{3m}$. The grain size of the powder particles increased while the micro Vickers hardness decreased with increasing annealing temperature within the range of 573 K and 723 K due to grain growth and loss of Te. In addition, the crystal structure of the powder went through a phase transformation from rhombohedral ($R_{3m}$) at low-temperature to cubic ($F_{m-3m}$) at high-temperature with increasing annealing temperature. The micro Vickers hardness of the as-atomized powder was around 165 Hv, while it decreased gradually to 130 Hv after annealing at 673K, which is still higher than most other fabrication processes.
전자빔 용접된 Cu / STS 304강의 미세조직에 관한 연구
박경태,김인호,백준호,천병선,Park, Kyoung-Tae,Kim, In-Ho,Baek, Jun-Ho,Chun, Byung-Sun 대한용접접합학회 2010 대한용접·접합학회지 Vol.28 No.2
According to the research report for the recent a few years, the dissimilar welding of Cu and STS 304 alloy have been presented that a weldability is very poor. This article present a study on Lap joint by Electron beam welding dissimilar materials. The weld metals was constituted between pure copper and STS 304 steel. The experiment was performed with 125mA welding current, 520mA focusing current. The Vacuum condition of chamber is 5${\times}$10-5torr and welding speed is 300mm/min. Showing the bead shape of weld metal, the thickness of the stainless 304 using as the protect materials is 3mm and the thickness of a copper is 15mm. The analysis about the microstructure were carried out in which it was observed with SEM. The results showed that complex heterogeneous fusion zone microstructure characterized both by rapid cooling and mixing of the molten metal, however the liquation crack was formated in the fusion line.
Al 5052 함금 후판재의 전자빔 용접부 단면 형상과 강도에 관한 연구
김인호,이길영,주정민,박경태,천병선,Kim, In-Ho,Lee, Gil-Young,Ju, Jeong-Min,Park, Kyoung-Tae,Chun, Byong-Sun 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.3
This present paper investigated the mechanical properties and the microstructures of each penetration shapes classifying the conduction shape area and the keyhole shape area about electron beam welded 120(T)mm thick plated aluminum 5052 112H. As a result the penetration depth is increased linearly according to the output power, but the aspect ratio is decreased after the regular output power. In the conduction shape area, the Heat affected zone is observed relatively wider than the keyhole shape area. In the material front surface of the welded specimen, the width is decreased but the width in the material rear surface is increased. After the measuring the Micro Vikers Hardness, it showed almost similar hardness range in all parts, and after testing the tensile strength, the ultimate tensile strength is similar to the ultimate tensile strength of the base material in all the specimens, also the fracture point was generated in the base materials of all the samples. In the result of the impact test, impact absorbed energy of the Keyhole shape area is turned up very high, and also shown up the effect about four times of fracture toughness comparing the base material. In the last result of observing the fractographs, typical ductile fraction is shown in each weld metal, and in the basic material, the dimple fraction is shown. The weld metals are shown that there are no other developments of any new chemical compound during the fastness melting and solidification.