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Jiujian Xu,Guangming Xu,Yong Li,Zhaodong Wang 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.10
In this study, a Ti/Al clad sheet was fabricated using horizontal twin-roll casting (HTRC) with the application of pulsedelectric field (PEF) and electromagnetic oscillation field (EOF), and the effects of different external fields on interfacialbonding strength were investigated in detail. The external electromagnetic fields have little influence on the stability of HTRCprocess. With the application of PEF and EOF, the width of diffusion layer at the Ti/Al interface increases obviously, andthe interfacial bonding strength increases from 20.1 to 21.4 N/mm and 24.5 N/mm, respectively. When the EOF is applied,the electromagnetic volumetric force is generated in the liquid cavity of cast-rolling zone, which is much larger than theelectromagnetic force caused by single PEF. Under the action of the electromagnetic volume force, aluminum melt in theliquid cavity oscillates repeatedly, which scours the surface of the titanium strip and makes the newly formed crystal nucleifall off the surface of strip. In addition, the oscillation effect reduces the temperature gradient at the contact area betweenstrip and melt and slows down the solidification process, thus prolonging the contact time between aluminum and titanium. All of these effects make the melt spread more sufficient on the surface of titanium strip and promote the interdiffusionbetween atoms. As a result, more metallurgical bonding regions are formed and enhanced, which leads to the improvementof bonding strength of the clad sheet.
Nb/Fe-C-(Si) 주조접합재에서 등온열처리시 계면반응층의 성장에 관한 연구
정병호 ( Jeong Byeong Ho ),김무길 ( Kim Mu Gil ),정상훈 ( Jeong Sang Hun ),박홍일 ( Park Hong Il ),안용식 ( An Yong Sig ),이성열 ( Lee Seong Yeol ) 한국열처리공학회 2003 熱處理工學會誌 Vol.16 No.5
N/A In order to study the interfacial reaction between Nb thin sheet and Fe-C-(Si) alloy with different chemical compositions, they were case-bonded. The growth of carbide layer formed at the interface after isothermal heat treatment at 1173K, 1223K, 1273K and 1323K for various times was investigated. The carbide formed at the interface was NbC and the thickness of NbC layer was increased linearly in proportional to the heat treating time. Therefore, It was found that the growth of NbC layer was controlled by the interfacial reaction. The growth rate constant of NbC layer was slightly increased with increase of carbon content when the silicon content is similar in the cast irons. However, as silicon content increases with no great difference in carbon content, the growth of NbC layer was greatly retarded. The calculated activation energy for the growth of NbC layer was varied in the range of 447.4-549.3kJ/㏖ with the compositions of cast irons.
열교환기 브레이징용 알루미늄 클래드 판재의 침식 거동에 미치는 가공열처리의 영향
어광준(K. Euh),김형욱(H. W. Kim),이윤수(Y. S. Lee),오영미(Y. M. Oh),백은지(E. Baek) 한국소성가공학회 2015 한국소성가공학회 학술대회 논문집 Vol.2015 No.10
Strip-cast 3000-series aluminum alloys having high strengths are used as core alloys for aluminum clad sheets. The core alloys contains relatively high Mn concentration (1.5wt%), which can be readily produced by the strip casting. The AA4343/3000-series clad sheets are fabricated by the roll bonding process and further cold-rolled down to the thickness of 0.2mm. An annealing is conducted at the final thickness for preferred tube formability and improved erosion resistance during brazing process. The effect of thermomechanical treatment on the tensile and erosion properties of aluminum clad sheets is elucidated by means of microstructural analysis.
현장타설 고강도콘크리트와 유리섬유 FRP 판 사이의 부착슬립관계에 관한 연구
박찬영(Park, Chan-Young),유승운(Yoo, Seung-Woon) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.3
GFRP 판을 영구 거푸집 및 주요 인장 보강재로 활용한 GFRP-콘크리트 하이브리드 구조의 활용에 대해 최근 활발하 게 연구가 이루어지고 있다. GFRP 판과 콘크리트 하이브리드 구조의 거동을 이해하기 위해서는 GFRP 판과 현장타설 고강 도콘크리트 사이의 정량적인 국부 부착슬립모델이 필요하다. 본 연구에서는 이러한 하이브리드 구조에 간단하게 적용할 수 있는 2중 직선 단순 부착슬립관계를 제안하고자 한다. 본 연구에서 제안된 단순 부착슬립관계의 최대 평균 부착응력은 3.29MPa이며, 초기 기울기는 35.66MPa/mm, 총 슬립은 0.23mm이고 계면 파괴에너지는 0.37kN/m로 나타났다 Recently it has been actively studied that the use of hybrid GFRP-concrete structure with dual purpose of both a permanent forwork and main tensile reinforcement of GFRP plank. In applying general analysis and design technique to evaluate the performance of hybrid structures with cast-in-place high strength concrete and GFRP plank, it is essential that the characteristics of the bond slip model is identified. In this study a simplified bilinear bond slip model for hybrid structure with GFRP plank and cast-in-place high strength concrete is proposed. Maximum average bond stress of simple bond slip relationship that has been proposed in this study is 3.29MPa, initial slope is 35.66MPa/mm, the total slip is 0.23mm and interfacial fracture energy is 0.37kN/m.
Park, Ji-Sook,Lee, Sung-Min,Han, Yoon-Soo,Hwang, Hae-Jin,Ryu, Sung-Soo The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.6
The effects of the debinding atmosphere on the properties of sintered reaction-bonded $Si_3N_4$ (SRBSN) ceramics prepared by tape casting method were investigated. Si green tape was produced from Si slurry of Si powder, using 11.5 wt% polyvinyl butyral as the organic binder and 35 wt% dioctyl phthalate as the plasticizer. The debinding process was conducted in air and $N_2$ atmospheres at $400^{\circ}C$ for 4 h. The nitridation process of the debinded Si specimens was performed at $1450^{\circ}C$, followed by sintering at $1850^{\circ}C$ and 20 MPa. The results revealed that the debinding atmosphere had a significant effect on $Si_3N_4$ densification and thermal conductivity. Owing to the higher sintered density and larger grain size, the thermal conductivity of $Si_3N_4$ specimens debinded in air was higher than that of the samples debinded in $N_2$. Thus, debinding in air could be suitable for the manufacture of high-performance SRBSN substrates by tape casting.
Park, Ji Sook,Lee, Hwa Jun,Ryu, Sung Soo,Lee, Sung Min,Hwang, Hae Jin,Han, Yoon Soo The Korean Ceramic Society 2015 한국세라믹학회지 Vol.52 No.6
It is a challenge from an industrial point of view to fabricate silicon nitride substrates with high thermal conductivity and good mechanical properties for power devices from high-purity Si scrap powder by means of thick film processes such as tape casting. We characterize the residual carbon and oxygen content after the binder burnout followed by nitridation as a function of the temperature in the temperature range of $300^{\circ}C-700^{\circ}C$ and the atmosphere in a green tape sample which consists of high-purity Si powder and polymer binders such as polyvinyl butyral and dioctyl phthalate. The optimum condition of binder burnout is suggested in terms of the binder removal temperature and atmosphere. If considering nitridation, the burnout of the organic binder in air compared to that in a nitrogen atmosphere could offer an advantage when fabricating reaction-bonded $Si_3N_4$ substrates for power devices to enable low carbon and oxygen contents in green tape samples.
구병춘(B. C. Goo),정현승(H. S. Jung) 대한기계학회 2012 대한기계학회 춘추학술대회 Vol.2012 No.11
Aluminum alloy composites with SiC particles are useful for weight reduction of mechanical components. But they are expensive and it is difficult to make complex components. If we found out a reliable method to join aluminum alloys and Al/SiC composites, we could make complex mechanical parts at a low price. In this study A356 aluminum alloy and A356/SiC 20 vol.% composite were chosen as dissimilar materials. To join two different materials by casting, first, A356 blocks were cast and cylindrical holes with conical end were drilled in the blocks. A mold with a cylindrical hole was placed on an A356 cast block. Molten A356/SiC at about 750℃ was poured into the mold. Before pouring molten A356/SiC, A356 blocks were heated and kept at 550℃. Using the specimens tensile strength tests were carried out. As tensile forces increased, some composite bars were pulled out from the A395 blocks and others fractured near the border. Tensile strengths depended on the surface conditions of the cast-bonded joints.
박지숙,이화준,류성수,이성민,황해진,한윤수 한국세라믹학회 2015 한국세라믹학회지 Vol.52 No.6
It is a challenge from an industrial point of view to fabricate silicon nitride substrates with high thermal conductivity and good mechanical properties for power devices from high-purity Si scrap powder by means of thick film processes such as tape casting. We characterize the residual carbon and oxygen content after the binder burnout followed by nitridation as a function of the temperature in the temperature range of 300°C - 700°C and the atmosphere in a green tape sample which consists of high-purity Si powder and polymer binders such as polyvinyl butyral and dioctyl phthalate. The optimum condition of binder burnout is suggested in terms of the binder removal temperature and atmosphere. If considering nitridation, the burnout of the organic binder in air compared to that in a nitrogen atmosphere could offer an advantage when fabricating reaction-bonded Si3N4 substrates for power devices to enable low carbon and oxygen contents in green tape samples.
류성룡(Ryu Seong-Ryong),정창헌(Cheong, Chang-Heon),서혜수(Suh, Hye-Soo) 한국건축친환경설비학회 2016 한국건축친환경설비학회 논문집 Vol.10 No.6
In Korea, there have been recently many studies to overcome weaknesses of exterior insulation in terms of workability and safety at high-rise building. And, the exterior insulation board in cast-in-place concrete form system was developed such as permanent insulation form system or integrated system for exterior insulation and wall. We utilized modified method for KS F 2762 to obtain test result for insulation bond strength in this study. Based on this method, we had measurements of bond strength for 12 cases and analyzed the result value of insulation bond strength test. In result, bond strength of EPS(expanded poly styrene, ‘B’ company) in E/F case is nearly 0.08 N/mm2(reference value of EOTA). Considering strong wind load by typhoon in Korea, it is necessary to use connection elements or to improve the bond strength of insulation by ribbed surface.