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Sn-Zn 공정합금의 응고속도에 따른 조직과 기계적 성질에 관한 연구
이주형,이계완 ( J . H . Lee,K . W . Lee ) 한국주조공학회 1985 한국주조공학회지 Vol.5 No.4
The structures and mechanical properties of undirectionally solidified Sn-Zn eutectic alloys have been examined over the growth range 7㎜/h to 6,000㎜/h. The structures of undirectionally solidified Sn-Zn eutectic alloys were primarily broken-lamellar at growth rates below 760㎜/h and became fibrous at higher growth rates above that. At a growth rate 3,084㎜/h the structures were fibrouse only. There is no dendrites at any growth rates, but occasionally ribbon-like morphologies were seen. The under cooling increased parabolically with growth rate increase. The hardness of specimes increased with growth rates increase but heat-treated specimen decreased after growth rates 760㎜/h and became constant value. The effect of heat-treatment was good at lower growth rate. At room temperature tensile strength increased with growth rates up to R=990㎜/h and then tensile strength became near-constant value. The effect of heat-treatment was well at lower growth rate.
이주형,박경우,박희용,Lee, J.H.,Park, K.W.,Pak, H.Y. 대한설비공학회 1996 설비공학 논문집 Vol.8 No.4
The interaction of turbulent mixed convection and surface radiation in a three-dimensional channel with the heated blocks is analyzed numerically. Two blocks are maintained at high temperature and the other bottom and horizontal walls are insulated. S-4 method is employed to calculate the effect of the radiative heat transfer. The low Reynolds number k-$\varepsilon$ model proposed by Launder and Sharma is used to estimate the turbulent influence on the heat transfer enhancement. From above modeling, the effects of various channel specifications on the flow and heat transfer characteristics are investigated. The variables used for the present study are Reynolds number, block spacing, the channel height spacing for block and the emissivity. Average Nusselt numbers along the block surfaces are correlated and presented in terms of Reynolds number, emissivity and dimensionless geometric parameters. For the range of conditions in this study, average Nusselt numbers along the block surfaces are strongly influenced by the Reynolds numbers and channel height spacing for block but weakly influenced by the block spacing and the emissivity of the adiabatic walls.