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Al 합금용탕의 (合金熔湯) C2Cl6 정제-탈가스에 의한 Mg 의 손실
이진형 ( Zin Hyoung Lee ) 한국주조공학회 1981 한국주조공학회지 Vol.1 No.3
N/A The Mg-loss of AlSi 7% melts containing from 0 to 0.8% Mg during the Hexachloroethane tablet degassing was investigated. The results of the experiment was discussed in view of the free energy change and kinetics of MgCl₂formation. The melts with Mg content less than 0.5% showed a Mg-loss proportional to Mg-content, while it was constant at about 24% of the weight of tablets, when Mg content of the melt became more than 0.5 %. The rate of Mg-loss was drastically reduced, when the amount of tablets used at a time increased ver a certain limit for a given melt quantity.
T5 열처리한 Al 합금 금형주조품에서 경도의 역분포현상
이진형 ( Zin Hyoung Lee ) 한국주조공학회 1988 한국주조공학회지 Vol.8 No.3
N/A Aluminum alloy permanent mold castings often exhibit in as-cast or T5-heat treated state an inverse distribution of hardness, i,e. thinner sections have lower hardness than thicker sections. This phenomina is explained by measuring the cooling curves in a test casting in an Aluminum piston alloy (AC8A or A332). Thinner sections solidify- faster but later cooles down more slowly than thicker sections in temperature range where coarse precipitation of supersaturated elements can take place. The precipitation rate of Mg₂Si phase in A332 alloy seems to be maximum at around 490℃.
Te 도핑된 InSb 의 수직 브릿지만 결정성장시 횡적자장이 거시편석에 미치는 영향
이근희,이진형,윤우영,백홍구,강춘식 ( Geun Hee Lee,Zin Hyoung Lee,Woo Young Yoon,Hong Ku Baek,Chun Sik Kang ) 한국주조공학회 1997 한국주조공학회지 Vol.17 No.1
N/A An investigation of the effects of transverse magnetic field on melt convection and macrosegregation in vertical Bridgman growth of Te doped InSb was carried out by means of microstructure observation, the measurement of Te distribution by Hall measurement, electrical resistivity measurement and X-ray analysis. Prior to the experiments, interface stability, convective instability and suppression of convection by magnetic field were examined. A thermosolutal convection in the Te doped InSb melt occurred in the examined growth condition without magnetic field. The effective distribution coefficient, k_(eff), was about 0.35 without magnetic field, 0.45 with magnetic field of 2kG, and 0.7 at 4kG. It was found that the stronger the applied magnetic field was, the more the convection was suppressed.
하만진,이진형,이상수,은희준 ( Man Jin Ha,Zin Hyoung Lee,Sang Soo Lee,Hee Joon Eun ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.1
N/A The possibility of using bulk talc as molding material was reviewed and tested with the measurement of thermal properties and computer simulations. The measured thermal conductivity and heat diffusivity(kpc) of talc were 2.4W/m℃ and 6.6×10^6 J²/m⁴℃²s, respectively. Thermal properties of talc could be ranked between those of sand mold and iron mold. Talc transforms into cristobalite and enstatite at 910℃, During the transformation volume and structure change, cracks appear on the surface and distortion occurs. Therefore talc can be used for molding material below 910℃ if carefully treated. Computer simulation was carried out to test whether talc insert could promote directional solidification in sand mold and iron mold. In sand mold, it was possible to achieve directional solidification of thin plate casting with the length to thickness ratio of 15, if both iron insert and talc insert were used. In iron mold, it was possible to achieve directional solidification only with talc insert.
유도코일 형태가 용융주석의 자유표면 형상에 미치는 영향
하만진,이진형 ( Man Jin Ha,Zin Hyoung Lee ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.2
N/A Electromagnetic continuous casting(EMC) is a novel continuous casting technique which utilizes electromagnetic force to maintain the melt free surface in a desired shape. In this study the effect of electromagnetic field on the free surface shape of tin melt was investigated. Tin was used because it has the similar density and electroconductivity to steel. High frequency(2.5㎑) coil current was calculated with the measurement of the electromotive force in a solenoid probe. The effect of the electromagnetic field on the melt shape was numerically analysed. The predicted results were compared with experimental results under the variation of melt mass and coil current. The influence of the cross section shape and inner diameter of the coil was studied. It has been shown that the coil which has a tapered inner wall was more suitable for EMC than the coil with a rectangular cross section. The tapered inner wall plays a role of screen without power dissipation. The predicted free surface was in a good agreement with experimental results.
레이들 내 와류 형성에 미치는 노즐 편심도의 영향에 관한 수치해석
최윤석,서준원,이진형 ( Yun Suk Choi,Jun Won Suh,Zin Hyoung Lee ) 한국주조공학회 1998 한국주조공학회지 Vol.18 No.1
N/A In steel making process, vortices may develope during the tapping of steel from ladle to tundish which take down undesired slag in their core. If the slag is dispersed finely in the melt, it can flow down further into the mold and finally becomes inclusion in the steel. Therefore, the suppression of the vortex formation is very important in steel making process. One of the methods used to suppress the vortex formation is using nozzle eccentricity. In this study the flow field and the free surface change during the drainage of melt from ladle were analyzed numerically with a commercial FDM package, CFX-F3D, to find out the effect of nozzle eccentricity. This calculation results showed the suppression effect of vortex formation by nozzle eccentricity in agreement with experiment. (Received November 14, 1997)
Cr 합금주철-주강의 원심주조 복합재 제조에 관한 연구
신현우,강춘식,이진형 ( Hyun Woo Shin,Choon Sik Kang,Zin Hyoung Lee ) 한국주조공학회 1989 한국주조공학회지 Vol.9 No.2
N/A Bonding of outer metal(low Cr-alloyed cast iron) and inner metal(cast steel) by centrifugal casting process is difficult to obtain ideal bonding because melting point of inner metal is higher than that of outer metal. Bonding is depended on mold rotary speed, melt pouring temperature, pouring position and pouring speed. Optimum bonding conditions were obtained at the range of bonding ratio 95% and mixing ratio 20% by using bonding map. Increasing of mold rotary speed expanded perfect bonding range but optimum bonding range was narrower at 1300rpm than 1000rpm according to mixing of two layers. In the case of outer metal surface temperature was lower than 110℃ when mold rotary speed was 1000rpm, perfect bonding could not be obtained even though inner metal pouring temperature was up to 1650℃. Bonding zone of two different metal made by casting process was dominated by fusion bonding. By testing the mechanical properties of bonding zone, the critical casting condition in bonding map could be obtained and the sound fabrication of composite material could be possible.
김지준,김진수,류관호,최정길,이진형,홍준표 ( Ji Joon Kim,Jin Soo Kim,Gwan Ho Ryu,Jeong Kil Choi,Zin Hyoung Lee,Chun Pyo Hong ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.3
N/A In gravity die casting, die cooling systems are frequently employed with water cooling to remove the heat of the solidifying metal. Thermal modeling is an important technique in mold design for improving the productivity of the process. Computer simulation system which consists of pre-processor, main solidification simulator and post-processor has been developed for three dimensional solidification analysis of cyclic gravity die casting. The pre-processor is used for mesh generation in a PC system. The modified finite difference method is adopted for the main solidification simulation algorithm during all the casting cycles. The post-processor graphically presents the simulation results. Several experiments in automotive cast piston were carried out. The temperature variations in casting and mold with time are measured experimentally, and the results are compared with calculation results. The effects of cycle number on solidification pattern are also studied. Several experimental results for the prediction of shrinkage defects are compared with calculated results.
FDM 에 의한 응고해석시 계산시간 단축을 위한 음적해법의 적용과 잠열처리방법
김태규,최정길,홍준표,이진형 ( Tae Gyu Kim,Jung Kil Choi,Jun Pyo Hong,Zin Hyoung Lee ) 한국주조공학회 1993 한국주조공학회지 Vol.13 No.4
N/A An implicit finite difference formulation with three methods of latent heat treatment, such as equivalent specific heat method, temperature recovery method and enthalpy method, was applied to solidification analysis. The Neumann problem was solved to compare the numerical results with the exact solution. The implicit solutions with the equivalent specific heat method and the temperature recovery method were comparatively consistent with the Neumann exact solution for smaller time steps, but its error increased with increasing time step, especially in predicting the solidification beginning time. Although the computing time to solve energy equation using temperature recovery method was shorter than using enthalpy method, the method of releasing latent heat is not realistic and causes error. The implicit formulation of phase change problem requires enthalpy method to treat the release of latent heat reasonably. We have modified the enthalpy formulation in such a way that the enthalpy gradient term is not needed, and as a result of this modification, the computation stability and the computing time were improved.
전자선 용해법에 의한 V 의 정련 및 용해에 관한 연구
김휘준,백홍구,윤우영,이진형,강춘식 ( Hwi Joon Kim,Hong Koo Baik,Woo Young Yun,Zin Hyoung Lee,Choon Sik Kang ) 한국주조공학회 1995 한국주조공학회지 Vol.15 No.3
N/A In order to improve the production process of low cost and high purity Vanadium, this study was done to reduce V₂O_5 into V-Al master alloy by Aluminothermic Reduction, followed by refining of V-Al master alloy electron beam melting. As melting time was increased in electron beam melting of V, the contents of interstitial impurities and Al, Fe were decreased but the contents of Si, Mo and W were increased due to lower vapor pressure of these elements than that of matrix V. Consequently, it was profitable that melting of V was done for 180 seconds. In addition, with number of melting, the purity of V did not significantly vary, because volatile impurities in V were removed mostly during the first step of melting. As a result of V refining by electron beam melting, high purity Vanadium of 3N(99.91wt%) was acquired including interstitial impurities total contents of which were maximum 400ppm.