• 대한기계학회논문집B
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• 제25권10호
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• pp.1365-1372
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• 2001

In the planar flow casting(PFC) process, the conditions of the melt puddle between nozzle and rotating wheel affect significantly the quality and dimensional uniformity of the downstream ribbon. For stable puddle formation, the nozzle is placed very close to the quenching wheel, so the surface-tension and wall-adhesion forces have an important effect upon the fluid flow.\`In this study the planar flow casting process has been mode]ed using the VOF method for free surface tracking. The transient puddle formation from the present analysis shows good agreements with the previous experimental results. Furthermore, the variation of melt temperature and the corresponding cooling rate of the melt have been examined. The present results also show how the melt puddle can be farmed on the rotating substrate, how the melt flows within the puddle, and how the changes of the process variables affect the puddle formation and its corresponding fluid flow and heat transfer behavior.

• 한국주조공학회지
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• 제15권4호
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• pp.408-415
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• 1995

Polycrystalline Al-Cu ribbons were produced by planar flow casting(PFC). Solidification behavior and microstructual changes of the ribbons have been investigated as a function of ribbon thickness and processing parameters. The solidification front velocity, V varies within the ribbon, decreasing with increasing the distance, S from the wheel-contact surface, as $V=17.6S^{-1}$. In Al-4.5wt%Cu alloy, rapid decrease in solidification velocity toward the free surface causes a change in solidification morphology from planar to cellular, and finally, to dendritic. The length and inclination of columnar grains solidified with planar front were related to the wheel velocity. The transition from particulate degenerate eutectic structure to regular lamellar eutectic structure was observed to be caused by a difference of the relative growth velocites of ${\alpha}-Al$ and ${\theta}$ during solidification in the Al-Cu eutectic alloy.

• 한국주조공학회지
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• 제27권5호
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• pp.224-227
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• 2007

원자로에 장전되는 $^{99}Mo$ 조사표적을 제조하기 위한 우라늄박판은, 박판 품질, 생산성, 경제성 문제로 인해, 기존의 열간압연방법에 의해 실험실 규모로는 제조가 가능하나, 상용 규모로는 제조되기 어려운 실정이므로, 새로운 제조방법의 개발이 요구되고 있다. 이와 같은 상황에서, $^{99m}Tc$의 모핵종인 방사선 동위원소$^{99}Mo$ 생산하기 위하여 planar flow casting (PFC) 법에 의해 다결정질 우라늄박판에 대한 새로운 제조방법이 연구되었다. $100{\sim}150\;{\mu}m$의 두께 및 너비 약 50mm의 연속적인 다결정질 우라늄박판이 하나의 batch에서 5m 이상의 길이로 제조되었다. 우라늄박판은 불순물이 거의 없었으며 양호한 표면조도를 가지고 있었다. 우라늄박판의 냉각를 접촉표면은 자유표면 보다 매끈한 자유표면을 가지고 있었다. 우라늄박판은 제조공정변수와는 상관없이 ${\alpha}-U$ 상을 가진 약 10 ${\mu}m$ 이하의 미세한 다결정립을 가지고 있었다.

• 한국자기학회지
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• 제25권1호
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• pp.4-9
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• 2015

본 연구는 PFC(Planar Flow Casting)프로세스에 의한 Fe기 $Fe_{78}Si_9B_{13}$ 비정질 합금리본 제조에 있어서 습도변화(55~85 %)가 비정질 합금리본의 표면결함 및 자기적 특성에 미치는 영향을 조사하였다. 그 결과, 비정질 합금리본의 접촉면과 자유면에서 관찰된 air pocket/droplet의 크기는 습도가 증가할수록 커지는 경향을 보임과 동시에 표면조도과 함께 크게 증가하였으며, 특히 습도 65 %에서 제조한 표면조도 값이 접촉면($Ra=0.60{\mu}m$, $Rz=3.11{\mu}m$)과 자유면($Ra=0.47{\mu}m$, $Rz=3.00{\mu}m$)에서 모두 가장 낮은 값이 얻어졌다. 또한 $23(OD)^*20(ID)^*20(H)$ 크기의 토로이달 코어로 제조된 자성코어의 연자기적 특성의 경우에도 65 %에서 제조한 비정질 합금리본의 시료에서 $B_s(B_{700})=1.055T$, $H_c=0.083Oe$, 투자율 = 1,197 및 core loss = 0.276 W/kg로 가장 우수한 값이 얻어졌다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.464-466
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• 2009

This study tried to examine the suitability of strip casting process such as PFC (Planar Flow Casting) method for soldering Au-Sn strip. The effect of heat treatment on the tensile behavior and mechanical properties of an Au-Sn strip was investigated through tensile test, micro hardness test, X-ray diffraction (XRD), SEM, and TEM observations. It was apparent that 20-mm width Au-Sn strip could be well produced by using planar flow casting process. Tensile results showed that tensile strength increased from 338.3MPa to 310MPa and plastic strain improved from 0% to 1.5% with heat treatment ($170^{\circ}C$/70 hrs.). The microstructure of Au-Sn strip mainly consisted of two phases; $Au_5Sn(\zeta)$ and AuSn($\sigma$). It was also found that inhomogeneous amorphous local structure continuously changed to the homogeneous two phases microstructure with heat treatment. The fractographical observation after tensile test indicated the cleavage fracture mode of as-casted Au-Sn strip. On the other hand, the heat treated Au-Sn strip showed that fracture propagated along interface between brittle AuSn and ductile $Au_5Sn$ phases. The deformation behavior of strip casted Au-Sn alloy with microstructural evolution and the improve method for ductility of this alloy was also suggested.

• 한국주조공학회지
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• 제15권4호
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• pp.397-407
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• 1995

The objectives of this study are first, to expand our understanding of relationship between magnetic properties and microstructural features such as grain size and texture, and second to reduce core loss of Fe-6.5%Si strip through optimizing heat treatment conditions. A rapid solidification technique, planar flow casting(PFC), was adopted to produce Fe-6.5%Si strips. The strips were heat treated under various conditions. The results show that heat treatment conditions can change not only grain size but also (200) texture formation on the strip surface. Variation in magnetic properties of Fe-6.5%Si strip is analyzed in terms of the change in grain size as well as (200) texture on the strip surface. The heat treatment conditions of $1100^{\circ}C$ over 2 hr or $1150^{\circ}C$ $1{\sim}2hr$ in $N_2+5%H_2$ appear to minimize core loss of Fe-6.5%Si strips.

• 대한전기학회논문지
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• 제41권4호
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• pp.379-384
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• 1992

The Fe-base amorphous ribbons with 15mm width and about 20x10S0-6Tm thickness, (FeS179-xTCrS1xT)BS116TSiS15T and (FeS181-xTMnS1xT) BS112TSiS17T (x:0-6), were prepared melt spinner. The thickness of the ribbons followed by PFC (Planar Flow Casting). The initial permeability and total core losses were measured as a function of additive elements (Cr, Mn) and annealing conditions in high frequency for the purpose of using these materials as a core of magnetic amplifier and switched mode power supplies. The initial permeabilities were enhanced and core losses were decreased by non-magnetic field annealing in proper conditions. The lowest core loss in 0.2T/10kHz was measured at 3% Cr addition amorphous ribbon, and the loss was 5.6W/kg. The permeability of the ribbon at 10kHz was about 9000.

• 한국자기학회지
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• 제25권3호
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• pp.67-73
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• 2015

본 연구는 철기(Fe based) $Fe_{73.5}Si_{13.5}B_9Nb_3Cu_1$ 나노결정 합금의 분말코어(powder core)의 연자기적 특성 향상을 위한 기초연구로서, 절연 코팅제의 첨가량 및 분말입도에 따른 투자율, 코어손실 및 DC 바이어스 특성을 주로 조사하였다. 우선 합금조성을 PFC 장치를 이용하여 비정질 합금리본을 제조한 후, 열처리, 미분쇄 및 분급하여 얻어진 합금분말에 절연 코팅제(PEI)의 첨가량을 0.5, 1.0, 2.0, 2.5 wt%로 변화시켜 $16ton/cm^2$으로 압축성형 및 결정화 열처리하여 제조한 토로이달 나노결정 분말코어($OD12.7mm{\times}ID7.62mm{\times}H4.75mm$)는 절연 코팅제 함량이 증가할수록 투자율은 감소하였지만, 코어손실 및 DC 바이어스 특성은 향상됨을 확인하였다. 이러한 이유는 합금분말 절연 코팅제 첨가량이 증가할수록 비정질 합금분말 입자가 적어져 분말코어의 성형밀도가 낮아지기 때문으로 추정되었으며, 절연 코팅제의 함량은 1 wt%가 가장 적합한 것으로 판단되었다. 또한 절연 코팅제 함량을 1 wt%로 고정하고, 합금분말의 입도에 따라 제조한 분말코어의 경우, 실효투자율 및 코어손실은 입도가 클수록 우수하였지만, DC 바이어스 특성은 인가자장이 증가함에 따라 더욱 나빠짐을 확인하였다. 그 이유는 합금분말 표면의 코팅층 두께 차이에 의한 절연효과, 잔류기공 혹은 분말코어의 성형밀도 차이 등에 기인하는 것으로 추정되었다.