• 대한화학회지
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• 제55권2호
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• pp.163-168
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• 2011

다양한 농도의 N-methyl acetamide 수용액에서 계면 활성제의 농도에 따른 계면활성제들 (sodium caprylate, sodium laurate, sodium palmitate, sodium stearate, sodium oleate, sodium dodecyl sulphate, lithium dodecyl sulphate)의 몰 전도도 변화를 $30{\pm}0.2^{\circ}C$의 일정온도에서 연구하였다. 각각의 계면활성제에 대한 임계 미셀 농도 (CMC)를 측정하였다. 수용액에 N-methyl acetamide이 공존할 때에는 여러 계면 활성제의 CMC 값이 수용액에서의 CMC 값보다 더 낮고, 미셀 형성에 대한 추진력은 소용매성과 관련되었다. N-methyl acetamide 수용액에서 양쪽성 자기-조직화를 추진하는 계면활성제-용매의 상호작용에 대해 논의하였다. 이 결과들을 설명하기 위하여 미셀 시스템에 대한 열역학적 매개변수들을 추정하였다.

• 한국재료학회지
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• 제18권3호
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• pp.153-158
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• 2008

Fe-aluminides have the potential to replace many types of stainless steels that are currently used in structural applications. Once commercialized, it is expected that they will be twice as strong as stainless steels with higher corrosion resistance at high temperatures, while their average production cost will be approximately 10% of that of stainless steels. Self-propagating, high-temperature Synthesis (SHS) has been used to produce intermetallic and ceramic compounds from reactions between elemental constituents. The driving force for the SHS is the high thermodynamic stability during the formation of the intermetallic compound. Therefore, the advantages of the SHS method include a higher purity of the products, low energy requirements and the relative simplicity of the process. In this work, a Fe-aluminide intermetallic compound was formed from high-purity elemental Fe and Al foils via a SHS reaction in a hot press. The formation of iron aluminides at the interface between the Fe and Al foil was observed to be controlled by the temperature, pressure and heating rate. Particularly, the heating rate plays the most important role in the formation of the intermetallic compound during the SHS reaction. According to a DSC analysis, a SHS reaction appeared at two different temperatures below and above the metaling point of Al. It was also observed that the SHS reaction temperatures increased as the heating rate increased. A fully dense, well-bonded intermetallic composite sheet with a thickness of $700\;{\mu}m$ was formed by a heat treatment at $665^{\circ}C$ for 15 hours after a SHS reaction of alternatively layered 10 Fe and 9 Al foils. The phases and microstructures of the intermetallic composite sheets were confirmed by EPMA and XRD analyses.