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Nb/MoSi<sub>2</sub> 접합재료의 계면 수정 및 특성
이상필,윤한기,Lee, Sang-Pill,Yoon, Han-Ki 대한기계학회 2003 大韓機械學會論文集A Vol.27 No.7
This study dealt with the suppression of interfacial reaction between Nb and MoSi$_2$ for the fabrication of high toughness Nb/MoSi$_2$ laminate composites, based on the results of a thermodynamical estimation. Especially, the effect of ZrO$_2$ particle on the interfacial reaction of Nb/MoSi$_2$ bonding materials has been examined. Nb/MoSi$_2$ bonding materials have been successfully fabricated by alternatively stacking matrix mixtures and Nb sheets and hot pressing in the graphite mould. The addition of ZrO$_2$ particle to MoSi$_2$ matrix is obviously effective for promoting both the interfacial reaction suppression and the sintered density of Nb/MoSi$_2$ bonding materials, since it is caused by the formation of ZrSiO$_4$ in the MoSi$_2$-ZrO$_2$ matrix mixture. The interfacial shear strength of Nb/MoSi$_2$ bonding materials also decreases with the reduction of interfacial reaction layer associated with the content of ZrO$_2$ particle and the fabrication temperature.
Nb/MoSi<sub>2</sub>적층복합재료의 제조 및 파괴특성
이상필,윤한기,Lee, Sang-Pill,Yoon, Han-Ki 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.6
The impact value, the interfacial shear strength, the tensile strength and the fracture strain of Nb/MoSi$_2$laminate composites, which were associated with the interfacial reaction layer, have been investigated. Three types of Nb/MoSi$_2$ laminate composites alternating sintered MoSi$_2$ layers and Nb foils were fabricated as the parameter of hot press temperature. The thickness of interfacial reaction layer of Nb/MoSi$_2$ laminate composites increased with increasing the fabrication temperature. The growth of interfacial reaction layer increased the interfacial shear strength and led to the decrease of impact value in Nb/MoSi$_2$ laminate composites. It was also found that in order to maximize the fracture energy of Nb/MoSi$_2$ laminate composites, interfacial shear strength and the thickness of interfacial reaction layer must be secured appropriately.
이상필(Sang Pill Lee),이문희(Moon Hee Lee),문승현(Seung Hyun Moon) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
This characterization of liquid phase sintered(LPS) SiC materials was studied for the elements of the high pressure valve. Especially, the effect of starting SiC particle size on the mechanical properties and microstructure was investigated, in conjunction with detailed analyses by SEM, XRD, bending test. The LPS-SiC materials were fabricated with the starting SiC particle sizes of 30㎚, 0.3㎛, 3.0㎛, respectively. The sintering additives were added to SiC particles with the constant composition ratio(Al₂O₃/Y₂O₃) of 1.5. The LPS-SiC materials were sintered by hot-pressing method at the temperature of 1820℃ under a argon atmosphere. The sintered LPS-SiC materials were shown dense morphology with the creation of a secondary phase. The increase of starting SiC particle sizes cause the degradation of the flexural strength with the increase of the micropores. In this study, the characterization of LPS-SiC materials was also examined by using nondestructive technique.
이상필(Sang-Pill Lee),조경서(Kyung-Seo Cho),이현욱(Hyun-Uk Lee),손인수(In-Soo Son),이진경(Jin-Kyung Lee) 한국해양공학회 2011 韓國海洋工學會誌 Vol.25 No.3
The thermal shock properties of SiC materials were investigated for high temperature applications. In particular, the effect of thermal shock temperature on the flexural strength of SiC materials was evaluated, in conjunction with a detailed analysis of their microstructures. The efficiency of a nondestructive technique using ultrasonic waves was also examined for the characterization of SiC materials suffering from a cyclic thermal shock history. SiC materials were fabricated by a liquid phase sintering process (LPS) associated with hot pressing, using a commercial submicron SiC powder. In the materials, a complex mixture of Al₂O₃ and Y₂O₃ powders was used as a sintering additive for the densification of the microstructure. Both the microstructure and mechanical properties of the sintered SiC materials were investigated using SEM XRD, and a three point bending test. The SiC materials had a high density of about 3.12 Mg/m3 and an excellent flexural strength of about 700 ㎫, accompanying the creation of a secondary phase in the microstructure. The SiC materials exhibited a rapid propagation of cracks with an increase in the thermal shock temperature. The flexural strength of the SiC materials was greatly decreased at thermal shock temperatures higher than 70 ℃, due to the creation of microcracks and their propagation. In addition, the SiC materials had a clear tendency for a variation in the attenuation coefficient in ultrasonic waves with an increase in thermal shock cycles.
Al₂O₃와 Y₂O₃ 입자를 함유한 액상소결 SiC 재료의 특성
이상필(SANG-PILL LEE),이문희(MOON-HEE LEE),이진경(JIN-KYUNG LEE) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.4
The mechanical properties of liquid phase sintered (LPS) SiC materials, with the addition of oxide powder, were investigated, in conjunction with a detailed analysis of their microstructures. LPS-SiC materials were fabricated at a temperature of 1820℃ under an argon atmosphere, using three different starting sizes of SiC particles. The sintering additive for the fobrication of the LPS-SiC materials was an Al₂O₃-Y₂O₃ mixture with a constant composition ratio (Al₂O₃/Y₂O₃: 1.5). The particle sizes of the commercial SiC powderswere 30㎚, 0.3 m, and 3.0 ㎛. The flexural strength of the LPS-SiC materials was also examined at elevated temperatures. A decrease in the starting size of the SiC particles led to an increase in the flexural strength of the LPS-SiC materials, accompanying a highly dense morphology with the creation of a secondary phase. Such a secondary phase was identified as Y₃Al₂(AlO₄)2. The flexural strength of the LPS-SiC materials greatly decreased with an increase in the test temperature, due to the creation of a large amount of pores.