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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.
액상소결 SiC 재료의 특성에 미치는 열충격 온도의 영향
이상필(Sang Pill Lee),이현욱(Uk Hyun Lee),조경서(Kyung Seo Cho),이진경(Jin Kyung Lee),손인수(In Soo Son),변준형(Joon Hyung Byun) 대한기계학회 2011 대한기계학회 춘추학술대회 Vol.2011 No.4
This paper dealt with mechanical properties of monolithic SiC materials, based on a detailed analysis of their microstructures. SiC materials were fabricated at the temperature of 1820℃ by a liquid phase sintering (LPS) process, using a sintering additive of Al₂O₃, and Y₂O₃ particles. The ratio of additive compound (Al₂O₃/Y₂O₃) was fixed as 1.5. The total amount of additive materials was constant as 10wt.%. Commercial SiC powders with an average size of 0.3 ㎛ were used in this study. The characterization of SiC materials was investigated by means of optical microscope, XRD and three point bending test. SiC materials showed the first cracking at the thermal shock temperature of 250 ℃. This materials exhibited a rapid propagation of cracks with the increase of thermal shock temperature. The thermal shock strength of SiC materials was greatly decreased at the temperature higher than 700 ℃.
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.