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Y₂O₃ 첨가량에 의한 Al₂O₃ 복합재 세라믹스의 균열 치유와 고온 굽힘강도 특성
남기우(K. W. Nam),김해숙(H. S. Kim),손창석(C. S. Son),김성광(S. K. Kim),안석환(S. H. Ahn) 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.11
The four kinds of Al₂O₃ composite ceramics were prepared using a mixture of 85 wt.% Al₂O₃ (mean size 0.5 ㎛), 15 wt.% SiC powder with Y₂O₃ as an additive powder (0, 1, 3 and 5 wt.%). The crack-healing strengths were studied as functions of crack-healing temperature and amount of Y₂O₃. The in-situ crack-healing behavior was observed at 1,573 K for 1 h in the air. The heat treated specimen with 3 wt.% of Y₂O₃ showed better crack-healing ability than specimen with 1 or 5 wt.% of Y₂O₃. In case of specimen with 3 wt.% of Y₂O₃, the bending strength of the crack-healed specimen at 1,473 K was recovered to the bending strength of smooth specimen treated at 1573 K. The heat-resistance limit temperature of Al₂O₃ composite ceramics was 1,073 K, 1,373 K, 873 K for the specimen with 1, 3, 5 wt.% of Y₂O₃.
Al₂O₃/SiC 세라믹스 균열치유능력에 미치는 첨가제 양의 영향
박성원(S. W. Park),안석환(S. H. Ahn),손창석(C. S. Son),김성광(S. K. Kim),남기우(K. W. Nam) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
The four kinds of Al₂O₃ composite ceramics were prepared using a mixture of 85 wt.% Al₂O₃ (mean size 0.5 μm), 15 wt.% SiC powder with Y₂O₃ as an additive powder (0, 1, 3 and 5 wt.%). The crack-healing strengths were studied as functions of crack-healing temperature and amount of Y₂O₃. The in-situ crack-healing behavior was observed at 1,573 K for 1 h in the air. The heat treated specimen with 3 wt.% of Y₂O₃ showed better crack-healing ability than specimen with 1 or 5 wt.% of Y₂O₃. In case of specimen with 3 wt.% of Y₂O₃, the bending strength of the crack-healed specimen at 1,473 K was recovered to the bending strength of smooth specimen treated at 1573 K. The heat-resistance limit temperature of Al₂O₃ composite ceramics was 1,073 K, 1,373 K, 873 K for the specimen with 1, 3, 5 wt.% of Y₂O₃.
균열치유능력을 가지는 Al₂O₃/SiC 세라믹스의 굽힘강도와 Morphology
박성원(S. W. Park),안석환(S. H. Ahn),손창석(C. S. Son),김성광(S. K. Kim),남기우(K. W. Nam) 대한기계학회 2007 대한기계학회 춘추학술대회 Vol.2007 No.10
Al₂O₃/SiC composite ceramics were sintered to evaluate the bending strength and elastic wave characteristics. The three-point bending test was carried out under room temperature. The elastic wave was detected by fracture wave detector. The crack healing behavior was investigated from 1373 K to 1723 K. The bending strength of Al₂O₃/SiC composite by nanocomposite is higher than that of Al₂O₃ monolithic. Crack-healing behavior depended on an amount of additive powder Y₂O₃. In Al₂O₃/SiC composite ceramics with 3 wt. % Y₂O₃ for additive powder, the bending strength at 1573 K is about 100% increase than that of the smooth specimens. The strength of Al₂O₃/SiC composite ceramics was a little higher than those of Al₂O₃ monolithic. In proposition to an amount of additive, a large amount of Si and O, and little C were detected.
Y<sub>2</sub>O<sub>3</sub> 첨가량에 의한 Al<sub>2</sub>O<sub>3</sub> 복합재 세라믹스의 균열 치유와 고온 굴힘강도 특성
남기우,김해숙,손창석,김성광,안석환,Nam, K.W.,Kim, H.S.,Son, C.S.,Kim, S.K.,Ahn, S.H. 대한기계학회 2007 大韓機械學會論文集A Vol.31 No.11
The low kinds of $Al_2O_3$ composite ceramics were prepared using a mixture of 85 wt.% $Al_2O_3$ (mean size $0.5\;{\mu}m$), 15 wt.% SiC Powder with $Y_2O_3$, as an additive powder (0, 1, 3 and 5 wt.%). The crack-healing strengths were studied as functions of crack-healing temperature and amount of $Y_2O_3$. The in-situ crack-healing behavior was observed at 1,573 K for 1 h in the air. The heat treated specimen with 3 wt.% of $Y_2O_3$ showed better crack-healing ability than specimen with 1 or 5 wt.% of $Y_2O_3$. In case of specimen with 3 wt.% of $Y_2O_3$, the bending strength of the crack-healed specimen at 1,473 K was recovered to the bending strength of smooth specimen treated at 1573 K. The heat-resistance limit temperature of $Al_2O_3$ composite ceramics was 1,073 K, 1,373 K, 873 K for the specimen with 1, 3, 5 wt.% of $Y_2O_3$.
김성광(S. K. Kim),안석환(S. H. Ahn),남기우(K. W. Nam) 한국동력기계공학회 2006 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The heat exchanger is dispersed in microelements and heat transfer coefficient, and the fin efficiency were predicted in control volume with regard to flow patterns, conditions and material properties. The computational program was developed by using the method of efficiency-NTU(Number of transfer unit). The modelling was applied to heat exchangers, also was integrated in power pack cooling system in an armored vehicle. The compatibility and the generality were proved with comparison of predicted and tested results. Therefore, this program may be useful for the design of the cooling system in an armored vehicle.
김성광(S. K. Kim),손창석(C. S. SON) 한국동력기계공학회 2005 한국동력기계공학회 학술대회 논문집 Vol.- No.-
On this study, numerical analysis was performed for the 3 dimensional flow field of gas and particle phase for axial inlet cyclone, a part of dust collector. We applied FVM to visualize the gas phase. The flow was solved using К-ε turbulence model. The major parameters considered in this study were helical guide vane, inner diameter, length. Particle trajectory calculations were performed for the particle sizes of 5㎛~75㎛. The distribution curve of particle sizes was made of Rosin-Rammler function. The simulation results show various gas flows, particle trajectories on numerical models.