http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
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.
SiO₂ 콜로이달에 의한 Si₃N₄ 복합 세라믹스의 상온굽힘강도 및 균열치유 현상
남기우(K. W. Nam),김종순(J. S. Kim),이희방(H. B. Lee) 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Strength characteristics of Si3N4 composite ceramics has been studied as functions of heat-treatment temperature and additive SiO₂. SiO₂ colloidal could significantly increase the bending strength. Crack healing temperature decreased 300 K by additive TiO₂. Bending strength of specimen added SiO₂ is higher than that of non-added SiO₂. Moreover, bending strength of specimen with SiO₂ colloidal coating is much higher that of non-coated specimen. In in-situ observation, crack-healed specimen at 1,573 K shows phenomenon like a fog on the surface. By SPM, both crack-healed specimen, non-coating and coating of SiO₂ colloidal, at 1,273 K were healed completely but both of 1,573 K exist crack. This was made by evaporation of SiO₂ at high temperature. Crack-healing materials of Si₃N₄ composite ceramics is crystallized Y₂Si₂O?, Y₂Ti₂O? and SiO₂. A large amount of Si and O, and little C were detected by EPMA. Si and O increase but C decreases according to heat treatment temperature. Specimens with additive SiO₂2 were more detected Si and O than that of non-additive SiO₂. Specimen with SiO₂ colloidal coatings were much more detected O.
〈논문〉SiO₂ 콜로이달 첨가에 의한 Si₃N₄ 복합 세라믹스의 Morphology
남기우(K. W. Nam),박승원(S. W. Park),김종순(J. S. Kim),안석환(S. H. Ahn) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Surface morphology of Si₃N₄ composite ceramics has been studied as functions of heat-treatment temperature and additive SiO₂. Additive SiO₂ colloidal and SiO₂ colloidal coating on crack could significantly increase the bending strength. Crack healing temperature decreased 300 K by additive TiO₂. Bending strength of specimen with additive SiO₂ is higher than that of non-additive SiO₂. Moreover, bending strength of specimen with SiO₂ colloidal coating is much higher that of non-coating specimen. In in-situ observation, crack-healed specimen at 1,573 K shows phenomenon like a fog on the surface. By SPM, both crack-healed specimen, non-coating and coating with SiO₂ colloidal, at 1,273 K were healed completely but both of 1,573 K exist crack. This was made by evaporation of SiO₂ at high temperature. Crack-healing materials of Si₃N₄ composite ceramics is crystallized Y₂Si₂O?, Y₂Ti₂O? and SiO₂. A large amount of Si and O, and little C were detected by EPMA. Si and a increase but C decreases according to heat treatment temperature. Specimens with additive SiO₂ were more detected Si and a than that of non-additive SiO₂. Specimen with SiO₂ colloidal coatings were much more detected O.
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.
김진환(J. H. KIM),남기우(K. W. Nam),안석환(S. H. Ahn),강창룡(C. R. Kang),박인덕(I. D. Park) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.3
Even if duplex steel made improvement the strength and corrosion resistance properties, the necessity of steel which has long life in severe environment increases with industrial development. Newly developed duplex stainless steel is the super duple stainless steel which contain 25% of chromium. We investigated the fatigue crack propagation of heat affected zone(HAZ) in super duplex stainless steel. The HAZ of super duplex stainless steel propagated more faster base metal of super duplex stainless steel. And we analysed acoustic emission signals during the fatigue test by time-frequency analysis method. And as a result of time-frequency was 200-400 ㎑ was obtained by fatigue crack propagation and 500 ㎑ was obtained by dimple and separate of inclusion.
Al₂O₃ 복합 세라믹스의 고온 굽힘강도에 미치는 Y₂O₃의 영향
김해숙(H.S. Kim),안석환(S.H Ahn),손창석(C.S. Son),김종순(J.S. Kim),남기우(K.W Nam) 한국동력기계공학회 2007 한국동력기계공학회 학술대회 논문집 Vol.- No.-
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.
정정환(J. H. Jeong),안석환(S. H. Ahn),남기우(K. W. Nam) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-
Simulated heat of heat affected zone and researched a mechanical properties in used the SS400 and the STS304. As the result, mechanical properties of steel that make drawing decreased because of residual stress by strain hardening due to the heat-simulated temperature rises, but by the temperature rising in materials that have done heat-simulated after annealing, the mechanical properties ware improved.
SiO<sub>2</sub> 콜로이달에 의한 Si<sub>3</sub>N<sub>4</sub> 복합 세라믹스의 상온굽힘강도 및 균열치유 현상
남기우,김종순,이희방,Nam, K.W.,Kim, J.S.,Lee, H.B. 대한기계학회 2009 大韓機械學會論文集A Vol.33 No.7
Strength characteristics of $Si_3N_4$ composite ceramics has been studied as functions of heat-treatment temperature and additive $SiO_2$. $SiO_2$ colloidal could significantly increase the bending strength. Crack healing temperature decreased 300 K by additive $TiO_2$. Bending strength of specimen added $SiO_2$ is higher than that of non-added $SiO_2$. Moreover, bending strength of specimen with $SiO_2$ colloidal coating is much higher that of non-coated specimen. In in-situ observation, crack-healed specimen at 1,573 K shows phenomenon like a fog on the surface. By SPM, both crack-healed specimen, non-coating and coating of $SiO_2$ colloidal, at 1,273 K were healed completely but both of 1,573 K exist crack. This was made by evaporation of $SiO_2$ at high temperature. Crack-healing materials of $Si_3N_4$ composite ceramics is crystallized $Y_2Si_2O_7$, $Y_2Ti_2O_7$ and $SiO_2$. A large amount of Si and O, and little C were detected by EPMA. Si and O increase but C decreases according to heat treatment temperature. Specimens with additive $SiO_2$ were more detected Si and O than that of non-additive $SiO_2$. Specimen with $SiO_2$ colloidal coatings were much more detected O.
〈학술논문〉 또는 〈응용논문〉 : 장 균열을 가지는 질화규소의 SiO₂ 나노 콜로이드에 의한 균열 치유 특성
남기우(K.W. Nam),박상현(S.H. Park),은경기(K.K. Eun),최창민(C.M. Choi),김종순(Jong Soon Kim) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
본 연구에서는 장균열을 가지는 Si₃N₄ 세라믹스의 균열 길이와 코팅 방법에 따르는 균열 치유 특성을 규명하였다. 약 100 ∼ 500 ㎛의 균열 길이는 24.5 ∼ 98 N의 하중을 사용하여 비커스 압자를 이용하여 만들었다. 24.5N의 하중으로 만든 단균열의 경우, SiO₂ 나노 콜로이드 코팅된 균열재는 모재보다 약 140 % 증가한 가장 높은 굽힘 강도를 보였지만, 장균열은 모재보다 낮은 굽힘 강도를 나타내었다. 그러나 대부분의 장균열 시험편의 굽힘 강도는 균열재보다 약간 증가하였다. 이러한 결과에 따라서, 복수 압입에 의한 Si₃N₄ 세라믹스의 균열 치유 특성을 코팅방법에 따라 연구하였다. 장균열 시험편의 가장 효과적인 코팅 방법은 정수압코팅방법이었다. This study analyzed the crack-healing characteristics of specimens according to the crack lengths and the coating methods of Si₃N₄ ceramics with long cracks. Crack lengths of about 100 ~ 500 ㎛ was obtained from a Vickers indenter using the load of 24.5 ~ 98 N. In the case of a crack using a load of 24.5 N, the crack-healed specimen with SiO₂ nano colloid coating exhibited the highest bending strength, which increased by about 140% compared to that of a smooth specimen, but the multiple crack-healed specimens with SiO₂ nano colloid coating had a lower bending strength than that of a smooth specimen. However, the bending strength of most multiple crack specimens slightly increased compared to that of the cracked specimens. Based on these results, the crack healing characteristic of Si₃N₄ ceramics with multiple indentation was studied according to the coating methods. The most effective coating method on the long-crack specimens was hydrostatic pressure coating.
남기우(K. W. Nam),김현수(H. S. Kim),안석환(S. H. Ahn),박인덕(I. D. Park),도재윤(J. Y. Do) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.10
Fatigue life and crack retardation behavior were examined experimentally using CT specimens of aluminum alloy 5083. Crack retardation life and fatigue life were a wide difference. between 0.8 and 0.6 in proportion to ratio of load reduction. The wheeler model retardation parameter was used successfully to predict crack growth behavior. By using a crack propagation rule, prediction of fatigue life can be evaluated quantitatively.