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불소계 플라즈마에 노출된 Al<sub>2</sub>O<sub>3</sub>의 미세구조 변화
김대민,이성민,김성원,김형태,오윤석,Kim, Dae-Min,Lee, Sung-Min,Kim, Seong-Won,Kim, Hyung-Tae,Oh, Yoon-Suk 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.7
Ceramics are widely used as plasma resistant materials in semiconductor industries. However, the plasma erosion resistance has not been properly evaluated in terms of microstructural changes during the exposure to plasma. In this study, microstructure developments of $Al_2O_3$ were investigated under the fluorine plasma conditions. In polycrystalline alumina, uniform erosion throughout the specimen as well as spatially distributed local erosion were observed. Local erosion was much more severe in lower purity alumina. In contrast to the polycrystalline alumina, only uniform erosion was observed in single crystalline sapphire. These specimens, however, had practically the same erosion depth, which results in the incorrectly similar plasma resistance. This implies that the plasma erosion resistance of ceramics should be evaluated in terms of the microstructural changes, as well as the conventionally accepted erosion depth.
김대민,한윤수,김성원,오윤석,임대순,김형태,이성민 한국세라믹학회 2015 한국세라믹학회지 Vol.52 No.6
Recently, a new Y2O3 coating deposited using the EB-PVD method has been developed for erosion resistant applications in fluorocarbon plasma environments. In this study, surface crack formation in the Y2O3 coating has been analyzed in terms of residual stress and elastic modulus. The coating, deposited on silicon substrate at temperatures higher than 600oC, showed itself to be sound, without surface cracks. When the residual stress of the coating was measured using the Stoney formula, it was found to be considerably lower than the value calculated using the elastic modulus and thermal expansion coefficient of bulk Y2O3. In addition, amorphous SiO2 and crystalline Al2O3 coatings were similarly prepared and their residual stresses were compared to the calculated values. From nano-indentation measurement, the elastic modulus of the Y2O3 coating in the direction parallel to the coating surface was found to be lower than that in the normal direction. The lower modulus in the parallel direction was confirmed independently using the load-deflection curves of a micro-cantilever made of Y2O3 coating and from the average residual stress-temperature curve of the coated sample. The elastic modulus in these experiments was around 33 ~ 35 GPa, which is much lower than that of a sintered bulk sample. Thus, this low elastic modulus, which may come from the columnar feather-like structure of the coating, contributed to decreasing the average residual tensile stress. Finally, in terms of toughness and thermal cycling stability, the implications of the lowered elastic modulus are discussed.
각 손가락 별 파지 폭 변경이 가능한 악력측정 장비 개발 및 적용
김대민,손성태,권구태,공용구 대한인간공학회 2008 대한인간공학회 학술대회논문집 Vol.- No.-
각 손가락에 대한 다양한 파지 폭에서의 손가락들의 힘과 총 악력의 측정을 위하여, 본 연구를 통하여 손가락 별로 파지 폭 변경이 가능한 악력 측정 장비인 “ An adjustable multi-finger force measurement(MFFM) system”을 개발하였다. 개발된 장비의 적용으로, 10 명의 피실험자들이 참여하였으며, 파지 폭을 45mm 에서 65mm 로 변경하여 각 손가락 별 힘과 총 악력을 측정하고, 개인적 선호도와의 관계에 대해서도 연구하였다. 본 연구를 통하여 기존의 연구결과들과의 비교 분석뿐 만 아니라, 새로운 데이터베이스 구축과 수공구 디자인을 위한 유용한 자료로서의 의미가 있다고 할 수 있을 것이다.
EB-PVD법으로 코팅된 Y<sub>2</sub>O<sub>3</sub>의 내플라즈마 특성
김대민,윤소영,김경범,김희식,오윤석,이성민,Kim, Dae-Min,Yoon, So-Young,Kim, Kyeong-Beom,Kim, Hui-Sik,Oh, Yoon-Suk,Lee, Sung-Min 한국세라믹학회 2008 한국세라믹학회지 Vol.45 No.11
Plasma resistant nanocrystalline $Y_2O_3$ films were deposited on alumina substrates through the electron-beam PVD technique. Increasing substrate temperature to $600^{\circ}C$ resulted in the textured microstructures with significantly enhanced adhesion force of the coating to the substrate. During the exposure to fluorine plasma, erosion rate of the coated specimen was higher than that of a sintered yttria specimen, but significantly lower than that of a single crystalline alumina. Considering the adhesion and erosion behaviors observed in the coated specimen prepared at $600^{\circ}C$, the deposition technique appears effective in reducing contamination particles generated from the ceramic parts in the plasma environment.