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김권후,이종엽 한국동력기계공학회 2019 동력시스템공학회지 Vol.23 No.6
이 논문에서는 CNT JT-20A모델의 초음파 교반조건에 따른 변화에 대해서 분석하였다. 이 연구에서 CNT(JT-20A 모델)가 함유된 고강도 탄소섬유복합재연구개발의 핵심선행공정인 교반공정에서의 조건에 대한 연구(분말교반기술연구, 교반조건생성연구)를 수행하였으며, 실험결과 전기방사에 적합한 기준점도 범위에 만족하는 최적화 교반비율(용매DMF_40g기준, PAN 4g_10wt%:DMF, CNT 0.12g 3wt%:PAN)과 교반기기별 교반생성조건에 대한 연구를 통해서 최적의 결과값을 확인할 수 있었다.
열처리조건에 따른 AZ61 마그네슘 합금의 미세조직과 감쇠능에 미치는 영향
안재현,김권후 한국열처리공학회 2018 熱處理工學會誌 Vol.31 No.2
Many researchers have studied on the precipitation control after solution treatment to improve the damping capacity without decreasing the strength. However, studies on the damping capacity and microstructure changes after deformation in the solid solution strengthening alloys were inadequate, such as the Al-Zn series magnesium alloys. Therefore, in order to investigate the effect of annealing condition on microstructure change and damping a capacity of AZ61 magnesium alloy. In this study, it was confirmed that the microstructure changes affect the damping capacity and hardness when annealed AZ61 alloy. AZ61 magnesium alloy was rolled at 400oC with rolling reduction of 30%. These specimens were annealed at 350oC to 450oC for 30-180 minutes. After annealing, microstructure was observed by using optical microscopy, and damping capacity was measured by using internal friction measurement machine. Hardness was measured by Vickers hardness tester under a condition of 0.3 N. In this study, static recrystallization was observed regardless of the annealing conditions. In addition, uniform equiaxed grain structure was developed by annealing treatment. Hardness is decreased with increasing grain size. This is associated with Hall-Petch equation and static recrystallization. In case of damping capacity, bigger grain size show the larger damping capacity.
피로손상된 제진합금의 인장성질에 미치는 피로응력 크기의 영향
이명수,김권후,강창룡 대한금속·재료학회 2019 대한금속·재료학회지 Vol.57 No.2
This study was carried out to investigate the effect of fatigue stress magnitude on the tensile properties of the damaged Fe – 22Mn – 12Cr – 3Ni – 2Si – 4Co damping alloy under various fatigue stress magnitudes. α and ε-martensite were formed by fatigue stress in the Fe – 22Mn – 12Cr – 3Ni – 2Si – 4Co damping alloy. The α and ε-martensite formed by fatigue stress in the fatigue damaged damping alloy was formed with a specific direction and surface relief, or crossing each other. With an increasing magnitude of fatigue stress, the volume fraction of α -martensite and ε-martensite was increased, and the increasing rate of volume fraction of α -martensite was more rapid than ε-martensite. At the same fatigue stress magnitude, a large amount of α -martensite was formed than ε-martensite. With the increasing of fatigue stress magnitude, the tensile strength slowly increased and elongation rapidly decreased, and then tensile strength slowly decreased by increasing the volume fraction of α -martensite. The tensile properties of the damaged Fe – 22Mn – 12Cr – 3Ni – 2Si – 4Co alloy under fatigue stress were strongly affected by the α -martensite formed by fatigue stress. This results were the same tendency for metal with the strain induced martensite transformation.
SWCNT 0.1%-PAN 3%-DMF 17% 교반용액을 활용한 전기방사 전압 및 강도특성연구
이종엽,배상대,김권후,Lee, Jongyeob,Bae, Sangdae,Kim, Kwonhoo 한국열처리공학회 2020 熱處理工學會誌 Vol.33 No.6
In this study, Electro spinning was carried out using Cabon nanotube 0.1%-Polyacrylonitrile 3%-Dimethylformamide 17% agitation solution. It was investigated the solute and solvent correlations according to the electro spinning voltages ranging form 5 to 40 kV, based on the SEM image. Except voltage 25 kV, electro spinning was failed due to the lack of electro spinning (less than 60%). Voltage 25 kV was showed excellent properties, and was confirmed Cabon nanotube 58.1 nm and diameter of Cabon nanotube + Polyacrylonitrile 1.76 ㎛ as shown SEM image. Also, the tensile test results were showed that SK Chemical prepreg electro spinning angle of 0 and 90 degrees were 137 MPa and 60 MPa, respectively.
곽주호,강창룡,김권후 한국동력기계공학회 2018 동력시스템공학회지 Vol.22 No.1
이 논문에서는 AZ31 마그네슘합금의 어닐링 이후 내부마찰의 거동을 조사하기 위해서, 열간압연한 시료를 다양한 온도와 시간의 어닐링을 행하였다. 주요 결과는 다음과 같다 : 다양한 조건의 어니링행한 도중 모든 시료에서 정적 재결정이 일어나는 것을 확인하였으며, 집합조직의 주성분 및 그 강도가 거의 변화하지 않는 것도 확인하였다. 이는 본 연구에서의 어닐링 조건이 집합조직 형성거동에는 영향이 거의 없으며, 이는 내부마찰에도 영향이 없다는 것을 시사한다. 또한, 미세조직결과에서, 결정립성장에 의해서 진동감쇠능에 영향을 미치는 것을 확인했으며, 진동감쇠능에는 결정립크기가 큰 영향을 미친다는 것을 알 수 있다.