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저온 분사 공정에서 니켈이 코팅된 다이아몬드 적용을 통한 금속/다이아몬드 복합재료의 코팅성 향상
나현택(Hyuntaek Na),배규열(Gyuyeol Bae),강기철(Kicheol Kang),김형준(Hyungjun Kim),이창희(Changhee Lee) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.6
Generally, deposition mechanism of diamond particle is mainly embedding effect in the kinetic spray process. Accordingly, in spite of high cost, helium gas was employed as process gas to get high diamond fraction in the composite coating. In this study, the deposition behavior of bronze/diamond by kinetic spray process was compared using different process gas (helium and nitrogen). Bare (mean size of 5 ㎛, 20 ㎛) and nickel coated diamond (mean size of 26 ㎛) were deposited on Al 6061-T6 substrate with fixed process temperature and pressure. For comparison with experimental results, plastic deformation behavior of nickel layer was simulated by finite element analysis (using ABAQUS/Explicit 6.7-2). The size, broken ratio, and fraction of diamond in the composite coating were analyzed through scanning electron microscopy and image analysis method. The uniform distribution and deposition efficiency of diamond particles in the coating layer could be achieved by tailoring the physical properties of the feedstock.
대기 플라즈마 용사공정을 이용한 Cu계 벌크 비정질 금속 코팅의 미세조직 분석과 나노 압입시험을 이용한 상 분석
김정환,강기철,윤상훈,나현택,이창희,Kim, Jung-Hwan,Kang, Ki-Cheol,Yoon, Sang-Hoon,Na, Hyun-Taek,Lee, Chang-Hee 대한용접접합학회 2009 대한용접·접합학회지 Vol.27 No.6
In this study, Cu-based bulk metallic glass (BMG) coatings were deposited by atmospheric plasma spraying (APS) process with different process conditions (with- and without hydrogen gas). As adding the hydrogen gas, thermal energy in the plasma flame increased and induced difference in the melting state of the Cu-based BMG particles. The microstructure and mechanical properties of the coatings were analyzed using a scanning electron microscope (SEM) with an energy dispersive spectroscopy (EDS) and nano-indentation tester in the light of phase analysis. It was elucidated by the nano-indentation tests that un-melted region was a mainly amorphous phase which showed discrete plasticity observed as the flow serrations on the load.displacement (P - h) curves, and the curves of solidified region showed lower flow serrations as amorphous phase mingled with crystalline phase. Oxides produced during the spraying process had the highest hardness value among the phases and were well mixed with other phases resulted from the increase in melting degree.
대기 플라즈마 용사공정을 이용한 Fe계 벌크 비정질 금속 코팅의 초기 분말의 화학조성과 크기에 대한 미세 조직 및 마모 특성
김정환(Junghwan Kim),윤상훈(Sanghoon Yoon),나현택(Hyuntaek Na),이창희(Changhee Lee) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.5
In this study, two kinds of Fe-based bulk metallic glasses (BMG) powder were built-up through atmospheric plasma spray (APS) technique. The microstructure of two coatings was analyzed through X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Crystallization and oxidation in coatings were affected by chemical composition and initial powder size. Then, both of them influenced the tribological property.