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용융 아연과 WC-Co 코팅층 내 코발트의 반응거동에 미치는 아연욕 중의 Al 첨가 영향
성병근(Byeong-Geun Seong),김규영(Kyoo-Young Kim),권성희(Sung-Hee Kwon),이기안(Kee-Ahn Lee) 한국표면공학회 2007 한국표면공학회지 Vol.40 No.1
The objective of this study is to investigate the effect of Al addition on the reaction behavior of cobalt with molten zinc. Pure cobalt specimen was immersion tested in the three kinds of molten zinc (pure, 0.12%Al added and 0.24%Al added) baths at 460℃, 490℃ and 520℃. For the understanding of degradation processes, specimens were analyzed with scanning electron microscope (SEM) and energy dispersive spectrum (EDS), and electrochemical stripping method. When 0.12% and 0.24% Al was added in molten zinc baths, three intermetallic compounds layers of γ, γ1, and γ2 were formed on the Co matrix and β1 layer was not formed between the Co matrix and the γ layer. Particles of CoAl intermetallic compound were formed at the interface between the γ2 layer and zinc melt and they did not adhere to the Co-Zn intermetallic layer. Weight loss of the Co specimen increased as Al content in the molten zinc increased and the relationship of weight loss vs. immersion time followed parabolic rate law. Rate controlling process for the reaction rate of Co with Al added molten zinc was analyzed as the diffusion process of Al atom through a boundary layer between the γ2 layer and the Al added zinc melt.
평판형 SOFC 스택의 밀봉재와 금속 분리판의 계면반응 및 보호층 효과
문지웅(Moon, J.W.),김영우(Kim, Y.W.),성병근(Seong, B.K.),김도형(Kim, D.H.),전중환(Jun, J.H.) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.11
평판형 고체산화물 연료전지 스택의 고온 밀봉 구조에 대하여 설명하고 스택 운전 후 사후 분석을 통하여 밀봉재와 금속 분리판의 계면반응에 대하여 고찰하였다. 대표적인 고온 밀봉재인 Barium-Silicate 계 결정화 유리와 Fe-Cr 계 금속 분리판은 스택의 작동온도인 700{sim}850?C 에서 고온 반응을 통하여 계면에 반응생성물을 형성하는 것이 확인되었다. 이러한 계면반응은 장기 운전시 SOFC 스택 성능 저하의 원인이 되고, 열 싸이클(작동온도{leftrightarrow}상온)을 가하면 계면반응 생성물이 delamination 되어 밀봉구조가 파괴되어 수명을 단축시키게 된다. 계면반응은 Fe-Cr 계 금속 분리판의 산화물인 Cr 산화물, Fe 산화물이 밀봉유리 소재와 반응을 일으키는 것이 주요 원인으로 판명되었다. SOFC 스택에서 열 싸이클시 계면반응에 의하여 기밀도가 감소하는 현상이 확인되었으며, 밀봉 구조의 어느 부분에서 계면반응이 진행되는지 관찰하였다. 이러한 계면반응을 막기 위해서는 금속 분리판과 밀봉유리 사이에 계면반응을 억제하는 보호층을 형성하는 방법이 효과적이다. 본 연구에서는 보호층으로서 밀봉유리 및 Fe-Cr 계 금속 분리판과의 계면반응성이 낮고 열팽창 계수가 비슷한 Yttria Stabilized Zirconia 층을 APS(Atmospheric Plasma Spray) 공정을 이용하여 형성하였다. 밀봉유리/YSZ 보호층/금속분리판은 gas-tight 한 밀봉 구조를 형성하였으며, YSZ 보호층은 밀봉유리와 Fe-Cr 계 금속 분리판 소재와 계면반응을 효과적으로 억제하는 것이 확인되었다.
알루미늄 확산코팅된 내열 스테인리스강의 반복주기 고온부식 거동
송진엽,황순영,성병근,김규영 대한금속재료학회(대한금속학회) 1992 대한금속·재료학회지 Vol.30 No.7
To improve the corrosion resistance of heat resistant stainless steels (HRSS) at high temperature, pack aluminization of these steels was performed. Two kinds of HRSS (MO-RE 1, HK40) were used for pack aluminization during which the activity of an aluminum source was varied. Various microstructures of the aluminized HRSS were studied. To evaluate and study the corrosion resistance, cyclic corrosion tests in simulated COG (coke oven gas) combustion environment were performed. After the tests, the degradation mechanisms of the pack aluminized HRSS were presented. Especially, the inward diffusion rate of aluminum in aluminized HRSS was more pronounced than that in aluminized Ni-base alloys. In addition, the pack aluminized HRSS in the medium low activity of the aluminum source showed much better corrosion resistance than the uncoated HRSS.
용융아연도금라인의 아연욕에서 사용한 WC-Co 용사코팅의 열화거동 분석
황순영,김문철,김규영,성병근 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.3
Degradation process of WC-Co coating was evaluated through analyses of a coated stabilizing roll used in a molten zinc pot of a CGL(Continuous Galvanizing Line) for 56 days. The roll was coated by high velocity oxygen fuel spraying with the WC-12%Co powder that was produced through sintering and crushing process. According to observation of the coating cross-section with SEM, the Zn and Al diffused into the coating layer with the same depth but the Fe in a zinc bath did not diffuse into the coating. Dross particles deposited on the pot rolls were analyzed to be Fe₂Al_5 by X-ray diffraction pattern analysis. Final reaction products of WC-Co coating with zinc bath have nearly the same chemical compositions as the Fe₂Al_5 dross. This phase acted as a diffusion barrier against Zn, Al and Co diffusion at the interface of molten zinc/spray coating and consequently diffusions of Al and Zn were suppressed in the coating layer under this phase.
초고속 용사법을 이용한 Zr65Al7.5Ni10Cu17.5 합금의 비정질 후막 형성
박찬경,김형준,임경묵,성병근 대한금속재료학회(대한금속학회) 2000 대한금속·재료학회지 Vol.38 No.4
This investigation was conducted to clarify the effects of process variables such as spraying distance and fuel flow rate on the formation of the new amorphous coating using Zr_(65)Al_(7.5)Ni_(10)Cu_(17.5) alloy by a HVOF(High Velocity Oxygen-Fuel) spraying process. Powder used for spraying was prepared by vacuum gas atomization and centrifugal-mill. HVOF spraying experiments were carried out using a Tafa JP-5000 spraying gun. The amorphous content was measured up to about 65% depending on the spraying parameters. The amorphous fraction is decreased with increasing the spray distance. Microstructural observations and XRD analysis reveal that the change of amorphous fraction is attributed to the degree of solidification of droplets and the oxide (ZrO₂) formation in coatings. The higher fuel flow rate resulted in the decrease of amorphous fraction, and this decreased amorphous fraction was caused by the increase of oxide fraction. Therefore, flame temperature and spray distance that can control the oxide formation in coating and undercooling effects of droplets are the most crucial factors for the formation of amorphous coating using this alloy system.