• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2009년도 제33회 추계학술대회논문집
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• pp.421-425
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• 2009

재생냉각형 액체로켓 연소기 챔버에서 열차폐 코팅이 미치는 열/구조적인 영향에 대하여 유한요소 해석을 통하여 고찰하였다. 열차폐 코팅은 현재 개발하고 있는 연소기에 사용되는 NiCrAlY-$ZrO_2$과 향후 적용할 가능성이 있는 Ni-Cr 두 종류를 적용하였다. 열/구조해석 결과 NiCrAlY-$ZrO_2$ 코팅이 Ni-Cr 코팅에 비하여 열차폐에 의한 온도감소 효과가 크게 나타났다. 결과적으로 냉각채널의 온도와 변형 또한 NiCrAlY-$ZrO_2$ 코팅을 적용하였을 때 Ni-Cr 코팅보다 감소하였다. 외측구조물의 구조안정성에 있어서 Ni-Cr 코팅이 미치는 영향은 없었으나, NiCrAlY-$ZrO_2$ 코팅은 외측구조물의 유효응력을 감소시켜 챔버의 구조안정성을 증가시켰다.

• 수산해양교육연구
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• 제11권2호
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• pp.139-149
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• 1999

Thermal sprayed Ni-Cr alloy coating on the carbon steel was carried out erosion-corrosion test and electrochemical corrosion test in the marine environment. The erosion-corrosion behavior and electrochemical corrosion characteristics of substrate(SS400) and thermal sprayed Ni-Cr coating was investigated. The erosion-corrosion control efficiency of Ni-Cr coating to substrate was also estimated quantitatively. The main results obtained are as follows : 1) The weight loss rate of Ni-Cr coating layer by the erosion-corrosion compared with substrate was smaller. With the lapse of time, the weight loss rate of substrate was linearly increased in $25{\Omega}{\cdot}cm$ solution, but that of Ni-Cr coating became stable. 2) The corrosion potential of substrate became less noble than that of Ni-Cr coating layer, and the corrosion current density of Ni-Cr coating became lower than that of substrate. 3) The control efficiency of erosion-corrosion of Ni-Cr coating compared to substrate became more dull than that of corrosion in $25{\Omega}{\cdot}cm$ and $5000{\Omega}{\cdot}cm$ solution.

• 한국재료학회지
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• 제9권1호
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• pp.73-80
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• 1999

The effect of alloy compositions of the bond coating on the plasma sprayed-thermal barrier coatings was investigated. The performance of the coating composed of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ and Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$was evaluated by isothermal and thermal cyclic test in an ambient atmosphere at 115$0^{\circ}C$. The failure of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ coatings was occurred at the bond coating/ceramic coating interface while Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$ coating was failed at the substrate/bond coating interface after thermal cyclic test. The lifetime of Rene80/NiCrAl/ZrO$_2$-CeO$_2$-Y$_2$O$_3$coatings was longer than Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$coating. The oxidation rate of the NiCrAl bond coating examined by TGA was lower than CoNiCrAlY bond coatings. In summary, these results suggest that Rene80/CoNiCrAlY/ZrO$_2$-CeO$_2$-Y$_2$O$_3$system as thermal barrier coating be not suitable considering the durability of the coating layer for high temperature oxidation and thermal stress.

• Journal of Advanced Marine Engineering and Technology
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• 제23권5호
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• pp.695-701
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• 1999

Thermal sprayed Ni-Cr alloy coating on the carbon steel was carried out erosion-corrosion test and electrochemical corrosion test in the marine environment. THe erosion-corrosion behavior and electrochemical corrosion characteristics of substrate(SS400) and thermal sprayed Ni-Cr coating was investigated, The erosion-corrosion control efficiency of Ni-Cr coating to substrate was also estimated quantitatively.

• Journal of Welding and Joining
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• 제19권1호
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• pp.95-103
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• 2001

The properties of the detonation sprayed cermet coating are investigated through the mechanical, corrosion and erosion test. The test results are also compared with the properties of the substrate materials, STS 329J1, dual phase stainless steel and the plasma sprayed cermet coatings. The two kinds of carbide cermet power, WC+NiCr, Cr$_3$C$_2$+NiCr were used in this experiment. The experimental results showed that the anti-corrosive and anti-erosive properties of the detonation sprayed cermet coatings are superior to the plasma sprayed cermet coatings. The WC+NiCr cermet coating appears to be more effective than Cr$_3$C$_2$+NiCr cermet coating in abrasive erosion environment, whereas the Cr$_3$C$_2$+NiCr cermet coatings are more effective in cavitation erosion environment.

• 한국분말재료학회지
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• 제25권5호
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• pp.408-414
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• 2018

This study investigates the microstructure and wear properties of cermet (ceramic + metal) coating materials manufactured using high velocity oxygen fuel (HVOF) process. Three types of HVOF coating layers are formed by depositing WC-12Co, WC-20Cr-7Ni, and Cr3C2-20NiCr (wt.%) powders on S45C steel substrate. The porosities of the coating layers are $1{\pm}0.5%$ for all three specimens. Microstructural analysis confirms the formation of second carbide phases of $W_2C$, $Co_6W_6C$, and $Cr_7C_3$ owing to decarburizing of WC phases on WC-based coating layers. In the case of WC-12Co coating, which has a high ratio of $W_2C$ phase with high brittleness, the interface property between the carbide and the metal binder slightly decreases. In the $Cr_3C_2-20CrNi$ coating layer, decarburizing almost does not occur, but fine cavities exist between the splats. The wear loss occurs in the descending order of $Cr_3C_2-20NiCr$, WC-12Co, and WC-20Cr-7Ni, where WC-20Cr-7Ni achieves the highest wear resistance property. It can be inferred that the ratio of the carbide and the binding properties between carbide-binder and binder-binder in a cermet coating material manufactured with HVOF as the primary factors determine the wear properties of the cermet coating material.

• 한국재료학회지
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• 제8권8호
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• pp.757-765
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• 1998

수소를 연료로 하여 HVOF 용사된 크롬카바이드 용사층의 산화거동을 이해하기 위해 용사분말의 제조방법이 서로 다른 두 종류의 용사용 분말을 ($\textrm{Cr}_{3}\textrm{C}_{2}$-20wt%NiCr로 구성된 크래드 분말과 $\textrm{Cr}_{3}\textrm{C}_{2}$-7wt%NiCr로 구성된 혼합분말)이용하여 F/O비를 3.2, 3.0, 2.8 로 변화시켜 용사한 후, $1000^{\circ}C$ 까지 등온 산화실험 후, 산화특성을 고찰하여 크롬카바이드 용사층의 F/O비에 의존하는 산화거동을 비교 검토하였다. 그 결과 NiCr이 20wt% 크래드된 분말로 용사된 용사층과 NiCr이 7wt% 혼합된 분말로 용사된 용사층은 전혀 다른 산화거동을 보였다. 혼합분말의 경우에 $1000^{\circ}C$에서 50시간 등온산화실험 후, F/O=3.2의 조건인 경우에는 산화물이 표면 요철을 따라 비교적 균일하게 성장한 반면 F/O=3.0과 F/O=2.8의 경우에는 용사층 표면이 다공성의 산화물이 형성되었으며, 또한 Ni, Cr으로 이루어진 복합산화물인 oxide cluster로 성장하였다. 반면에 크래드 분말로 용사된 용사층의표면 산화물 층은 다공성을 변화되지 않았다. 이러한 용사분말의 제조방법에 따라 산화거동이 차이를 보이는 것은 용사 중에 발생하는 카바이드분해와 밀접한 관계가 있는 것으로 생각되며 또한 일반적으로 알려진 크롬카바이드 소결체 보다 산화율이 높았다. 이러한 결과로 볼 때, 환원성의 수소의 양에 따른 용사층의산화거동에 대해서도 연구가 필요할 것으로 생각된다.

• 한국재료학회지
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• 제24권8호
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• pp.393-400
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• 2014

NiO catalysts were successfully coated onto FeCrAl metal alloy foam as a catalyst support via a dip-coating method. To demonstrate the optimum amount of NiO catalyst on the FeCrAl metal alloy foam, the molar concentration of the Ni precursor in a coating solution was controlled, with five different amounts of 0.4 M, 0.6 M, 0.8 M, 1.0 M, and 1.2 M for a dip-coating process. The structural, morphological, and chemical bonding properties of the NiO-catalyst-coated FeCrAl metal alloy foam samples were assessed by means of field-emission scanning electron microscopy(FESEM), scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS). In particular, when the FeCrAl metal alloy foam samples were coated using a coating solution with a 0.8 M Ni precursor, well-dispersed NiO catalysts on the FeCrAl metal alloy foam compared to the other samples were confirmed. Also, the XPS results exhibited the chemical bonding states of the NiO phases and the FeCrAl metal alloy foam. The results showed that a dip-coating method is one of best ways to coat well-dispersed NiO catalysts onto FeCrAl metal alloy foam.

• 대한기계학회논문집A
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• 제23권7호
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• pp.1245-1252
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• 1999

The sliding wear behavior of $Al_2O_3/NiCr$ coating deposited on steel(SM45C) was investigated under lubrication. The parameters of sliding wear are normal loads, coating thickness. As a result, the wear resistance of $Al_2O_3/NiCr$ coating was remarkably greater than that of $Al_2O_3$ coating. The optimized coating thickness was found to be $300{\mu}m$ to ensure good anti-wear. The bond coating played important role in decreasing residual stress. The residual stress had much influence on wear mechanism. These results were correlated with the stress state of coating and the microstructure of coating.

• 항공우주기술
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• 제8권1호
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• pp.138-143
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• 2009

액체로켓엔진 연소기에 적용된 대기 플라즈마 코팅 및 전해/무전해 도금 코팅의 열차폐 효율과 내구성 평가를 수행하였다. 연소시험 결과 대기 플라즈마 방식의 $ZrO_2$, NiCrAlY 코팅은 로켓엔진 연소기의 초음속 유동영역에서 코팅이 표면에서 박리되는 현상이 간헐적으로 발생하였으며 따라서 이러한 문제를 극복할 수 있는 대체 코팅 방식이 요구되었다. 시험 결과 열차폐 효율 및 내구성 관점에서 대기 플라즈마 방식의 $ZrO_2$, NiCrAlY 코팅의 대안으로 무전해/전해 방식을 사용한 니켈-크롬 코팅을 사용할 수 있음을 알 수 있었다.