• 한국안전학회지
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• 제18권4호
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• pp.39-43
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• 2003

An experimental study was conducted to develop and understanding of fracture behavior of ceramic thermal barrier coating when subjected to a thermal shock loading. The thermal loading was applied using a 1.5kW $CO_2$ laser. In the experiments, beam-shaped specimens were subjected to a high heat flux for 4sec and cooling of 7sec in air. The interface crack length was increased as the crack density, the surface pre-crack legth and the coating thickness were increased. The center surface crack length was increased as the maximum surface temperature got higher and the surface pre-crack length for shorter.

• 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.

• 한국표면공학회지
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• 제49권1호
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• pp.32-39
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• 2016

In this study, Al and Zn arc thermal spray coatings were carried out onto the substrate of SS400 steel to improve corrosion resistance and durability of hull structural steel for ship in marine environment. Therefore cavitation-erosion test was conducted to evaluate the durability of painted and thermal spray coated specimens. And then the damaged surface morphology and weight loss were obtained to compare with each other, respectively. As a result, the painted specimen was the poorest cavitation resistance characteristics because surface damage behavior appeared to be exfoliated in bulk shape during the cavitation experiment. And Zn thermal spray coating layer presented the significant surface damage depth due to relatively low surface hardness and local cavitation damage tendency. On the other hand, as a result of the weight loss analysis, the painting layer presented the poorest cavitation resistance and the Al thermal spray coating layer relatively showed the best results after cavitation experiment.

• 한국추진공학회지
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• 제14권5호
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• pp.45-50
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• 2010

연료링의 위치 및 열차폐 코팅의 종류에 따른 연소기의 재생냉각 특성을 검토하였다. 연료링을 노즐의 중간 부분에 위치시키고 냉각채널을 분기시켜서 설계하는 방법이 열적으로 타당함을 확인하였다. 또한 복합재를 이용한 노즐확장부가 적용 가능한 기술적 상황이라면, 팽창비가 높고 열유속이 낮은 노즐 후류 부분은 이를 이용하는 것이 매우 적절하다고 판단된다. 적용 가능한 열차폐 코팅 중에서 30톤급 연소기 및 가스발생기 개발과정에서 사용했던 $Y_2O_3$ stabilized $ZrO_2$과 내산화성이 우수한 Ni/Cr을 고려하였다. 내산화성이 우수한 Ni/Cr에 비해 세라믹 코팅($Y_2O_3$ stabilized $ZrO_2$)이 열차폐 효과가 우수한 것으로 파악되었다.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제34회 춘계학술대회논문집
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• pp.145-149
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• 2010

연료링의 위치 및 열차폐 코팅의 종류에 따른 연소기의 재생냉각 특성을 검토하였다. 연료링을 노즐의 중간 부분에 위치시키고 냉각채널을 분기시켜서 설계하는 방법이 열적으로 타당함을 확인하였다. 또한 복합재를 이용한 노즐확장부가 적용 가능한 기술적 상황이라면, 팽창비가 높고 열유속이 낮은 노즐 후류 부분은 이를 이용하는 것이 매우 적절하다고 판단된다. 적용 가능한 열차폐 코팅 중에서 30톤급 연소기 및 가스발생기 개발과정에서 사용했던 $Y_2O_3$ stabilized $ZrO_2$과 내산화성이 우수한 Ni/Cr을 고려하였다. 내산화성이 우수한 Ni/Cr에 비해 세라믹 코팅($Y_2O_3$ stabilized $ZrO_2$)이 열차폐 효과가 우수한 것으로 파악되었다.

• 한국분말재료학회지
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• 제20권6호
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• pp.460-466
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• 2013

4 mol% Yttria-stabilized zirconia (4YSZ) coatings with $200{\mu}m$ thick are fabricated by Electron Beam Physical Vapor Deposition (EB-PVD) for thermal barrier coating (TBC). $150{\mu}m$ of NiCrAlY based bond coat is prepared by conventional APS (Air Plasma Spray) method on the NiCrCoAl alloy substrate before deposition of top coating. 4 mol% YSZ top coating shows typical tetragonal phase and columnar structure due to vapor phase deposition process. The adhesion strength of coating is measured about 40 MPa. There is no delamination or cracking of coatings after thermal cyclic fatigue and shock test at $850^{\circ}C$.

• 해양환경안전학회지
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• 제27권4호
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• pp.521-528
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• 2021

본 연구는 손상된 선박용 절탄기 핀튜브에 대하여 보수를 목적으로 Inconel 625 아크 열용사 코팅기술 적용 후 실링처리를 실시하였다. 모재(Substrate), 열용사 코팅(Thermal Srpay Coating; TSC) 그리고 열용사 코팅+실링처리(TSC+Sealing) 시편에 대하여 내구성을 평가하기 위해 ASTM G76-05에 의거하여 고상입자 침식(Solid Particle Erosion; SPE) 실험을 실시하였다. 표면 손상 형상은 주사전자현미경과 3D 레이져 현미경을 통해 관찰했으며, 무게 감소량과 표면 거칠기 분석을 실시하여 내구성을 평가하였다. 그 결과 내구성은 TSC와 TSC+Sealing에 비해 Substrate가 우수하게 나타났으며, 이는 TSC 층 내에 존재하는 다수의 기공 결함에 기인한 것으로 판단된다. 또한 고상입자 침식 손상 메카니즘은 Substrate의 경우 연성 재질 특성인 소성변형과 피로에 의한 균열 생성이 동반되었으며, TSC와 TSC+Sealing의 경우 취성파괴 경향이 확인되었다.

• 한국표면공학회지
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• 제56권1호
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• pp.69-76
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• 2023

The effects of hairline treatment on surface blackening and thermal diffusion behaviors of Zn-Al-Mg alloy coated steel sheet were evaluated by the three-dimensional surface profiler and laser-flash technique. The metallographic observation of coating damages by hairline treatments showed that several cracks were initiated and propagated along the interface between primary Zn/eutectic phases. As the hairline processing became more severe, the crack occurrence frequency in eutectic phase of coating layer and the surface roughness increased, which had a proportional relationship with the level of blackening on the coating surface. In addition, the higher interfacial areas of the blackened coating surface, caused by the hairline process, led to an increase in thermal diffusivity and conductivity of the coated steel sheet. On the other hand, when the coating damage by hairline treatment was excessive and the steel substrate was exposed, there was little difference between the thermal diffusivity/conductivity of the untreated sample though the blackening degree was higher than that of untreated sample. This work suggests that the increase in the surface areas of the coating layer without exposure to steel substrate through hairline treatment can be one of the effective technical strategies for the development of Zn-Al-Mg alloy coated steel sheets with higher blackening level and thermal diffusivity.

• 대한금속재료학회지
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• 제46권3호
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• pp.182-188
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• 2008

Carbon nanotubes(CNTs) have outstanding mechanical, thermal, and electrical properties. Thus, by placing nanotubes into appropriate matrix, it is postulated that the resulting composites will have enhanced properties. Cold spray can produce thick metal-based composite coatings with very high density, low oxygen content, and phase purity, which leads to excellent physical properties. In this study, we applied cold spray coating process for the consolidation of Cu/CNT composite powder. The precursor powder mixture, in which CNTs were filled into copper particles, was prepared to improve the distribution of the CNT in copper matrix. Pure copper coating was also conducted by cold spraying as a reference. Annealing heat treatment was applied to the coating to examine its effect on the properties of the composite coating. The hardness of Cu/CNT composite coating represented similar value to that of pure copper coating. It was importantly found that the electrical conductivity of the Cu/CNT composite coating significantly increased from 53% for the standard condition to almost 55% in the optimized condition, taking annealed ($500^{\circ}C/1hr$.) copper coating as a reference (100%). The thermal conductivity of Cu/CNT composite coating layer was higher than that of pure Cu coating. It was also found that the electrical and thermal conductivities of Cu/CNT composite could be improved through annealing heat treatment. The microstructural evolution of Cu/CNT coating was also investigated and related to the macroscopic properties.

• 한국자동차공학회논문집
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• 제14권4호
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• pp.99-106
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• 2006

High velocity oxygen-fuel thermal spray coating of the WC-Co cermet material is a well-established process for modifying the surface properties of the structural components exposed to the corrosive and wear attacks, and also these coating are well-known method to improve the fatigue strength of material. In this study, HVOF coated SM490B are prepared to evaluation of the effect of coating on tension and fatigue crack growth behavior. The pre-crack of the fatigue crack growth test specimens machined at deposited material area, heat affected zone and boundary, respectively. Through these test, the following results are obtained: 1) Tensile strength was about 498 MPa, and fracture occurred on base metal area. 2) The fatigue crack of coated specimens propagated more rapidly than non-coated specimen in all specimens. 3) In the same coating thickness specimens, the specimens with pre-crack at boundary more rapidly propagated than the specimens with pre-crack at HAZ and deposited material area. These results can be used as basic data in a structural integrity evaluation of rolled SM490B weldments considering HVOF coating.