Inconel 625로 아크 용사코팅된 SS400강의 해수 내 전기화학적 특성

박일초(Il-Cho Park),김성종(Seong-Jong Kim) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.2

In this paper, various electrochemical experiments were conducted in seawater solution to evaluate corrosion damage behavior of arc thermal sprayed Inconel 625 coating on SS400 steel in marine environment. As a result, corrosion damages of thermal sprayed Inconel 625 coating preferentially occurred at the defect area, and they were observed as a form of pitting corrosion in the galvanostatic experiments. In Tafel analysis, corrosion current density of Inconel 625 coating was relatively high due to influence of interconnected pores and Cr oxides in the thermal spray coating layer. On the other hand, the result of the potential measurement, thermal sprayed Inconel 625 coating should need the post-treatment which can compensate the defects like pores and cracks because Inconel 625 coating presented a higher potential of about 290 mV than that of the SS400 steel.

후처리 적용에 따른 방식용 Al-3%Mg 용사코팅 층의 해수 내 전기화학적 특성

박일초(Il-Cho Park),김성종(Seong-Jong Kim) 한국통신학회 2015 韓國通信學會論文誌 Vol.40 No.5

알루미늄 합금 및 스테인리스강의 해수 농도 변화에 따른 전기화학적 부식 손상 특성

박일초(Il-Cho Park),김영복(Young-Bok Kim),김성종(Seong-Jong Kim) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.4

5000 series aluminium alloys and austenitic stainless steels have excellent corrosion resistance and sufficient strength, which are widely used as materials for marine equipment and their parts in the marine environment. The corrosion characteristics of materials are important factors for selecting the appropriate material due to fluid component changes in the estuarine and coastal areas where seawater and fresh water are mixed. Therefore, for 5083 Al alloy, STS304 and STS316L widely used in the marine environment, anodic polarization experiments were performed to compare the corrosion damage characteristics of each material by three kinds of solutions of 100 % tap water, 50 % tap water+50 % natural seawater and 100 % natural seawater. As a result of the anodic polarization experiments, aluminum alloy (5083) caused locally corrosion on the surface in the tap water, and corrosion damage occurred all over the surface when the seawater was included. Stainless steels (STS304 and STS316L) presented almost no corrosion damage in tap water, but they grew pitting corrosion damage with increasing seawater concentration. STS316L showed better corrosion resistance than STS304.

대형요트의 내구성 향상을 위한 도장작업의 최적화 및 캐비테이션 침식 특성

박일초(Il-Cho Park),한민수(Min-Su Han),김성종(Seong-Jong Kim) 대한용접·접합학회 2019 대한용접·접합학회지 Vol.37 No.3

The purpose of this study is to investigate the correlation between roughness and adhesion force of each painting step to improve the durability of mega yacht hull painting and to analyze cavitation erosion characteristics according to the number of finish paintings. As a result, the adhesion force of the paint with each painting step was greatly influenced by the surface roughness according to the pretreatment work. However, in some painting steps, sandpaper work that forms the surface roughness was not performed by considering the work efficiency and economic efficiency. On the other hand, the cavitation erosion test presented that cavitation erosion resistance was improved by increasing the cohesion force of the urethane coating itself as the number of coatings increased. We also discussed the cavitation erosion mechanism for the optimized urethane coating.

Inconel 625 열용사 코팅 층의 고상입자 침식 거동

박일초,한민수,Park, Il-Cho,Han, Min-Su 해양환경안전학회 2021 海洋環境安全學會誌 Vol.27 No.4

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. In this study, to repair damaged economizer fin tubes on ships, sealing treatment was performed after applying arc thermal spray coating technology using Inconel 625. A solid particle erosion (SPE) experiment was conducted according to ASTM G76-05 to evaluate the durability of the substrate, thermal spray coating (TSC), and thermal spray coating+sealing treatment (TSC+Sealing) specimens. The surface damage shape was observed using a scanning electron microscope and 3D laser microscope, and the durability was evaluated through the weight loss and surface roughness analysis. Consequently, the durability of the substrate was superior to that of TSC and TSC+Sealing, which was believed to be owing to numerous pore defects in the TSC layer. In addition, the mechanism of solid particle erosion damage was accompanied by plastic deformation and fatigue, which were the characteristics of ductile materials in the case of the substrate, and the tendency of brittle fracture in the case of TSC and TSC+Sealing was confirmed.

용융 알루미늄 도금된 절탄기 강재 튜브의 고상입자 침식 특성

박일초 ( Il-cho Park ),한민수 ( Min-su Han ) 한국부식방식학회 2021 Corrosion Science and Technology Vol.20 No.6

In this paper, durability evaluation and surface damage mechanism were investigated through solid particle erosion (SPE) test after applying hot-dip aluminizing (HDA) technology for the purpose of maintenance of marine economizer tube. Damaged surface shape was analyzed using SEM and 3D microscope. Compositional changes and microstructure of the HDA layer were analyzed through EDS and XRD. Durability was evaluated by analyzing weight loss and surface damage depth after SPE. HDA was confirmed to have a two-layer structure of Al and Al₅Fe₂. HDA+HT was made into a single alloy layer of Al₅Fe₂ by diffusion treatment. In the microstructure of HDA+HT, void and crack defect were induced during the crystal phase transformation process. The SPE damage mechanism depends on material properties. Plastic deformation occurred in the substrate and HDA due to ductility, whereas weight loss due to brittleness occurred significantly in HDA+HT. As a result, the substrate and HDA showed better SPE resistance than HDA+HT.

쇼트피닝이 회주철의 캐비테이션 침식 저항성에 미치는 영향

박일초 ( Il-cho Park ) 한국부식방식학회(구 한국부식학회) 2021 Corrosion Science and Technology Vol.20 No.3

In this study, optimal shot peening process conditions were investigated for improving the cavitation erosion resistance of gray cast iron under a marine environment. Shot peening was performed with variables of injection pressure and injection time. The durability was then evaluated through cavitation erosion test which was conducted according to the modified ASTM G-32 standard. The tendency of cavitation erosion damage according to shot peening process condition was investigated through weight loss rate, surface and cross-sectional analysis of the specimen before and after the test. As a result, the shot peening process condition that could minimize cavitation erosion was when the injection pressure was the lowest and when the injection time was the shortest. This was because the flake graphite exposed on the gray cast iron surface could be easily removed under such condition. Therefore, the notch effect can be prevented by surface modification. In addition, the cavitation erosion damage mechanism of gray cast iron was discussed in detail.

양극산화 후 실링처리된 알루미늄 합금의 해수 내 내식성과 캐비테이션 침식 저항성 평가

박일초(Il-Cho Park),이정형(Jung-Hyung Lee),한민수(Min-Su Han),김성종(Seong-Jong Kim) 한국표면공학회 2018 한국표면공학회지 Vol.51 No.2

Various sealing techniques were applied to the anodized 5083 aluminum alloy for marine environment to reduce corrosion and cavitation erosion damage. Electrochemical experiments and cavitation erosion tests were conducted to evaluate the corrosion resistance and cavitation resistance of the anodic oxide film treated with sealing in natural seawater solution. Then, damaged surface morphology was analyzed by scanning electron microscope(SEM) and 3D microscope. As the results of the electrochemical experiments, it was observed that the surface damage of all the experimental conditions in the anodic polarization experiment was locally grown by the combination of crack and corrosion damage. In the Tafel analysis, the corrosion resistance of all sealing treatment conditions was improved compared to the anodizing. On the other hand, cavitation erosion tests showed that the anodizing and all the sealing treatment conditions generated local pit damage by cavitation erosion attack and grew to crater damage in the observation of damaged surface by SEM. Also, the weight loss and the surface damage depth measured with the experiment time presented that most of the sealing treatment conditions showed better cavitation erosion resistance than the anodizing, and they had an incubation period at the beginning of the experiment.

양극산화 처리된 5083 알루미늄 합금의 해수 내 유속변화에 따른 전기화학적 손상 특성

박일초(Il-Cho Park),김성종(Seong-Jong Kim) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.4

In this study, electrochemical damage behaviors with flow rate were investigated for anodized 5083 aluminum alloy in seawater. As the results of anodic polarization experiments and potentiostatic experiments at +1.0V (vs. SSCE), the non-flow condition presented largely damaged surface resulting from a tendency of local pitting damage. Under various flow rate conditions, however, less surface damages under the application of anodic potential was obtained which is attributed to no accumulation of H<SUP>+</SUP> and Cl<SUP>-</SUP> ions on the surface. On the other hand, the results of the potentiostatic experiments at –1.0 V (vs. SSCE) with flow rate showed that anodized 5083 aluminum alloys could achieve the effective cathodic protection by low cathodic protection current density less than 2.61 x 10<SUP>-7</SUP> A/cm² even under high flow rate of 1 m/s.

선체 구조용 강재에 대한 Al과 Zn 아크용사코팅 층의 캐비테이션 손상 특성

박일초(Il-Cho Park),김성종(Seong-Jong Kim) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.1

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.