전기화학적 가속 부식 평가법에서 강재의 부식 손상에 미치는 인가전류밀도의 영향

이정형(Jung-Hyung Lee),박일초(Il-Cho Park),박재철(Jae-Cheul Park),김성종(Seong-Jong Kim) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.5

In this study, we investigated the corrosion damage characteristics of steel for offshore wind turbine tower substructure using an accelerated electrochemical test. The galvanostatic corrosion test method was employed with a conventional 3 electrode cell in natural sea water, and the steel specimen was served as a working electrode to induce corrosion in an accelerated manner. Surface and cross-sectional image of the damaged area were obtained by optical microscope and scanning electron microscope. The weight of the specimens was measured to determine the gravimetric change before and after corrosion test. The result revealed that the steel tended to suffer uniform corrosion rather than localized corrosion due to active dissolution reaction under the constant current regime. With increasing galvanostatic current density, the damage depth and surface roughness of surface was increased, showing approximately 25 times difference in damage depth between the lowest current density (1 ㎃/㎠) and the highest current density (200 ㎃/㎠). The gravimetric observation showed that the weight loss was proportionally increased with increment of current density that has 75 times different according by experimental conditions. Consequently, uniform corrosion of the steel specimen was conveniently induced by the electrochemically accelerated corrosion technique, and it was possible to control the extent of the corrosion damage by varying the current density.

해양환경 하에서 동합금의 캐비테이션-부식손상 방지를 위한 방식정전류 기법 연구

박재철(Jae-Cheul Park),김성종(Seong-Jong Kim) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.1

The galvanostatic tests for corrosion protection are conducted at various applied current densities during 93,600 sec, and evaluated in terms of the variations in current density with time and in the potential at the applied current density. In addition, the corrosion damage depth is analyzed with 3D analysis optical microscope after galvanostatic tests. In this study, it was investigated to decide condition of the corrosion protection gavalnostatic method for Cu-Al alloy that has an excellent corrosion resistance. In the galvanostatic test under the cavitation environment, the energy was reflected or cancelled out by the collision with the oxygen gas generated by the oxygen reduction action. The surface observation showed neither the cavitation damage nor the electrochemical damage in the current density over 0.01 A/㎠ in the dynamic state under the cavitation environment.

임베디드 부식감지센서를 이용한 해상 콘크리트 교각의 부식 및 음극방식전류밀도의 측정에 관한 연구

정진아(Jin-A Jeong),김기준(Ki-Joon Kim),이명훈(Myong-Hoon Lee),이우철(Woo-Chul Lee) 한국마린엔지니어링학회 2007 한국마린엔지니어링학회 학술대회 논문집 Vol.2007 No.-

Recently, corrosion problems have been increased in various structures surrounded by marine environment like marine bridges. Especially tidal and splash zones of concrete piles supported bridge deck are more serious. The most common method of preventing corrosion is the cathodic protection such as impressed current cathodic protection(ICCP) or sacrificial anode cathodic protection(SACP). At any rate, it is necessary to measure accurately corrosion data like potential, cathodic protection current density, and resistivity on the concrete pile to diagnose corrosion. Therefore, a series of laboratory tests have been performed to verify the behavior of corrosion and protection for concrete pile in sea water using the corrosion monitoring sensors. It was useful to monitor the condition change with time using the embedded corrosion monitoring sensors, and the condition change was classified by the location of pile(immersed, tidal, splash, and atmospheric zones).

인가전류밀도에 따른 플라즈마 전해산화코팅된 AZ91 마그네슘 합금의 내식성 변화

이병욱 ( Byung Uk Lee ),황인준 ( In Jun Hwang ),이재식 ( Jae Sik Lee ),고영건 ( Young Gun Ko ),신동혁 ( Dong Hyuk Shin ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.8

The study investigated the influence of current density on the corrosion-protection properties of an AZ91 Mg alloy subjected to plasma electrolytic oxidation coating. The present coatings were carried out under an AC condition at three different current densities, i.e., 100, 150, and 200 mA/cm2. From microstructural observations, the micro cracks connecting each micro pore were pronounced on the oxide surface of the samples coated at current densities higher than 150 mA/cm2 since increasing the current density in this study led to an increment in the relative volume fraction of the MgO compound. Based on potentio dynamic polarization and immersion tests, the sample coated at a current density of 100 mA/cm2 showed superior corrosion resistance.

철근콘크리트 구조물에 Zn-Al 금속용사 전기방식 공법의 적용성에 관한 실험적 연구

한만해,유조형,임영철,이한승 한국건축시공학회 2010 한국건축시공학회지 Vol.10 No.5

희생양극방식은 지하구조물이나 해양환경하에서 구조물의 방식공법으로 소개되어지고 있다. 1970년대 이후, 희생양극방식이 철근콘크리트 구조물에 적용되어지고 있다. 희생양극방식은 전세계적으로 1990년대 이후 그 유효성을 검증되었다. 그러나, 희생양극방식은 시공적이나 경제적인 약간의 문제점을 가지고 있다. 그 문제점을 해결하기 위하여 고 내구성 금속을 용사시키는 희생양극방식이 개발되었다. 양극재(아연, 알루미늄)를 금속용사로 도포하여 실험체를 제작한 후, 실험체의 부식전류를 측정하여 양극재의 방식성능을 확인하였다. 실험결과 철근 콘크리트 구조물을 대상으로 금속용사를 이용한 희생양극방식이 우수한 방식성능을 가지는 것을 알 수 있었다. Cathodic Protection has been introduced as a method of protecting metals under the ground or sea from corrosion. Since 1970, it has been applied to reinforced concrete structures as a corrosion protection method. After 1990, it became used around the world, and its usability has been well confirmed. But this method has some problems in terms of construction and economy. To solve these problems, a Cathodic Protection Method using a highly-durable metal spray was developed. First, the specimen was covered with anodic materials (Zn, Al) by using metal spray. The corrosion protection performance was confirmed by measuring the corrosion current of the specimen. Through the experiment, it is possible to confirm that the Cathodic Protection Method using a high metal spray provides effective protection against corrosion to reinforced concrete structures.

크롬도구의 부식-마멸에 미치는 산성환경의 영향

임우조(Uh Joh Lim),곽남인(Nam-In Kwak) 한국트라이볼로지학회 2003 한국트라이볼로지학회 학술대회 Vol.36 No.-

This paper was studied on the corrosion and corrosion-wear behavior of chromium(Cr) plating in the acidic environments. In the various pH of acidic solutions, the electrochemical polarization test and wear-corrosion test of Cr plating were carried out. And thus potential, corrosion current density and corrosion-wear loss behav:our of Cr plating are investigated.

해수전착 코팅을 이용한 내부식성 철근의 개발 및 적용성에 대한 연구 1 : 해수전착 코팅 시스템 개발

권성준,이명훈,박상순 한국구조물진단유지관리공학회 2012 한국구조물진단유지관리공학회 논문집 Vol.16 No.5

본 연구는 해수에 존재하는 다량의 칼슘 및 마그네슘 이온을 전기적으로 강판에 전착하는 전착시스템을 개발하는 것이다. 최종적인 목표는 해수를 이용하여 전착한 구조용 철근의 개발이며, 본 연구는 1단계 연구로서 고내구성 철근개발을 위한 전착시스템 개발에 목적을 두었다. 다양한 전극과 온도, 전류밀도, 코팅시간 등을 변수로 하고 실험을 수행하여 철근 코팅을 위한 최적의 조건을 도출하였다. 탄산칼슘(CaCO3)과 수산화마그네슘(Mg(OH)2)으로 구성된 코팅층은 SEM, EDS, XRD 등을 통하여 성분을 파악하였으며, 자연전위 및 전류밀도를 분석하여 기존의 철보다 부식에 대하여 매우 안전함을 확인하였다. 본 연구의 성과를 이용하여 고내구성 강재의 구조적, 내구적 실험에 대한 토의가 2차 연구에서 추가적으로 수행될 것이다. This study is for developing a system for electro-deposition utilizing sea water containing various ions like calcium and magnesium. This is the first step research for the final goal which is a development of anti-corrosive steel for RC structure, so that this paper is mainly focused on the development for electro-deposition system. Optimum conditions for steel coating is obtained through various tests considering anode type, temperature, duration time, and current density. The composition of electro-deposition is analyzed through SEM, EDS, and XRD and it is evaluated to be CaCO3 and Mg(OH)2. Through measuring polarization potential and current density in the coated steel, the coating layer from the developed system is evaluated to have high resistance to steel corrosion. Additional tests and discussions on durability and structural performance in the coated steel from this work will be performed for the second step research.

PEO 전류밀도 조건에 따른 알루미늄도금 강재상 산화코팅막의 특성

최인혜(In-Hye Choi),이훈성(Hoon-Seung Lee),이명훈(Myeong-Hoon Lee) 한국표면공학회 2017 한국표면공학회지 Vol.50 No.5

Plasma electrolytic oxidation(PEO) has attracted attention as a surface treatment which has high wear resistance and corrosion resistance. PEO is generally considered as cost-effective, environmentally friendly and superior in terms of coating performance. Most of studies about the PEO processes have been applied to light metals such as Al and Mg. Because the strength of Al and Mg is weaker than that of steel, there is a limit to the application. In this study, PEO process was used to form oxide coatings on Hot dipped aluminized(HDA) steel and the characteristics of the coating film according to the PEO current density were studied. The morphology was observed by SEM and component was analyzed by using EDS. The corrosion behaviors of PEO coating films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of PEO process current density, the pore size of the coating surface and the thickness of coating increased. It was confirmed that no Fe component was present on the coating surface. PEO coating films obviously showed good corrosion resistance compared with HDA. It is considered that the PEO coating acts as a barrier to protect the base material from external factors causing corrosion.

Numerical and Empirical Models for Service Life Assessment of RC Structures in Marine Environment

Xuandong Chen,Yang Ming,Feng Fu,Ping Chen 한국콘크리트학회 2022 International Journal of Concrete Structures and M Vol.16 No.2

The service life prediction of reinforced concrete (RC) structures in marine environment is essential in structural repair and health monitoring. In this paper, a numerical model for predicting the service life of reinforced concrete is first developed which considering the time-varying boundary of chloride concentration, critical chloride concentration and density of corrosion current. Based on the model, the effects of water–cement ratio, reinforcement diameter, concrete cover thickness and critical chloride ion concentration on the service life and deterioration duration of RC structures are investigated. The key factors affecting the service life of reinforced concrete structures are determined. More importantly, based on regression analysis, a new simplified empirical model for predicting the service life of RC structures is also developed. It provides a fast assessment tool for practical engineers. Both the numerical model and empirical model validated are suitable for practical engineering applications. The results show that with the increase of water–cement ratio, the service life of reinforced concrete structure decreases exponentially. And with the increase of the thickness of the concrete cover, the service life, deterioration duration, and safety reserve increase linearly. However, the influence of the diameter of the reinforcing bar on the service life can be ignored.

An Electrochemical Evaluation on Relationship between Corrosion Resistance and Oxygen Diffusion Limiting Current Density of Anti-Corrosive paints

Kyung-Man Moon,Sung-Yul Lee,Yun-Hae Kim,Myung-Hoon Lee 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-

Relationship between corrosion current density and oxygen diffusion limiting current density or its diffusion coefficient were investigated with electrochemical methods such as measurements of corrosion potential, anodic and cathodic polarization curves etc. to five kinds of anti-corrosive paints including acryl, fluorine and epoxy resin series. it is supposed that there are considerably somewhat good relationships between corrosion current density and oxygen diffusion limiting current density or its diffusion coefficient for example, corrosion current density is decreased with decreasing of oxygen diffusion limiting current density or its diffusion coefficient. Consequently it is considered that corrosion resistance of anticorrosive paint can conveniently qualitatively be evaluated by measuring of oxygen diffusion limiting current density or its diffusion coefficient.