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마찰교반용접한 5456-H116 알루미늄 합금 용접부 표면의 기계적 및 전기화학적 특성
장석기(Seok-Ki Jang),김성종(Seong-Jong Kim) 한국표면공학회 2008 한국표면공학회지 Vol.41 No.4
Small FRP (fiber-reinforced polymer) fishing ships have numerous problems with the point of the environmental and recycling perspectives. In light of these aspects, aluminum can be used as a material for ship building. It is environmental friendly, easy to recycle, and provides a high added value to fishing boats. In this paper, we report on mechanical and electrochemical characteristics of welding parts for friction stir welded 5456-H116 Al alloy. In friction stir welded at various traveling speeds under the rotation speed of 500 RPM, the best characteristics presented in traveling speed of 15㎜/min. The anodic polarizations of base metal and welding metal were observed tendency which current density from the open circuit potential suddenly increase. The cathodic polarization presented concentrated polarization caused by the dissolved oxygen reduction reaction and activation polarization caused by hydrogen generation. From result of Tafel analysis, the corrosion potential of 5456 alloy (Base metal) was lower than that of friction stir welded part, as were its corrosion current densities.
다양한 화성처리 용액 조건에서 마그네슘-알루미늄 합금위에 형성된 박막의 특성 평가
장석기,김성종,김정일,Jang Seok-Ki,Kim Seong-Jong,Kim Jeong-Il 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.1
The chemical conversion film formed on magnesium alloy was investigated by using the colloidal silica with some parameters such as solution pH. temperature, solution conditions, and treatment time. Moreover. the solutions consisted of colloidal silica titanium sulfate, and cobalt ions were used for the colloidal silica film to having a good corrosion resistance and adhesion properties. It was thought that the film at 298K was made with combination of Si-O. The quantity of film formed at high temperature such as 333K and 353K is smaller than dissolved quantity during chemical conversion treatment. Adding $CoSO_4$ to the colloidal silica solution enhanced the adhesion force between the silica film and magnesium substrate, The optimum conditions for the chemical conversion treatment solution were PH 2.90 s treatment, and 298K.
장석기 ( Seok Ki Jang ),이승준 ( Seung Jun Lee ),박재철 ( Jae Cheul Park ),김성종 ( Seong Jong Kim ) 한국부식방식학회 2015 Corrosion Science and Technology Vol.14 No.5
Corrosion is of greatest concern for metallic materials exposed to corrosive seawater or aggressive marine atmospheres.Marine structures and components made of metallic materials incur an initial cost and additional large costs for corrosion control and maintenance. There have been worldwide efforts to minimize marine corrosion and extend service life of the materials. It is believed that various factors are associated with corrosion of marine grade metallic materials, particularly the temperature of the solution affecting the corrosion rate by changing dissolved oxygen solubility and concentrations of chloride. In the present study, the electrochemical characteristics of S355ML steel are investigated to identify corrosion acceleration tendencies with changes in solution temperature under marine environments. It was found that increasing seawater temperature, promoted not only activation of chloride ion transfer,but also the formation of porous Fe(OH)3 or Fe2O3, leading to the acceleration of corrosion.
알카리 수용액에서 Mg-Al 합금의 양극산화시 전류밀도와 양극산화 시간의 효과
장석기,김성종,김정일,Jang Seok-Ki,Kim Seong-Jong,Kim Jeong-Il 한국마린엔지니어링학회 2005 한국마린엔지니어링학회지 Vol.29 No.1
The effects on the formation of anodic oxide films on Mg-Al alloy (AZ91) in 1M-NaOH solution was investigated using parameters of current density and time during anodizing The general tendency has been confirmed that the increase of anodizing time improves the corrosion resistance. It is considered that the formation of anodic oxide film was increased by increasing the applied current and the anodizing time to generate active dissolution reaction In anodizing at constant current density. passivity potentials shifted to noble direction with increasing current densities. It was confirmed that oxygen quantify in anodic oxide films increased with anodizing time. The compact films above 4 $mA/cm^2$ were formed with the shape of an island in grooves at early stage and then grew with combination of the islands
해수 환경 하에서 304 스테인리스강의 캐비테이션 조건에 따른 특성 평가
장석기(Seok-Ki Jang),정상옥(Sang-Ok Chong),한민수(Min-Su Hana),김성종(Seong-Jong Kim) 한국표면공학회 2012 한국표면공학회지 Vol.45 No.6
This investigation evaluated the effect of cavitation condition on electrochemical characteristics of 304 stainless steel, which is widely used for marine environment. The cavitation test with time were conducted on 304 stainless steel in seawater solution. Surface morphologies of specimen were observed by scanning electron microscope (SEM) and 3D microscope. Pitting depth, weight loss and damage rate were analyzed after each cavitation experiment. The surface damage was more severe as the current density increased. A dramatical increase in the damage depth and weight loss was observed after 7 hours of cavitation experiment.
장석기(Seok Ki Jang),김성종(Seong Jong Kim),우용빈(Yong Bin Woo),박종식(Jong Seek Park) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
The joining of dissimilar aluminum 6061-T6 alloy to aluminum 5083-O alloy and vice versa was performed using friction stir welding technique. It apparently results in defect-free weld zone that traverse speed was changed to l24㎜/min under the tool rotation speed of 1250rpm and tilting angle of 2° with tool's pin diameter of 5㎜, the shoulder diameter of l5㎜ and the pin length of 4.5㎜.