Jae-Yong Jeong

Mechanical and electrochemical characteristics in sea water of 5052-O aluminum alloy for ship

Abstract The optimum corrosion protection potentials were examined for 5052-O Al alloy, which is mainly used in ships. Various electrochemical experiments were carried out and the surface morphologies of specimens were observed by scanning electron microscopy (SEM) in order to determine the optimum corrosion protection potential to overcome pitting, corrosion, stress corrosion cracking (SCC), and hydrogen embrittlement in sea water. An optimum protection potential range of −1.3 V to −0.7 V was determined under the application of an impressed current cathodic protection (ICCP) system. The low current densities were shown in the range of −1.3 V to −0.7 V in the electrochemical experiments and good specimen surface morphologies were observed after potentiostatic experiment.

Electrochemical characteristics of Al–Mg and Al–Mg–Si alloy in sea water

Abstract Among Al alloys, particularly 5000 series Al–Mg and 6000 series Al–Mg–Si often used as marine materials have excellent corrosion resistance, low melting point, and thereby showing recycling availability when compared to other metals. Variety experiments were conducted to select the most suitable material for marine environments. All electrochemical experiments were conducted in natural seawater. The corrosion test was performed in many methods such as anodic/cathodic polarization and Tafel analysis using multi-channel potentio/galvanostat WMPG–1000. As results, anodic and cathodic polarization behaviors indicate the characteristics of passive state and concentration polarization by reduction reaction in dissolved oxygen, which shows excellent electrochemical behaviors. Tafel analysis results show no significant difference but 5052-O alloy of various alloy materials indicates the lowest corrosion current density. Therefore, 5052-O Al alloy presents most anti-corrosion material in marine environment.

Electrochemical Behavior of CoNiCrAlY/ZrO2–Y2O3 Coated Layers with Atmospheric Pressure Plasma Technology in Seawater

Application of surface treatment has become common for protecting machine parts from oxidation, abrasion and corrosion induced by external environment. In particular, thermal spraying techniques are widely employed to improve wear, corrosion and thermal resistance. And compared to other methods they are simple and cost effective. However, the presence of porosity in the thermal spray coating can be highly detrimental because it provides access to penetration of corrosive matters, lowering corrosion resistance. Therefore, this research evaluate the electrochemical behavior under marine environment for aluminum–bronze alloy coated with MCrAlY and yttria-stabillized zirconia (YSZ) by atmospheric pressure plasma (APP) coating technology. Further application of carbon-based sealer removed voids and defects in the coating. The result reveled that, in case the voids and defects are completely removed, excellent corrosion resistance can be archived by application of good coating material along with formation of compact sealing layer.