The Al alloy is environmental friendly, easy to recycle, and provides a high added value to fishing boats. Aluminum alloy do not corrode due to the formation of an anticorrosive passive film, such as Al2O3or Al2O33H2O, which resists corrosion in neutral solution. In seawater, however, Cl-ions destroy this passive film. We investigated on several electrochemical tests undertaken to determine the optimum conditions in seawater for corrosion protection of casted AC7AV aluminum alloy. The components of casted AC7AV aluminum alloy are similar with Al-Mg alloys (5xxx series) which are used for ship. Result of electochemical experiment, the optimum protection potential range with regards to hydrogen embrittlement and stress corrosion cracking was determined to lie between-1.3 and-0.7 V(vs Ag/AgCl).
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 Fe 2 O 3 , leading to the acceleration of corrosion.
The sustainable development of engineering, mechanical instrument requires higher speed and higher power. It cause a physical damage is excessive damage for underwater rotating system as cavitations and erosion, but also electrochemical corrosion by chloride ion and flow of current in marine environment. In this study, we assessed electrochemical corrosion characteristics of aluminum-bronze that are the material for the underwater rotating system used in the ocean industry and studied the complex behavior of electrochemical corrosion and cavitation corrosion through the hybrid test that also included cavitation corrosion environment. After the cavitation hybrid tests, surface of specimens are observed to measurement damage degree using 3D optical microscope and compared the average of damage depth by immersion time. The observation of the surface micro-structure suggested that the corrosion took place initially in β phase that has poor corrosion resistance in spite of high hardness.
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