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URN etd-0708108-140410 Statistics This thesis had been viewed 3323 times. Download 351 times. Author Fang-Wei Chou Author's Email Address No Public. Department Materials Engineering Year 2007 Semester 2 Degree Master Type of Document Master's Thesis Language Chinese&English Page Count 102 Title The Effects of Pulse Duration of Anodic Coating of AZ31 Magnesium Alloy on the Corrosion Resistance Keyword Corrosion resistance Microarc Oxidation Plasma Electrolytic Oxidation Oxide film Magnesium alloy Magnesium alloy Oxide film Plasma Electrolytic Oxidation Microarc Oxidation Corrosion resistance Abstract Magnesium alloys have many advantages, but the poor corrosion resistance restricts the development and application of magnesium alloys. The electrochemical anodic treatment is one of the effective surface modification methods, and the pulse voltage anodic method of micro-arc oxidation process is used in this paper. The main parameters of pulse anodic process used in this work include voltage, frequency, and duty ratio. The electrolytic solution of anodic process contains fluorine and silicon ions. From SEM observation, the pore size of anodic coating surface prepared at higher frequency and lower duty ratio is smaller and the more narrow pore size distribution. The diameter of the pore is approximately 0.5 μm. From electrochemical polarization analysis in 3.5wt% NaCl, the corrosion resistance of anodic coating prepared at higher frequency and lower duty ratio is better than the corrosion resistance of anodic coating prepared at lower frequency and higher duty ratio. For the best result in this study, say anodic coating prepared at higher frequency and lower duty, the corrosion potential can shift toward noble potential by 0.25V, and corrosion current density is decreased by 4 orders, and passive region can reach as high as 1V. From salt spray test, the time of spray salt test for the sample of anodic coating can be reached over than 200 hours. Advisor Committee Mu-Rong Yang - advisor
Hsing-Hsiang Shih - co-chair
Ming-Der Ger - co-chair
Files Date of Defense 2008-06-05 Date of Submission 2008-07-08