Aluminum-Based Conversion Coatings on AZ31 Magnesium Alloys

• Main Authors: Chia-Hang Tu, 杜家杭
• Other Authors: Chao-Sung Lin
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/fc7p2v

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 105 === Magnesium possesses high specific strength and biocompatibility, hence, with potential to be applied in automobile industry, commercial electronics, and bio-implant. Nonetheless, magnesium is limited for high chemical activity and porous film naturally-formed without prevention for corrosion media attack. Corrosion resistance enhancement is, therefore, the critical problem required to solve in magnesium for various application. This study has been divided in to two parts: Part1 mainly comprises the set-up of real-time gas collection equipment with video recorder and magnesium AZ31in various aqueous environment studied through this equipment. Part2 focus on the design in chemical conversion coatings solution, in attempt to substitute non-toxic trivalent aluminum for highly toxic hexavalent chromium species. As result, the corrosion fronts apparently formed when AZ31 in chloride containing solution, and the propagation for corrosion fronts is apparently related to hydrogen evolution rate in observation. Conversion coatings formed in aqueous solution containing aluminum sulfate with potassium dihydrogen phosphate, and single aluminum salt with silicate post-treatment both highly improved the corrosion resistance. (estimated by polarization resistance and corrosion current density showing that approximately one order improvement).