Anodization of Magnesium-Aluminum Alloys

• Main Authors: Yan-Jyun Fu, 傅延俊
• Other Authors: Chao-Sung Lin
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/65181585760113844329

碩士 === 國立臺灣大學 === 材料科學與工程學研究所 === 93 === Abstract AZ31B and AZ91D magnesium alloys were anodized using the direct current with current density of 1 A/dm2 for 10 min. in the solutions composed of potassium hydroxide, potassium fluoride, trisodium phosphate and aluminum nitrate at room temperature. Experimental results indicate that addition of resulted in the formation of dense MgF2, as shown by the TEM/EDS analysis on cross-sectional TEM specimen. This dense MgF2 film caused an increase in anodic voltage. Subsequent dielectric breakdown and sparking led to the formation of a relatively thick anodic film. Adding to the solution also promoted the growth of the anodic film. The presence of in the solution resulted in a delay in reaching a voltage plateau at a higher value, and brought about a more uniform anodic film. The anodic film formed without sparking consisted of a porous inner layer contacting the substrate and a relatively dense overlay, as revealed by cross-sectional TEM. The anodic film formed after sparking also contained two layers with microvoids residing at the interface between the two layers. Finally, glancing-angle XRD showed the anodic film form with and without sparking was mainly composed of MgO and Mg(OH)2, respectively. Key word:Anodization;Magnesium alloys:Sparking