Al[sub 2]O[sub 3] Films Formed by Anodic Oxidation of Al-1 Weight Percent Si-0.5 Weight Percent Cu Films

Re-Long Chiu
1995 Journal of the Electrochemical Society  
The structure of the barrier-type anodic oxide formed on preannealed Al-1 weight percent (w/o) Si-0.5 w/o Cu thin film in a tartaric acid electrolyte was investigated. The oxide film is basically an amorphous layer with a thin dispersed ~'-A1203 crystalline layer interposed in the center. Pores are observed to be associated with the -y'-A1203 layer. Silicon nodu]es and A12Cu particles originally present in the AI-1 w/o Si-0.5 w/o Cu film behave differently during anodization. Silicon nodules
more » ... oxidized to various degree during anodizing. The silica formed in the Si nodules is amorphous and somewhat porous possibly due to oxygen evolution associated with the Si anodization. A dark rim was found to surround each nodule in the anodic oxide film. This rim is shown to be thicker amorphous A120~ material, and its origin is attributed to the faster oxidation rate in the vicinity of Si nodules. A12Cu precipitates are oxidized to form A1203 at about the same rate as the surrounding A1 matrix. Copper is rejected by A1203 and accumulates at the A12OJA1 interface.
doi:10.1149/1.2044093 fatcat:fvfxwbjerradva5lggsknkhkka