| Summary: | 碩士 === 國立中央大學 === 機械工程研究所 === 100 === The aim of the study is to investigate the effect of the anodic aluminum oxide film (AAO film) formed on the 7005 aluminum alloy by using anodizing treatment. Through the manufacturing processes including annealing, artificial aging treatment and cold-rolling, the variation of AAO film of 7005 aluminum alloy revealed especially on its microstructure and the status of precipitate materials. Furthermore, anodize was utilized to explore the influence on the AAO film from the basic structure. Also, voltage-time (V-t) curvature changes in the process of anodizing were recorded. After the above manufacturing processes, the effect of the microstructure on the growing behavior of the porous AAO film was observed by using SEM. In addition, the XPS was utilized to analyze the composition of AAO film surface and interface (film/metal). Then, the electrochemical tests were conducted and recorded by AUTO LAB PGSTAT30 potentiostat. The CIE L*a*b* colorimeter were used to analyzed the AAO film surface Colour properties.
By analyzing the Transmission Electron Microscopy (TEM), we found that near the grain boundary (G.B.) has dislocations and precipitates in RSAT(1) samples. In SRAT(1) sample, the bands developed from dense dislocation walls were called microbands. SAT(2) and RSAT(2) are affected by natural aging and generated the phenomenon of recovery, which lower the hardness. With observing by TEM, the density of precipitates is smaller. In respect to the variation of V-t curvature, the lower the conductivity of RSAT(1) sample, the voltage and the energy consumption of the test fragment with RA sample became higher in step 1. The voltage of the test fragment with RSAT(1) sample became higher in step 2. Concerning the RSAT(1) sample, it is suggested that the pore diameter increases by using the AAO films.
The anodized samples were then analyzed by X-ray Photoelectron Spectroscopy (XPS). We found that the constituted phases in the AAO film are composed by amorphous alumina (Al-O-H), hydrated oxide (Al(OH)3) and crystallite oxide (AlOOH) phases. In the corrosion test, hydrated Al(OH)3 that formed at the subsurface of AAO film were found to inversely influence the pitting potential (Epit) of anodized samples.
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