Abstract:The pure aluminum and Al-Mg-Mn alloy were anodized in 4%, 10% and 18.5% phosphoric acid solution, respectively. As for pure Al, the maximum thickness of anodized aluminum oxide (AAO) membrane, 216nm, is obtained by being anodized in 4% solution. Its average pore diameter is around 70nm, and pore density exceeds 10¹⁰/cm². Under the same technology condition, the membrane thickness decreases with increment of electrolyte content. TEM images show that element Mg or Mn added into aluminum alloy can damage the integration of AAO membrane. During anodizing of aluminum, the formed oxide layer is amorphous. After being annealed at 600℃ for 24h, it is still amorphous. However, when membrane is annealed at 930℃, the amorphous oxide begins to transform to γ-Al₂O₃ .

Key words:  anodized aluminum oxide; nanopore; phosphoric acid; membrane; alloying element; annealing