Synthesis of Porous Anodic Alumina on Aluminium Manganese Alloys

In this study, porous anodic alumina was formed on aluminium alloy substrate with increasing manganese content, from high purity aluminium with 0 wt% Mn to aluminium alloy with 2.0 wt% manganese by anodizing. Substrates were anodized at 50 V in 0.3 M oxalic acid of 15°C for 60 minutes. Images from the optical microscope revealed that no secondary phase existed in high purity aluminium and aluminium substrate with 0.5 wt% manganese while two phases were observed when the manganese contents were higher than 0.5 wt%. Element dispersive X ray spectroscopy spot analysis suggested that the secondary phase consists of both aluminium and manganese. Well ordered porous anodic alumina was obtained on high purity aluminium and aluminium substrate with 0.5 wt% manganese while pore arrangement of porous anodic alumina was significant disturbed when aluminium alloys with manganese contents higher than 0.5 wt% were anodized.