Synthesis and characterization of nanoporous anodic oxide film on Aluminum in H_3PO_4 + KMnO_4 electrolyte mixture at different anodization conditions

摘要

The micro structural properties of nanoporous anodic oxide film formed in H_3PO_4 were highly influenced by addition of a low concentration of KMnO_4 (0.0005 M) in 1 M H_3PO_4 solution. The KMnO_4 as additive enhanced the growth rate of oxide film formation as well as thickness of pore walls. Furthermore the growth rate was found increased with increase in applied current density. The increase in temperature and lack of stirring during anodization causes the thinness of pore wall which leads to increase in pore volume. With the decrease in concentration of H_3PO_4 in anodizing electrolyte from 1M to 0.3 M, keeping all other conditions constant, the decrease in porosity was observed. This might be due to the dissolution of aluminium oxide film in highly concentrated acidic solution.