シュウ酸浴によるアルミニウムの高速陽極酸化

抄録

The anodization of aluminum at high current densities in acid baths known as causes a concentration of anodic current at certain points on the Al surface ‘burning’. It was found that in an oxalic acid bath, the film thickness at the start of the burning (d_b) and the applied current density (i) can be related by d_b=A/i where A is a constant. Based on this equation, a new high speed anodization process has been developed, In which after initial galvanostatic anodization at a high current density, anodic current is decreased with time to prevent burning. Theoretical equations for changing the current density as a function of anodization time were derived from above the equation. Experimental results using an automatic power supply that controlled anodic current in accordance with the theoretical equations demonstrated that thick anodic oxide films could be formed rapidly on aluminum without burning and that the films formed had Hv hardness values as high as 400-450.