| abstract |
Disclosed is a forming electrolyte for forming metal oxide coating films which comprises one or more kinds of solutes selected from the group consisting a salt of inorganic acid and salt of organic carboxylic acid dissolved in a solvent having analcoholic hydroxyl group or aprotic organic solvent, provided that, when the solvent having an alcoholic hydroxyl group is selected, the salt of organic carboxylic acid is selected from salts of aromatic carboxylic acids, salts of aliphatic polycarboxylic acid having 3-5 carbon atoms with no hydroxyl groups, salts of monohydroxy carboxylic acid having 2-5 carbon atoms, and salts of amino acid. By anodically oxidizing metal using the forming electrolyte, there can be formed an oxide coating film of high insulation property with a high throughput, in which hillocks are effectively suppressed. |