| 摘要 |
In a method of anodizing aluminium or aluminium alloy articles to form an opaque protective layer on the surface thereof, using an acidic electrolyte to which salts of titanium and/or zirconium and/or thorium have been added, a cobalt or nickel salt such as cobalt or nickel acetate is also added to said bath, preferably in an amount of less than 6 grams/1000 grams water. The bath may comprise oxalic acid to which boric acid and citric have been added as buffers, 0.5-2.5 gms/1 of cobalt or nickel acetate being present therein. The cobalt or nickel acetate may be added to the bath following activation thereof by using the bath to treat dummy specimens. In examples given the bath also contains potassium-titanyl oxalate. |
