| 摘要 |
Oxide coatings are formed on the surface of aluminium and aluminium alloys by treating them with an aqueous solution containing 0.5-6.0 per cent by weight of alkali metal carbonate and 0.2-5.0 of polyvinyl alcohol. When the solution contains only 0.2-3.0 of polyvinyl alcohol it may also contain 0.05-0.5 per cent of alkali metal chromate. Preferably the carbonate content is at least equal to the polyvinyl alcohol content. The oxide coating may be treated with hot sulphonated castor oil followed by a 15-minute treatment in 5 per cent sodium chromate solution. |
