| 摘要 |
A phosphate coating is formed on a metal surface (ferrous or aluminium) by spraying it at a temperature below 120 DEG F. with an aqueous solution having a pH not exceeding 3.5 and containing zinc, phosphate, a coating accelerator and an aliphatic -hydroxy carboxylic acid or salt thereof. The latter constituent may be tartaric acid, Rochelle salt, or dihydroxytartaric, tartronic, glycollic, lactic, d-malic, dihydroxymaleic, gluconic or citric acid. The accelerator may be nitrite, nitrate or chlorate. The solution should also contain fluoride if aluminium is to be coated. Specification 865,497 is referred to. |
