| 摘要 |
<p>1. Process for preparing a black coating on at least one face of metal parts, in particular panels, this face being composed of pure zinc or zinc alloy, characterized in that a black coating based on copper and phosphate is formed by bringing the said face into contact, at a temperature of between room temperature and 75 degrees C and for a period of between 120 and 5 seconds, with an aqueous solution containing from 3 to 25 g/l of cupric ions, from 5 to 25 g/l of zinc ions, from 1 to 20 g/l of nickel ions, from 15 to 40 g/l of orthophosphoric ions and, where appropriate, anions not capable of forming insoluble salts with the abovementioned metal ions, the pH of the solution being between 1.6 and 3.0, and the part is cleaned after the end of the contact period.</p> |
