| 摘要 |
<p>Title: TREATMENT OF METAL SURFACES WITH TRIVALENT CHROMIUM SOLUTIONS Inventor: Donald Edward Wells Conversion coatings are produced on ferrous metal or galvanized surfaces by treatment with an aqueous solution of a trivalent chromium compound. The solution is preferably formed by the reduction of a hexavalent chromium solution with an alkali metal sulfite or bisulfite. The temperature of the metal treatment is substantially lower than is required to produce an iron phosphate coating, and the absence of hexavalent chromium results in a substantial decrease in pollutants in the effluent. The conversion coating obtained is usually deep blue in color and improves paint adhesion of the treated surface and corrosion resistance, especially under paint and other, siccative organic coatings.</p> |
