Verfahren zum Erzeugen besonders reiner Eisen- und Stahloberflaechen

摘要

1,129,824. Pickling and passivating iron and steel. FARBWERKE HOECHST, A.G. Feb.17, 1966. [Feb.17,1965] No. 7016/66. Headings C7E and C7U. Iron and steel surfaces are cleaned by (a) alkaline degreasing (b) acid pickling (c) neutralizing (d) pickling and (e) passivating. A hydroxyethylated polyoxypropylene compound of M.W. 1900- 3,100 and containing 60-90% of polyoxypropylene is incorporated in acid pickling solution (b). The steps (c) and (d) may be combined by using a single solution of pH 7-9 containing one or more condensed phosphates e.g. pentasodium tripolyphosphate and tetrasodium pyrophosphate. The preferred concentration of hydroxyethylated polyoxypropylene in solution (b) is not less than 0À03 g.p.l. The passivating step (e) may be effected with a solution of sodium nitrite.