Metal (pre)treatment, used for wire, strip, sheet or part, including tube, profile or small part, uses aqueous composition containing water-soluble, hydrolysable or/and (partly) hydrolyzed fluorine-free silane and fluorosilane compounds

摘要

In (pre)treating metal surface with aqueous composition (I), (almost) free from chromium(VI) compounds, (I) contains fluorine-free silane(s) and fluorosilane(s), which are hydrolysable or/and (partly) hydrolyzed and are or become water-soluble before application. (I) is contacted with the clean(ed), pickled or/and pretreated metal surface and resultant film is dried and optionally hardened, giving 0.001-10 micron thick film. In coating a metal surface with an aqueous composition (I), optionally containing organic solvent and other components but largely or completely free from chromium(VI) compounds, for pretreatment before further coating or for treatment, (I) contains hydrolysable or/and (partly) hydrolyzed fluorine-free silane(s) (II) and hydrolysable or/and (partly) hydrolyzed fluorosilane(s) (III), which are water-soluble or especially become water-soluble by (further) hydrolysis or/and chemical reactions before application to the metal surface. (I) is contacted with the clean, pickled, cleaned or/and pretreated metal surface and forms a film on this, which is then dried and optionally hardened, giving a 0.001-10 micron thick film. An independent claim is also included for (I) for the cited purposes, in which the ratio of (II) to (III), including their reaction products, is 1:(0.01-4).