Patent ID: 6558480
Filing Date: 2003-05-06
Classification: C23C

Abstract:
An aqueous liquid composition suitable, optionally after dilution with water, for forming a colorless transparent conversion coating on a metal substrate, said liquid composition comprising water and the following components:(A) a component of one or more dissolved transition metal compounds that contains zirconium and may also include titanium, said component comprising at least about 0.25 mM/l of total zirconium and titanium atoms, provided that zirconium constitutes more than 30% of the moles of the total moles of zirconium and titanium; (B) a component of at least one dissolved compound that contains inorganically bonded fluorine and is not part of component (A), such that the molar ratio of fluorine atoms to the total of zirconium and titanium atoms is at least 6.05:1:00 and a fluoride sensitive electrode in contact with the composition has a potential that is from about âˆ’200 to about 100 mv when compared with the same fluoride sensitive electrode in contact with Standard Solution 120 MC; and (C) a component of dissolved organic polymer molecules, wherein component (C) constitutes at least about 0.009 g/l of the composition and contains at least one of: a sufficient number of acid moieties that the number ratio of acid moieties to total carbon atoms within component (C) is at least about 1.0:9.0; and a sufficient number of nucleophilic moieties that the number ratio of nucleophilic moieties to total carbon atoms within component (C) is at least about 1.0:50.