Phosphate conversion coating process and composition
AssigneeHenkel Kommanditgesellschaft auf Aktien
InventorMervet S. Boulos
Life of this patent
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Abstract
By including nitric acid and hydroxylamine in a manganese phosphating composition and controlling the ratio of nitric to phosphoric acids and the ratio of Total Acid to Free Acid within a specified range, satisfactory manganese phosphate conversion coatings can be obtained within a reasonable time at temperatures much lower than has previously been thought necessary for operating a manganese phosphating composition with no other metal cations (except possibly for iron).
Claims17
An aqueous liquid composition of matter that will form a conversion coating by spontaneous chemical reaction on a ferriferous substrate that is contacted with said liquid composition at a temperature that is not more than 80° C., said liquid composition comprising water and the following components:
- (A) dissolved divalent manganese cations at a concentration of at least about 0.40 g/l;
- (B) dissolved phosphate anions at a concentration of at least about 2 g/l;
- (C) dissolved nitrate anions;
- and
- (D) at least one dissolved source of hydroxylamine, at a stoichiometric equivalent concentration as hydroxylamine of all of the dissolved sources of hydroxylamine present in the composition of at least about 0.03 g/l;
- wherein the ratio by weight of nitrate anions to phosphate anions is from about 0.10:1.00 to 0.75:1.00;
- and the Free Acid content is from about 2.2 to about 15 points.
An aqueous liquid composition of matter that will form a conversion coating by spontaneous chemical reaction on a ferriferous substrate that is contacted with said liquid composition at a temperature that is not more than 800° C., said liquid composition having been made by mixing with water at least the following components:
- (A) a source of dissolved divialent manganese cations mixed in an amount sufficient to supply at least about 0.40 g/l of dissolved divalent manganese cations to the aqueous liquid composition;
- (B) a source of dissolved phosphate anions mixed in an amount sufficient to supply at least about 2 g/l of dissolved phosphate anions to the aqueous liquid composition;
- (C) a source of dissolved nitrate anions;
- and
- (D) at least one source of dissolved hydroxylamine mixed in an amount sufficient to supply a stoichiometric equivalent concentration as hydroxylamine that is at least about 0.03 g/l in the aqueous liquid composition;
- wherein the ratio by weight of the mass of nitrate anions supplied by the source thereof to the mass of phosphate anions supplied by the source thereof is from about 0.10:1.00 to 0.75:1.00;
- and the Free Acid content is from about 2.2 to about 15 points.
A make-up concentrate composition from which a conversion coating composition can be made by dilution with water only, said make-up concentrate composition comprising water and:
- (A′) a concentration of dissolved divalent manganese cations that is at least about 20 parts per thousand;
- (B′) a concentration of dissolved phosphate anions that is at least about 100 parts per thousand;
- (C′) a concentration of dissolved nitrate anions that is at least about 40 parts per thousand;
- (D′) a stoichiometric equivalent concentration as hydroxylamine that is at least about 1-0 parts per thousand;
- and
- (E′) a concentration of dissolved metal cations, other than manganese and iron, with a valence of two or more, that is no more than 1.0 percent.
A process of bonding a ferriferous substrate to a rubber substrate comprising the steps of:
- (A) contacting the ferriferous substrate with a liquid composition at a temperature that is not more than 80° C. comprising water and the following components:
- (1) dissolved divalent manganese cations at a concentration of at least about 1.00 g/l;
- (2) dissolved phosphate anions at a concentration of at least about 6 g/l;
- (3) dissolved nitrate anions;
- and
- (4) at least one dissolved source of hydroxylamine at a stoichiometric equivalent concentration as hydroxylamine of at least about 0.09 g/l;
- wherein the ratio by weight of nitrate anions to phosphate anions is from about 0.10:1.00 to 0.75:1.00, to form a conversion coating on the ferriferous substrate;
- and
- (B) adhering the rubber substrate to the ferriferous substrate having the conversion coating thereon using an adhesive.
Dependencies are inferred from the claim text.