US4713121A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Alkaline resistant phosphate conversion coatings
Assignee: Henkel Corp
•
Filing: 1987-01-20
•
Granted: 1987-12-15
•
Expires: 2007-01-20
Abstract
Abstract A method for increasing the resistance to alkaline dissolution of a phosphate conversion coating on a corrodible metal surface by an improved zinc phosphate conversion coating together with articles coated by this method are disclosed. The substrate is exposed to the phosphating solution by spraying or immersion to chemically effect a reaction with the substrate. First divalent metal cations are selected from magnesium and transition metals having a hydroxide with lower solubility in alkaline solution than zinc hydroxide. The other source of necessary metal cations is zinc and its cations are herein termed second divalent metal cations. In the preferred embodiment, the first divalent metal cations comprise about 84 to about 94 mole percent of the total first and second divalent metal cations in the bath. The deposited coating has first divalent metal cations (chemically combined with phosphate ions) present in an amount of at least 15 mole percent of the total first and second divalent metal cations in the coating.
Inventors
- 👤 Ronald W. Zurilla
- 👤 John Huff
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:42
CPC Classifications
C; C23; C23C; C23C22/00; C23C22/05; C23C22/06; C23C22/07; C23C22/08; C23C22/12
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
132 words
A method for increasing the resistance to alkaline dissolution of a phosphate conversion coating on a corrodible metal substrate, said coating being deposited by exposing said substrate to an acidic, aqueous solution containing first and second divalent metal cations and phosphate ions, the method comprising: (a) selecting cobalt cations as said first divalent metal cations; (b) selecting zinc cations as said second divalent metal cations; (c) maintaining a minimum zinc ion concentration in said solution of 0.2 grams per liter; and (d) controlling the concentrations of said first and said second divalent metal cations in said solution so that the concentration of said cobalt cations is maintained at the time of coating between about 65 and about 95 mole percent of the total first and second divalent metal cations in said solution.
Claim 2
Independent Claim
132 words
A method for increasing the resistance to alkaline dissolution of a phosphate conversion coating on a corrodible metal substrate, said coating being deposited by exposing said substrate to an acidic, aqueous solution containing first and second divalent metal cations and phosphate ions, the method comprising: (a) selecting cobalt cations as said first divalent metal cations; (b) selecting zinc cations as said second divalent metal cations; (c) maintaining a minimum zinc ion concentration in said solution of 0.2 grams per liter; and (d) controlling the concentrations of said first and said second divalent metal cations in said solution so that the concentration of said cobalt cations is maintained at the time of coating between about 65 and about 95 mole percent of the total first and second divalent metal cations in said solution.
Claim 3
Dependent Claim
43 words
A method in accordance with claim 1, wherein the concentration of said cobalt cations in said solution at the time of coating is maintained between about 75 and 94 mole percent of the total first and second divalent metal cations in said solution.
Claim 4
Dependent Claim
43 words
A method in accordance with claim 2, wherein the concentration of said cobalt cations in said solution at the time of coating is maintained between about 84 and 94 mole percent of the total first and second divalent metal cations in said solution.
Claim 5
Dependent Claim
13 words
A corrosion resistant coated metal object prepared by the method of claim 1.
Claim 6
Independent Claim
184 words
A method for increasing the resistance to alkaline dissolution of a phosphate conversion coating on a corrodible metal substrate, said coating being deposited by exposing said substrate to an acidic, aqueous solution containing first and second divalent metal cations and phosphate ions, the method comprising: (a) selecting cobalt cations as said first divalent metal cations; (b) selecting zinc cations as said second divalent metal cations; (c) maintaining a minimum zinc ion concentration in said solution of 0.2 grams per liter; (d) controlling the concentrations of said first and said second divalent metal cations in said solution so that the concentration of said cobalt cations is maintained at the time of coating between about 65 and about 95 mole percent of the total first and second divalent metal cations in said solution; and (e) maintaining the total acid content of said solution in the range of 10 to 40 points, maintaining the free acid content of said solution in the range of 0.5 to 2.0 points and maintaining the total acid to free acid ratio in said solution in the range of 10 to 60.
Claim 7
Independent Claim
184 words
A method for increasing the resistance to alkaline dissolution of a phosphate conversion coating on a corrodible metal substrate, said coating being deposited by exposing said substrate to an acidic, aqueous solution containing first and second divalent metal cations and phosphate ions, the method comprising: (a) selecting cobalt cations as said first divalent metal cations; (b) selecting zinc cations as said second divalent metal cations; (c) maintaining a minimum zinc ion concentration in said solution of 0.2 grams per liter; (d) controlling the concentrations of said first and said second divalent metal cations in said solution so that the concentration of said cobalt cations is maintained at the time of coating between about 65 and about 95 mole percent of the total first and second divalent metal cations in said solution; and (e) maintaining the total acid content of said solution in the range of 10 to 40 points, maintaining the free acid content of said solution in the range of 0.5 to 2.0 points and maintaining the total acid to free acid ratio in said solution in the range of 10 to 60.
Claim 8
Dependent Claim
43 words
A method in accordance with claim 5, wherein the concentration of said cobalt cations in said solution at the time of coating is maintained between about 75 and 94 mole percent of the total first and second divalent metal cations in said solution.
Claim 9
Dependent Claim
43 words
A method in accordance with claim 6, wherein the concentration of said cobalt cations in said solution at the time of coating is maintained between about 84 and 94 mole percent of the total first and second divalent metal cations in said solution.
Claim 10
Dependent Claim
13 words
A corrosion resistant coated metal object prepared by the method of claim 5.
Claim 11
Dependent Claim
118 words
A corrosion-resistant, coated metal object having a metal substrate and a continuous phosphate conversion coating deposited thereon comprising a mixed metal phosphate containing at least one first divalent metal element and a second divalent metal element, the cations of which are chemically combined with phosphate ions, wherein said coating is further characterized in that: (a) about 15.0 to about 43.0 mole percent of the total first and second divalent metal cations in the deposited coating are first divalent metal cations consisting essentially of cobalt cations; (b) the second divalent metal element is zinc; and (c) about 85.0 to about 57.0 mole percent of the total first and second divalent metal cations in the deposited coating are zinc cations.
Claim 12
Dependent Claim
118 words
A corrosion-resistant, coated metal object having a metal substrate and a continuous phosphate conversion coating deposited thereon comprising a mixed metal phosphate containing at least one first divalent metal element and a second divalent metal element, the cations of which are chemically combined with phosphate ions, wherein said coating is further characterized in that: (a) about 15.0 to about 43.0 mole percent of the total first and second divalent metal cations in the deposited coating are first divalent metal cations consisting essentially of cobalt cations; (b) the second divalent metal element is zinc; and (c) about 85.0 to about 57.0 mole percent of the total first and second divalent metal cations in the deposited coating are zinc cations.
Claim 13
Dependent Claim
103 words
A corrosion-resistant, coated metal object having a metal substrate and a continuous phosphate conversion coating deposited thereon comprising a mixed metal phosphate containing zinc and at least one first divalent metal element, the cations of which are chemically combined with phosphate ions, wherein said coating is further characterized that: (a) about 15.0 to about 43.0 mole percent of the total zinc/first divalent metal cations in the deposited coating, exclusive of incidental cations from the substrate, are first divalent metal cations consisting essentially of cobalt cations; and (b) the remainder of divalent metal cations in the deposited coating is comprised predominantly of zinc cations.
Claim 14
Dependent Claim
103 words
A corrosion-resistant, coated metal object having a metal substrate and a continuous phosphate conversion coating deposited thereon comprising a mixed metal phosphate containing zinc and at least one first divalent metal element, the cations of which are chemically combined with phosphate ions, wherein said coating is further characterized that: (a) about 15.0 to about 43.0 mole percent of the total zinc/first divalent metal cations in the deposited coating, exclusive of incidental cations from the substrate, are first divalent metal cations consisting essentially of cobalt cations; and (b) the remainder of divalent metal cations in the deposited coating is comprised predominantly of zinc cations.
Claim 15
Dependent Claim
67 words
An aqueous concentrate for use in an aqueous solution for depositing a zinc phosphate conversion coating comprising water, phosphate ions, zinc cations and cobalt cations and further characterized in that said concentrate contains said cobalt cations and said zinc cations in the mole ratio range of about 5.2:1 to about 16:1 and said zinc cations are present in a concentration in excess of 0.2 grams per liter.
Claim 16
Dependent Claim
67 words
An aqueous concentrate for use in an aqueous solution for depositing a zinc phosphate conversion coating comprising water, phosphate ions, zinc cations and cobalt cations and further characterized in that said concentrate contains said cobalt cations and said zinc cations in the mole ratio range of about 5.2:1 to about 16:1 and said zinc cations are present in a concentration in excess of 0.2 grams per liter.
Claim 17
Dependent Claim
20 words
An aqueous concentrate in accordance with claim 11, wherein a portion of said phosphate ions are replaced with nitrate ions.
Claim 18
Dependent Claim
20 words
An aqueous concentrate in accordance with claim 11, wherein a portion of said phosphate ions are replaced with nitrate ions.
References Cited (Backward Citations)
US2554139A
Cited
US3810792A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-12-14 | 1991-06-15 | 1991-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-12-14 | 1995-06-15 | 1995-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-12-14 | 1999-06-15 | 1999-12-15 | $7700.00 | Window Closed / Lapsed |