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US3642541A
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Method for applying corrosion-resistant composite coating to ferrous metals and product resulting therefrom
Assignee: Republic Steel Corp
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Filing: 1969-02-12
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Granted: 1972-02-15
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Expires: 1989-02-12
Abstract
Abstract A method for the manufacture of a corrosion-resistant aluminum metal-coated ferrous product and particularly a product composed of a zinc-coated ferrous metal substrate having superimposed thereon a coating of aluminum metal. The product prepared therefrom is characterized by having an intermediate layer of phosphate crystals of a minimum thickness sufficient to prevent interaction between the zinc undercoating on the ferrous metal substrate and water passing through the superimposed aluminum metal surface coating. The interposing layer of phosphate crystals has a critical maximum thickness such that not more than 100 milligrams of phosphate crystals is distributed over each square foot of surface area of the zinc ferrous metal substrate. Optimally, the interposing crystalline phosphate layer has a thickness such that 10 to 30 milligrams of phosphate crystals are distributed over each square foot of zinc ferrous metal substrate. The method of applying the said corrosion-resistant aluminum coating to the zinc ferrous metal substrate comprises: (a) contacting said zinc-coated ferrous metal substrate with a solution containing phosphate ion for about 2 to 15 seconds at a processing temperature of about 70* to 100* F. and (b) subsequently applying thereto a superimposed overcoat of an aluminum metal and bonding the composite coatings and substrate into a corrosion-resistant product.
Inventors
- 👤 George A Shepard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 21:32
CPC Classifications
C; C23; C23C; C23C28/00; C23C22/00; C23C22/05; C23C22/06; C23C22/07; C23C22/08; C23C22/12; Y; Y10; Y10T; Y10T428/00; Y10T428/12; Y10T428/12493; Y10T428/12535; Y10T428/12583; Y10T428/27; Y10T428/273
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
27 words
A method for applying a corrosion-resistant composite coating to a ferrous metal substrate according to claim 1 wherein the crystalline phosphate layer deposited is of zinc phosphate.
Claim 2
Dependent Claim
18 words
A method according to claim 1 wherein the surface coating applied in (b) is an aluminum metal coating.
Claim 3
Dependent Claim
52 words
A method for applying a corrosion-resistant composite coating to a ferrous metal substrate according to claim 1 which comprises contacting the zinc-coated ferrous metal substrate with a phosphating solutiOn for a period of from about 2 to about 15 seconds at a processing temperature of from about 70* to about 130* F.
Claim 4
Dependent Claim
41 words
A method for applying a corrosion-resistant composite coating to a ferrous metal substrate according to claim 1 which comprises contacting the substrate with a phosphating solution for a period of about 8 seconds at a processing temperature of about 75* F.
Claim 5
Dependent Claim
34 words
A method according to claim 1 wherein said crystalline phosphate layer contains from about 10 to about 30 milligrams of phosphate crystals distributed over each square foot of surface area of the substrate treated.
Claim 6
Dependent Claim
33 words
A method for applying a corrosion-resistant composite coating to a ferrous metal substrate according to claim 1 wherein the surface coating of a metal applied in step (b) is applied by vapor deposition.
Claim 7
Dependent Claim
15 words
A method according to claim 7 wherein the metal which is vapor deposited is aluminum.
Claim 8
Dependent Claim
22 words
A method according to claim 8 wherein the aluminum coating applied as a surface coating has a thickness of about 50 microinches.
Claim 9
Independent Claim
145 words
A method for application of a corrosion-resistant phosphate crystal coating to a zinc metal substrate which comprises: a. applying to the surface of the zinc metal an aqueous phosphating solution comprising free phosphoric acid and a soluble metallic phosphate salt: b. maintaining the zinc metal substrate in contact with the aqueous phosphating solution for a sufficient period of time to cause the phosphoric acid to react with the zinc substrate to form an excess of zinc phosphate which precipitates out of solution as a corrosion-resistant phosphate crystal coating on the zinc metal base such that no more than about 100 milligrams per square foot of phosphate crystals are precipitated out of solution on the zinc metal base; and c. applying thereto a surface coating of at least one metal selected from the class consisting of aluminum, copper, brass, titanium, zinc, chromium, steel and alloys thereof.
Claim 10
Dependent Claim
99 words
A corrosion-resistant composite coated ferrous metal product having interposed between a zinc-treated ferrous metal substrate and a metal overlay coating a layer of phosphate crystals of sufficient minimum thickness to inhibit corrosive interaction between the zinc layer of the substrate and water penetrating through the metal overlay and a maximum thickness such that not more than about 100 milligrams of phosphate crystals is uniformly distributed over each square foot of zinc-coated ferrous substrate, wherein said metal overlay coating comprises at least one metal selected from the class consisting of aluminum, copper, brass, titanium, zinc, chromium, steel and alloys thereof.
Claim 11
Dependent Claim
19 words
A corrosion-resistant composite coated ferrous metal product according to claim 11 wherein the metal overlay is of aluminum metal.
Claim 12
Dependent Claim
22 words
A corrosion-resistant composite coated ferrous metal product according to claim 11 wherein the phosphate crystal layer is composed of zinc phosphate crystals.
Claim 13
Dependent Claim
49 words
A corrosion-resistant composite coated ferrous metal product according to claim 11 wherein the layer of phosphate crystals thereon has a uniform thickness such that from about 10 to about 30 milligrams of phosphate crystals is distributed over each square foot of surface area of the zinc-coated ferrous metal substrate.
Claim 14
Dependent Claim
46 words
A corrosion-resistant composite coated ferrous metal product according to claim 14 wherein the layer of phosphate crystals thereon has a uniform thickness such that about 20 milligrams of phosphate crystals is distributed over each square foot of the surface area of the zinc-coated ferrous metal substrate.
Claim 15
Dependent Claim
111 words
A corrosion-resistant aluminum-zinc metal composite coated ferrous metal product comprising: a. a steel substrate of sufficient thickness to support a plurality of coatings; b. a zinc layer deposited thereon which comprises from about 15 to about 300 microinches of zinc; c. deposited on the surfacE of the zinc layer and beneath the aluminum overcoat of (d) a layer of phosphate crystals having an approximate thickness of from about 10 to about 100 milligrams uniformly distributed over each square foot of the zinc substrate; and d. an aluminum overcoat superimposed on the phosphate crystal layer wherein the aluminum metal has an approximate thickness extending from about 5 to about 100 microinches. C
Claim 16
Dependent Claim
62 words
A coating method comprising applying to the surface of a zinc substrate a coating of phosphate crystals of no more than about 100 milligrams of crystals per square foot of substrate, and applying over the coating of phosphate crystals a coating of at least one metal selected from the class consisting of aluminum, copper, brass, titanium, zinc, chromium, steel and alloys thereof.
Claim 17
Dependent Claim
27 words
A coating method according to claim 17, in which there is applied from about 10 to about 30 milligrams of phosphate crystals per square foot of substrate.
Claim 18
Dependent Claim
54 words
A zinc-coated article, comprising a zinc substrate coated with phosphate crystals of no more than about 100 milligrams of crystals per square foot of substrate, and an overcoat over the phosphate crystal layer of at least one metal selected from the class consisting of aluminum, copper, brass, titanium, zinc, chromium, steel and alloys thereof.
Claim 19
Dependent Claim
26 words
A zinc-coated article according to claim 19, in which there are from about 10 to about 30 milligram of phosphate crystals per square foot of substrate.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |