CA2425213C - Method for selective control of corrosion using kinetic spraying - Google Patents
Method for selective control of corrosion using kinetic spraying Download PDFInfo
- Publication number
- CA2425213C CA2425213C CA002425213A CA2425213A CA2425213C CA 2425213 C CA2425213 C CA 2425213C CA 002425213 A CA002425213 A CA 002425213A CA 2425213 A CA2425213 A CA 2425213A CA 2425213 C CA2425213 C CA 2425213C
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- Prior art keywords
- surface portion
- protective coating
- metal sheet
- metal
- corrosion
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Links
- 238000000034 method Methods 0.000 title claims abstract description 54
- 230000007797 corrosion Effects 0.000 title claims abstract description 52
- 238000005260 corrosion Methods 0.000 title claims abstract description 52
- 238000005507 spraying Methods 0.000 title description 7
- 229910052751 metal Inorganic materials 0.000 claims abstract description 92
- 239000002184 metal Substances 0.000 claims abstract description 92
- 239000011253 protective coating Substances 0.000 claims abstract description 48
- 238000007788 roughening Methods 0.000 claims abstract description 11
- 230000002708 enhancing effect Effects 0.000 claims abstract description 7
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims description 28
- 229910052725 zinc Inorganic materials 0.000 claims description 28
- 239000011701 zinc Substances 0.000 claims description 28
- 238000000576 coating method Methods 0.000 claims description 20
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- 239000011248 coating agent Substances 0.000 claims description 15
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- 229910001297 Zn alloy Inorganic materials 0.000 claims description 12
- 239000002828 fuel tank Substances 0.000 claims description 11
- 239000002923 metal particle Substances 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 8
- 229910052782 aluminium Inorganic materials 0.000 claims description 7
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 7
- 239000007787 solid Substances 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 claims description 3
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052749 magnesium Inorganic materials 0.000 claims description 3
- 239000011777 magnesium Substances 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 3
- 229910000838 Al alloy Inorganic materials 0.000 claims description 2
- 229910000640 Fe alloy Inorganic materials 0.000 claims 1
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- 238000005452 bending Methods 0.000 claims 1
- 230000000873 masking effect Effects 0.000 claims 1
- 239000000843 powder Substances 0.000 description 25
- 239000007789 gas Substances 0.000 description 18
- 238000005246 galvanizing Methods 0.000 description 17
- 239000002245 particle Substances 0.000 description 17
- 230000008569 process Effects 0.000 description 15
- 239000010410 layer Substances 0.000 description 13
- 239000007921 spray Substances 0.000 description 9
- 239000000758 substrate Substances 0.000 description 9
- 239000003380 propellant Substances 0.000 description 8
- 239000000463 material Substances 0.000 description 6
- 239000000446 fuel Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 4
- 229910045601 alloy Inorganic materials 0.000 description 4
- 239000000956 alloy Substances 0.000 description 4
- 239000010953 base metal Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- 238000005422 blasting Methods 0.000 description 3
- 239000001307 helium Substances 0.000 description 3
- 229910052734 helium Inorganic materials 0.000 description 3
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 3
- 230000001965 increasing effect Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000011133 lead Substances 0.000 description 3
- 239000011241 protective layer Substances 0.000 description 3
- 230000000153 supplemental effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- 239000004593 Epoxy Substances 0.000 description 2
- CWYNVVGOOAEACU-UHFFFAOYSA-N Fe2+ Chemical compound [Fe+2] CWYNVVGOOAEACU-UHFFFAOYSA-N 0.000 description 2
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 2
- 229910007567 Zn-Ni Inorganic materials 0.000 description 2
- 229910007614 Zn—Ni Inorganic materials 0.000 description 2
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- 229910052802 copper Inorganic materials 0.000 description 2
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- 238000007598 dipping method Methods 0.000 description 2
- 238000003754 machining Methods 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 238000010422 painting Methods 0.000 description 2
- 238000002360 preparation method Methods 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000001681 protective effect Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 229910052718 tin Inorganic materials 0.000 description 2
- 239000011135 tin Substances 0.000 description 2
- 238000011282 treatment Methods 0.000 description 2
- 229910001335 Galvanized steel Inorganic materials 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 238000002679 ablation Methods 0.000 description 1
- 239000003082 abrasive agent Substances 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000001464 adherent effect Effects 0.000 description 1
- 239000003570 air Substances 0.000 description 1
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- 238000002048 anodisation reaction Methods 0.000 description 1
- 230000003190 augmentative effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052793 cadmium Inorganic materials 0.000 description 1
- BDOSMKKIYDKNTQ-UHFFFAOYSA-N cadmium atom Chemical compound [Cd] BDOSMKKIYDKNTQ-UHFFFAOYSA-N 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
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- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
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- 230000001419 dependent effect Effects 0.000 description 1
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- 238000009826 distribution Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000008397 galvanized steel Substances 0.000 description 1
- 238000005244 galvannealing Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 238000007749 high velocity oxygen fuel spraying Methods 0.000 description 1
- 230000003116 impacting effect Effects 0.000 description 1
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 1
- 238000005304 joining Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 238000009740 moulding (composite fabrication) Methods 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 238000002161 passivation Methods 0.000 description 1
- 239000012255 powdered metal Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000002910 solid waste Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000012855 volatile organic compound Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/26—After-treatment
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C2/00—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor
- C23C2/04—Hot-dipping or immersion processes for applying the coating material in the molten state without affecting the shape; Apparatus therefor characterised by the coating material
- C23C2/06—Zinc or cadmium or alloys based thereon
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C24/00—Coating starting from inorganic powder
- C23C24/02—Coating starting from inorganic powder by application of pressure only
- C23C24/04—Impact or kinetic deposition of particles
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C28/00—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D
- C23C28/02—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material
- C23C28/023—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only
- C23C28/025—Coating for obtaining at least two superposed coatings either by methods not provided for in a single one of groups C23C2/00 - C23C26/00 or by combinations of methods provided for in subclasses C23C and C25C or C25D only coatings only including layers of metallic material only coatings of metal elements only with at least one zinc-based layer
Abstract
The present invention related to methods for selectively enhancing corrosion protection of fabricated metal parts. One method of the present invention includes providing a non-galvanized metal sheet to be processed to form the fabricated metal part; selecting a localized region on the non-galvanized metal sheet; roughening the localized region for acceptance of a protective coating; applying a protective coating to localized region; and fabricating the non-galvanized metal sheet into a fabricated metal part. Another method includes providing a galvanized metal sheet; selecting a localized region on the galvanized metal sheet; applying a protective coating to the localized region; and fabricating the galvanized metal sheet into a fabricated metal part. Yet another method includes selecting a localized region on a fabricated metal part; roughening the localized region for acceptance of a protective coating; and applying the protective coating to the localized region.
Description
'_MC 1426 PUS
METHOD FOR SELECTIVE CONTROL OF
CORROSION USING KINETIC SPRAYING
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to selective:Ly enhancing corrosion protection of fabricated metal structures and, more particularly, to methods of app:Lying a protective coating to metal parts using kinetic spraying.
METHOD FOR SELECTIVE CONTROL OF
CORROSION USING KINETIC SPRAYING
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to selective:Ly enhancing corrosion protection of fabricated metal structures and, more particularly, to methods of app:Lying a protective coating to metal parts using kinetic spraying.
2. Background Art "Galvanizing" refers to a broad category of surface coating processes wherein zinc or zinc-rich alloys are deposited on the surfaces of steel sheets or fabricated metal parts. In the automotive industry, as well as other industries, the use of galvanizing for corrosion prot:ection of steel is ubiquitous. The International Zinc Association estimates that worldwide annual usage of zinc for thi.s purpose exceeds 3 million metric tons. Coils of steel, for example, are frequently provided with galvanized coatings through processes such as hot dipping, electro-galvar.iizing or galvannealing. Such coil-coated steel is subsequently formed into products such as automobile bodies, architectural materials and other products for commex=cial and household use. The coil-coated steel can be further finished by additional treatments that include phosphating electrophoretic coatings.
Even with the application of galvanic protective coatings to steel, corrosion may still occur, particularly in localized regions where the mechanical integrity cf the coatings may be compromised by such processes as joining, cutting, forming or any other manufacturing process which may diminish the capability of protective layers to provide protection to the steel sheet. Hence, to compensate for these potential deficiencies produced during the manufacturing of the galvanized metal parts, post processes, such as painting or phosphating have been utilized.
Fabricated metal parts suffer from corrosion resistance problems as well. For example, metal fuel. tanks have extremely high corrosion reliability requirement.s.
Currently, only metal fuel tanks are capable of meeting the most stringent regulatory requirements for low emission vehicles. Corrosion of metal fuel tanks, however, is a critical concern since a single pit can lead to fuel leakage and attendant system failure. Current practice for corrosion prevent:ion of steel fuel tanks involves use of electro-galvanized (e.g., Zn-Ni alloy) sheet steel as the base metal, combined with an aluminum-rich, epoxy paint. At the tank seam element as well as attachment points for inlets and fuel pump, the corrosion performance can be diminished due to possible inherent defects associated with the manufacture of the tank.
There exists a need in the automotive industry, as well as other industries, for a simple, low-cost method for selectively applying a protective coating to metal parts for corrosion resistance of localized regions that may or may not have an existing protective coating. This type of method would be especially advantageous where an oriclinal coating protection has been compromised by various manufacturing processes such as cutting or welding.
Furthermore, there is a need to provide for enhanced corrosion protection at localized regions of fabricated metal structures that may or may not have an existincr protective coating.
SUMMARY OF THE INVENTION
The present invention is related to methodro for selectively enhancing corrosion protection of fabricated metal parts.
One preferred method of the present invention involves selectively enhancing corrosion protection of a fabricated metal part. The preferred method includes providing a non-galvanized metal sheet to be processed to form a fabricated metal part; selecting a localized region on the non-galvanized metal sheet; roughening the localized region for acceptance of a protective coating; apply_Lng a protective coating to the localized region; and fabr:Lcating the non-galvanized metal sheet into a fabricated metal part.
If not treated with the protective coating, the localized region becomes a post-fabricated area part:Lcularly susceptible to corrosion. Upon applying the protective coating to the localized region, the post-fabricated area is particularly resistant to corrosion. The protective coating is applied by a device capable of impact fusion of solid metal particles. The corrosion protection of the poSt-fabricated area is enhanced by the selectively deposited protective coating. The protective coating may be a galvanized coating. However, non-galvanized coatings can be utilized as long as corrosion resistance is enhanced (viz.
oxidative or high temperature corrosion protection).
In another preferred embodiment, a method includes providing a galvanized metal sheet to be processed to form a fabricated metal part; selecting a localized region on the galvanized metal sheet; applying a supplemental galvanized coating to the localized region; and fabricating the galvanized metal sheet into the fabricated metal part. The application of the galvanizing coating forms a galvariic layer on the surface of the prefabricated metal sheet:. If not treated with the supplemental galvanized coating, the localized region becomes a post-fabricated area particularly susceptible to corrosion. Upon applying the supplemental galvanic coating to the localized region, the post-fabricated area is particularly resistant to corrosion. The corrosion protection of the post-fabricated area is enhanced due to the selective application of the galvanic coating.
The galvanized coating is applied by a device capable of impact fusion of solid metal particles.
One preferred method includes selecting a localized region on a fabricated metal part; roughening the localized region for acceptance of a protective coating; and applying a protective coating to the localized region. The protective coating is applied by a device capable of impact fusion. According to this method, the fabricated met:al part is treated. For example, an element on a fuel tank seam may lack corrosion protection. The method contemplated enhances or restores corrosion protection to the localized reqion defined by the weldment.
These and other advantages, features, and objects of the present invention will become more apparent to those of ordinary skill in the art upon reference to the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 depicts an application of a protective coating on a metal sheet using impact fusion;
Figure 2 is a schematic representative of a cold gas dynamic spray system;
Even with the application of galvanic protective coatings to steel, corrosion may still occur, particularly in localized regions where the mechanical integrity cf the coatings may be compromised by such processes as joining, cutting, forming or any other manufacturing process which may diminish the capability of protective layers to provide protection to the steel sheet. Hence, to compensate for these potential deficiencies produced during the manufacturing of the galvanized metal parts, post processes, such as painting or phosphating have been utilized.
Fabricated metal parts suffer from corrosion resistance problems as well. For example, metal fuel. tanks have extremely high corrosion reliability requirement.s.
Currently, only metal fuel tanks are capable of meeting the most stringent regulatory requirements for low emission vehicles. Corrosion of metal fuel tanks, however, is a critical concern since a single pit can lead to fuel leakage and attendant system failure. Current practice for corrosion prevent:ion of steel fuel tanks involves use of electro-galvanized (e.g., Zn-Ni alloy) sheet steel as the base metal, combined with an aluminum-rich, epoxy paint. At the tank seam element as well as attachment points for inlets and fuel pump, the corrosion performance can be diminished due to possible inherent defects associated with the manufacture of the tank.
There exists a need in the automotive industry, as well as other industries, for a simple, low-cost method for selectively applying a protective coating to metal parts for corrosion resistance of localized regions that may or may not have an existing protective coating. This type of method would be especially advantageous where an oriclinal coating protection has been compromised by various manufacturing processes such as cutting or welding.
Furthermore, there is a need to provide for enhanced corrosion protection at localized regions of fabricated metal structures that may or may not have an existincr protective coating.
SUMMARY OF THE INVENTION
The present invention is related to methodro for selectively enhancing corrosion protection of fabricated metal parts.
One preferred method of the present invention involves selectively enhancing corrosion protection of a fabricated metal part. The preferred method includes providing a non-galvanized metal sheet to be processed to form a fabricated metal part; selecting a localized region on the non-galvanized metal sheet; roughening the localized region for acceptance of a protective coating; apply_Lng a protective coating to the localized region; and fabr:Lcating the non-galvanized metal sheet into a fabricated metal part.
If not treated with the protective coating, the localized region becomes a post-fabricated area part:Lcularly susceptible to corrosion. Upon applying the protective coating to the localized region, the post-fabricated area is particularly resistant to corrosion. The protective coating is applied by a device capable of impact fusion of solid metal particles. The corrosion protection of the poSt-fabricated area is enhanced by the selectively deposited protective coating. The protective coating may be a galvanized coating. However, non-galvanized coatings can be utilized as long as corrosion resistance is enhanced (viz.
oxidative or high temperature corrosion protection).
In another preferred embodiment, a method includes providing a galvanized metal sheet to be processed to form a fabricated metal part; selecting a localized region on the galvanized metal sheet; applying a supplemental galvanized coating to the localized region; and fabricating the galvanized metal sheet into the fabricated metal part. The application of the galvanizing coating forms a galvariic layer on the surface of the prefabricated metal sheet:. If not treated with the supplemental galvanized coating, the localized region becomes a post-fabricated area particularly susceptible to corrosion. Upon applying the supplemental galvanic coating to the localized region, the post-fabricated area is particularly resistant to corrosion. The corrosion protection of the post-fabricated area is enhanced due to the selective application of the galvanic coating.
The galvanized coating is applied by a device capable of impact fusion of solid metal particles.
One preferred method includes selecting a localized region on a fabricated metal part; roughening the localized region for acceptance of a protective coating; and applying a protective coating to the localized region. The protective coating is applied by a device capable of impact fusion. According to this method, the fabricated met:al part is treated. For example, an element on a fuel tank seam may lack corrosion protection. The method contemplated enhances or restores corrosion protection to the localized reqion defined by the weldment.
These and other advantages, features, and objects of the present invention will become more apparent to those of ordinary skill in the art upon reference to the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 depicts an application of a protective coating on a metal sheet using impact fusion;
Figure 2 is a schematic representative of a cold gas dynamic spray system;
Figure 3 depicts an application of a protective coating on a metal sheet using a high-velocity, gas-clynamic nozzle;
Figure 4 depicts in cross-section a hem joint formed between two panels with a protective coating applied to each panel before forming the joint;
Figure 5 depicts in cross-section a hem joint formed between two panels with a protective coating applied to each panel with an additional fillet before forming the joint; and Figure 6 depicts an application of a protective coating to a weldment on a fuel tank seam.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) In accordance with the present invention, protective coatings are applied to localized regions of metal sheets or fabricated metal parts. The applicat:ion device is capable of impact fusion.
Figure 1 illustrates a process of applying a protective coating 2 with a device capable of impact fusion onto a metal surface. Zinc-rich galvanized layer 6 is formed on a surface of steel substrate 4 by any conventional means such as hot dipping or electro-galvanizing.
Kinetically accelerated zinc (or zinc alloy) particles 8 impact on the galvanized layer 6, and form the protective coating 2 through a repetitive process of ballistic impaction and self-adherence or "impact fusion". Zinc particles 8 readily adhere to the zinc already present in the galvanized pre-coating, as well as to zinc particles which have already impacted and adhered to this surface.
For any given powder metal, there exists a critical particle velocity at which particles accumu=Late on substrate 4 at a rate greater than which they are renioved by ablation due to the incoming stream. Principal paranieters contributing to the critical particle velocity for a given powder metal. are: (1) powder metal type, (2) powder nletal crystal and micro-structure, (3) substrate type, (4) substrate surface finish, (5) powder size distribution, (6) propellant gas type, (7) propellant gas velocity determined by the pressure and temperature of the propellant gas entering the kinetic spray system, (8) converging/diverging nozzle internal shape, and (9) nozzle standoff distance from the substrate surface.
In the case of spraying of zinc-based powders on galvanized or welded steel, the condition of substrate 4 may reflect either the preexisting zinc alloy layer from the galvanizing process, or a metallic surface as would exist following weldment by resistance, laser fusion, or other process.
In the case of either bare steel or pre-we:Lded zones to be coated by selective galvanizing, the surface is preferably prepared to remove poorly adherent oxide films or debris from the welding process, thereby permitting accumulation of the zinc or zinc-alloy spray by direct attachment to the base metal. A variety of surface preparation techniques for this purpose are well known in the thermal-spray art, including grit blasting with abrasive particles, water-jet blasting either with pure water or suspended abrasives, blasting with solid CO2 particles, electro-discharge machining, plasma discharge roughening, machining and coining. The preferred method of the present invention for surface roughening of pre-welded or ba:re steel surfaces for protection with zinc, is roughening with focused jets of abrasive particles or water jets.
Figure 4 depicts in cross-section a hem joint formed between two panels with a protective coating applied to each panel before forming the joint;
Figure 5 depicts in cross-section a hem joint formed between two panels with a protective coating applied to each panel with an additional fillet before forming the joint; and Figure 6 depicts an application of a protective coating to a weldment on a fuel tank seam.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S) In accordance with the present invention, protective coatings are applied to localized regions of metal sheets or fabricated metal parts. The applicat:ion device is capable of impact fusion.
Figure 1 illustrates a process of applying a protective coating 2 with a device capable of impact fusion onto a metal surface. Zinc-rich galvanized layer 6 is formed on a surface of steel substrate 4 by any conventional means such as hot dipping or electro-galvanizing.
Kinetically accelerated zinc (or zinc alloy) particles 8 impact on the galvanized layer 6, and form the protective coating 2 through a repetitive process of ballistic impaction and self-adherence or "impact fusion". Zinc particles 8 readily adhere to the zinc already present in the galvanized pre-coating, as well as to zinc particles which have already impacted and adhered to this surface.
For any given powder metal, there exists a critical particle velocity at which particles accumu=Late on substrate 4 at a rate greater than which they are renioved by ablation due to the incoming stream. Principal paranieters contributing to the critical particle velocity for a given powder metal. are: (1) powder metal type, (2) powder nletal crystal and micro-structure, (3) substrate type, (4) substrate surface finish, (5) powder size distribution, (6) propellant gas type, (7) propellant gas velocity determined by the pressure and temperature of the propellant gas entering the kinetic spray system, (8) converging/diverging nozzle internal shape, and (9) nozzle standoff distance from the substrate surface.
In the case of spraying of zinc-based powders on galvanized or welded steel, the condition of substrate 4 may reflect either the preexisting zinc alloy layer from the galvanizing process, or a metallic surface as would exist following weldment by resistance, laser fusion, or other process.
In the case of either bare steel or pre-we:Lded zones to be coated by selective galvanizing, the surface is preferably prepared to remove poorly adherent oxide films or debris from the welding process, thereby permitting accumulation of the zinc or zinc-alloy spray by direct attachment to the base metal. A variety of surface preparation techniques for this purpose are well known in the thermal-spray art, including grit blasting with abrasive particles, water-jet blasting either with pure water or suspended abrasives, blasting with solid CO2 particles, electro-discharge machining, plasma discharge roughening, machining and coining. The preferred method of the present invention for surface roughening of pre-welded or ba:re steel surfaces for protection with zinc, is roughening with focused jets of abrasive particles or water jets.
In the case of the preexisting zinc alloy layer, the remnant galvanizing zinc alloy layer is sufficieritly compliant to permit a ready development of the impact-fusion protective layer without additional surface modificat:ion.
In the case of selectively supplanting preexisting galvanized layers with zinc or zinc alloy powders, or for addition of zinc to pre-roughened surfaces, the conditions which promote formation of zinc-rich surfaces are: (:_) zinc or zinc-alloy powder of at least 70% by weight zinc, with typical alloying additions of aluminum, copper, magnesium, iron, lead, cadmium, tin or nickel, (2) particle powder size in the range of 5-50 cnicrons; (3) for helium as a propellant, gas pressure in the range 100-300 psi, gas preheat temperature in the range of 150-4000'C, particle velocities in the range of from 350-650 m/sec., (4) for air or nitrogen propellant, gas pressure in the range 100-450 psi, gas temperatures in the range of 170-5000-C, particle velocities in the range of 350-650 m/sec.
According to one embodiment of the present invention, a high-velocity, gas-dynamic spray system is utilized to apply the protective coating to the loca:Lized region. Figure 2 schematically illustrates a typica:L high-velocity, gas-dynamic system, where propellant gas 10, typically helium, nitrogen, air or a mixture of these gasses, is introduced at an elevated pressure into powder feeder 12, capable of withstanding high pressure, and gas pre-heater 14. Powdered metal is introduced into the feeder 12 via a sealing closure 16. Typical powder metals of interest include, but are not limited to, zinc, aluminum, copper, iron, tin, nickel, titanium, molybdenum, silver, gold, and alloys thereof.
Desirable characteristics of pure metal powders for high-velocity, gas-dynamic spraying are generally: (1) a degree of plasticity of the powder, allowing it to generate dense deposits through impact fusion, (2) size range of the powder in the vicinity of 5-50 microns, and (3) sufficiently high purity as to permit an active metal to render galvanic protection by sacrificial anodization to the metal sheet or fabricated metal part upon which it is deposited.
The choice of a metal powder for a given application will generally depend upon its galvanic potential relative to the base metal where protection is desired. For example, the most common galvanic protection of ferrous materials will be by zinc. Ferrous materials can be galvanically protected by aluminum, magnesium and alloys thereof. It should be understood that the selection of a galvanical metal powder is dependent upon the metal used for the metal sheet or fabricated metal part and the economics and practicality of spraying the metal powder. It should also be understood that metals which form stable and protective passivations, even while not sacrificially anodic to the base metal, are likely to be used to form protective coatings as well. An example is the application of high-purity aluminum to an aluminum alloy for purposes of developing a surface which is more readily passivated or less corrosion prone than the base material.
Powder metal introduced into the powder feeder 12 is entrained in a high-pressure gas flow 18 entering powder feeder 12. Entrained powder 20 exits powder feeder 12, and is introduced into the converging/diverging nozzle 2:2. High pressure, high-temperature gas stream 24 is introduced into converging/diverging nozzle 22. The introduction of entrained powder 20 and gas stream 24 into converging/diverging nozzle 22 causes a simultaneous temperature reduction and gas volume expansion, with an attendant velocity increase, often approaching or exceeding the sound velocity for the particular propellant gas 10 for the conditions in nozzle cone 25.
Upon exiting converging/diverging nozzle 22, metal particles 26 are collected upon substrate 4 to form protective coating 30. The kinetic energy of the impacting metal particles 26 is partially converted into a work of deformation, such that particles plastically flow and can thus adhere to one or more of the following substrate features: (1) surface irregularities, either naturally present or introduced by processing on the surface of the parent metal being protected, (2) an accepting prior metal coating (e.g., pre-galvanized steel), which deforms under impact of the spray particles, or (3) previously adhering particles of the spray metal itself.
Selective deposits are produced using the high-velocity, gas-dynamic applicator of Figure 2. The converging/diverging nozzle may be placed on a programmable robot arm to produce selective regions of increased Zinc alloy or other metallic protection.
Alternatively, the work piece can be manipulated under a stationary nozzle for the case of simple geonletries such as strips or coils as illustrated in Figure 3. Figure 3 shows a piece of sheet material 40, receiving a protective layer of zinc 42 near edge 44. Edge 44 may become a fabricated metal part, such as a hem flange.
Selective corrosion protection affords the opportunity to place additional amounts of galvanic protection where needed on either a pre-galvanized or an untreated structure. The thickness of the selectively galvanized layer can be determined by adjusting one or more of the following parameters: (1) powder feed rate irito the gun, (2) work piece or gun traverse speed, (3) number of passes of gun over region.
The thickness will typically be in the rancre of 10-100 microns of zinc or zinc alloy added to either a preexisting uniform layer or the bare substrate which has been prepared to accept the coating layer by appropriate surface roughening. For the case of pre-galvanized sheet, additional pretreatment of the sheet is not required.
For component pieces which are assembled irito structures such as automobile bodies and closures (e.g., doors, hoods, deck lids, lift gates), selective application of a protective coating can be used to augment corrosion protection. Figure 4 illustrates a hem region 64. Outer body panel 60 receives a galvanizing coating 67 and a selective protective coating 62. Inner body panel 66 receives a galvanizing coating 65 and a selective protective coating 68. Outer body panel 60 is bent to form hem 64 with inner panel 66.
The selective galvanizing process as depicted in Figure 4 is preferred when it is possible for each individual panel of the assembly to receive selective galvanizing in advance of assembly, thereby impartinq additional galvanic and barrier properties to each constituent part of an assembly. Such a structure is expected to significantly delay the onset of perforation corrosion in the hem area by providing a more extensive reservoir of sacrificial anode than is available from the pre-galvanized sheet steel typically used without the necessity of increasing the galvanic protection in areas of the sheet removed.from the hem. This provides a level of increased corrosion resistance only at areas where corrosion resistance is particularly sought, while keeping any increase in cost at a minimum.
According to another embodiment of the present invention, the se:Lective coating is placed on either outer body panel 60 or inner body panel 66, thereby providing a single reservoir of additional sacrificial anode, but without the benefit of providing the additional barrier protection on each component piece.
Figure 5 depicts an alternative embodiment using the selective galvanizing process of the present invention.
According to Figure 5, a final sealing layer 70 of zinc alloy is placed as a filler to augment corrosion resistance of the cut edge 72. Since cut edge 72 does not have any zinc coating on the surface, it is more vulnerable to corrosion than regions where a more uniform layer of galvanizing has been developed on the parent metal.
Experimentally, two hem flanges were produced with galvanized metal sheets. One of the flanges receiveci an additional 50 microns of kinetically sprayed zinc, depicted as protective coatings 62 and 68 in Figures 4 and 5.
Corrosion tests were conducted on the two flanges by controlling the level of humidity, temperature and salt-water exposure. This corrosion test was run for 100 cycles, where a cycle is a period of 24 hours. Results of the corrosion test showed that the selectively galvanized hem flange showed minimal blistering adjacent to cut edge 72, whereas the conventional processing resulted in substantial red rust corrosion and blistering.
The methods of the current invention are particularly applicable to localized enhancement of corrosion performance of components that have extremely high corrosion reliability requirements. Fabricated metal parts suffer from diminished corrosion resistance as well. For example, metal fuel tanks have extremely high corros:_on reliability requirements. Selective kinetic sprayinq can be applied augmenting the corrosion resistance of localized areas such as the seam weldment (found in fuel tanks, for example), filler-tube weldments, and attachment flanc{es for fuel pump or sender units.
According to Figure 6, the cross section of: a steel fuel tank weld seam 80, has been impact fusion sprayed with high-purity zinc to form the protective beads 82, following a surface preparation step by grit-blastinq the seam area with aluminum oxide prior to cold spray application. Weld bead 84 has caused disruption of the original protective coatings 86, comprised of electro-galvanized Zn-Ni with aluminum-filled epoxy over-layer.
Protective coating 82 of thickness approximately 25 rlicrons of pure zinc is deposited on the seam 80 according to the parameters set forth earlier, using helium gas as the propellant. By selectively galvanizing the seam 80, it is potentially possible to eliminate the post-weld painting step on some fuel tanks, and thereby the environmental burdens associated with the paint process including VOCs, water treatment and solid waste sludge.
While cold-gas dynamic spraying is a preferred method for achieving selective galvanizing, it will be apparent that other "kinetic" processes based either on gas dynamics or other means of particle acceleration wou:Ld also be applicable. The gas-dynamic approach employing a converging/diverging nozzle develops a highly collimated "beam" of metal particles that form the galvanizing :layer.
Other "high-velocity, oxy-fuel" or HVOF thermal spray processes can equally develop such collimated particle streams. For zinc or zinc-alloy powder as would be used in selective galvanizing, thermal excursions can lead to undesirable zinc fuming. Emerging "kinetic" processes based on tribo-accleration as disclosed in U.S. Patent 5,795,626, or pulsed plasma processes as disclosed in U.S. Patent 6,001,426, might equally be envisioned in lieu of the gas-dynamic approach for producing highly collimated material beams.
While the present invention has been described in detail in connection with preferred embodiments, it is understood that these embodiments are merely exemplary and the invention is not restricted thereto. It will be recognize by those skilled in the art that other variations and modifications can be easily made within the scope of this invention that is defined by the appended claims.
In the case of selectively supplanting preexisting galvanized layers with zinc or zinc alloy powders, or for addition of zinc to pre-roughened surfaces, the conditions which promote formation of zinc-rich surfaces are: (:_) zinc or zinc-alloy powder of at least 70% by weight zinc, with typical alloying additions of aluminum, copper, magnesium, iron, lead, cadmium, tin or nickel, (2) particle powder size in the range of 5-50 cnicrons; (3) for helium as a propellant, gas pressure in the range 100-300 psi, gas preheat temperature in the range of 150-4000'C, particle velocities in the range of from 350-650 m/sec., (4) for air or nitrogen propellant, gas pressure in the range 100-450 psi, gas temperatures in the range of 170-5000-C, particle velocities in the range of 350-650 m/sec.
According to one embodiment of the present invention, a high-velocity, gas-dynamic spray system is utilized to apply the protective coating to the loca:Lized region. Figure 2 schematically illustrates a typica:L high-velocity, gas-dynamic system, where propellant gas 10, typically helium, nitrogen, air or a mixture of these gasses, is introduced at an elevated pressure into powder feeder 12, capable of withstanding high pressure, and gas pre-heater 14. Powdered metal is introduced into the feeder 12 via a sealing closure 16. Typical powder metals of interest include, but are not limited to, zinc, aluminum, copper, iron, tin, nickel, titanium, molybdenum, silver, gold, and alloys thereof.
Desirable characteristics of pure metal powders for high-velocity, gas-dynamic spraying are generally: (1) a degree of plasticity of the powder, allowing it to generate dense deposits through impact fusion, (2) size range of the powder in the vicinity of 5-50 microns, and (3) sufficiently high purity as to permit an active metal to render galvanic protection by sacrificial anodization to the metal sheet or fabricated metal part upon which it is deposited.
The choice of a metal powder for a given application will generally depend upon its galvanic potential relative to the base metal where protection is desired. For example, the most common galvanic protection of ferrous materials will be by zinc. Ferrous materials can be galvanically protected by aluminum, magnesium and alloys thereof. It should be understood that the selection of a galvanical metal powder is dependent upon the metal used for the metal sheet or fabricated metal part and the economics and practicality of spraying the metal powder. It should also be understood that metals which form stable and protective passivations, even while not sacrificially anodic to the base metal, are likely to be used to form protective coatings as well. An example is the application of high-purity aluminum to an aluminum alloy for purposes of developing a surface which is more readily passivated or less corrosion prone than the base material.
Powder metal introduced into the powder feeder 12 is entrained in a high-pressure gas flow 18 entering powder feeder 12. Entrained powder 20 exits powder feeder 12, and is introduced into the converging/diverging nozzle 2:2. High pressure, high-temperature gas stream 24 is introduced into converging/diverging nozzle 22. The introduction of entrained powder 20 and gas stream 24 into converging/diverging nozzle 22 causes a simultaneous temperature reduction and gas volume expansion, with an attendant velocity increase, often approaching or exceeding the sound velocity for the particular propellant gas 10 for the conditions in nozzle cone 25.
Upon exiting converging/diverging nozzle 22, metal particles 26 are collected upon substrate 4 to form protective coating 30. The kinetic energy of the impacting metal particles 26 is partially converted into a work of deformation, such that particles plastically flow and can thus adhere to one or more of the following substrate features: (1) surface irregularities, either naturally present or introduced by processing on the surface of the parent metal being protected, (2) an accepting prior metal coating (e.g., pre-galvanized steel), which deforms under impact of the spray particles, or (3) previously adhering particles of the spray metal itself.
Selective deposits are produced using the high-velocity, gas-dynamic applicator of Figure 2. The converging/diverging nozzle may be placed on a programmable robot arm to produce selective regions of increased Zinc alloy or other metallic protection.
Alternatively, the work piece can be manipulated under a stationary nozzle for the case of simple geonletries such as strips or coils as illustrated in Figure 3. Figure 3 shows a piece of sheet material 40, receiving a protective layer of zinc 42 near edge 44. Edge 44 may become a fabricated metal part, such as a hem flange.
Selective corrosion protection affords the opportunity to place additional amounts of galvanic protection where needed on either a pre-galvanized or an untreated structure. The thickness of the selectively galvanized layer can be determined by adjusting one or more of the following parameters: (1) powder feed rate irito the gun, (2) work piece or gun traverse speed, (3) number of passes of gun over region.
The thickness will typically be in the rancre of 10-100 microns of zinc or zinc alloy added to either a preexisting uniform layer or the bare substrate which has been prepared to accept the coating layer by appropriate surface roughening. For the case of pre-galvanized sheet, additional pretreatment of the sheet is not required.
For component pieces which are assembled irito structures such as automobile bodies and closures (e.g., doors, hoods, deck lids, lift gates), selective application of a protective coating can be used to augment corrosion protection. Figure 4 illustrates a hem region 64. Outer body panel 60 receives a galvanizing coating 67 and a selective protective coating 62. Inner body panel 66 receives a galvanizing coating 65 and a selective protective coating 68. Outer body panel 60 is bent to form hem 64 with inner panel 66.
The selective galvanizing process as depicted in Figure 4 is preferred when it is possible for each individual panel of the assembly to receive selective galvanizing in advance of assembly, thereby impartinq additional galvanic and barrier properties to each constituent part of an assembly. Such a structure is expected to significantly delay the onset of perforation corrosion in the hem area by providing a more extensive reservoir of sacrificial anode than is available from the pre-galvanized sheet steel typically used without the necessity of increasing the galvanic protection in areas of the sheet removed.from the hem. This provides a level of increased corrosion resistance only at areas where corrosion resistance is particularly sought, while keeping any increase in cost at a minimum.
According to another embodiment of the present invention, the se:Lective coating is placed on either outer body panel 60 or inner body panel 66, thereby providing a single reservoir of additional sacrificial anode, but without the benefit of providing the additional barrier protection on each component piece.
Figure 5 depicts an alternative embodiment using the selective galvanizing process of the present invention.
According to Figure 5, a final sealing layer 70 of zinc alloy is placed as a filler to augment corrosion resistance of the cut edge 72. Since cut edge 72 does not have any zinc coating on the surface, it is more vulnerable to corrosion than regions where a more uniform layer of galvanizing has been developed on the parent metal.
Experimentally, two hem flanges were produced with galvanized metal sheets. One of the flanges receiveci an additional 50 microns of kinetically sprayed zinc, depicted as protective coatings 62 and 68 in Figures 4 and 5.
Corrosion tests were conducted on the two flanges by controlling the level of humidity, temperature and salt-water exposure. This corrosion test was run for 100 cycles, where a cycle is a period of 24 hours. Results of the corrosion test showed that the selectively galvanized hem flange showed minimal blistering adjacent to cut edge 72, whereas the conventional processing resulted in substantial red rust corrosion and blistering.
The methods of the current invention are particularly applicable to localized enhancement of corrosion performance of components that have extremely high corrosion reliability requirements. Fabricated metal parts suffer from diminished corrosion resistance as well. For example, metal fuel tanks have extremely high corros:_on reliability requirements. Selective kinetic sprayinq can be applied augmenting the corrosion resistance of localized areas such as the seam weldment (found in fuel tanks, for example), filler-tube weldments, and attachment flanc{es for fuel pump or sender units.
According to Figure 6, the cross section of: a steel fuel tank weld seam 80, has been impact fusion sprayed with high-purity zinc to form the protective beads 82, following a surface preparation step by grit-blastinq the seam area with aluminum oxide prior to cold spray application. Weld bead 84 has caused disruption of the original protective coatings 86, comprised of electro-galvanized Zn-Ni with aluminum-filled epoxy over-layer.
Protective coating 82 of thickness approximately 25 rlicrons of pure zinc is deposited on the seam 80 according to the parameters set forth earlier, using helium gas as the propellant. By selectively galvanizing the seam 80, it is potentially possible to eliminate the post-weld painting step on some fuel tanks, and thereby the environmental burdens associated with the paint process including VOCs, water treatment and solid waste sludge.
While cold-gas dynamic spraying is a preferred method for achieving selective galvanizing, it will be apparent that other "kinetic" processes based either on gas dynamics or other means of particle acceleration wou:Ld also be applicable. The gas-dynamic approach employing a converging/diverging nozzle develops a highly collimated "beam" of metal particles that form the galvanizing :layer.
Other "high-velocity, oxy-fuel" or HVOF thermal spray processes can equally develop such collimated particle streams. For zinc or zinc-alloy powder as would be used in selective galvanizing, thermal excursions can lead to undesirable zinc fuming. Emerging "kinetic" processes based on tribo-accleration as disclosed in U.S. Patent 5,795,626, or pulsed plasma processes as disclosed in U.S. Patent 6,001,426, might equally be envisioned in lieu of the gas-dynamic approach for producing highly collimated material beams.
While the present invention has been described in detail in connection with preferred embodiments, it is understood that these embodiments are merely exemplary and the invention is not restricted thereto. It will be recognize by those skilled in the art that other variations and modifications can be easily made within the scope of this invention that is defined by the appended claims.
Claims (17)
1. A method for enhancing the corrosion protection of a galvanized metal part having a first surface portion and a second surface portion, less susceptible to corrosion than the first surface portion, the method comprising:
identifying the first surface portion on the metal part, wherein the first surface portion having degraded galvanic protection relative to the second surface portion due to a manufacturing process;
roughening the first surface portion for acceptance of a galvanic protective coating; and applying the galvanic protective coating to essentially only the first surface portion by a device capable of impact fusion of solid metal particles onto the galvanized metal part, wherein the corrosion protection of the first surface portion is enhanced.
identifying the first surface portion on the metal part, wherein the first surface portion having degraded galvanic protection relative to the second surface portion due to a manufacturing process;
roughening the first surface portion for acceptance of a galvanic protective coating; and applying the galvanic protective coating to essentially only the first surface portion by a device capable of impact fusion of solid metal particles onto the galvanized metal part, wherein the corrosion protection of the first surface portion is enhanced.
2. The method of claim 1 wherein the galvanic metal part comprises a steel fuel tank, the first surface portion comprises a weldment on the steel fuel tank, and the manufacturing process is comprised of welding.
3. A method for enhancing corrosion protection of a fabricated metal part, the method comprising:
providing a metal sheet to be processed to form the fabricated metal part and having a first surface portion adjacent to a second surface portion;
selecting the first surface portion on the metal sheet, wherein the first surface portion is more susceptible to corrosion than the second surface portion after fabrication of the metal sheet into the fabricated metal part; and applying a protective coating to essentially only the first surface portion by a device capable of impact fusion of solid metal particles onto the metal sheet, without application of the protective coating, the first portion becomes a post-fabricated area particularly susceptible to corrosion after the metal sheet is processed to form the fabricated metal part.
providing a metal sheet to be processed to form the fabricated metal part and having a first surface portion adjacent to a second surface portion;
selecting the first surface portion on the metal sheet, wherein the first surface portion is more susceptible to corrosion than the second surface portion after fabrication of the metal sheet into the fabricated metal part; and applying a protective coating to essentially only the first surface portion by a device capable of impact fusion of solid metal particles onto the metal sheet, without application of the protective coating, the first portion becomes a post-fabricated area particularly susceptible to corrosion after the metal sheet is processed to form the fabricated metal part.
4. The method of claim 3 wherein the device capable of impact fusion of solid metal particles onto the metal sheet is a high-velocity, cold gas-dynamic nozzle.
5. The method of claim 4 wherein the applying step is accomplished without masking the metal sheet.
6. The method of claim 4 wherein the protective coating is comprised of a galvanic coating.
7. The method of claim 6 wherein the metal sheet is comprised of iron or iron alloy.
8. The method of claim 7 wherein the galvanic protective coating is comprised of zinc or zinc alloy.
9. The method of claim 3 further comprising manipulating the partially coated metal sheet to form the fabricated metal part.
10. The method of claim 9 wherein the manipulating step is comprised of bending the metal sheet over a second metal sheet to form a hem flange structure.
11. The method of claim 10 wherein the post-fabricated area particularly susceptible to corrosion without application of the protective coating is comprised of the hem flange structure.
12. The method of claim 3 wherein the metal sheet is comprised of a galvanized metal sheet.
13. The method of claim 3 wherein the metal sheet is a nongalvanized metal sheet.
14. The method of claim 3 further comprising roughening the first surface portion for acceptance of the protective coating prior to the application step.
15. A method for enhancing the corrosion protection of a metal part having a first surface portion and a second surface portion, less susceptible to corrosion than the first surface portion, the method comprising:
identifying the first surface portion on the metal part, wherein the first surface portion having degraded corrosion protection relative to the second surface portion due to a manufacturing process;
roughening the first surface portion for acceptance of a passivating protective coating; and applying the passivating protective coating to essentially only the first surface portion by a device capable of impact fusion of solid metal particles onto the metal part, wherein the corrosion protection of the first surface portion is enhanced.
identifying the first surface portion on the metal part, wherein the first surface portion having degraded corrosion protection relative to the second surface portion due to a manufacturing process;
roughening the first surface portion for acceptance of a passivating protective coating; and applying the passivating protective coating to essentially only the first surface portion by a device capable of impact fusion of solid metal particles onto the metal part, wherein the corrosion protection of the first surface portion is enhanced.
16. The method of claim 15 wherein the metal part is comprised of magnesium or magnesium alloy.
17. The method of claim 16 wherein the passivating protective coating is comprised of aluminum or aluminum alloy.
Applications Claiming Priority (2)
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| US10/063,335 US6592947B1 (en) | 2002-04-12 | 2002-04-12 | Method for selective control of corrosion using kinetic spraying |
| US10/063,335 | 2002-04-12 |
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| US5795626A (en) | 1995-04-28 | 1998-08-18 | Innovative Technology Inc. | Coating or ablation applicator with a debris recovery attachment |
| US5980659A (en) * | 1996-07-15 | 1999-11-09 | Kabushiki Kaisha Toyota Chuo Kenkyusho | Surface-treated metallic part and processing method thereof |
| US6001426A (en) | 1996-07-25 | 1999-12-14 | Utron Inc. | High velocity pulsed wire-arc spray |
| DE59709043D1 (en) * | 1996-08-07 | 2003-02-06 | Elpatronic Ag Bergdietikon | Injector arrangement for conveying a powdery material |
| EP0860516A3 (en) * | 1997-02-04 | 1999-05-19 | Fuji Kihan Co., Ltd. | Method for forming metallic coat |
| DE19748105C1 (en) | 1997-10-31 | 1998-10-29 | Grillo Werke Ag | Increasing corrosion-resistance of thermally sprayed metal coating on steel-reinforced cement concrete |
| JP3828675B2 (en) * | 1998-04-23 | 2006-10-04 | 新日本製鐵株式会社 | Surface-treated steel sheet with excellent corrosion resistance and workability and method for producing the same |
| DE19918758B4 (en) * | 1999-04-24 | 2007-04-26 | Volkswagen Ag | Method for producing a coating, in particular a corrosion protection layer |
| DE19934418A1 (en) * | 1999-07-22 | 2001-01-25 | Abb Alstom Power Ch Ag | Process for coating a locally differently stressed component |
| US6372374B1 (en) * | 1999-11-30 | 2002-04-16 | Fuelcell Energy, Inc. | Bipolar separator plate with improved wet seals |
| ES2248021T3 (en) * | 1999-12-20 | 2006-03-16 | United Technologies Corporation | ITEMS PROVIDED WITH CORROSION RESISTANT COATINGS. |
| US6874214B1 (en) * | 2000-05-30 | 2005-04-05 | Meritor Suspension Systems Company | Anti-corrosion coating applied during shot peening process |
-
2002
- 2002-04-12 US US10/063,335 patent/US6592947B1/en not_active Expired - Lifetime
-
2003
- 2003-04-02 EP EP03100874A patent/EP1352992A3/en not_active Withdrawn
- 2003-04-11 CA CA002425213A patent/CA2425213C/en not_active Expired - Fee Related
- 2003-04-11 JP JP2003107558A patent/JP2003301279A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003301279A (en) | 2003-10-24 |
| EP1352992A3 (en) | 2003-10-22 |
| EP1352992A2 (en) | 2003-10-15 |
| US6592947B1 (en) | 2003-07-15 |
| CA2425213A1 (en) | 2003-10-12 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20190411 |