ELECTROLYTIC COATING FOR ALUMINUM COMPONENTS WITH WELDED JOINTS

Abstract

A coated component comprises a metallic body defining an internal volume configured to retain a fluid. The metallic body comprises a plurality of segments, at least one weld joint securing the plurality of segments, and an external and an internal surface facing and defining the internal volume. The component further comprises a chrome-free protective coating disposed on each of the external and internal surfaces. The coating comprises an epoxy layer and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces. Fig. 5

Description

Title of the invention: ELECTROLYTIC COATING FOR ALUMINUM COMPONENTS WITH WELDED JOINTS Field of the invention

[0001] The present invention relates generally to protective coatings for metallic substrates and, more particularly, to an epoxy coating and its application.

[0002] Aluminum and aluminum alloy components used in aeronautical and aerospace applications are subjected to environments that cause corrosion. Such components have traditionally been anodized or coated by conversion using chromic acid or anodized using sulfuric acid. Hexavalent chromium is heavily regulated by environmental agencies and is banned in many countries, while either acid can be difficult to remove by rinsing from certain components after treatment, resulting in cosmetic defects and / or corrosion. Thus, there is a need for improved coatings. Summary of the invention

[0003] A coated component comprises a metallic body defining an internal volume configured to retain a fluid. The metallic body comprises a plurality of segments, at least one weld joint securing the plurality of segments, and an external and an internal surface facing and defining the internal volume. The component further comprises a chrome-free protective coating disposed on each of the external and internal surfaces. The coating comprises an epoxy layer and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces.

[0004] A coated component comprises a metallic body defining an internal volume configured to retain a fluid. The metallic body includes a support, a weld joint securing the support to the metallic body, an external surface, and an internal surface facing and defining the internal volume. The component further comprises a chrome-free protective coating disposed on each of the external and internal surfaces. The coating comprises an epoxy layer and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces.

[0005] A method for electrodepositing a protective coating on an aluminum component comprising at least one solder joint includes immersing the component in an electrodeposition bath, configuring the component as a positively charged anode, and applying a voltage through the component. to allow the deposition of the protective coating to form a coated component, the rinsing of the coated component and the curing of the coated component. Brief description of the drawings

[0006] [Fig-1] is a perspective view of a first embodiment of a metallic conduit.

[0007] [Fig.2] is a perspective view of a second embodiment of a metallic conduit.

[0008] [Fig.3] is a perspective view of a third embodiment of a metallic conduit.

[0009] [Fig.4] is a flowchart illustrating a process for electrodeposition of a protective coating on a metallic component.

[0010] [Fig.5] is a simplified cross-sectional illustration of a coated metallic component.

[0011] Although the figures identified above illustrate embodiments of the present invention, other embodiments are also envisaged, as noted in the discussion. In all cases, this disclosure presents the invention by way of illustration and not limitation. It should be understood that many other modifications and embodiments can be imagined by those skilled in the art, which fall within the scope and spirit of the principles of the invention. The figures may not be drawn to scale, and applications and embodiments of the present invention may include features, steps, and / or components not specifically shown in the drawings. Detailed description

[0012] This disclosure describes a chromium-free electrolytic protective coating for welded aluminum components (i.e., those with weld joints). The coating is an electrodeposited anodic epoxy coating that includes a thin oxide layer for increased corrosion resistance and adhesion of the subsequent organic coating. The coating is more environmentally friendly than chromium-based coatings and does not negatively interact with weld joints by trapping electrolyte in crevices.

[0013] Figure 1 is a perspective view of the conduit 100 adapted to retain and / or convey fluids (e.g., gases or liquids) in a larger fluid management system. In one embodiment, the conduit 100 may be a gas conveying conduit forming part of an aircraft air sampling or environmental control (ECS) system. The conduit 100 comprises a hollow metallic body 102 defining an internal volume 104 through which the fluid may pass. In one embodiment, the body 102 may The body 102 can be made of aluminum (including aluminum alloys). It can be composed of several smaller segments 106 (not all of which are shown in Fig. 1) joined by weld joints 108 (not all of which are shown in Fig. 1). In the illustrated embodiment, the segments 106 are hollow / tubular structures, so the weld joints 108 completely enclose the body 102, making it fluid-tight. Welding the smaller segments 106 together allows for the formation of an elongated body 102 with precisely positioned straight and curved sections, which may be desirable in confined spaces (e.g., small compartments, partitions, etc.). The conduit 100 further includes external features 110, which, in the illustrated embodiment, are bosses (hereafter referred to as "bosses 110").The bosses 110 can also be connected to the body 102 via weld joints 108. The bosses 110 can interconnect the conduit 100 to various aircraft mounting and / or support structures. The conduit 100 may further include flanged ends 112, which can also be connected to the body 102 by weld joints 108. The flanged ends 112 can help to couple the conduit 100 to other conduits and / or components.

[0014] Figure 2 is a perspective view of the conduit 200, also adapted for conveying fluids. The conduit 200 is similar to the conduit 100 in that it comprises a hollow body 202, preferably made of aluminum, defining the internal volume 204. Consequently, the conduit 200 can be part of the same fluid handling system as the conduit 100, or of a different system. The hollow body 202 is curved so that the fluid passing through it rotates approximately 90°. The conduit 200 includes an external feature 210 which, in the embodiment shown, is a support (hereinafter referred to as "support 210"). The support 210 can also be made of aluminium or another metal and fixed to the body 202 by the weld joint 208. The conduit 200 can further include flanged ends 212, each fixed via a weld joint 208, to make an interface of the conduit 200 with another conduit (for example, the conduit 100) and / or component.

[0015] Figure 3 is a perspective view of the conduit 300, also adapted for conveying fluids. The conduit 300 is similar to conduits 100 and 200 in that it comprises a hollow body 302, preferably made of aluminum, defining the internal volume 304 (indicated by a dashed guideline). The conduit 300 is a tee for the 90° transition of the fluid flow and comprises straight segments 306 arranged perpendicularly. The conduit 300 can alternatively be used to introduce a first fluid flow moving in a first direction into a second fluid flow moving in a second orthogonal direction. The angled weld joint 308 attaches one segment 306 to the other. The weld joint 308 is called angled because it is arranged at an angle to the segments 306. The conduit 300 may also include flanged ends 312, each secured via a (circumferential) weld joint 308, to provide an interface of the conduit 300 with another conduit (e.g., conduit 100 and / or conduit 200) and / or component.

[0016] The conduits 100, 200, and / or 300 may ideally include a protective coating (e.g., corrosion-resistant). When anodizing such welded aluminum components with chromic acid and / or sulfuric acid, the acid can become trapped in the weld joints, even after meticulous rinsing of the component. Accordingly, [Fig. 4] illustrates steps 416 to 424 of the process 414 for electroplating a protective coating onto a welded aluminum component to form a coated component.As used here with respect to process 414, "electrodeposition" and "electrodeposit" refer to anodic deposition. Figure 5 is a simplified cross-sectional illustration of the coated tubular component 500. Figures 4 and 5 are discussed together.

[0017] The coated component 500 can be a conduit substantially similar to any of the conduits 100, 200 or 300. The coated component 500 comprises a body 502 formed from segments 506 attached at the weld joint 508. The body 502 defines the internal volume 504 through which a fluid can pass. Also visible in [Fig. 5] are the respective external and internal surfaces 524 and 526 of the body 502. As illustrated, the weld joint 508 generally extends perpendicularly between the respective external and internal surfaces 524 and 526. In step 416, the body 502 can undergo optional preparation of the surfaces 524 and 526, such as degreasing, rinsing, deoxidation, and further rinsing. Each substep can be carried out by immersing the component 500 in a bath of the appropriate solution. Such surface preparation can facilitate the subsequent electrodeposition step.

[0018] In step 418, the protective coating 528 can be electrodeposited onto the body 502, and more specifically, onto the surfaces 524 and 526. The coating 528 can be a chromium-free, water-based epoxy coating (or primer) in one embodiment. The body 502 is immersed in an electrolytic bath and positively charged, such that the body 502 acts as the anode. In this respect, the coating 528 can be an anodic coating. The coating 528 is deposited relatively uniformly on each of the external and internal surfaces 524 and 526, respectively. In some cases, the coating 528 may be slightly thinner on the internal surface 526 compared to its thickness on the external surface 524. The coating 528 is generally coextensive with the areas of the respective external and internal surfaces 524 and 526, because the body 502 is completely immersed in the electroplating bath.The thickness of the 528 coating can be controlled by one of the immersion times. and the applied voltage, or a combination thereof. The coating 528 comprises an epoxy layer 530 and a relatively thin oxide layer (e.g., Al2O3) 532 initially formed during electrodeposition. The oxide layer 532 may be a dense layer of oxide filaments. The oxide layer 532 can anchor the epoxy layer 530 to the underlying aluminum, and thus imparts greater corrosion resistance to the surfaces 524 and 526 than the epoxy layer 530 alone.

[0019] After electrodeposition, the now-coated component 500 can be rinsed at Step 420. Rinsing may involve immersing component 500 in one or more tanks of a rinsing solution. In step 422, component 500 may be placed in an oven to cure coating 528 at a temperature ranging from 100 °C to approximately 120 °C. In step 424, optional additional coatings, such as a topcoat, may be applied to the cured coating 528.

[0020] Coating 528 and process 414 offer numerous advantages. First, coating 528 does not involve corrosive materials that can become trapped in solder joints, potentially leading to discoloration and / or corrosion of a component. Electrodeposition is more controlled than, for example, spray coating techniques, so coating 528 can be applied more uniformly and in less time. It provides a more uniform deposition on the internal surfaces of complex-shaped components. Coating 528 and process 414 are also environmentally friendly. Coating 528 is chromium-free, low in VOCs (volatile organic compounds), and has low solvent emissions. Process 414 can be automated, for example, by using a robotic arm or gantry to transfer component 500 between the tanks and, finally, the oven.Automation and the absence of harmful chemicals minimize worker exposure to any hazardous materials during the coating process. Finally, the 528 coating can be applied in fewer steps than traditional protective coatings, and automation reduces processing time per component.

[0021] The 528 coating can be applied to aluminium components in both commercial and military aviation, and therefore meets all relevant standards (e.g., MIL-STD), as well as international environmental standards.

[0022] Discussion of possible embodiments

[0023] The following are non-exclusive descriptions of possible embodiments of the present invention.

[0024] A coated component comprises a metallic body defining an internal volume configured to retain a fluid. The metallic body comprises a plurality of segments, at least one weld joint securing the plurality of segments, an external surface, and an internal surface facing and defining the internal volume. The component further comprises a chrome-free protective coating on both the external and internal surfaces. The coating consists of an epoxy layer and an oxide layer positioned between the epoxy layer and the respective external and internal surfaces.

[0025] The component of the preceding paragraph may optionally include, in addition and / or alternatively, any or more of the following additional features, configurations and / or components:

[0026] In the above component, the component may be a fluid conduit.

[0027] In any of the above components, the metallic body may comprise aluminum.

[0028] In any of the above components, the plurality of segments may include a first tubular segment and a second tubular segment, and at least one weld joint may include a first weld joint completely surrounding the metal body.

[0029] Any one of the above components may further comprise a third tubular segment attached to the second tubular segment by a second weld joint. The second weld joint may completely enclose the metal body.

[0030] In any of the above components, one of the first, second and third tubular segments may be straight, and another of the first, second and third tubular segments may be curved.

[0031] Any one of the above components may further include a boss fixed to at least one of the first, second and third tubular segments.

[0032] In any of the above components, the plurality of segments may include a first tubular segment and a second tubular segment arranged perpendicular to the first tubular segment.

[0033] In any of the above components, at least one weld joint may be an angle weld joint.

[0034] Any one of the above components may further include at least one flanged end.

[0035] In any of the above components, at least one flanged end can be fixed to the metal body via a weld joint.

[0036] In any of the above components, at least one flanged end may comprise three flanged ends.

[0037] A coated component comprises a metallic body defining an internal volume configured to retain a fluid. The metallic body includes a support, a weld joint fixing the support to the metallic body, an external surface, and an internal surface facing and defining the internal volume. The component further comprises a chrome-free protective coating disposed on each of the external and internal surfaces. the internal surface. The coating comprises an epoxy layer and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces.

[0038] The component of the preceding paragraph may optionally include, in addition and / or alternatively, any or more of the following additional features, configurations and / or components:

[0039] In the above component, the component may be a fluid conduit.

[0040] In any of the above components, the metallic body may comprise aluminum.

[0041] A method for electrodepositing a protective coating on an aluminum component comprising at least one solder joint includes immersing the component in an electrodeposition bath, configuring the component as a positively charged anode, applying a voltage through the component to allow the deposition of the protective coating to form a coated component, rinsing the coated component and curing the coated component.

[0042] The process of the preceding paragraph may optionally include, in addition and / or alternatively, any or more of the following additional features, configurations and / or components:

[0043] The above process may further include, before immersing the component in the electrodeposition bath, degreasing an internal surface and an external surface of the component.

[0044] In any of the above processes, the protective coating may comprise an epoxy layer and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces.

[0045] Any one of the above processes may further include, after the component hardening step, the application of a topcoat to the coated component.

[0046] In any of the above processes, the component is a fluid conduit.

[0047] Although the invention has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various modifications can be made and equivalents can be substituted for its elements without departing from the scope of the invention. Furthermore, numerous modifications can be made to adapt a particular situation or material to the teachings of the invention without departing from its essential scope. Therefore, it is intended that the invention is not limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

Demands

1. Coated component comprising: a metallic body defining an internal volume configured to retain a fluid, the metallic body comprising: a plurality of segments; at least one weld joint fixing the plurality of segments; an external surface; and an internal surface facing and defining the internal volume; and a chrome-free protective coating disposed uniformly on each of the external and internal surfaces, the coating comprising: an epoxy layer; and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces.

2. Component according to claim 1, wherein the coated component is a fluid conduit.

3. Component according to claim 2, wherein the metallic body comprises aluminum.

4. Component according to claim 3, wherein the plurality of segments comprises a first tubular segment and a second tubular segment, and wherein the at least one weld joint comprises a first weld joint completely surrounding the metal body.

5. Component according to claim 4, and further comprising: a third tubular segment attached to the second tubular segment by a second weld joint; in which the second weld joint completely circumscribes the metal body.

6. Component according to claim 5, wherein one of the first, second and third tubular segments is straight, and wherein another of the first, second and third tubular segments is curved.

7. Component according to claim 6 and further comprising: a boss fixed to at least one of the first, second and third tubular segments.

8. Component according to claim 3, wherein the plurality of segments comprises a first tubular segment and a second tubular segment arranged perpendicularly to the first tubular segment.

9. Component according to claim 8, wherein at least one weld joint is an angle weld joint.

10. Component according to claim 9 and further comprising: at least one flanged end.

11. Component according to claim 10, wherein at least one flanged end is fixed to the metal body via a weld joint.

12. Component according to claim 11, wherein at least one flanged end comprises three flanged ends.

13. Coated component comprising: a metallic body defining an internal volume configured to retain a fluid, the metallic body comprising: a support; a weld joint fixing the support to the metallic body; an external surface; and an internal surface facing and defining the internal volume; and a chrome-free protective coating disposed uniformly on each of the external and internal surfaces, the coating comprising: an epoxy layer; and an oxide layer disposed between the epoxy layer and the respective external and internal surfaces.

14. Component according to claim 13, wherein the component is a fluid conduit.

15. Component according to claim 14, wherein the metallic body comprises aluminum.

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