A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
Not Applicable
The present invention relates to an apparatus and method for electrodepositing composite coatings in which a matrix containing embedded particles is produced through codeposition of insoluble particles suspended in a plating solution.
Electrodeposition of a metallic coating on the surface of an article is well known, as disclosed in U.S. Pat. Nos. 2,425,359; 2,447,270; and 2,706,175, all of which are incorporated herein by specific reference for all purposes. U.S. Pat. No. 4,305,792, also incorporated herein by specific reference for all purposes, discloses a hollow container for the electrodeposition of composite coatings, consisting of a metal matrix and embedded particles. Part of the container wall is impervious to the particles but pervious to the plating solution. The container is immersed in a plating tank containing the electrolyte. The pervious wall of the container is made of two outer layers of porous neoprene and an inner layer of filter paper. The neoprene layers, which are 3 millimeters thick, exhibits a nominal pore size of 10 micrometers while the filter paper has a nominal pore size of 2 micrometers. During electrodeposition, the article that was placed inside the container was rotating with the container along a horizontal axis or an axis that was slightly inclined to the horizontal.
A major disadvantage of prior art devices is that the particles placed inside the container need to be large enough to stay in the container. Particles smaller than the pore size of the pervious wall would either escape from the container or be trapped in the wall. Prior art devices therefore are not suitable for electrodeposition of composite coatings containing small particles, particularly for submicron particles or nanoparticles. In addition, the prior art devices cannot be used to apply composite coatings to internal surfaces of hollow articles.
This Brief Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
One aspect of the present invention is an apparatus for applying a coating to a desired object. The apparatus can include a rotatable container having at least one container wall. An electrolyte can be retained within the container, the at least one container wall made of a material that does not allow the electrolyte to pass through the at least one container wall of the container. An anode can be positioned within the container. The apparatus can include a mount for securing the desired object such that a surface of the desired object is exposed to the electrolyte. A controller can be in electrical communication with the anode and the mount, wherein when power is supplied from the controller to the anode and the mount, particles in the electrolyte are deposited on the desired object forming a composite coating.
Another aspect of the present disclosure is an apparatus for applying a coating to a desired object including a frame and a container rotatably disposed on the frame, the container having at least one container wall. A motor can be connected to the frame and coupled to the container, the motor selectively operable to rotate the container. A plating solution can be retained within the container, the plating solution containing submicron sized particles for coating the desired object, the at least one container wall made of a material that does not allow the plating solution or the particles contained therein to pass through the at least one container wall of the container. A mount can be provided for securing the desired object such that a surface of the desired object is exposed to the plating solution. When the desired object is secured, connected, mounted, or attached to the mount and the container is rotated via the motor, particles from the plating solution are deposited on the desired object as a coating.
Another aspect of the present disclosure is an apparatus for applying a coating to an object, the apparatus including a frame and a hollow desired object rotatably disposed on the frame, the desired object having at least one wall. A motor can be connected to the frame and coupled to the desired object, the motor selectively operable to rotate the desired object. An electrolyte can be retained within the desired object, the at least one wall of the desired object made of a material that does not allow the electrolyte to pass through the at least one wall of the desired object. As such, the desired object can be the container for retaining the electrolyte. An anode can be positioned within the desired object and the electrolyte. A controller can be in electrical communication with the anode and the desired object. Wherein when power is supplied from the controller to the anode and the desired object, particles in the electrolyte are deposited on the desired object forming a composite coating.
In various embodiments, the present invention can include an apparatus and related process for producing electrodeposited composite coatings, in which a metal matrix containing embedded particles is produced through codeposition of insoluble articles suspended in a plating solution. The particles can be ceramic, metallic, polymeric, or a combination of the three. Advantages for these coatings can include corrosion and oxidation resistance, wear resistance, and lubrication. The present apparatus can also be used in electroless plating processes. The composite coatings produced can be used as-deposited, or a post-deposition procedure such as a heat treatment can be performed to obtain the desired coating.
The present invention thus helps extend the capability of electrodepositing composite coatings containing particles smaller than the pore size of the prior art pervious wall containers and can be used to coat objects with particles in the submicron and nanometer range. The present invention also has the capability of producing composite coatings on internal surfaces of hollow articles.
Numerous other objects, advantages and features of the present disclosure will be readily apparent to those of skill in the art upon a review of the following drawings and description of a preferred embodiment.
While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that are embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention and do not delimit the scope of the invention. Those of ordinary skill in the art will recognize numerous equivalents to the specific apparatus and methods described herein. Such equivalents are considered to be within the scope of this invention and are covered by the claims.
In the drawings, not all reference numbers are included in each drawing, for the sake of clarity. In addition, positional terms such as “upper,” “lower,” “side,” “top,” “bottom,” etc. refer to the apparatus when in the orientation shown in the drawing. A person of skill in the art will recognize that the apparatus can assume different orientations when in use.
One aspect of the present invention, as shown in
The container 7 and the container walls 7a can be made of any suitable material that will not allow a plating solution or any particles containing therein to pass through the container walls 7a, or is otherwise impervious to the plating solution or any particles therein. The container wall 7a materials may be selected from a variety of materials, including for example materials such as polypropylene and polyethylene. In other embodiments, the container wall 7a material may be corrosion resistant and should not react with the electrolyte 11. In other embodiments, the container wall 7a materials can include, but are not limited to, metals, plastics, polymers, rubbers, etc. In some embodiments, the materials utilized for the container walls 7a can be rigid materials that can withstand and maintain their shape as the plating solution or electrolyte 11 move within the container as the container rotates.
In some embodiments, the apparatus 100 can include a frame 1, and a motor 2 can be mounted to the frame 1 and coupled to the container 7, the motor 2 selectively operable by the controller 22 to rotate the container 7. The controller 22 can control the motor 2 to rotate the container 7 at variable speeds as desired to facilitate particles 20 in the electrolyte 11 falling onto and coating various sides of the desired object 14 or article to be coated. In some embodiments, the container 7 can further include a cap 6. The motor 2 can be coupled to the cap 6 such that the container 7 is rotated by the motor 2 via the cap 6. In such embodiments, the mount 18 can be positioned on the cap 6 and/or integrated with the cap 6. As such, the container 7 and the mount 18 can be rotated via the cap 6 to rotate at the same rotational speed and both be driven by the motor 2. In other embodiments, the cap 6 and/or the mount 18 can be fixed such that the container 7 can rotate independently of the cap 2 and the mount 18, or the container 7 and the cap 2 and/or mount 18 can rotate at varying speeds.
In some embodiments, the apparatus 100 can further include a gear system 3 and 4 coupled between the motor 2 and the container 7 and/or the cap 6, wherein the container 7 is rotated by the motor 2 via the gear system 3 and 4. The gear assembly 3 and 4 in some embodiments can include a driving gear 3 mounted to the drive shaft of the motor 2 and a driven gear 4 that can be rotatably attached to the frame 1 using one or more pins 5. The cap 6 for the container 7 can be attached to the driven gear 4 using any suitable connection mechanism, including but not limited to screws, bolts, adhesives, etc. In some embodiments, the cap 6 can be designed to form a twist-lock or threaded engagement with the container 7. This connection allows the electric motor 2 to rotate the container 7 via the gear assembly 3 and 4 and the cap 6. In other embodiments, the container 7 can be directly coupled to the driven gear 4. In some embodiments, the cap 6 can include a plug 9 that can be used to seal the container 7 during electrodeposition by using the cap 6 to compress an O-ring positioned on an underside of the plug 9 between the container 7 and the plug 9.
In some embodiments, as shown in
In some embodiments, a first electrically conductive wire 17 can be electrically connected between the mount 18 and the controller (not shown), and a second electrically conductive wire 16 can be connected between the controller and the anode 15. As power from a power source of the controller is supplied to the anode 15 and the desired object via the mount 18, the anode 15 can become positively charged and the desired object 14 can become negatively charged, or become a cathode.
The article 14 and anode 15 are shown in
In some embodiments, the container 7 can further include a trunnion 8, the anode 15 in electrical communication with the trunnion 8. In some embodiments, the container 7 can be a hollow cylinder or a cylinder with an internal cavity that is open on one end 26, the open end connecting to the cap 6 and/or the mount 18, the container 7 having a trunnion 8 extending from an opposing closed end (see
In some embodiments, the apparatus 100 can further include a heating element 10 positioned on the container 7, wherein the electrolyte 11 can be heated as the heating element heats the container 7. In some embodiments, the heating element 10 can be a heating tape mounted outside the container 7. Having the heating element outside 10 of the electrolyte can help prevent corrosion of the heating element 10. In other embodiments, the heating element 10 can be placed inside the container to heat the electrolyte 11 directly, or the heating element 10 can be embedded in the container walls 7a. The heating element 10 can be any suitable heating structure, including heating tape, resistance electrical wiring, etc. In some embodiments, the apparatus 100 can further include a temperature sensor 12 extending through the container 7 and into the electrolyte 11, the temperature sensor 12 operable to monitor a temperature of the electrolyte 11. In some embodiments, the temperature sensor 12 can be any suitable thermocouple.
As the container 7 rotates on the frame 1, the heating element 10 and the temperature sensor 12 will rotate with the container 7. However, it is necessary to maintain electrical contact between the heating element 10 and the controller as well as between the temperature sensor 12 and the controller so that power can continuously be supplied to both heating element 10 and the temperature sensor 12 along with the anode 15, the motor 2, and the desired object 14. In embodiments wherein the container 7 further includes a trunnion 8 and the apparatus 100 includes a slip ring 13 in electrical contact with the controller, the anode 15, the heating element 10, and the temperature sensor 12 can each be in electrical communication with the trunnion 8, and specifically an electrical contact or circumferential electrical contact plate on the trunnion 8. A schematic diagram of this arrangement is shown in
In some embodiments, the container 7 can be a hollow object or an object with an internal cavity and can be the desired object to be coated, and particularly an inner surface 14a of the container 7, as shown in
As power is supplied from the controller to the container 7 and the anode 15, positively charged particles 20 in the electrolyte 11 are deposited on the inner surface 14a of the container 7.
In the embodiment show in
In the embodiments discussed herein, the particles 20 in the electrolyte can include micron-, submicron- and nano-sized particles, and the container wall 7a can be made of a material that does not allow the particles 20 to pass through the at least one container wall 7a. As such, nanoparticle coatings can be applied to desired objects 14 utilizing the apparatuses 100 described herein without loss of the nanoparticles through the container 7, which provides a significant benefit over prior art devices that included porous container walls that were submerged in an electrolyte bath or plating solution.
In some embodiments, the apparatus 100 can include one or more baffles 19 positioned within the container 7 and extending into the electrolyte 11. The baffles or paddles 19 can help agitate the electrolyte as the container 7 is rotated which can help disperse particles within the electrolyte 11 to help ensure particles are spread out across the intended coating surface 14a of a desired object 14.
In various embodiments, the present disclosure includes an apparatus 100 and related process for producing electrodeposited composite coatings, in which a metal matrix containing embedded particles 20 is produced through codeposition of insoluble particles suspended in a plating solution or electrolyte 11. The particles 20 can be ceramic, metallic, polymeric, or a combination of the three. Advantages for these coatings include corrosion and oxidation resistance, wear resistance, and lubrication. The apparatuses 100 of the present disclosure can also be used in electroless plating processes by applying a chemical catalyst to a plating solution to produce desired particles to be coated on a desired object. For the electroless process, the present invention can be used without an external power source. In this case, an appropriate electroless bath should be used. The composite coatings produced can be used as-deposited, or a post-deposition procedure such as a heat treatment can be performed to obtain the desired coating.
In several exemplary embodiments discussed above, the present invention comprises a hollow container or a container with an internal cavity (such as, but not limited to, a hollow cylinder or a cylinder with an internal cavity) with walls that are impervious to the electrolyte 11 or plating solution and the particles 20 therein. The hollow container 7 holds the article 14 to be coated, the particles 20, and the electrolyte 11, or is the article 14 to be coated and holds the particles 20, the electrolyte 11 and the anode 15. In some embodiments, the apparatus 100 rotates during the coating process via an electric motor 2 and a gear assembly 3 and 4.
The container 7 in the present invention can be a variety of hollow geometric shapes, such as, but not limited to, a hollow tube or cylinder, a sphere, a polygonal tube, or a shape conforming to the article. In some embodiments, the container 7 itself can act as the anode or cathode. As an example, to apply coatings on the internal surface of a hollow article, the article 14 is the container 7 itself and the anode can be placed inside the container 7. By eliminating the plating tank in which the apparatus was immersed (as used, for example, in the prior-art system described in U.S. Pat. No. 4,305,792), the present invention leads to a significant reduction in the amount of particles and electrolyte needed to produce composite coatings. This advantage becomes very attractive when high cost items such as electrolytes for noble metal plating or diamond particles are involved in the process, or very long internal surfaces are to be coated with composite coatings.
The behavior of the particles 20 inside the container 7 is such that the particles 20 will be recirculated to the top of the container 7 and fall slowly downward due to gravity once the said particles 20 reach a particular height. This allows for a gentle interaction between the article surface 14a and the particles 20, thus increasing the likelihood of the particles 20 being incorporated in the coating. This behavior also allows for the particles 20 to be suspended in the container 7 with minimal agitation of the electrolyte, thereby reducing the chance of particles 20 not being incorporated due to crossflow across the article surface. For cases that do exhibit downward flow of particles 20, gravitational forces help the particles to penetrate the boundary layer at the article surface 14a, thus increasing the incorporation of particles 20. However, due to the settling of particles 20 onto the article surface 14a the article 14 can be rotated to prevent the buildup of sediment that can block the electrodeposition of the metal matrix. In various embodiments of the present invention, the rotation of the article 14 can be either coupled to the container (i.e., forcing it to rotate at the same speed), or the article can rotate at a different speed or direction by use of its own driving mechanism.
For the electrolyte, the composition should be appropriate for the particular application in which the apparatus is used. For example, for an MCrAlY coating (where the M represents a mixture of nickel and cobalt), a nickel-cobalt Watts solution or a nickel-cobalt all chlorideplating bath can be used. Another example is in the case of electroless deposition of a nickel-phosphorous coating containing alumina particles, where an appropriate electroless bath should be used.
In several embodiments, the walls of the container are impervious to the electrolyte, so that both electrolyte and particles are contained within the container 7. Therefore, small particles down to the nanometer range can be codeposited in the composite coatings using the present apparatus. In the prior art, rotating containers have pervious walls, and particles must be large enough to remain within the container.
Additionally, for the present invention there is no need for a tank containing a large amount of electrolyte, which helps make the present apparatus more cost effective than prior art methods.
A further advantage of the present invention is that it helps enable deposition of composite coatings on internal surfaces, since the article itself can act as the container for the apparatus as well as the cathode, thereby leading to significant cost savings, particularly for extremely long articles such as a pipe. In special cases, the container 7 itself can also be the anode. Prior art devices did not have the capability of depositing composite coatings on internal surfaces of a hollow article.
Another advantage of the invention is that for applications that require the electrolyte to be at a controlled temperature, the heat source can be placed on the outside of the container, within the walls of the container, or inside the container. When the heat source is placed on the outside of the container (such as the heating tape in
The present apparatus can stand on a dry floor or a desktop. Additionally, a slip ring is used in the present invention to allow the heating system and thermostats to function on the rotating system.
Prior art systems typically use large tanks containing stationary heaters to heat a much larger volume of plating solution. The present invention makes it possible to deposit composite coatings containing small particles down to the nanometer range on external or internal surfaces of articles with substantially uniform particle incorporation in the coating, which has not been previously demonstrated.
The present invention may be used in a variety of industries, since both composite and nano-composite coatings can be produced using the present invention. In particular, the present invention may be particularly useful for low-cost processes to produce composite coatings with improved oxidation/corrosion resistance, or with better lubricative properties.
In the field of high-temperature oxidation coatings (such as coatings on hot-section gas turbine components), the present invention offers a low-cost alternative to more expensive deposition processes such as plasma spraying, sputtering, and electron-beam physical vapor deposition. In fields such as tribology where electrodeposited composite coatings are already common practice, the present invention allows for incorporation of smaller particles while also reducing the amount of electrolyte needed. In cases where composite coatings are needed on internal surfaces of hollow articles for improved corrosion resistance, wear resistance, or lubrication, this unique design is the first reported approach, which also significantly reduces the coating processing cost by eliminating the need of a large plating tank containing a large amount of electrolyte. The present invention may be used in industries seeking a low-cost process to produce coatings with improved oxidation/corrosion resistance or better tribological properties, including but not limited to the following four categories:
(1) Anti-corrosion coatings: anti-corrosion coatings for metallic objects are prevalent in nearly every U.S. industry sector, from infrastructure and transportation to production and manufacturing. Protective coatings are one of the most commonly used methods to prevent corrosion in industries such as the infrastructure and transportation, as well as the marine and container industries.
(2) High-temperature oxidation coatings: coatings to protect against high-temperature oxidation, such as thermal barrier coatings (TBCs), are being used in a variety of market segments, including diesel and gas engines, aerospace and land based turbine engines, and aerospace structure applications. One of applications of the present invention is to apply the metallic bond coat on gas turbine components with significant cost reduction compared to the prior art plasma spraying or electron-beam physical vapor deposition.
(3) Tribological coatings: The field of tribology, including friction, wear, and lubrication, is of enormous practical importance, because many mechanical and electromechanical systems rely on friction and wear properties. The apparatus in this invention has the capability of codepositing hard ceramic particles to strengthen metallic coatings and improve wear resistance codepositing solid lubricant particles such as polytetrafluoroethylene (PTFE) and graphite to produce self-lubricated composite coatings.
(4) Nanostructured coatings: Nanostructured coatings are likely to replace traditional coatings in the medium to long-term in end use segments such as anti-microbial, architectural, industrial manufacturing, marine, auto refinish, and transportation. The present invention makes electrodeposition of nanostructured coatings possible via utilization of an impervious rotating container.
Thus, it should be understood that the embodiments and examples described herein have been chosen and described in order to best illustrate the principles of the invention and its practical applications to thereby enable one of ordinary skill in the art to best utilize the invention in various embodiments and with various modifications as are suited for particular uses contemplated. Even though specific embodiments of this invention have been described, they are not to be taken as exhaustive. There are several variations that will be apparent to those skilled in the art.
Thus, although there have been described particular embodiments of the present invention of a new and useful APPARATUS AND PROCESS FOR PRODUCING COATINGS, it is not intended that such references be construed as limitations upon the scope of this invention.
This application claims priority to and the benefit of U.S. Provisional Patent Application No. 62/921,968 filed Jul. 18, 2019 entitled APPARATUS USED FOR PRODUCING COATINGS, which is hereby incorporated by reference in its entirety.
The subject matter herein was funded in part by Department of Energy Grant DE-FC26-FE0007332 and the Office of Naval Research Grant N00014-14-1-0341.
Number | Date | Country | |
---|---|---|---|
62921968 | Jul 2019 | US |