Patent Application
20120171374
The present disclosure is directed to a nozzle for use with a spray coating gun, and in particular, to an angled nozzle for cold spraying particles on surfaces with poor access.
Cold spray coating systems and methods are used to apply various types of coatings to a surface or substrate of an object. For example, a steel mechanical component may be coated with a protective layer of material to prevent corrosion of the mechanical component.
Cold spray methods use a spray gun that receives a high pressure gas such as, for example, helium, nitrogen, and air, and a coating material, such as, for example, metals, refractory metals, alloys, and composite materials in powder form. The powder granules are introduced at pressure into a gas stream in the spray gun and emitted from a nozzle. The gas stream velocity may be supersonic in the nozzle and/or after exiting the nozzle. The particles are accelerated to a high velocity in the gas stream that may reach a supersonic velocity.
The powder impacts the substrate at a high velocity. The kinetic energy of the powder causes the powder granules to deform and flatten on impact with the substrate. The flattening promotes a metallurgical, mechanical, or combination metallurgical and mechanical bond with the substrate and results in a protective coating on the substrate. Advantages of cold spraying methods include the negligible to nil phase change or oxidation of particles during flight and high adhesion strength of the bonded particles.
The spray gun with the converging/diverging nozzle that is used to accelerate the process gas to supersonic velocities is generally cumbersome, measuring 3-10 inches along a cylindrical or rectangular axis. While appropriate for use in many applications, these standard, straight-nozzle spray guns often cannot be used on internal areas and enclosed spaces, e.g., in transition pieces of a gas turbine or cylinders of internal combustion engines, as the nozzle cannot be properly positioned to deposit particles on the surface of the object in these areas of poor access.
Optimum spraying conditions are usually achieved when the high velocity particles impact the substrate as close to right angle as possible. This remains a challenge in smaller enclosed areas as the length of the nozzle does not allow a right angle spray. For e.g. an 8 inch long nozzle will require at least 10 inches of clearance to spray at right angles. Often such clearances are not available in smaller parts. If spraying is done at angle other than an angle which is approximately ninety degrees to the substrate, there is a decrease in the efficiency of the process, as the particles do not bond as effectively to the part or substrate, causing the affected area to have less deposited material.
It would, therefore, be beneficial to provide a spray gun with a nozzle that has the ability to spray locations that have poor access, i.e., in enclosed areas that are not accessible to conventional nozzles.
An exemplary embodiment includes a nozzle for applying a coating material to a substrate. The nozzle includes a discharge portion operative to emit the coating material therefrom. The nozzle also includes a material-receiving portion operative to receive feedstock therein. The discharge portion is angled from the material-receiving portion such that coating material is discharged from the discharge portion and impacts and bonds with a region of the substrate. The discharge portion can be positioned to apply the coating material in various locations.
An exemplary embodiment includes a kinetic spray coating gun for applying a coating material to a substrate. The kinetic spray coating gun includes a nozzle having a material-receiving portion and a nozzle discharge portion. The nozzle discharge portion operative to emit the coating material therefrom. A longitudinal axis of the nozzle discharge portion being angled relative to a longitudinal axis of the material-receiving portion such that the coating material impacts and bonds with a region of the substrate. The nozzle discharge opening can be positioned to apply the coating material in various locations.
An exemplary method of applying coating material to a substrate through a kinetic process includes: supplying feedstock to a material-receiving portion of a nozzle; mixing the feedstock to form a coating material; accelerating the coating material; and discharging the coating material from a discharge portion of the nozzle at an angle relative to a longitudinal axis of the material-receiving portion. The nozzle discharge portion can be positioned to apply the coating material to the substrate in various locations.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments. However, those skilled in the art will understand that the embodiments may be practiced without these specific details, that the embodiments are not limited to the depicted embodiments, and that the embodiments may be practiced in a variety of alternative embodiments. In other instances, well known methods, procedures, and components have not been described in detail.
Further, various operations may be described as multiple discrete steps performed in a manner that is helpful for understanding the embodiments. However, the order of description should not be construed as to imply that these operations need be performed in the order they are presented, or that they are even order-dependent. Moreover, repeated usage of the phrase “in an embodiment” does not necessarily refer to the same embodiment, although it may. Lastly, the terms “comprising,” “including,” “having,” and the like, as used in the present application, are intended to be synonymous unless otherwise indicated.
The disclosure relates to an article and process of applying cold spray technology to enclosed areas and areas having internal diameters which conventional cold spray nozzles cannot access.
In general, kinetic spray processes, such as cold spray process for depositing powder materials, such as, but not limited to, metal, alloy, cermet, or composite materials onto a surface or substrate are advantageous in that they provide sufficient energy to accelerate particles to high enough velocities such that, upon impact, the particles plastically deform and bond to the surface or onto a previously deposited layer. The process allows the build-up of a relatively dense coating or structural deposit.
Kinetic systems use a kinetic spray gun to apply a coating to a surface of an object (substrate).
In operation, the spray gun 102 receives pressurized gas from a gas source via the gas heater 112. The gas heater 112 heats the gas to a temperature of up to 1000 degrees Celsius, but usually to a temperature of less than 600 degrees Celsius. In alternate embodiments, the gas heater 112 may be bypassed, resulting in the pressurized gas not being heated. Feedstock, such as, but not limited to, coating material or powderized coating material is supplied under pressure to the spray gun 102 via the powder line 114. The coating material is introduced into a stream of gas internally in the spray gun 102. The coating material may be fed in a convergent or divergent region of the spray gun 102. The stream of expanding gas and coating material exits a divergent region of a nozzle in the spray gun 102. When the coating material impacts an object (substrate) 122, granules in the coating material flatten and deform to form a coating on the substrate 122. The control unit 106 controls the process—including, for example, the gas heater 112 and the powder feeder 104—and receives pressure and temperature readings from the spray gun sensors.
The optional heat source 108 may include one or more lasers or other type of heat source such as, for example, a heating element. For illustrative purposes, the embodiment includes a laser unit as the heat source 108. The lasers emit a beam of laser light (not shown). The beam of laser light may be used to pre-heat a region of the substrate 122 prior to the application of the coating material. Pre-heating a region of the substrate 122 prior to the application of the coating material may be desirable to improve the performance and properties of the applied coating. The pre-heating may also be used to heat coated regions of the substrate prior to the application of additional coats of coating material. The laser may also be used to anneal the deposits, substrate and/or the combination thereof.
The angle or bend 214 allows the nozzle 202 to be used to apply the cold spray to internal areas and enclosed spaces, e.g., in transition piece of gas turbines, cylinders of IC engines, etc. While the embodiment shown in
The extension portion 204 may be integral with the converging/diverging portion 206 and the angle or bend 214, forming a unitary, single-piece nozzle 202 where the nozzle bends towards the spraying side. Alternatively, the extension portion 204 and/or bend 214 and/or converging/diverging portion 206 may be formed as separate pieces and joined together in any known manner. Additionally, the angle or bend 214 may be a single piece or multiple pieces to form the angle required. The nozzles 202 can be either cylindrical or rectangular, or have any other cross-sectional shape, so long as the coating material is properly accelerated.
In operation, the spray gun assembly 200 receives process gas via a process inlet 210 and coating material via a granule or powder inlet 212. The coating material is introduced to the process gas in the extension portion 204 of the nozzle 202. Alternatively, the coating material may also be introduced in the diverging portion of the nozzle 202, thereby allowing the use of a lower pressure powder feed device as the back pressure in the diverging portion is lower than that prevailing upstream. The mixture of the stream of gas and granules or particles or the coating material and the process gas is moved through the converging/diverging portion 206. The coating material and the process gas exit the converging/diverging portion 206 and the nozzle 202 at an accelerated rate and the granules are deposited on the substrate or surface of the article. The nozzle 202 can be positioned to spray in locations that may be in enclosed areas that are not accessible to conventional, straight nozzles, which do not have an angle on the spraying side.
The angle or bend 314 allows the nozzle 302 to be used to apply the cold spray to internal areas and enclosed spaces, e.g., in transition piece of gas turbines, cylinders of IC engines, etc. While the embodiment shown in
The converging/diverging portion 306 may be integral with the extension portion 304 and the angle or bend 314, forming a unitary, single-piece nozzle 302 where the nozzle bends towards the spraying side. Alternatively, the converging/diverging portion 306 and/or bend 314 and/or extension portion 304 may be formed as separate pieces and joined together in any known manner. Additionally, the angle or bend 314 may be a single piece or multiple pieces to form the angle required. The nozzles 302 can be either cylindrical or rectangular, or have any other cross-sectional shape, so long as the coating material is properly accelerated.
In operation, the spray gun assembly 300 receives process gas via a process inlet 310 and coating material via a powder inlet 312. The coating material is introduced to the process gas in the converging/diverging portion 306 of the nozzle 302 and accelerated therein. The mixture of the granules of the coating material and the process gas is moved through the extension portion 304. The coating material and the process gas exit the extension portion 304 and the nozzle 302, and the granules are deposited onto the substrate or surface of the article. The nozzle 302 can be positioned to spray in locations that may be in enclosed areas that are not accessible to conventional, straight nozzles, which do not have an angle on the spraying side.
In this embodiment, inline gas heaters 420 may provided in the extension portion 404 to heat the process gas. An air inlet 422 is provided about the perimeter of the converging/diverging portion 406 and the extension portion 404, the air inlet 422 provides air to cool the substrate and the coating material when it is applied to the substrate.
The angle or bend 414 allows the nozzle 402 to be used to apply the cold spray to internal areas and enclosed spaces, e.g. in transition piece of gas turbines, cylinders of IC engines etc. While the embodiment shown in
The nozzle may be formed in one piece to include the process inlet 410 and the powder inlet 412. Alternatively, the nozzle 402 may be enclosed in a sheath or the nozzle 402 may include tubular sections throughout the length to form process gas and powder feed channels. The nozzles 402 can be either cylindrical or rectangular, or have any other cross-sectional shape, so long as the coating material is properly accelerated.
In operation, the spray gun assembly 400 receives process gas via a process inlet 410 and coating material via a powder inlet 412. The coating material is introduced to the process gas in the extension portion 404 of the nozzle 402 and heated by heaters 420. The mixture of the coating material and the process gas is moved through the converging/diverging portion 406. The coating material and the process gas exit the converging/diverging portion 406 and the nozzle 402 at an accelerated rate, and the granules of the coating material are deposited onto the substrate or surface of the article. Air is supplied through the air inlet 422 of the nozzle 402 to cool the substrate and the coating material. The nozzle 402 can be positioned to spray in locations that may be in enclosed areas that are not accessible to conventional, straight nozzles, which do not have an angle on the spraying side.
In this embodiment, inline gas heaters 520 are provided in the first extension portion 504 to heat the process gas. An air inlet 522 is provided about the perimeter of the first extension portion 504, the converging/diverging portion 506 and the second extension portion 507, the air inlet 522 providing air to cool the substrate and the coating material when it is applied to the substrate. Substrate/coating cooling may be required in some situations where the process gas is heated and the process requirement is to keep the substrate/coating temperature low.
The angle or bend 514 allows the nozzle 502 to be used to apply the cold spray to internal areas and enclosed spaces, e.g., in transition piece of gas turbines, cylinders of IC engines, etc. While the embodiment shown in
The nozzle may be formed in one piece to include the process inlet 510 and the powder inlet 512. Alternatively, the nozzle 502 may be enclosed in a sheath or the nozzle 502 may include tubular sections throughout the length to form process gas and powder feed channels. The nozzles 502 can be either cylindrical or rectangular, or have any other cross-sectional shape, so long as the coating material is properly accelerated.
In operation, the spray gun assembly 500 receives process gas via a process inlet 510 and coating material via a powder inlet 512. The coating material is introduced to the process gas in the first extension portion 504 of the nozzle 502 and heated by heaters 520. The coating material is introduced to the process gas in the converging/diverging portion 506 of the nozzle 502 and accelerated therein. The mixture of the coating material and the process gas is moved through the extension portion 504. The coating material and the process gas exit the second extension portion 507 and the nozzle 502, and the granules of the coating mixture are deposited onto the substrate or surface of the article. Air is supplied through the air inlet 522 of the nozzle 502 to cool the substrate and the coating material. The nozzle 502 can be positioned to spray in locations that may be in enclosed areas that are not accessible to conventional, straight nozzles, which do not have an angle on the spraying side.
The relative movement of the components of the nozzle 602 allows the nozzle 602 to be used to apply the cold spray to internal areas and enclosed spaces, e.g., in transition piece of gas turbines, cylinders of IC engines, etc. While the embodiment shown in
In operation, the spray gun assembly 600 receives process gas via a process inlet 610 and coating material via a powder inlet 612. The coating material is introduced to the process gas in the extension portion 604 of the nozzle 602. The process gas is moved through the rotating portion 605 and the converging/diverging portion 606. The coating material is injected into the gas stream via a feeder tube 605 in the converging portion of the diverging portion. The coating material and the process gas exit the converging/diverging portion 606 and the nozzle 602 at an accelerated rate, and the coating material is deposited onto the substrate or surface of the article. The nozzle 602 can be positioned to spray in locations that may be in enclosed areas that are not accessible to conventional, straight nozzles, which do not have an angle on the spraying side.
While
In any of the embodiments, the nozzles may include temperature and pressure sensor connections and tubing to carry the cables for such sensor connections. Sensors may be attached to the sensor connections, which may be located at various positions in the nozzle to enable appropriate temperature and pressure measurements.
An extension attachment may be provided at the end of the nozzle. The attachment may be made as long as the part requires, such as length of 2 meters, more specifically 1 meter, and even more specifically 0.5 meters. This will facilitate to coating of long tubular parts. The flow of the coating material through the attachment would create a laminar effect in the flow. In one embodiment, an extension attachment may be attached to the discharge end, such that the extension attachment can be rotated along the radial axis of the discharge end to allow the coating material to be deposited as desired.
The nozzles and method for use with a kinetic spray gun described and claimed herein, allows for the coating material to be applied to surfaces in enclosed areas, internal areas of components, and other areas which are difficult to reach using known nozzles. This allows the surfaces or substrates to be uniformly coated using cold spray technology. Benefits of such coatings include, but are not limited to, improvement in the life of the components and permitting the use of higher temperatures in turbines. In addition, lower quality fuel [and high moisture fuels] could also be used if suitable coatings can be applied to mitigate corrosion and erosion issues arising from using lower quality fuel.
While the written description has referred to a preferred embodiment, it will be understood by those skilled in the art that various changes and modifications may be made and equivalents may be substituted for elements thereof without departing from the patentable scope as defined by the claims. Therefore, it is intended that the patentable scope not be limited to the particular embodiments disclosed as the best mode contemplated, but rather other embodiments are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
