Design of multiple nozzles in cold spray systems and related methods.

Abstract

Disclosed herein is a cold spray system. The cold spray system includes a nozzle unit including a coating nozzle member configured to apply at least a portion of a metal coating to a substrate. The cold spray system is configured to preheat the substrate prior to applying at least a portion of the metal coating to the substrate. Also disclosed herein is a method for applying a coating via cold spray techniques.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 62 / 923,878, entitled "MULTIPLE NOZZLE DESIGN IN A COLD SPRAY SYSTEM FOR ACCIDENT TOLERANT FUEL PRODUCTION," filed October 21, 2019, the contents of which are incorporated herein by reference. [Background technology]

[0002] 1.Technical Field The present disclosure relates to an apparatus and method for applying cold spray coatings.

[0003] 2. Related Technologies Accident Tolerant Fuel (ATF) is a term used to describe new technologies that improve the safety and performance of nuclear fuel. Such fuel may incorporate the use of new materials and designs for the cladding and fuel pellets. The goal of such fuel is to better tolerate the loss of active cooling in the core while maintaining or improving the performance and economics of the fuel during normal operation.

[0004] Cold spray deposition is an excellent method for coating a chromium (Cr) layer on a base Zr alloy fuel cladding, such as ZIRLO® or Optimized ZIRLO™ cladding, which will be a product associated with Westinghouse EnCore® accident tolerant fuel. However, the availability of helium for use as a carrier gas for cold spray is limited. Also, the helium consumed during cold spray is very expensive, and no completely satisfactory solution has been found. Nitrogen is an alternative gas that can be used in place of helium in cold spray. However, in current system designs, the traverse speed of the cold spray nozzle with nitrogen is limited to maintain a satisfactory coating thickness. Thus, the overall cost of producing Cr-coated cladding remains relatively high. Summary of the Invention

[0005] The present disclosure provides a new multiple nozzle design in a cold spray system that can be used in the production of ATF. In this arrangement, several nozzles are used to achieve an optional gas-tight metal coated layer on the cladding that can function in the actual operating conditions of a PWR or BWR, even under accident conditions. The multiple nozzles are deployed in three (3) dimensions and do not have to be deployed in the same plane, for example. The design can coat a high quality chrome layer with nitrogen while increasing the nozzle traverse speed.

[0006] Disclosed herein is a cold spray system comprising a nozzle unit comprising a coating nozzle member configured to apply at least a portion of a metal coating to a substrate, the cold spray system being configured to preheat the substrate prior to applying at least a portion of the metal coating to the substrate.

[0007] Also disclosed herein is a method for applying a coating via cold spray techniques, the method including preheating a substrate and applying at least a portion of a metallic coating to the preheated substrate.

[0008] These and other objects, features and characteristics of the present disclosure, together with the method of operation and function of the associated structural elements and combinations of parts and economy of manufacture, will become more apparent from a consideration of the following description and the appended claims, all of which form a part hereof, when taken in conjunction with the accompanying drawings in which like reference numerals indicate corresponding parts in the various views, It is to be expressly understood, however, that the drawings are for the purpose of illustration and description only and are not intended as a definition of the limits of the invention. [Brief description of the drawings]

[0009] A further understanding of the present disclosure can be obtained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings.

[0010] [Figure 1] 2 is a perspective, partially schematic view of a dual nozzle arrangement for applying a coating onto a fuel rod cladding according to one embodiment of the present disclosure; FIG. [Diagram 2] FIG. 13 is a perspective partial schematic diagram of another arrangement according to one embodiment of the present disclosure utilizing three of the dual nozzle arrangements to apply coating to three rods simultaneously. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] In the following description, like reference numerals designate like or corresponding parts throughout the several views of the drawings. It should also be understood that in the following description, terms such as "front", "rear", "left", "right", "upward", "downward", etc. are terms of convenience and should not be construed as limiting terms. As used herein, the term "number" shall be used to refer to any non-zero integer quantity, i.e., 1 or any integer greater than 1 (e.g., 1, 2, 3, ...).

[0012] The present disclosure includes a cold spray system comprising one or more nozzle members for applying a cold spray coating. The nozzle members may be arranged in pairs to form a dual nozzle unit. As used herein, "dual" implies a pair of nozzle members. However, unless otherwise stated, when "dual" is used, embodiments comprising three or more nozzle members per unit are also contemplated. A partial schematic diagram of a dual nozzle unit 100 according to the present disclosure is shown in FIG. 1. The exemplary dual nozzle unit 100 shown in FIG. 1 may comprise various components (e.g., 102-110). The preheat nozzle member 102a may function as a preheater for heating the substrate 112 (e.g., cladding tube). Alternatively or additionally, the substrate 112 may be pre-cleaned by the preheat nozzle member 102a (e.g., by the preheat nozzle member 102a spraying hot gas onto the substrate 112). The cold spray system may further comprise a coating nozzle member 102b. The coating nozzle member 102b can be configured to apply at least a portion of the metal coating via a cold spray process to a preheated substrate 112. As used herein, "preheat" means increasing the temperature of the substrate above ambient temperature before at least a portion of the metal coating is applied to the substrate 112 via a cold spray process.

[0013] Alternatively, or in addition to the preheat nozzle member 102a, other heat sources may be included. Thus, the cold spray system may include a heat gun, a preheat chamber, an inductive heating element, an electrical local heating device, or a combination thereof, to preheat and / or preclean the substrate 112.

[0014] The substrate 112 may include, for example, zirconium or zirconium alloy tubing (e.g., nuclear fuel rod cladding, control rod cladding). The zirconium alloy may include, for example, alloys including zirconium and tin and / or niobium (e.g., ZIRLO® and Optimized ZIRLO™ alloys available from Westinghouse Electric Company of Cranberry Twp., Pennsylvania, United States).

[0015] Metallic coatings may be applied to the substrate 112 via a cold spray process performed by the cold spray system of the present disclosure. The metallic coating may include a single metallic material or alloy, or the metallic coating may include multiple layers or regions, each layer or region including a different metallic material or alloy. Without being limited thereto, the metallic coating may be applied using metallic materials (e.g., powders) including one or more of chromium, niobium, copper, nickel, and aluminum. Although described herein for use in applying coatings for the production of ATFs, it should be understood that the systems and components described herein may be used in other cold spray applications, such as crack repair, pipe coating, or other coatings, without departing from the scope of the present disclosure.

[0016] The preheat nozzle member 102a, if used, can deposit a first layer of metal coating on the substrate 112, optionally in addition to preheating and / or precleaning the substrate 112. The application of the first layer of metal coating can also accomplish preheating / precleaning of the substrate 112. The coating nozzle member 102b can then apply a second coating layer to the same area of ​​the substrate 112 that was first coated and preheated by the preheat nozzle member 102a. The substrate 112 can move relative to the dual nozzle unit 100 and / or the unit 100 can move relative to the substrate 112. In this manner, a multi-layer coating can be formed. The multi-layer coating can include, for example, niobium arranged on the substrate 112 by the preheat nozzle member 102a and chromium arranged on the niobium by the coating nozzle member 102b.

[0017] If the preheat nozzle member 102a is not used to deposit a coating (but is still used to preheat / preclean the substrate), the preheat nozzle member 102a can be supplied with heated and / or pressurized gas. The gas can be heated such that the substrate 112 is not heated above an oxidation acceleration threshold (e.g., not more than 500° C., not more than 400° C., not more than 300° C.). In this case, the heated gas can include a carrier gas, as described below, and / or another gas, such as air. In this case, the coating nozzle member 102b can apply a single layer coating, e.g., a coating including chromium.

[0018] When the pre-heated nozzle member 102a is used for depositing a coating and for pre-heating / pre-cleaning a substrate, the pre-heated nozzle member can be supplied with heated carrier gas and metal coating material (e.g., powder).

[0019] A gas line 104 can be connected to the preheat nozzle member 102a, and heated and / or pressurized gas can be delivered from the gas line 104 to the preheat nozzle member 102a. The heated gas can act as a medium to carry heat to the substrate 112 to achieve preheating / precleaning of the substrate 112. The dual nozzle unit 100 can optionally include a second line (not shown) in communication with the preheat nozzle member 102a. If a second line is present, the gas line 104 can deliver a heated carrier gas and the second line can deliver a metal coating material (e.g., a metal powder as described above). If both lines are present, the preheat nozzle member 102a can also mix the gas with the powder and / or allow the gas to heat the powder prior to application.

[0020] Two lines 106, 108 may be in communication with the coating nozzle member 102b. Line 106 may carry a heated and / or pressurized carrier gas and may deliver the gas to the coating nozzle member 102b. Line 108 may carry the metal coating material. The coating nozzle member 102b may also mix the gas with the powder and allow the gas to heat the powder before application.

[0021] The gas and / or powder delivery lines 104, 106, 108 may include flexible lines.

[0022] The nozzle connector 110 allows the two nozzles 102a, 102b to be clamped together and aligned with the substrate 112. The other end of the nozzle connector 110 can be connected to a robotic arm (not shown) to maneuver the unit around the substrate 112, or can be fixed in place and the substrate 112 can move relative to the static unit 100.

[0023] For cold spray processing, the method can proceed by delivering the carrier gas to a heater where the carrier gas is heated to a temperature sufficient to maintain the gas at a desired temperature. The desired temperature (after expansion of the gas as it passes through the nozzle members 102a, 102b) can be less than half the melting temperature of the metal coating material (e.g., 100°C to 750°C). The desired temperature can also be below the oxidation acceleration temperature of the substrate 112 (e.g., 400°C to 500°C). The carrier gas can be initially pressurized, for example, at a pressure of 5.0 MPa.

[0024] The carrier gas may optionally be preheated to a temperature of 200°C to 1000°C, 300°C to 900°C, or 500°C to 800°C. The optional preheat temperature will depend on the Joule-Thomson cooling coefficient of the particular gas used as the carrier. Whether the gas cools as the pressure of the gas changes and it expands or compresses depends on the value of the Joule-Thomson coefficient. If the Joule-Thomson coefficient is positive, the carrier gas will cool and therefore needs to be preheated to prevent excessive cooling, which may affect the performance of the cold spray process. Those skilled in the art can use calculations to determine the degree of heating to prevent excessive cooling. For example, if the carrier gas is N2, then if the inlet temperature is 130°C, the Joule-Thomson coefficient is 0.1°C / bar. If the initial pressure is 10 bar (about 146.9 psig) and the final pressure is 1 bar (about 14.69 psig), in order to impinge the gas on the tube at 130°C, the gas needs to be preheated to about 9 bar * 0.1°C / bar or about 0.9°C to about 130.9°C. As another example, the temperature of the helium gas as the carrier can be 450°C at a pressure of 3.0-4.0 MPa, and the temperature of the nitrogen gas as the carrier can be 1100°C at a pressure of 5.0 MPa, but can also be 600°C to 800°C at a pressure of 3.0-4.0 MPa. Those skilled in the art will understand that the temperature and pressure variables will vary depending on the type of equipment used, and that the temperature, pressure and volume parameters can be adjusted by modifying the equipment.

[0025] The cold spray process propels particles onto the substrate 112 by controlling the expansion of a heated carrier gas. The particles impact the substrate 112 or a previously deposited layer and undergo plastic deformation by adiabatic shear. Subsequent particle impacts accumulate to form a coating. The particles may also be warmed to one-third to one-half of the powder's melting point before the carrier gas is introduced to facilitate deformation. The nozzles 102a, 102b may be rastered (e.g., sprayed in a pattern where an area is sprayed side-by-side, top-to-bottom) across the area to be coated or where material accumulation is required.

[0026] Suitable carrier gases are inert (e.g., non-reactive) gases and gases that do not specifically react with the particles or substrate 112. Exemplary carrier gases include nitrogen (N2), argon (Ar), carbon dioxide (CO2), and helium (He).

[0027] There is considerable flexibility regarding the carrier gas selected. Mixtures of gases may be used. The selection is driven by both physical properties and economics. For example, low molecular weight gases provide higher velocities, but the highest velocities should be avoided as they may result in particle bouncing, thereby reducing the number of deposited particles. The present disclosure allows for increased flexibility in choosing a carrier gas and may allow for increased use of nitrogen rather than helium, while maintaining or improving coating quality and deposition speed.

[0028] A partial schematic diagram of a multi-nozzle design 200 in a cold spray system is shown in FIG. 2. Typically, the multi-nozzle system 200 may comprise two or more dual nozzle units 100, such as the dual nozzle unit discussed above with respect to FIG. 1. For example, FIG. 2 shows three dual nozzle units 200a, 200b, and 200c controlled together by one cold spray system. The dual nozzle units 200a, 200b, and 200c may be aligned with the substrates 212a, 212b, and 212c, respectively. The three dual nozzle units 200a, 200b, and 200c, which may be integrated into a robot arm or fixed in place as the substrate moves relative to the static nozzle, are controlled by one cold spray system. Three Zr alloy cladding tubes (for example) may be coated simultaneously. Such a multi-nozzle design 200 may further increase the production rate of coated substrates 212a-c. For example, the design shown in Figure 2 will result in a 3x increase in production rate (compared to one dual nozzle unit 100). In summary, using N dual nozzle units can result in an Nx increase in production rate (compared to one dual nozzle unit). Note that the dual nozzle unit, powder feeder, robot controller, and cold spray main unit can all optionally be integrated together for optimized operation.

[0029] The cold spray system of the present disclosure may further include additional components. For example, the cold spray system may include one or more of a plurality of nozzle units 200a-c, a plurality of powder feeders (and feed lines 108) for feeding powder to the nozzle units 200a-c, a robotic controller providing an operator means for controlling the system, and a cold spray main unit, integrated together for operation.

[0030] In summary, the multiple nozzle is an important new device in cold spray systems utilized for coating substrates such as fuel rod cladding. Such devices are very practical to implement and can be constructed to produce coated cladding more efficiently by increasing the amount of deposited powder (by pre-heating / pre-cleaning the substrate) and with higher coating quality.

[0031] Also disclosed herein is a method for applying a coating via cold spray techniques. The method may be performed by a cold spray system disclosed herein. The method may include preheating a substrate 112, 212a-c to be coated and applying at least a portion of a metal coating to the preheated substrate. Preheating may be accomplished by any heat source described herein and may help increase bonding between the substrate 112, 212a-c and the coating.

[0032] Pre-heating the substrate 112, 212a-c may be accomplished via a nozzle member or heat gun capable of spraying hot gas onto the substrate 112, 212a-c, a pre-heat chamber in which the substrate 112, 212a-c may be located for a period of time before at least a portion of the coating is applied, an induction heating element capable of inducing an electric current in the substrate 112, 212a-c to heat the substrate 112, 212a-c, an electric local heating device, or a combination thereof.

[0033] Pre-heating of the substrate 112, 212a-c may be accomplished via pre-heat nozzle member 102a, and at least a portion of the metal coating may be applied via coating nozzle member 102b.

[0034] The pre-heat nozzle member 102a can also optionally apply a first portion of the metal coating, thereby pre-heating and coating the substrates 112, 212a-c, and the coating nozzle member 102b can apply a second portion of the metal coating.

[0035] The method may further include pre-cleaning the substrate 112, 212a-c using the first nozzle member 102a.

[0036] An advantage of the cold spray system and method described herein is that after preheating the substrate 112, 212a-c, a metal coating layer with improved bond strength and hermeticity can be achieved. Preheating can improve the bond formation between the substrate 112, 212a-c and the coating or between two coatings. Furthermore, preheating can increase the possible deposition and / or traversal speed (e.g., by improving the bond to the substrate). Precleaning can also remove contaminants that may interfere with the coating process, such as residues, chemical impurities, and / or particulate debris. This approach not only significantly improves the quality of the coating layer, but also smoothly increases the production rate.

[0037] Additionally, the cold spray systems described herein may allow for time and cost savings during coating of substrates by using cheaper nitrogen gas to at least partially replace the more expensive and hard to obtain helium.

[0038] Various aspects of the subject matter described herein are illustrated in the following examples.

[0039] Example 1 - A cold spray system comprising a nozzle unit, the nozzle unit comprising a coating nozzle member configured to apply at least a portion of a metal coating to a substrate, the cold spray system configured to preheat the substrate prior to applying at least a portion of the metal coating to the substrate. Example 2 - The cold spray system of Example 1, wherein the nozzle unit further comprises a preheat nozzle member, a heat gun, a preheat chamber, an induction heating element, an electrical local heating device, or a combination thereof, configured to preheat the substrate prior to applying at least a portion of the metal coating to the substrate. Example 3 - The cold spray system of example 1 or 2, further comprising a preheat nozzle member configured to preheat the substrate prior to applying at least a portion of the metal coating to the substrate. Example 4 - The cold spray system of Example 3, wherein the preheat nozzle is configured to both preheat the substrate prior to applying at least a portion of the metal coating to the substrate and to apply a portion of the metal coating to the substrate. Example 5 - A cold spray system as described in Example 3 or 4, wherein the preheat nozzle and the coating nozzle are configured to apply two different metal coating components, respectively. Example 6 - A cold spray system described in any one of Examples 1 to 5, comprising one or more of a plurality of nozzle units, a plurality of powder feeders, a robotic control device, and a cold spray main unit, integrated together for operation. Example 7 - A method for applying a coating by cold spray technique, comprising a preheating step of preheating a substrate, and an application step of applying at least a portion of a metal coating to the preheated substrate. Example 8 - The method of Example 7, wherein the preheating step is accomplished by a preheat nozzle member, a heat gun, a preheat chamber, an induction heating element, an electrical local heating device, or a combination thereof configured to preheat the substrate. Example 9 - The method of example 7 or 8, wherein the preheating step is accomplished by a preheating nozzle member and at least a portion of the metal coating is applied by a coating nozzle member. Example 10 - The method of example 9, wherein a preheating nozzle member applies a first portion of the metal coating, thereby coating and preheating the substrate, and a second nozzle member applies a second portion of the metal coating. Example 11 - The method of example 9 or 10, further comprising a cleaning step of pre-cleaning the substrate using a pre-heated nozzle member. Example 12 - The method of example 9, wherein the metal coating comprises chromium. Example 13 - The method of example 10, wherein the first portion of the metal coating comprises niobium and the second portion of the metal coating comprises chromium.

[0040] Although specific embodiments of the present invention have been described in detail, it will be understood that various modifications and alternatives to these details may be developed by those skilled in the art in light of the overall teachings of the present disclosure. Accordingly, the specific embodiments disclosed are intended to be illustrative only and not limiting as to the scope of the invention, which is to be given the full scope of the appended claims and any and all equivalents thereof.

Claims

1. 1. A cold spray system comprising: A nozzle unit is provided. The nozzle unit is a coating nozzle member configured to apply a first portion of a metal coating, the first portion comprising chromium, to a specific portion of a substrate; a preheat nozzle member configured to deliver a gas to the substrate to preheat the substrate prior to applying the first portion of the metal coating to the specific portion of the substrate, and to apply a second portion of the metal coating, the second portion comprising niobium, to the specific portion of the substrate. Cold spray system.

2. 10. The cold spray system of claim 1, further comprising a heat gun, a preheat chamber, an induction heating element, an electrical local heating device, or a combination thereof configured to preheat the substrate prior to applying the at least a portion of the metal coating to the substrate.

3. 3. The cold spray system of claim 1 or 2, comprising one or more of a plurality of the nozzle units, a plurality of powder feeders, a robotic controller, and a cold spray main unit integrated together for operation.

4. 1. A method for applying a coating by cold spray technology, comprising: delivering gas to the substrate with a preheat nozzle member to preheat the substrate and applying a first portion of a metal coating with the preheat nozzle member, the first portion including niobium, to a specific portion of the substrate; applying a second portion of the metal coating, the second portion comprising chromium, to the specific portion of the pre-heated substrate with a coating nozzle member.

5. The method of claim 4 , further comprising preheating the substrate with a heat gun, a preheat chamber, an induction heating element, an electrical local heating device, or a combination thereof.

6. The method of claim 4 or 5, further comprising a cleaning step of pre-cleaning the substrate using the pre-heated nozzle member.

Images