Method for manufacturing nanostructured and compositionally tailored tubes and components by cryogenic solid-state cold spray powder deposition

Abstract

The present invention discloses a method for manufacturing a freestanding cladding tube having a multi-layer structure. According to the method, a cylindrical mandrel substrate defining a hollow cylindrical inner space is provided. A first cold spray powder metal is selected. The cylindrical mandrel substrate is rotated, and the first cold spray powder metal is applied to the outer surface of the cylindrical mandrel substrate to form a first layer. The cylindrical mandrel substrate is removed.

Description

[0001] Cross - Reference to Related Applications

[0002] This application claims the benefit of U.S. Non - Provisional Application No. 16 / 878,523, filed on May 19, 2020, entitled "METHODS FOR MANUFACTURING NANOSTRUCTURED AND COMPOSITIONALLY - TAILORED TUBES AND COMPONENTS BY LOW TEMPERATURE, SOLID - STATE COLD SPRAY POWDER DEPOSITION", the content of which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure generally relates to methods for manufacturing nanostructured and compositionally - tailored tubes and components. More specifically, the present disclosure relates to methods for manufacturing nanostructured and compositionally - tailored tubes and components by low - temperature, solid - state cold - spray powder deposition. Applications include, for example, nuclear reactor cladding tubes for containing uranium - based fuel. Background Art

[0004] Conventional melting and casting methods are not suitable for manufacturing oxide - dispersion - strengthened (ODS) steels because they result in upward stratification of oxide nanoparticles. Figure 1 Method 100 for manufacturing a nanostructured ODS steel cladding tube 114 is shown. Thus, as Figure 1As shown, the solid-state processing method involves a combination of powder consolidation and extrusion to fabricate an ODS steel cladding tube 114. According to method 100, the milled powder 102 is canned and degassed in a vacuum at about 400 °C, and mechanically alloyed 104 to produce a mechanically alloyed (MA) powder tube 106 loaded into low-carbon steel, which is then hot extruded 108 at about 1100 °C. First, the matrix powder (ferritic steel) is milled with oxide nanoparticles to make a mechanically alloyed powder. Then the powder is consolidated by canning in a low-carbon steel outer shell. The bulk material undergoes hot / warm extrusion, followed by multiple pilgering and intermediate heat treatments to make the final dimensions. To reduce the diameter and wall thickness of the tube 106 to the dimensions of the final cladding tube 114, further extrusion is required, reaching a ratio of 5 to 8. This is achieved by multiple warm extrusions 108 at a temperature of about 850 °C and intermediate annealing steps to avoid cracking. These multiple extrusions 108 result in a large anisotropy in the grain structure and mechanical properties. To produce fine equiaxed grains, further cold extrusion 110 with an intermediate annealing treatment 112 is required to cause recrystallization. All these extrusion steps are inherently slow, low strain rate processes and are not suitable for rapidly and economically fabricating the ODS steel cladding tube 114. In addition, a large number of thermomechanical steps can lead to random variations in the microstructure and properties of the cladding tube 114.

[0005] Accordingly, there is a need for a cold spray method to provide a rapid, cost-saving method for fabricating ODS steel cladding tubes with potentially more uniform microstructures and enhanced properties. There is also a need to apply the basic principles described in the present disclosure to the near-net shape fabrication of other components and materials. SUMMARY OF THE INVENTION

[0006] In one aspect, the present disclosure provides a method for fabricating a freestanding cladding tube having a multi-layer structure. The method includes providing a cylindrical mandrel substrate defining a hollow cylindrical inner space; selecting a first cold spray powder metal; rotating the cylindrical mandrel substrate; applying the first cold spray powder metal to an outer surface of the cylindrical mandrel substrate to form a first layer; and removing the cylindrical mandrel substrate.

[0007] In addition to the foregoing, various other methods are set forth and described in the teachings such as in the text of the present disclosure (e.g., claims and / or detailed description) and / or the drawings.

[0008] The foregoing is a summary of the invention and, as such, may contain simplifications, generalizations, inclusions, and / or omissions of detail; accordingly, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be limiting in any way. Other aspects, features, and advantages of the apparatus and / or process and / or other subject matter described herein will become apparent from the teachings set forth herein.

[0009] In addition, it should be understood that any one or more of the forms, form expressions, and examples described below can be combined with any one or more of the other forms, form expressions, and examples described below.

[0010] The foregoing summary is merely illustrative and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, additional aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The novel features of the forms are particularly set forth in the appended claims. However, the forms with respect to the organization and method of operation may best be understood by reference to the following description in conjunction with the accompanying drawings, in which:

[0012] Figure 1 A method for typically manufacturing a nanostructured ODS steel cladding tube is shown.

[0013] Figure 2 A cold spray method for manufacturing a freestanding ODS steel cladding tube having a multi-layer structure according to at least one aspect of the present disclosure is shown.

[0014] Figure 3 For use according to at least one aspect of the present disclosure Figure 2 A cross-sectional view of an ODS steel cladding tube having a multi-layer structure manufactured by the cold spray method shown.

[0015] Figure 4 A micro cross-sectional view of a freestanding ODS steel cladding tube according to at least one aspect of the present disclosure, the freestanding ODS steel cladding tube including an ODS steel material having a protective outer coating, the protective outer coating having an iron-chromium-aluminum alloy prepared using Figure 2 the cold spray method.

[0016] Figure 5 A micro cross-sectional view of a freestanding ODS steel cladding tube according to at least one aspect of the present disclosure, the freestanding ODS steel cladding tube including an ODS steel material having a protective outer coating, the protective outer coating having pure chromium prepared using Figure 2 the cold spray method.

[0017] Figure 6 A micrograph view of the morphology and size of ODS steel feedstock powder prepared by a gas atomization method according to at least one aspect of the present disclosure.

[0018] Figure 7 For according to at least one aspect of the present disclosure by using Figure 6Micrograph views of the morphology and size of an ODS steel feedstock powder prepared by ball milling a gas atomized powder with oxide nanoparticles.

[0019] Figure 8 For an ODS steel feedstock powder prepared by cryogenic milling of a ball milled gas atomized powder according to at least one aspect of the present disclosure Figure 7 Micrograph views of the morphology and size of an ODS steel feedstock powder prepared by cryogenic milling of a ball milled gas atomized powder according to at least one aspect of the present disclosure.

[0020] Figure 9 For a method of fabricating a freestanding ODS steel cladding tube having a multi-layer structure using Figure 10 the cold spray method shown in.

[0021] Figure 10 A schematic view of a cold spray method according to at least one aspect of the present disclosure is shown. Detailed Description

[0022] Before explaining in detail the aspects of a method for fabricating nanostructured and compositionally tailored tubes and components, and more particularly, a method for fabricating nanostructured and compositionally tailored tubes and components by cryogenic solid-state cold spray powder deposition, it should be noted that the illustrative aspects are not limited in application or use to the details of the construction and arrangement of the components shown in the figures and the specification. The illustrative aspects can be implemented or incorporated in other aspects, variations, and modifications and can be practiced or implemented in various ways. Further, unless otherwise noted, the terms and expressions used herein are selected for the purpose of facilitating the description of the illustrative aspects to the reader and not for the purpose of limiting them.

[0023] In addition, it should be understood that any one or more of the forms, form expressions, examples described below can be combined with any one or more of the other forms, form expressions, and examples described below.

[0024] In one aspect, as described above, the present disclosure relates to a method for fabricating nanostructured and compositionally tailored tubes and components. In other aspects, the present disclosure relates to a method for fabricating nanostructured and compositionally tailored tubes and components by cryogenic solid-state cold spray powder deposition.

[0025] Oxide dispersion strengthened (ODS) steels are good cladding candidates for Generation IV nuclear reactors such as lead fast reactors (LFRs), microreactors, and potential fossil plant boiler tube applications due to their excellent high-temperature strength and radiation stability. However, ODS steels may lack corrosion resistance in certain high-temperature environments that is disproportionate to the improved high-temperature strength that such steels can provide. Additionally, in nuclear fuel cladding applications, the inner surface of the cladding tube contacts the fuel, and over time, at high temperatures, due to interdiffusion between the tube and the fuel material, low melting point compounds can form.

[0026] Methods involving melting and solidification cannot produce nanostructured ODS steels because the oxide particles will coalesce, resulting in macroscopic scale inhomogeneities. Melting and solidification methods for preparing oxidation and corrosion resistant coatings or internal diffusion barrier coatings can result in loss of the basic nanostructural quality of the ODS steels. Even high temperature, high pressure solid state coating treatments can result in similar effects.

[0027] According to aspects of the present disclosure, a low temperature solid state cold spray method is used and is necessary for the preservation of the nanostructures in the ODS steel cladding. Different from current extrusion - annealing - extrusion methods (such as those Figure 1 described therein), the cold spray method is rapid and can be used for rapid prototyping / manufacturing.

[0028] According to aspects of the present disclosure, random variations in the microstructure are minimized due to the elimination of multiple processing steps. There is no or minimal high energy input and high temperature involved in manufacturing the tube. Although scribing the inner surface of a long low - diameter tube is very challenging, in one aspect, the present disclosure provides a method for very easily manufacturing a long low - diameter tube by an alternative, technically smaller, superior and more cost - saving method. For manufacturing a lining on the inner surface of the tube, the method according to the present disclosure eliminates problems associated with different thermo - mechanical properties (behavior) between two materials, which can lead to stresses and cracking during manufacturing.

[0029] The cold spray method according to various aspects of the present disclosure is suitable for various types of powder forms, including gas atomized spherical powders, ball - milled or cryo - milled powders, and post - heat - treated powders prepared by mechanical milling. This allows optimization of the microstructure of the ODS steel cladding tube and is used to manufacture outer and inner coatings with different compositions and functional gradings that may have different compositions for protection in various extreme environments. The latter greatly expands the ability of the high - strength ODS cladding tube to be used in harsh environments while also eliminating its direct contact with the fuel.

[0030] Turning now to the drawings, Figure 2The cold spray method 200 for manufacturing a freestanding nanostructured ODS steel cladding tube with a multi-layer structure using a cold (low-temperature) spray method is shown, in accordance with at least one aspect of the present disclosure. In one aspect, the freestanding nanostructured ODS steel cladding tube manufactured using the cold spray method 200 may include a multi-layer structure that includes a liner and / or an external coating. Generally, various forms of powder materials having a nanostructured grain structure are spray-deposited at a low temperature onto the surface of a cylindrical mandrel substrate 202 that defines a hollow cylindrical internal space 204, while the cylindrical mandrel substrate 202 rotates about its longitudinal axis A. The powder liner material is loaded in a powder feeder / hopper that is in fluid communication with a powder nozzle 206. As the powder nozzle 206 is translated along the length of the cylindrical mandrel substrate 202 in the forward direction shown by arrow B, the powder nozzle 206 ejects a beam 208 of the powdered liner material. This deposits a liner layer 210 on the outer surface of the cylindrical mandrel substrate 202. To increase the thickness of the liner layer 210, the powder nozzle 206 may be translated backward and forward in multiple passes to deposit additional liner material until the desired thickness of the inner layer 210 is achieved. In another aspect, the translation speed may be reduced to increase the coating thickness. Generally, the layer thickness may be controlled by adjusting the translation or traverse speed of the powder nozzle 206. The liner layer 210 material may be a powdered refractory metal and alloy of nanoparticle size that provides a diffusion barrier layer in nuclear power applications. The liner layer 210 material includes metals (and alloys) that generally exhibit low solid solubility in uranium and steel and have a high melting point, including but not limited to refractory alloys such as V, Mo, Mo-Re alloys, Ta, Nb, W, Cr, or Zr.

[0031] Next, the ODS steel layer 214 is prepared by loading a powdered ODS steel material in a powder feeder / hopper, rotating the cylindrical mandrel substrate 202 about its longitudinal axis A, and translating along the length of the cylindrical mandrel substrate 202 in the forward direction shown by arrow B to eject a beam 212 of the powdered ODS steel material from the powder nozzle 206 while depositing the ODS steel layer 214 on the liner layer 210. To increase the thickness of the ODS steel layer 214, the powder nozzle 206 may be translated backward and forward in multiple passes to deposit additional powdered ODS steel material until the desired thickness of the ODS steel layer 214 is achieved. The ODS steel layer 214 material may be nanostructured steel powder and is used as a cladding in nuclear power applications. The ODS steel layer 214 material may be selected from ODS steel and other alloys – for example, having a novel powder pre-preparation method such as cryomilling that may enhance microstructure uniformity and properties. Cryomilled ODS powder may produce an excellent microstructure.

[0032] Next, the outer layer 218 is prepared by loading the powdered outer coating material in a powder feeder / hopper, rotating the cylindrical mandrel substrate 202 about its longitudinal axis A, and ejecting a beam 216 of the powdered outer coating material from the powder nozzle 206 in the forward direction shown by arrow B while the powder nozzle 206 is translated along the length of the cylindrical mandrel substrate in the forward direction shown by arrow B to deposit the outer layer 218 on the ODS steel layer 214. To increase the thickness of the outer layer 218, the powder nozzle 206 can be translated backward and forward in multiple passes to deposit additional outer coating material until the desired thickness of the outer layer 218 is achieved. The outer layer 218 material can include powdered materials that provide corrosion resistance and oxidation resistance to the ODS steel layer 214 in various environments. Depending on the application, such materials include chromium and its alloys, iron, chromium, yttrium, silicon, nickel alloys, molybdenum alloys, and tungsten alloys. For light water reactor (LWR) applications, the outer layer 218 material can include Cr, FeCrAl. For lead-cooled fast reactor (LFR) applications, the outer layer 218 material can include Mo, Mo-Re alloys, Nb, Ta, FeCrAl, FeCrAlY, FeCrSi. For molten salt reactor (MSR) applications, the outer layer 218 material can include Ni alloys, Mo alloys, W alloys. For fusion reactor applications, the outer layer 218 material can include Be alloys, W alloys.

[0033] After depositing the outer layer 218 to the desired thickness, the cylindrical mandrel substrate 202 is removed in the direction shown by arrow C by a chemical dissolution method or a low-temperature heat treatment depending on the mandrel material, which will be discussed in more detail below. This leaves the freestanding ODS steel cladding tube 230 having a multi-layer structure. In other aspects, the cold spray method 200 can be used to prepare a freestanding monolithic ODS steel cladding tube.

[0034] The cold spray method 200 can be used to prepare freestanding ODS steel cladding tubes 230 of any suitable length. The length of the tube that can be prepared by the cold spray method 200 depends on the length of the cylindrical mandrel substrate 202 and the translation limits of the powder nozzle 206. In nuclear power applications, the length of the freestanding ODS steel cladding tube 230 can be selected to accommodate nuclear fuel rods of various lengths in the core of a typical nuclear reactor. In one aspect of the present disclosure, the length of the freestanding ODS steel cladding tube 230 can be selected from the range of 1.5 m (∼5 ft.) to 5 m (∼16.4 ft.). In another aspect, the length can be selected from the range of 2.5 m (∼8.2 ft.) to 3.5 m (∼11.5 ft.). In other aspects, the length can be selected as 4 m (∼13 ft.) to accommodate nuclear fuel rods of typical size.

[0035] In some aspects of the present disclosure, the freestanding ODS steel cladding tube 230 can be annealed by applying a heat treatment that alters the physical and chemical properties of the inner lining, ODS steel, and external coating material. Typical annealing methods involve heating the freestanding ODS steel cladding tube 230 to a temperature above a predetermined temperature of 220, and holding the appropriate temperature of 222 for an appropriate amount of time, followed by cooling. This achieves a dense microstructure, fine recrystallized grains, and oxide nanoparticle precipitation.

[0036] Important variables in the cold spray method 200 include the propellant gas, gas preheat temperature and pressure, as well as the powder shape, powder particle size and size distribution, and the compositional uniformity of the powder.

[0037] In one aspect, the cold spray method 200 according to the present disclosure provides a highly unique dissolution method for removing the cylindrical mandrel substrate 202. In another aspect, the mandrel substrate 202 can be made of a low melting point metal that can be removed by heat treatment. Instead of using a solid mandrel, the cylindrical mandrel substrate 202 is a tube that defines a hollow cylindrical internal space 204 and is made of an aluminum alloy material. After depositing the final material layer onto the cylindrical mandrel substrate 202, the aluminum alloy cylindrical mandrel substrate 202 tube is conveniently dissolved from the inside out using a sodium hydroxide solution, leaving the freestanding ODS steel cladding tube 230. In Figure 2 the disclosed embodiments, the last deposited layer is the outer layer 218. In other aspects, the final deposited layer can be the inner layer 210 or the ODS steel layer 214. Generally, the mandrel substrate 202 material can include metals (and alloys) having a low melting point or low boiling point, as well as metals (and alloys) that are readily soluble in non-toxic and environmentally friendly solvents. For chemical dissolution removal, the mandrel substrate 202 material can include Al, Al alloys, and Mg, Mg alloys. For removal by heating above its melting point (~420 °C), the mandrel substrate 202 material can include Zn and Zn alloys.

[0038] Figure 3 For use in accordance with at least one aspect of the present disclosure Figure 2 A cross-sectional view of a freestanding ODS steel cladding tube 230 having a multi-layer structure manufactured by the cold spray method 200 shown. The freestanding ODS steel cladding tube 230 includes an inner layer 210, an ODS steel layer 214, and an outer layer 218 formed according to the cold spray method 200 described with reference to Figure 2 In one aspect, the diameter (2r) of the freestanding ODS steel cladding tube 230 is selected from the range of 8 mm (~0.3 in.) to 15 mm (~0.6 in.). The thicknesses t 1 、t 2 、t 3 of the layers 210, 214, 218 can be defined as follows. In one aspect, the thickness t 1Selected from 10 μm (~3.94x 10 -4 in.) to 200 μm (~7.87x 10 -3 in.). In one aspect, the thickness t of the ODS steel layer 214 (e.g., the cladding layer) 2 is selected from 200 μm (~7.87x 10 -3 in.) to 1.00 mm (~3.94x 10 -2 in.). In one aspect, the thickness t of the outer layer 218 (e.g., the corrosion protection layer) 3 is selected from 1 μm (~3.94x 10 -5 in.) to 100 μm (~3.94x 10 -3 in.). The inner layer 210 serves as a diffusion barrier layer, and the material can be a refractory metal including vanadium, tantalum, rhenium, niobium, tungsten, chromium, zirconium, or molybdenum or a combination thereof. For example, the ODS steel layer 214 cladding material can include ODS steel. For example, the outer layer 218 material can include chromium or a chromium alloy. The three-material system shown in Figure 3 produced in a solid state by the cold spray method 200 provides excellent high-temperature strength, corrosion resistance, and an inner layer to prevent fuel transfer into the cladding, thereby creating a molten region at low temperatures. Refer to Figure 4 and Figure 5 for a more detailed description of the composition of the inner layer 210, the ODS steel layer 214, and the outer layer 218.

[0039] The fabricated scale tube (such as the freestanding ODS steel cladding tube 230) can be manufactured according to the cold spray method 200 described in Figure 2 . For example, in Figure 3 a fabricated scale tube with a cross-section revealing multiple layers of material is shown. As Figure 3 shown, the freestanding ODS steel cladding tube 230 is lined with an inner layer 210 that provides a diffusion barrier layer between the ODS steel layer 214 and the nuclear fuel. The freestanding ODS steel cladding tube 230 includes an outer layer 218 that serves as a protective outer layer and provides corrosion / oxidation resistance for the freestanding ODS steel cladding tube 230 in high-temperature, corrosive, and oxidative environments.

[0040] Alternative techniques are very cumbersome. Coating the inner surface of the tube is very difficult due to slow processes and non-uniform coating thickness, especially for narrow-diameter tubes. Coextrusion can be used, but it requires a large amount of resources (e.g., power, force, time). Coextrusion is also a technically challenging method due to the mismatch in thermo-mechanical properties between the two materials, which can lead to tube failure during processing. Coextrusion of the liner may require very high forces, a slow process, and may not be feasible for long tubes and all the associated drawbacks discussed above. Additionally, to fabricate a liner on the inner surface of the tube, refer toFigure 2 The described cold spray method 200 eliminates problems associated with the different mechanical properties (behavior) between two materials, which can lead to stress and cracking during manufacturing.

[0041] In one aspect, the inner layer 210 material is vanadium or a vanadium alloy because it is suitable for nuclear reactors. However, the inner layer 210 material is not limited to this. In a nuclear reactor, uranium dioxide fuel pellets are placed inside an ODS steel cladding tube. Over time, the fuel expands and contacts the inner surface of the cladding, and a chemical reaction will occur between the two. This is not desirable because such reactions can lead to the formation of low-melting-point compounds at the interface. The vanadium inner layer 210 of the freestanding ODS steel cladding tube 230 is an excellent barrier layer to prevent such reactions from occurring. There are many other applications in the industry where custom-made tubes (such as the freestanding ODS steel cladding tube 230) can meet the various performance requirements typically needed in harsh environments.

[0042] Similarly, it can be expected that the outer surface of the freestanding ODS steel cladding tube 230 is exposed to a very harsh high-temperature oxidation environment, and an outer layer 218 coating will be required, which provides corrosion resistance at the high temperatures where the freestanding ODS steel cladding tube 230 is expected to be used. Here again, high-temperature methods are not suitable because they have an impact on the nanostructure of the base ODS steel.

[0043] Reference Figure 2 The described cold spray method 200 provides a fast and cost-saving way to prepare such oxidation-resistant coatings. Examples of such coatings are shown in Figure 4 , which is a micrographic cross-section of a freestanding ODS steel cladding tube 300 according to at least one aspect of the present disclosure. The freestanding ODS steel cladding tube includes an ODS steel layer 214 material having a protective outer layer 218 coating, and the protective outer layer coating includes iron-chromium-aluminum alloy (FeCrAl or Fe20Cr5Al) prepared using Figure 2 the cold spray method. Although the inner layer 210 is not shown in Figure 4 due to scaling considerations, it is located below the ODS steel layer 214. Another example of such a coating is shown in Figure 5 , which is a micrographic cross-section of a freestanding ODS steel cladding tube 310 according to at least one aspect of the present disclosure. The freestanding ODS steel cladding tube includes an ODS steel layer 214 material having a protective outer layer 218 coating, and the protective outer layer coating includes chromium (Cr) prepared using Figure 2 the cold spray method. Although the inner layer 210 is not shown in Figure 4 due to scaling considerations, it is located below the ODS steel layer 214. The protective outer layer 218 (such as FeCrAl, Fe20Cr5Al, or pure Cr metal) provides corrosion resistance / oxidation resistance for the ODS steel cladding tube 230 in a high-temperature environment.

[0044] Figures 6 to 8 shows the morphology and size of ODS steel feedstock powder depending on the powder manufacturing method, where Figure 6 is a micrograph view 400 of an ODS steel feedstock powder 402 prepared by a gas atomization method, Figure 7 is for Figure 6 a micrograph view 420 of an ODS steel feedstock powder 422 prepared by ball milling a gas atomized powder 402 with oxide nanoparticles (e.g., Y2O3) as shown in Figure 8 is for Figure 7 a micrograph view 440 of an ODS steel feedstock powder 442 prepared by cryogenic milling of the ball milled gas atomized powder 422 as shown in Figure 2 . The properties of the ODS steel cladding tube 230 prepared by the cold spray method 200 of Figure 6 will change depending on the type of feedstock powder form. The size of the steel feedstock powder 402 shown in Figure 7 is 40 μm, the size of the steel feedstock powder 422 shown in Figure 8 is 400 μm, and the size of the steel feedstock powder 442 shown in

[0045] Referring to Figure 2 the cold spray manufacturing method 200 described, various types of metal powder can be employed as shown in Figures 6 to 8 . The characteristics of the feedstock powder are a factor in tailoring the resulting microstructure of the cold spray ODS steel cladding tube 230. The cold spray manufacturing method 200 can use various types of feedstock powder prepared by different preparation methods (such as gas atomization method, ball milling method, cryogenic milling method, and post heat treatment of the powder) to prepare the ODS steel cladding tube 230. The powder manufacturing method affects the shape and size distribution, chemical composition, grain structure, compositional uniformity, and mechanical properties (e.g., hardness) of the powder. The size and morphology of the feedstock powder depending on the powder manufacturing route are shown in Figures 6 to 8 . The feedstock powder can be selected based on the desired properties of the cladding tube (e.g., microstructure, mechanical properties, and radiation response) and economic efficiency.

[0046] Figure 9 is a method 500 for manufacturing a freestanding ODS steel cladding tube with a multi-layer structure using the cold spray method 600 according to at least one aspect of the present disclosure. Also referring to Figure 10 and Figure 9 and Figure 10, Method 500 includes providing 502 a cylindrical mandrel substrate 618 that defines a hollow cylindrical internal space. Pressurized gas 614 is introduced 608 into a heating element 602 that is fluidly connected to a converging-diverging powder nozzle 604. Cold spray powder metal 612 is selected 504 and loaded into a hopper to be injected 610 through a powder feeder 606 into the powder nozzle 604, where it is mixed with the heated pressurized gas 614. The powder nozzle 604 emits a supersonic stream 616 of powder metal 612 mixed with the pressurized gas 614. The cylindrical mandrel substrate 618 is rotated 506 about its longitudinal axis. Next, the powder nozzle 604 is positioned near the cylindrical mandrel substrate 618. While the powder nozzle 604 is translated along the length of the cylindrical mandrel substrate 618, the supersonic stream 616 of a selected cold (low temperature) powdered metal is applied 508 to the outer surface of the cylindrical mandrel substrate 618. The thickness of the first powder metal layer 620 can be changed by traversing the powder nozzle 604 in a back-and-forth direction along the length of the cylindrical mandrel substrate until the desired thickness of the first powder metal layer is achieved. On the other hand, the thickness of layer 620 can be controlled by adjusting the traverse speed of the powder nozzle 604. For example, a faster traverse speed can be used to deposit a thinner layer 620, and a slower traverse speed can be used to deposit a thicker layer 620. Next, according to method 500, it is determined 510 whether a different cold spray powder layer will be applied over the previous powder metal layer 620. If "yes", a different powder metal is selected 512 and loaded into the hopper, and a second powder metal material is injected 610 through the powder feeder 606 into the powder nozzle 604, where it is mixed with the pressurized gas 608, exits the powder nozzle 604, and is applied 508 over the first powder metal layer 620 until the desired thickness of the second powder metal layer is achieved. The determination 510 is repeated until a plurality of "n" different powder metal layers are applied 508 over the cylindrical mandrel substrate 618 to form a multi-layer tube structure.

[0047] The cold spray powder metal layers that can be applied by method 500 include an inner liner layer, an intermediate layer, and an outer layer. The inner layer can be made of a refractory metal including vanadium, tantalum, tungsten, rhenium, niobium, chromium, zirconium, or molybdenum or combinations thereof to provide a diffusion barrier layer in nuclear power applications. Additional inner layer materials typically have low solid solubility with the fuel and intermediate structural layers. The intermediate layer can be made of ODS steel. The outer layer can be made of chromium or a chromium alloy (such as pure chromium (Cr), iron-chromium-aluminum (FeCrAl, Fe20Cr5Al, or FeCrAlY), molybdenum, rhenium, niobium, tantalum, nickel, tungsten, beryllium, or an alloy thereof, including MCrAlY, or FeCrSi) to provide corrosion / oxidation resistance to the ODS steel or other structural layers. The thickness of the inner layer (e.g., refractory layer) is selected from 10 μm (~3.94x 10 -4 in.) to 200 μm (~7.87x10-3 in.). The thickness of the intermediate layer (e.g., the cladding layer) is selected from 200 μm (~7.87x 10 -3 in.) to 1.00 mm (~3.94x 10 -2 in.). The thickness of the outer layer (e.g., the corrosion protection layer) is selected from 1 μm (~3.94x 10 -5 in.) to 100 μm (~3.94x 10 -3 in.).

[0048] Once the desired number of different "n" layers are deposited on the cylindrical mandrel substrate 618, the method proceeds along the "No" path and the cylindrical mandrel substrate 618 is removed 514. In one aspect, the cylindrical mandrel substrate 618 is removed 514 by a chemical dissolution method or a low-temperature heat treatment depending on the mandrel material to produce a freestanding monolithic or multi-layer tube structure. In one aspect, the cylindrical mandrel substrate 618 is made of an aluminum alloy material that is soluble in a sodium hydroxide solution. In one aspect, the cylindrical mandrel substrate 618 is made of or soluble in a low melting point or low boiling point metal or alloy, and possible materials include magnesium, zinc, or a combination of their alloys.

[0049] The disclosed manufacturing techniques are revolutionary and fundamentally different from existing manufacturing methods. The disclosed cold spray manufacturing method 600 optimizes the microstructure and materials and ultimately improves the material properties to provide several key advantages over existing methods. The tubes manufactured using this new method are highly competitive in terms of manufacturing cost, efficiency, yield, and quality. The expected performance will be much better than current products from the market.

[0050] The development and selection of cladding materials are one of the key elements in advanced reactor design. The performance of the fuel highly depends on the cladding material, and ODS provides excellent mechanical properties and radiation resistance, which are crucial for an advanced reactor environment as the temperature and flux are much higher than those in LWRs.

[0051] Although certain aspects are illustrated and described herein for purposes of description, various alternative and / or equivalent aspects or embodiments for achieving the same purpose may be substituted for the aspects shown and described without departing from the scope of the present disclosure. This application is intended to cover any modifications or variations of the embodiments discussed herein.

[0052] Embodiments of the method according to various aspects of the present disclosure are provided below. One aspect of the method may include any one or more than one of the embodiments described below and any combination of the embodiments described below.

[0053] Example 1. A method for manufacturing a freestanding cladding tube having a multi-layer structure, the method comprising: providing a cylindrical mandrel substrate defining a hollow cylindrical internal space; selecting a first cold spray powder metal; rotating the cylindrical mandrel substrate; applying the first cold spray powder metal to an outer surface of the cylindrical mandrel substrate to form a first layer; and removing the cylindrical mandrel substrate.

[0054] Example 2. The method according to Example 1, wherein the thickness of the first layer is selected from the range of 10 μm to 5000 μm.

[0055] Example 3. The method according to any one of Examples 1 to 2, wherein the first cold spray powder metal comprises a refractory metal.

[0056] Example 4. The method according to Example 3, wherein the refractory metal comprises vanadium, tantalum, rhenium, niobium, tungsten, chromium, zirconium, or molybdenum or a combination thereof.

[0057] Example 5. The method according to any one of Examples 1 to 4, wherein before removing the cylindrical mandrel substrate, the method comprises: selecting a second cold spray powder metal; and applying the second cold spray powder metal on the first layer.

[0058] Example 6. The method according to Example 5, wherein the thickness of the second layer is selected from the range of 200 μm to 1.00 mm.

[0059] Example 7. The method according to any one of Examples 5 to 6, wherein the second cold spray powder metal comprises oxide dispersion strengthened (ODS) steel powder.

[0060] Example 8. The method according to Example 7, wherein the ODS steel powder is cryogenically milled.

[0061] Example 9. The method according to any one of Examples 5 to 8, wherein before removing the cylindrical mandrel substrate, the method comprises: selecting a third cold spray powder metal; and applying the third cold spray powder metal on the second layer.

[0062] Example 10. The method according to Example 9, wherein the thickness of the third layer is selected from the range of 1 μm to 100 μm.

[0063] Example 11. The method according to any one of Examples 9 to 10, wherein the third cold spray powder metal comprises a corrosion / oxidation resistant material.

[0064] Example 12. The method according to Example 11, wherein the corrosion / oxidation resistant material comprises chromium or a chromium alloy.

[0065] Example 13. The method according to Example 12, wherein the chromium alloy comprises FeCrAl or Fe20Cr5Al.

[0066] Example 14. The method according to any one of Examples 11 to 13, wherein the oxidation-resistant material is suitable for environmental types, such as molybdenum, rhenium, niobium, tantalum, FeCrAl, FeCrAlY, and FeCrSi or their alloys for lead fast reactors; nickel, molybdenum, or tungsten or their alloys for molten salts; beryllium, tungsten, or their alloys for fusion applications.

[0067] Example 15. The method according to any one of Examples 1 to 14, wherein removing the cylindrical mandrel substrate comprises dissolving the cylindrical mandrel substrate.

[0068] Example 16. The method according to Example 15, wherein the cylindrical mandrel substrate is made of an aluminum alloy or a magnesium alloy, and the cylindrical mandrel substrate is dissolved from the inside out using a sodium hydroxide solution.

[0069] Example 17. The method according to any one of Examples 1 to 16, wherein removing the cylindrical mandrel substrate comprises a heat treatment, the heat treatment comprising melting or boiling to remove the cylindrical mandrel substrate.

[0070] Example 18. The method according to Example 17, wherein the cylindrical mandrel substrate is made of a zinc alloy that is removed by heating above its melting point.

Claims

1. A method for manufacturing a nuclear reactor cladding tube with a multi-layer structure, the method comprises: providing a cylindrical mandrel substrate defining a hollow cylindrical inner space; selecting a first cold spray powder metal; rotating the cylindrical mandrel substrate; applying the first cold spray powder metal to the outer surface of the cylindrical mandrel substrate to form a first layer; selecting a second cold spray powder metal; applying the second cold spray powder metal on the first layer to form a second layer, wherein the second cold spray powder metal comprises oxide dispersion strengthened (ODS) steel powder; and removing the cylindrical mandrel substrate.

2. The method according to claim 1, wherein the thickness of the first layer is selected from the range of 10 μm to 5000 μm.

3. The method according to claim 1, wherein the first cold spray powder metal comprises a refractory metal.

4. The method according to claim 3, wherein the refractory metal comprises vanadium, tantalum, rhenium, niobium, tungsten, chromium, zirconium or molybdenum or a combination thereof.

5. The method according to claim 1, wherein the thickness of the second layer is selected from the range of 200 μm to 1000 μm.

6. The method according to claim 1, wherein the ODS steel powder is cryogenically milled.

7. The method according to claim 1, wherein before removing the cylindrical mandrel substrate, the method comprises: selecting a third cold spray powder metal; and applying the third cold spray powder metal on the second layer to form a third layer.

8. The method according to claim 7, wherein the thickness of the third layer is selected from the range of 1 μm to 100 μm.

9. The method according to claim 7, wherein the third cold spray powder metal comprises an anti-corrosion / anti-oxidation material.

10. The method according to claim 9, wherein the anti-corrosion / anti-oxidation material comprises chromium or a chromium alloy.

11. The method according to claim 10, wherein the chromium alloy comprises FeCrAl or Fe20Cr5Al.

12. The method according to claim 9, wherein the anti-oxidation material is suitable for environmental types, including molybdenum, rhenium, niobium, tantalum, FeCrAl, FeCrAlY, FeCrSi or their alloys for lead fast reactors; nickel, molybdenum or tungsten or their alloys for molten salts; beryllium, tungsten or their alloys for fusion applications.

13. The method according to claim 1, wherein removing the cylindrical mandrel substrate comprises dissolving the cylindrical mandrel substrate.

14. The method according to claim 13, wherein the cylindrical mandrel substrate is made of an aluminum alloy or a magnesium alloy, and the cylindrical mandrel substrate is dissolved from the inside out using a sodium hydroxide solution.

15. The method according to claim 1, wherein removing the cylindrical mandrel substrate comprises a heat treatment, the heat treatment comprising melting or boiling to remove the cylindrical mandrel substrate.

16. The method according to claim 15, wherein the cylindrical mandrel substrate is made of a zinc alloy removed by heating above its melting point.

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