Ceramic coating

Abstract

A method of producing an assembly wherein the assembly comprises a body and a ceramic coating, the method comprising: at least partially filling a container with a powdered material; subjecting the container to compressive pressure at a temperature and a length of time sufficient to at least partially consolidate the powdered material to form a body of the assembly; and subjecting the container to oxidizing, nitriding and / or carbonizing conditions, thereby forming the ceramic coating.

Description

Field of the Invention

[0001] The present invention relates to a method for producing a component having a ceramic coating, a device comprising a component produced by this method, and the use of the device, in particular in a tritium breeder blanket. Background Art

[0002] Tritium is a proposed fuel for fusion reactors. However, because it is a relatively short-lived isotope (with a half-life of 12.3 years), existing fusion reactor designs require a so-called "breeder" element to ensure that the amount of tritium remains at an acceptable level. Numerous types of breeders are known to those skilled in the art, primarily including lithium as the breeding element. Examples include liquid (or molten) lithium, lithium-containing ceramics, lithium-lead eutectics, molten lithium salts, lithium-containing intermetallic compounds, and ternary lithium alloys. Expected problems include corrosion of the reactor's structural components, magnetohydrodynamic (MHD) pressure drop when using liquid metal breeders, tritium penetration into these components, or a combination of these issues.

[0003] To this end, it has been proposed to coat structural components of fusion reactors that come into contact with lithium-containing materials and / or tritium with a ceramic layer (<100 μm). Materials used for the coating vary depending on the breeder design but include aluminum oxide, silicon carbide, aluminum nitride, calcium oxide, erbium oxide, yttrium oxide, titanium carbide or nitride, zirconium carbide, and others. Such ceramic coatings provide a physical barrier to tritium permeation between the breeder and the structural components, as well as an electrical resistive barrier to limit MHD pressure drop and corrosion rates. The coatings are also compatible with the breeder material and, to a certain extent, resilient to physical and property degradation (e.g., neutron irradiation) during its use.

[0004] Traditionally, ceramic coatings have been applied via (a) line-of-sight methods such as chemical vapor deposition (CVD), plasma vapor deposition (PVD), magnetron sputtering, and the like. A problem with most of these methods is that they are not suitable for coating complex surfaces (i.e., large and / or non-planar surfaces), and the coated components cannot subsequently be joined and / or formed without compromising the quality of the coating. Another problem is that ceramic coatings are susceptible to localized failure (e.g., cracking, flaking, etc.) due to their brittle nature. More specifically, due to the mismatch in thermal expansion coefficients between the ceramic coating and the more ductile underlying structural material, high stresses arise in the presence of steep thermal gradients in the breeder layer, leading to crack formation. This is further exacerbated by neutron irradiation. Localized failure areas (e.g., cracks) in the coating serve as tritium penetration "highways" into the underlying structural components and / or as conductive paths in the case of liquid metal breeders, as well as areas of accelerated corrosion.

[0005] Therefore, an improved method of producing ceramic coatings on components with more complex geometries, as well as an improved coating that is more robust to localized failures, particularly during operation, is desired. Summary of the Invention

[0006] According to a first aspect of the present invention, there is provided a method of producing a component comprising a body and a ceramic coating, the method comprising: at least partially filling a container with a powdered material; subjecting the container to a compressive pressure at a temperature and for a time period sufficient to at least partially consolidate the powdered material to form the body of the component; and subjecting the container to oxidizing conditions, nitriding conditions and / or carbonizing conditions to form the ceramic coating.

[0007] Optionally, the thickness of the ceramic coating formed by the oxidation, nitridation, and / or carbonization conditions is less than the thickness of the container, thereby defining a cladding layer between the body and the ceramic coating. The cladding layer is an intermediate layer disposed between the body and the ceramic coating of the component. The cladding layer constitutes a portion of the container that is not converted to ceramic or remains substantially unaffected by the oxidation, nitridation, or carbonization conditions.

[0008] Optionally, the container has a thickness of about 1 mm to 3 mm and the ceramic coating has a thickness of about 5 to 15 μm. In some examples, the container may be acid leached or pickled to reduce its thickness to 200 to 500 microns prior to the oxidation, nitridation and / or carbonization steps.

[0009] The ceramic coating may include oxides, nitrides and / or carbides of metallic components present in the composition of the container.

[0010] In some examples, the ceramic coating comprises a metal oxide, and the method further comprises providing one or more elements having a higher affinity for oxygen than the metal in the metal oxide has for oxygen in the vicinity of the ceramic coating by subjecting the ceramic coating to a carrier fluid comprising the one or more elements, whereby the step replaces the metal oxide in the ceramic coating with an oxide of the one or more elements.

[0011] The container can be made using additive manufacturing methods.

[0012] The bulk density of the powdered material in the container may be less than 70%. This may be achieved, for example, by using a powdered material with a unimodal size distribution.

[0013] The compression pressure may be isostatic, wherein the average isostatic pressure is in the range of 50 to 150 MPa, the average temperature is in the range of 1000 to 1300° C., and the time period at said temperature and said pressure is in the range of 3 to 5 hours. These average isostatic pressures, average temperatures, and time periods may result in dynamic grain recrystallization of the powdered material.

[0014] Powdered materials can be produced by nitrogen or argon atomization.

[0015] The powdered material may be a pre-alloyed powder comprising an alloy of vanadium, chromium, and at least one selected from titanium or zirconium. For example, the pre-alloyed powder may contain 4-5% by weight chromium, 4-5% by weight titanium, <0.2% by weight yttrium, and 89.8-91.8% by weight vanadium. Alternatively, the powdered material may comprise any of the following: ODS steel, austenitic stainless steel, or reduction-activated ferritic / martensitic steel.

[0016] The container may comprise any one or more of: iron, chromium, aluminum, titanium, zirconium, or alloys thereof.

[0017] According to a second aspect of the present invention, there is provided a component comprising a sintered body, a cladding layer surrounding the sintered body, and a ceramic coating surrounding the cladding layer, wherein the ceramic coating comprises a metal oxide, metal nitride, and / or metal carbide of the metal present in the cladding layer. The component can be produced by the method according to the first aspect of the present invention.

[0018] According to a third aspect of the invention, there is provided an apparatus comprising an assembly according to the second aspect, wherein, in use, the apparatus comprises a carrier fluid in contact with the ceramic coating, the carrier fluid comprising one or more gaseous molecules containing carbon, nitrogen and / or oxygen.

[0019] According to a fourth aspect of the present invention, there is provided use of an assembly according to the second aspect or an apparatus according to the third aspect in a magnetically confined plasma chamber.

[0020] According to a fifth aspect of the present invention, there is provided a tokamak comprising a tritium breeder layer, wherein the tritium breeder layer comprises the assembly according to the second aspect.

[0021] The tritium breeder layer may include a carrier fluid in contact with a ceramic coating, wherein the ceramic coating includes a metal oxide and the carrier fluid includes one or more elements having a higher affinity for oxygen than a metal in the metal oxide.

[0022] Optionally, the carrier fluid further comprises liquid lithium or a lithium-lead eutectic, and wherein the one or more elements are erbium, yttrium and calcium dissolved in the carrier fluid at a concentration of 5 to 10 wt%.

[0023] In use, the tritium breeder layer may include a carrier fluid in contact with the ceramic coating, the carrier fluid comprising one or more gaseous molecules containing carbon, nitrogen, and / or oxygen, wherein the gaseous molecules are any one or more of: nitrogen, nitrogen oxides, carbon monoxide, carbon dioxide, water vapor, and oxygen, and wherein the carrier fluid further comprises any one of: a helium-hydrogen mixture; liquid lithium; and a lead-lithium eutectic.

[0024] According to a sixth aspect of the present invention, there is provided use of a component produced according to the method of the first aspect in a device. The device may be a component of a magnetic confinement plasma chamber or a hydrogen (e.g., tritium) and / or liquid lithium delivery system (e.g., a pipeline).

[0025] According to a seventh aspect of the present invention, a method for producing a component having a ceramic coating is provided, the method comprising: at least partially filling a container with a powdered material; subjecting the powdered material to a compressive pressure at a temperature and for a time period sufficient to at least partially consolidate the powdered material to form a body of the component; and converting an outer surface of the container to the ceramic coating, such that an unconverted layer of the container remains between the body of the component and the ceramic coating. The ceramic coating provides a protective barrier against hydrogen, particularly tritium, for the body of the component. The unconverted layer enables self-repair of the ceramic coating in the event of a crack or other failure in the ceramic coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Some embodiments of the present invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0027] Figure 1 is a schematic diagram of a component having a ceramic coating;

[0028] Figure 2 is a schematic diagram of another component having a ceramic coating;

[0029] Figure 3 is a method diagram; and

[0030] Figure 4 is a schematic diagram of the assembly during fabrication. DETAILED DESCRIPTION

[0031] The present disclosure provides a method for producing components with ceramic coatings. When used in a tritium breeder layer, the ceramic coating acts to: limit tritium permeation; limit corrosion of underlying structural components; and / or act as an electrical insulator to reduce MHD voltage drop. The method is particularly advantageous for producing ceramic coatings on components with complex geometries that cannot be coated using traditional line-of-sight techniques. Similarly, because the method involves the integrated fabrication of net-shape or near-net-shape assemblies (which may be complex in shape) with the ceramic coating, assemblies including arrangements of these net-shape or near-net-shape assemblies (e.g., those of complex geometry) can be produced with fewer joints than when using components produced using traditional methods (which are limited to simpler shapes).

[0032] refer to Figure 1 , shows a cross-section of an assembly 100 having a ceramic coating 106. Assembly 100 comprises: a body 102 surrounded by a cladding 104 having a ceramic coating 106 on its exterior. The cladding 104 and the body 102 are composed of different metals or metal alloys and are chemically bonded to each other via a peripheral interface. The ceramic coating 106 on the cladding 104 is a ceramic composed of at least one of the following: a nitride, an oxide, a carbide. The ceramic may be a nitride, an oxide, a carbide of at least one metal component contained in the composition of the cladding 104. Alternatively or additionally, the ceramic may include a nitride, an oxide, a carbide of another metal component (i.e., not present in the cladding 104).

[0033] In some examples, the assembly may not include the cladding layer 104. This may occur if the vessel in step 208 is completely converted to the ceramic coating 106 (thus leaving no cladding layer). The requirement that the assembly 100 include the cladding layer 104 is not essential in this regard.

[0034] Figure 1 The cross section in Figure 1 Those skilled in the art will appreciate that the component 100 may have any other regular or even irregular cross-section.

[0035] Go to Figure 2 , shows a cross-section of another assembly 200 in the form of a hollow tube. The assembly includes a body 102 having a cladding 104 and a ceramic coating 106 disposed on the radially inner and radially outer surfaces of the body portion 102. The cross-section of the tube is shown as circular, but other cross-sections are possible.

[0036] In some examples (not shown), the cladding 104 and the ceramic coating 106 are disposed on only one of the radially inner surface or the radially outer surface of the body portion 102. The assembly 200, having the cladding and the ceramic coating disposed on at least the radially inner surface, is particularly useful as a pipe or other form of container for transporting, holding, or otherwise exposing materials containing lithium or tritium (or other isotopes of hydrogen).

[0037] Figure 3 Shown is a method for manufacturing Figure 1 The method of the assembly 100 is shown. The result of each step is Figure 4 A person skilled in the art will appreciate that this method can be applied in a similar manner to prepare Figure 2 The primary differences are that the vessel 402 defines an annular cavity for receiving the powdered material 404 and that, after step 306 , the oxidation, carburization, and nitridation conditions of step 308 may be applied to one or both of the radially inner and outer surfaces of the vessel 402 .

[0038] In step 302, a container 402 is produced.

[0039] In step 304 , the container 402 is at least partially filled with a powdered material 404 .

[0040] In step 306, the container 402 is subjected to isostatic pressure at a temperature and for a length of time sufficient to cause:

[0041] The metal powder 404 contained within the metal container 402 is at least partially consolidated (ie, densified by sintering) to form the body 102 of the assembly 100; and

[0042] The inward-facing surface of the metal container 402 is bonded to the body 102 .

[0043] In optional step 307, the container 402 may be subjected to a heat treatment for a period of time, such as heating until dynamic recrystallization of the body 102 of the component occurs.

[0044] In step 308, the container 402 is subjected to any one or more of: an oxidizing, nitriding, and carburizing environment, thereby causing a ceramic coating 106 to form on at least the outwardly facing surface of the container 402. The formed ceramic coating 106 comprises oxides, nitrides, and / or carbides of the metallic components present in the container 402. The remaining container components, which are substantially unaffected by the oxidizing, nitriding, and carburizing steps, are formed. Figure 1 In step 302, the material composition of the container and the coating are substantially the same.

[0045] Optionally, in step 310, ceramic coating 106 is subjected to a carrier fluid. The carrier fluid is used to transport one or more elements that have a higher affinity for oxygen than the metal in the metal oxide present in ceramic coating 106. These elements at least partially reduce the metal oxides present in ceramic coating 106 from step 308, thereby replacing them with their oxides.

[0046] Figure 3 The steps described in the embodiment of the present invention may be performed sequentially, simultaneously or according to any other working order. For example, steps 306, 307 and / or 308 may be performed together.

[0047] Now describe Figure 3 Further details of the method are given in .

[0048] container

[0049] The container 402 can be produced by known additive manufacturing methods or by known subtractive methods. Suitable additive manufacturing methods include powder-based processing routes such as direct metal laser sintering (DMLS), selective laser sintering (SLS), direct metal printing (DMP), laser powder bed fusion (LPBF), electron beam melting (EBM), electron beam additive manufacturing (EBAM), laser engineered net shaping (LENS), direct metal deposition (DMD), selective laser melting (SLM), metal injection molding (MIM), etc.

[0050] Figure 4 The container 402 shown in FIG is at least partially hollow and has an opening at one of its ends. The container is metal. The produced container is considered to be net shape or near net shape, that is, having a shape corresponding to the intended shape of the final component.

[0051] The composition of container 402 includes at least one component capable of forming an oxide, nitride, or carbide in an oxidizing, nitriding, or carbiding environment. Example components include iron, aluminum, chromium, titanium, and / or zirconium. In some examples, the container is an alloy (e.g., FeCrAl, Fe-Ti). In some examples, the weight fraction of each of aluminum, titanium, zirconium, and / or chromium is greater than 5%. Some alloys may include erbium and yttrium.

[0052] For components 100, 200 intended for structural components, follow Figure 3In the method described herein, the thickness of the container is preferably less than the lateral extent of the hollow interior of the container. This ensures that the mechanical strength of assembly 100, 200 is primarily determined by the mechanical properties of the material comprising body 102, rather than cladding 104 and / or ceramic coating 106 (which may typically be weaker). More specifically, the thickness of the container is less than a fractional threshold relative to the lateral extent of the hollow interior of the container. Specifically, this fraction is less than 0.25, more specifically less than 0.1, and even more specifically less than 0.05. At sufficiently low fractions, the mechanical properties of the cladding and / or ceramic coating can be neglected.

[0053] At the same time, the thickness of the container is large enough to ensure that no breakage and loss of powder occurs during the isostatic compression in step 306. Generally speaking, this means that the container 402 produced in step 302 is at least 1 to 2 mm (or 1 to 3 mm) thick, unless, however, the total thickness of the produced component 100, 200 is less than this.

[0054] Thus, in examples where the thickness of the container is preferably minimal (e.g., less than 5% of the lateral extent of the hollow portion of the container, as described above), the container 402 may initially have a greater fractional thickness (>5%) and, after step 306, be reduced to an appropriate thickness as needed (e.g., down to 200 to 500 microns by acid leaching or pickling).

[0055] Powdered materials

[0056] The powdered material may be gas atomized. Exemplary gases include nitrogen, argon (or other inert gases), etc. Powdered material 404 has a powder size distribution, which may include multiple peaks at different powder sizes, or only a single peak (unimodal). As known to those skilled in the art, the powder size distribution affects the bulk density of the powder during filling in step 304 and the degree of deformation during the powder consolidation process in step 306. Bulk density is defined as the volume occupied by the powdered material divided by the volume of the hollow portion of the container.

[0057] For a powder distribution having multiple peaks (spaced apart to allow smaller powder particles to reside in the spaces between larger powder particles), at least partially filling in step 304 means filling container 402 with powder at a high bulk density (greater than 80%, more preferably 90%, and even more preferably greater than 95%). Powdered material 404 with a higher bulk density requires less consolidation to achieve its theoretical density. As a result, powder consolidation in step 306 requires lower temperatures, lower pressures, and / or less time spent under these conditions.

[0058] For a powder distribution having a single peak (or multiple peaks that are not spaced sufficiently apart to allow smaller powder particles to reside within the voids between larger powder particles), at least partially filling in step 304 means filling container 404 with powder at a relatively low bulk density (e.g., less than approximately 70%). Powdered material 404 with a lower bulk density (e.g., less than approximately 70%) requires greater consolidation to achieve its theoretical density. One corollary is that powdered material 404 undergoes plastic deformation to a greater extent. The stored energy associated with this plastic deformation can lead to dynamic recrystallization, which can improve the microstructure of the component's body 102 after powder consolidation. For example, grain size can be refined and impurities (e.g., in the form of oxides) at previous grain boundaries can be eliminated (described in more detail below).

[0059] A narrow powder size distribution (eg, unimodal distribution) can be generated using sieving or other size sorting methods known to those skilled in the art. Since the bulk density of the powder is less for a narrower size distribution, relatively more plastic deformation occurs during the consolidation step 306.

[0060] The inventors have recognized that by reducing the bulk density (e.g., to less than 75%, more specifically less than 70%), the plastic deformation induced in step 306 can be large enough that dynamic recrystallization of some alloys can occur, particularly for austenitic steels and vanadium alloys. For vanadium alloys, this is a surprising result because the phenomenon of dynamic recrystallization is typically only observed for low to medium bulk density materials (e.g., austenitic steels, nickel-based alloys, copper, etc.).

[0061] Consolidation of powdered materials

[0062] Step 304 may also include closing the opening of the container 402, such as by applying a fluid seal to the open end of the container, by crimping the open end of the container closed, etc. This step is known to those skilled in the art and ensures that the powdered material remains within the container 402 during consolidation.

[0063] Preferably, after step 306, the density of the body 102 is greater than 90%, more preferably greater than 95%, and even more preferably greater than 99% of the theoretical density. The theoretical density of the body 102 is the average density of the individual powder particles without voids or pores. This value is known to those skilled in the art.

[0064] The bond formed between the metal container 402 and the body 102 in step 306 may be a diffusion bond. This type of bond is provided when at least one of the metal components of the container 402 is at least partially soluble in at least one of the metal components present in the powdered material 404 / body 102, or vice versa; and the container 402 is maintained at elevated temperature and isostatic pressure for a sufficient time (e.g., several hours) to allow significant diffusion of these components to occur. Diffusion bonding can include metal components of the container 402 (e.g., Zr, Al, Ti, Cr, Y, Er) in solid solution within the body 102, or vice versa. In diffusion bonding, a dispersion of precipitates may be present. The composition and microstructure of the diffusion bond depend on the chemical composition of the container and powdered material, as well as the HIPing conditions (time, temperature, and pressure). Diffusion bonding creates a composition gradient of the metal components present in the container 402 within the body 102. This composition gradient increases monotonically from the fractional amount of the component in the bulk (ie, powdered material), which may be a trace amount (<0.01 wt %), to the fractional amount of the component in container 402 .

[0065] In some examples, the compressive pressure is applied via hot isostatic pressing.Other methods suitable for achieving consolidation and sintering of powdered materials are known to the skilled artisan.

[0066] In a specific example, the average temperature during step 306 is in the range of 1000 to 1300° C., more specifically 1100 to 1200° C., even more specifically 1130 to 1170° C.; the average isostatic compression pressure is 50 to 150 MPa, more specifically 75 to 125 MPa, even more specifically 90 to 110 MPa, and the predetermined length of time (at which the pressure and temperature are applied) is 3 to 5 hours, more specifically 3.5 to 4.5 hours, even more specifically 4 hours.

[0067] The skilled person will understand that the values ​​for temperature and pressure used in the process are interchangeable to a certain extent. For example, a process at a relatively high pressure and a low temperature may densify the metal powder to a comparable theoretical density as a process at a relatively low pressure and a high temperature.

[0068] In some examples, steps 302 to 306 are replaced by additive manufacturing steps to generate a compositional hierarchy comprising a body 102 (representing the sintered powder from step 206) and a "container" layer 402 (e.g., Figure 4 ), which have different compositions. The use of additive manufacturing to produce compositionally graded structures is known per se.

[0069] Heat treatment

[0070] In optional step 307 , the container 402 may be heated for a period of time to recrystallize the body 102 of the component. This recrystallization process eliminates pre-existing grain boundaries (PPBs) and may result in a finer grain structure, thereby improving the mechanical properties of the component 100 .

[0071] Recrystallization is a process in which "high-energy" grains are replaced by a new set of "low-energy" grains that nucleate and grow at the expense of those "high-energy" grains. The "low-energy" grains are typically defect-free, while the "high-energy" grains have defects or deformation (i.e., stored plastic energy) that provide the driving force for recrystallization.

[0072] The recrystallization that occurs during step 306 is beneficial because: it reduces the overall concentration of defects in the body 102 of the component; and it eliminates previous grain boundaries (PPBs).

[0073] PPBs are particularly common in components produced by hot isostatic pressing (HIP) and result from imperfect consolidation of powdered materials. PPBs correspond to the boundaries of powder particles before consolidation occurs. Since powdered materials often have an oxide coating, PPBs are correspondingly associated with the oxides, which form weak links through the body 102 of the component 100, 200. Additional oxides and / or impurities can also segregate at the PPBs. These weak links significantly reduce ductility. Recrystallization advantageously removes these PPBs and, therefore, prevents oxide and / or impurity segregation at those boundaries, thereby improving the mechanical properties (e.g., ductility) of the body 102.

[0074] The skilled person will appreciate that software tools known to the skilled person can be used to model the plastic deformation induced in step 306, which can change the shape of the container 402. Thus, the container 402 can be manufactured according to the shape of the component forming the desired shape after the plastic deformation in step 306.

[0075] Step 307 can be performed simultaneously with step 306. For example, a known hot isostatic pressing (HIP) machine capable of uniform rapid quenching (URQ) as well as heating (e.g., AVURE / Quintus technology) can be used. Thus, the recrystallization-inducing heat treatment can be performed while powder consolidation is occurring. This reduces manufacturing costs and means, for example, that no additional heat treatment is required after forming the ceramic coating in step 310.

[0076] In some examples, the container 402 is completely transformed into the ceramic coating 106 , such that no cladding layer 104 remains after step 308 .

[0077] carrier fluid

[0078] The carrier fluid may be a liquid or a gas. Subjecting the ceramic coating 106 to the carrier fluid means providing these elements in the vicinity of the ceramic coating. Step 310 may include flowing the carrier fluid over a portion or all of the ceramic coating 106, placing the ceramic coating 106 in the carrier fluid, and the like.

[0079] In one example, the carrier fluid is liquid lithium and the element it transports is calcium dissolved therein. If the metal oxide present in the ceramic coating after step 308 is iron oxide, then during step 308 the iron oxide present in the ceramic coating is replaced by a calcium oxide deposit.

[0080] As will be appreciated by those skilled in the art, exemplary ceramic coatings depend on: i) the type of conditions in step 308; ii) whether optional step 310 is performed; and iii) the composition of the container 402, including: aluminum oxide, titanium oxide, zirconium oxide, yttrium oxide, zirconium carbide, titanium nitride, titanium carbide, erbium oxide, aluminum nitride, etc.

[0081] Components produced

[0082] Preferably, though not necessarily, the thickness of the container after step 310 is greater than the thickness of the ceramic coating 106 formed on its surface after steps 308 and 310. This difference in thickness defines the cladding layer 104. Typical values ​​for the thickness of the container, ceramic coating 106, and cladding layer 104 are approximately 1 to 2 mm (or 1 to 3 mm), 5-15 μm, and 50-100 μm, respectively. However, other thickness values ​​are also possible.

[0083] Under certain operating conditions, for example, where wear is prevalent, the ceramic coating 106 may chip or crack, thereby forming areas on the outer surface of the component 100 that are free of the ceramic coating 106. These areas can serve as sites for accelerated corrosion (potentially of the body 102) and are therefore undesirable. By ensuring that the cladding layer 104 is provided around the body 102, a "reservoir" of metallic components (e.g., Al, Ti, Zr, Cr) can be supplied to form new ceramic coating 106 without causing damage to the body 102.

[0084] The process of using container 402 to hold metal powder for densification is known to those skilled in the art. However, typically, the prior art container 402 for holding powder is completely removed (e.g., by pickling) after consolidation in step 306. It does not form part of the produced component. In contrast, in the proposed method, at least a portion of container 402 forms an integral part of component 100—cladding layer 104—and / or is used to form a ceramic coating. Because the container forms part of the produced component, wasteful subtractive manufacturing processes, which are wasteful in terms of material, cost, and time, can be avoided.

[0085] vanadium

[0086] Figure 3 The method is particularly advantageous for producing components having a body comprising a vanadium alloy, such as a V-Cr-Ti alloy (e.g., V-4Cr-4Ti by weight), a V-Cr-Ti-Y alloy (e.g., V-4Cr-4Ti-0.2Y by weight), or an oxide dispersion strengthened (ODS) vanadium alloy.

[0087] This is because vanadium alloys are traditionally produced through complex processes involving ingot casting, hot forging, hot or cold rolling, and subsequent heat treatment at temperatures above 700°C. Unavoidable impurities of carbon, oxygen, and nitrogen present in the melt precipitate from the alloy as Ti-CON, providing strengthening up to their dissolution temperature (~1000°C). Another challenge with melt processing is that vanadium has high solid solubility limits for oxygen and nitrogen (e.g., 2.7 wt% and 1.7 wt%, respectively, at 1000°C). Due to the difficulty in excluding oxygen and nitrogen, solid solution strengthening is unavoidable to a certain extent, which leads to an undesirable reduction in ductility at such high levels (e.g., 2.7 wt% and 1.7 wt%, as described above). Small amounts of yttrium (<0.2 wt%), which scavenge oxygen and form Y2O3 precipitates (i.e., oxide dispersion strengthened vanadium alloys; ODS-vanadium alloys), can be added to vanadium alloys during melting, but uniformly distributing these Y2O3 precipitates in the microstructure (which leads to improved mechanical properties) is a challenge.

[0088] While mechanical (MA) alloying of elemental powders (i.e., vanadium, chromium, titanium, yttrium (and possibly TiC particles)) in a ball mill and consolidation by hot extrusion or hot isostatic pressing (HIPing) is an alternative processing route, it is energy intensive and has poor scalability.

[0089] Return Reference Figure 3 The powdered material can be a V-Cr-Ti-Y pre-alloyed powder produced by inert gas atomization (e.g., in nitrogen or argon). The composition can be 4-5 wt% Cr, 4-5 wt% Ti, <0.2 wt% Y, and V (balance).

[0090] If nitrogen is used as the inert gas for atomization, some nitrogen will be interstitially dissolved in solid solution within the powder. Some nitrogen may precipitate out as nitride precipitates. Because oxygen is present as an impurity in nitrogen and is difficult to completely remove during powder storage, pre-alloyed powders may also have an oxide layer on their surface. The oxides may be chromium oxide, titanium oxide, vanadium oxide, yttrium oxide, or a combination thereof. Pre-alloyed powders may also include oxygen dissolved in solid solution within the alloy (interstitially). In some examples, oxygen may also preferentially combine with alloying elements (Cr, Ti, Y) to form discrete oxide particles (<1 μm). In summary, the powdered material can include oxide and nitride particles embedded within the powder, an oxide layer on the powder surface, and oxygen and nitrogen dissolved interstitially in solid solution within the powder.

[0091] As already noted, dynamic recrystallization of the vanadium alloy during consolidation in step 306 is possible if the bulk density of the powdered vanadium is sufficiently low (e.g., less than 75%, more specifically less than 70%, which are typical values ​​for a narrow powder size distribution).

[0092] It has also been discovered that with the presence of yttrium in the pre-alloyed powdered material, further improvements in the mechanical properties (e.g., ductility, toughness, and strength) of body 102 are possible during dynamic recrystallization. Specifically, the yttrium in solid solution in the powdered material scavenges any "free" oxygen that forms as previous oxides present in the powder are reduced at elevated temperatures during consolidation in step 306. The yttrium forms yttrium oxide. During recrystallization, grain boundaries migrate, carrying the yttrium oxide with them, thereby evenly distributing the yttrium oxide within body 102 during the process. This even distribution of fine yttrium oxide results in synergistic improvements in mechanical properties.

[0093] The vanadium alloys mentioned above, and in particular V-4Cr-4Ti (wt%) and ODS V-4Cr-4Ti (wt%), are promising candidates for structural components of breeder layers in tokamaks or spherical tokamaks. The exact composition of the alloy is guided by the desired end properties, such as creep resistance and oxidation resistance. Thus, in some cases, a relatively large chromium content and a relatively small vanadium content may be desirable (i.e., to improve creep resistance and oxidation resistance), or a V-Cr-Zi alloy may be preferred over a V-Cr-Ti alloy. Advantages of such alloys include:

[0094] Low induction (neutron and gamma) activation characteristics;

[0095] High resistance to neutron radiation damage;

[0096] High strength within the expected operating temperature window of approximately 400°C-700°C;

[0097] Excellent compatibility with liquid lithium; and

[0098] • Their use does not directly affect magnetic plasma confinement since they are not ferromagnetic.

[0099] Magnetic confinement plasma chamber

[0100] Figure 3 The method is particularly suitable for producing structural components for magnetic confinement plasma chambers (e.g., tokamaks, preferably spherical tokamaks). Preferably, but not necessarily, the aspect ratio of the spherical tokamak is less than or equal to 2.5. The aspect ratio is the ratio of the major radius to the minor radius of the annular plasma confinement region of the tokamak. More specifically, Figure 3 The method is applicable to the production of structural components in a tokamak or a tritium breeder layer in a spherical tokamak.

[0101] As already mentioned, the tritium breeder layer comprises a lithium-containing element, which may be solid (eg, a lithium compound) or liquid (eg, liquid lithium, lithium-lead eutectic, or molten salt).

[0102] The present inventors have recognized that the ceramic coating 106 of the component can be formed or repaired in situ in the presence of a carrier fluid (e.g., liquid lithium, Li-Pb eutectic, H-He gas mixture) in a breeder layer. This corresponds to Figure 3 Step 310 in .

[0103] Due to the low oxygen potential in lithium (~-500 kJ / mol), most oxide coatings in ceramic coating 106 are unstable and readily dissolve in the presence of a carrier fluid containing lithium. This is undesirable. To prevent dissolution of ceramic coating 106, it has been proposed to add oxide-forming additives (e.g., erbium, yttrium, or calcium) to the carrier fluid. The additives form stable oxides, even in the presence of a carrier fluid containing lithium. Erbium oxide, yttrium oxide, and calcium oxide are particularly beneficial because: they are stable in liquid lithium under normal operating conditions (i.e., temperatures up to 700°C), they have high resistivity, and they are highly resistant to tritium permeation.

[0104] By controlling the flow rate of the carrier fluid, the concentration of additives in the carrier fluid, the temperature and / or pressure of the carrier fluid, the oxides in the ceramic coating 106 formed in step 208 can be reduced and replaced with more stable oxides. Exemplary conditions include: erbium, yttrium, and / or calcium at a concentration between 5% and 10% by weight at a temperature below 60° C. Furthermore, ceramic coatings containing these stable oxides are difficult to achieve because making containers from these elements (i.e., erbium, calcium, or yttrium) is impractical due to their high affinity for oxygen.

[0105] If the carrier fluid does not include lithium, it has been proposed to add (e.g., dissolve, suspend) gaseous molecules containing carbon, nitrogen, or oxygen (e.g., nitrogen, carbon dioxide, carbon monoxide, water vapor, oxygen, nitrogen oxides, etc.) to the carrier fluid so that if the ceramic coating 106 is damaged (e.g., due to wear, erosion, etc.), the coating 104 spontaneously reacts with these gaseous molecules to repair the ceramic coating 106. In this regard, the presence of the coating 104 advantageously provides a self-healing effect during use. Exemplary carrier fluids include: helium-hydrogen mixtures, liquid lithium, lithium-lead eutectics, and molten lithium salts.

[0106] Exemplary Systems

[0107] Solid lithium multiplier: lithium-containing ceramics (Li2 TiO3、Li 4 SiO 4 or a mixture thereof)

[0108] In one specific example, the components 100, 200 are used for a lithium-containing ceramic multiplier layer, for example as a structural component. The components 100, 200 include a body 102 formed of steel, preferably oxide dispersion strengthened (ODS) steel or reduction activated ferrite / martensite (RAF / M) steel, such as Eurofer-97 (hereinafter referred to as Eurofer) or F82H steel, a cladding layer 104 comprising an aluminum alloy, and a ceramic coating comprising aluminum oxide. Thus, Figure 3In the method, (i) container 402 and (ii) powdered material 404 are, respectively: (i) an aluminum-containing alloy (e.g., FeCrAl alloy); and (ii) ODS steel or RAF / M steel. The ceramic coating can be formed via an oxidation process in step 308 or, alternatively, via step 310 using a carrier fluid. The carrier fluid is a gas mixture of helium and hydrogen supplied through a bed of lithium ceramic pebbles and conveying water vapor. Supplying a helium-hydrogen gas mixture (but without water vapor) to the pebble bed is well known to those skilled in the art and is the basis for tritium extraction. By varying the flow rate of the helium-hydrogen mixture, the water vapor concentration, the temperature, and / or the pressure, the breeder layer conditions can be controlled to energetically favor oxidation of the cladding layer 104 to form aluminum oxide. This ability to form the ceramic layer 106 in situ is advantageous because if the ceramic coating 106 is damaged (e.g., through wear, erosion, etc.), the coating 106 can be spontaneously replenished by oxidation of the cladding layer 104. Damage to lower components of the system is thereby reduced.

[0109] Unless expressly stated to the contrary, steel comprises one or more of the following phase components: austenite, ferrite, martensite, bainite, and includes precipitates or particles dispersed within these one or more components, such as carbides, nitrides, and oxides. Exemplary steels include ferritic / martensitic steels (e.g., Eurofer-97, a cast nanostructured alloy), austenitic stainless steels (e.g., 316L), ferritic steels, or oxide-dispersion-strengthened (ODS) steels (ferrite and ferrite / martensite).

[0110] The composition of Eurofer-97 is <0.01 wt% aluminum, <0.01 wt% nickel, <0.02 wt% titanium, 0.015-0.045 wt% nitrogen, <0.01 wt% cobalt, <0.01 wt% oxygen, <0.05 wt% silicon, 0.15-0.25 wt% vanadium, 8.50-9.50 wt% chromium, 0.20-0.60 wt% manganese, 0.10-0.14 wt% tantalum, 0.1-1.2 wt% tungsten, <0.01 wt% copper, 0.090-0.120 wt% carbon, and <0.072 wt% other impurities (including phosphorus, sulfur, molybdenum, niobium, boron, arsenic, tin, antimony, and zirconium), with the balance being iron.

[0111] The composition of F82H is iron (balance), 0.098 wt% carbon, 7.81 wt% (8 wt%) chromium, 1.88 wt% (~2 wt%) tungsten, 0.44 wt% manganese, 0.19 wt% vanadium, 0.037 wt% tantalum.

[0112] The ODS steel may be ferritic (with 9-16 wt% Cr) or martensitic (with 8-9 wt% Cr) as pre-alloyed powdered material 404. Exemplary compositions include: 9Cr-0.13C-0.2Ti-2W-0.35Y2O3, 13Cr-0.02C-3W-0.7Ti-0.46Y2O3, 13Cr-0.05C-3W-0.5Ti-0.34Y2O3, 11Cr-0.09C-3W-0.4Ti-0.66Y2O3 (all compositions are in wt% with the balance being iron). 。

[0113] These compositional details of the steel apply to the other breeder layer type examples and are not repeated for the sake of brevity.

[0114] Breeder layer type – Pb-Li eutectic (14-17 atomic % Li)

[0115] In one specific example, the components 100, 200 are used in a lithium-lead eutectic breeder layer, for example as a structural component. The components 100, 200 include a body 102 formed of steel, preferably oxide dispersion strengthened (ODS) steel or RAF / M steel (such as Eurofer), a cladding layer 104 comprising a FeCrAl alloy (e.g., 20-30 wt. % Cr, 4-7.5 wt. % Al, the balance being Fe), and a ceramic coating comprising aluminum oxide. Thus, Figure 3 In the method, (i) container 402 and (ii) powdered material 404 are: (i) FeCrAl alloy; and (ii) ODS steel or RAF / M steel, respectively. The ceramic coating can be formed via oxidation treatment in step 308 or alternatively using a carrier fluid in step 310. The carrier fluid is a lithium-lead eutectic containing dissolved oxygen. The oxygen concentration in the lithium-lead eutectic and / or the rate (e.g., flow rate) of replenishment of the lithium-lead eutectic onto the components 100, 200 can be controlled to ensure sufficient dissolved oxygen is present to form or replenish the alumina ceramic coating. As described above, the ability to form the ceramic layer 106 in situ is advantageous because, if the ceramic coating 106 is damaged (e.g., due to wear, erosion, etc.), the coating 106 is spontaneously replenished by oxidation of the cladding layer 104. This reduces damage to underlying components of the system.

[0116] Breeder Layer Type - Liquid Lithium

[0117] In one specific example, the assemblies 100, 200 are used in a liquid lithium breeder layer, for example as a structural component.

[0118] Components 100, 200 may include a body 102 formed from a vanadium alloy (e.g., containing 4-5 wt.% Cr, 4-5 wt.% Ti, with the balance being V), and a cladding layer 104 comprising an FeCrAl alloy (e.g., 20-30 wt.% Cr, 4-7.5 wt.% Al, with the balance being Fe) or an Fe-containing alloy (e.g., substantially pure iron). The ceramic coating 106 is initially iron oxide and / or aluminum oxide (e.g., formed during the oxidation treatment in step 308). However, during operation in the breeder layer, the ceramic coating 106 includes Er2O3, Y2O3, and / or CaO. Specifically, these oxides are generated in situ by reducing the iron oxide and / or aluminum oxide present in the ceramic coating 106 formed in step 308. This can be achieved by dissolving 5 to 10 wt.% of erbium, yttrium, and / or calcium in liquid lithium at a temperature of 500 to 600°C. Thus, the oxide coating can be replenished in situ during operation, which is advantageous.

[0119] Components 100, 200 may alternatively include a body 102 formed from a vanadium alloy (e.g., containing 4-5 wt% Cr, 4-5 wt% Ti, the balance V, and less than 1 wt% yttrium, more preferably less than 0.2 wt% as a pre-alloyed powder) and a cladding layer 104 comprising an FeCrAl alloy (e.g., 20-30 wt% Cr, 4-7.5 wt% Al, the balance Fe) or a Ti-containing alloy (e.g., substantially pure titanium, 5-10 wt% Fe-Ti). Yttrium effectively removes oxygen from solid solution within the vanadium alloy, thereby improving its ductility. This scavenging property of yttrium has been described above. Therefore, the powdered material 404 may include less than 1 wt% yttrium in the form of a pre-alloyed powder. The ceramic coating 106 comprises titanium nitride and / or aluminum nitride (e.g., formed during the nitriding process in step 308 or alternatively via step 310 using a carrier fluid). The carrier fluid is liquid lithium containing dissolved nitrogen. The nitrogen concentration in the liquid lithium and the flow rate of the liquid lithium over the components 100, 200 can be controlled to ensure that sufficient dissolved nitrogen is present to form or replenish the titanium nitride and / or aluminum nitride ceramic coating. As described above, the ability to form the ceramic layer 106 in situ is advantageous because if the ceramic coating 106 is damaged (e.g., through wear, erosion, etc.), the coating 106 is spontaneously replenished through oxidation of the cladding layer 104. This reduces damage to underlying components of the system.

[0120] Components 100, 200 may alternatively include a body 102 formed of steel, preferably Eurofer or ODS steel, and a cladding layer 104 comprising an FeCrAl alloy (e.g., 20-30 wt. % Cr, 4-7.5 wt. % Al, balance Fe) or a Ti-containing alloy (e.g., substantially pure titanium, 5-10 wt. % Fe-Ti). The ceramic coating 106 comprises titanium nitride and / or aluminum nitride (e.g., formed during the nitriding process in step 308 or alternatively via step 310 using a carrier fluid). The carrier fluid is liquid lithium containing dissolved nitrogen. The nitrogen concentration in the liquid lithium and the flow rate of the liquid lithium through components 100, 200 may be controlled to ensure that sufficient dissolved nitrogen is present to form or replenish the titanium nitride and / or aluminum nitride ceramic coating. As described above, the ability to form ceramic layer 106 in situ is advantageous because if ceramic coating 106 is damaged (eg, via wear, erosion, etc.), coating 106 is spontaneously replenished by oxidation of cladding layer 104. Damage to underlying components of the system is thus mitigated.

[0121] Components 100, 200 may alternatively include a body 102 formed of steel, preferably Eurofer or ODS steel, and a cladding layer 104 comprising an FeCrAl alloy (e.g., 20-30 wt.% Cr, 4-7.5 wt.% Al, the balance Fe) or an Fe-containing alloy (e.g., substantially pure iron). The ceramic coating 106 is initially iron oxide and / or aluminum oxide (e.g., formed during the oxidation treatment in step 308). However, during operation in the breeder layer, the ceramic coating 106 includes Er2O3, Y2O3, and / or CaO. Specifically, these oxides are generated in situ by reducing the iron oxide and / or aluminum oxide present in the ceramic coating 106 formed in step 308. This can be achieved by dissolving 5 to 10 wt.% erbium, yttrium, and / or calcium in liquid lithium at a temperature of 500 to 600°C. Thus, the oxide coating can be replenished in situ during operation, which is advantageous.

[0122] Breeder layer type - molten lithium salt (e.g., FLiBe)

[0123] In one specific example, the assembly 100, 200 is used in a molten lithium salt breeder layer, for example as a structural component. The assembly 100, 200 includes a body 102 formed of steel, preferably oxide dispersion strengthened (ODS) steel or Eurofer steel, a cladding layer 104 comprising a FeCrAl alloy (e.g., 20-30 wt. % Cr, 4-7.5 wt. % Al, the balance being Fe), and a ceramic coating comprising aluminum oxide. Thus, Figure 3In the method, (i) the container 402 and (ii) the powdered material 404 are respectively: (i) FeCrAl alloy and (ii) steel, such as ODS steel or Eurofer steel. The ceramic coating may be formed in step 308 via an oxidation treatment.

[0124] An exemplary system is summarized in Table 1 below.

[0125] Table 1

[0126]

[0127] More generally, the cladding layer 106 of the component thus comprises any one or more of the following: Fe, Cr, Al, Ti, and optionally Zr. The weight fractions of Al and Ti are sufficiently high to enable the formation of the ceramic coating 106 (e.g., AlN, Al2O3, TiN) in step 308. The powdered material 404 constituting the body 102 of the component after consolidation is steel, a vanadium alloy, or a conventional nickel-based alloy.

[0128] Traditionally, corrosion-resistant nickel-based alloys (e.g., Hastelloy TM ) are used as structural components in tokamaks, for example, in lithium-molten-salt (FLiBe) breeder layers. However, under neutron irradiation, nickel-based alloys develop high activation levels, which is undesirable from a nuclear waste management perspective. The proposed method of forming a protective barrier coating 106 on the body 102 of the structural component allows for the use of less activated structural alloys (e.g., Eurofer 97, ODS steel, vanadium alloys) in corrosive environments where they would otherwise be unsuitable.

[0129] Other uses for the assemblies 100, 200 include: replacing refractory metals (e.g., tungsten) in tokamak divertors with ceramic-coated non-refractory metals (e.g., steel); heat exchanger elements, particularly for gas-cooled reactors; tritium permeation barriers in molten salt fission reactors (e.g., fluoride salt-cooled high-temperature nuclear reactors); high-performance structural components in Gen-IV reactors (using 4-5 wt% Cr, 4-5 wt% Ti, <0.2 wt% Y and V (balance)); and even hydrogen storage technology, as the ceramic coating 106 effectively protects the body 102 from hydrogen embrittlement.

[0130] Although the present invention has been described in terms of the preferred embodiments described above, it should be understood that these embodiments are merely illustrative and that the claims are not limited to these embodiments. Features from different embodiments may be combined where appropriate to form other working embodiments.

Claims

1. A method of producing a component, wherein the component comprises a body and a ceramic coating, the method comprising: at least partially filling the container with a powdered material; subjecting the container to a compressive pressure at a temperature and for a length of time sufficient to at least partially consolidate the powdered material to form the body of the assembly; as well as The container is subjected to oxidizing conditions, nitriding conditions, and / or carbonizing conditions to form the ceramic coating.

2. The method of claim 1, wherein the thickness of the ceramic coating is less than the thickness of the container.

3. The method of claim 1 or claim 2, further comprising a cladding layer between the body and the ceramic coating.

4. A method according to any preceding claim, wherein the container has a thickness of about 1 to 3 mm and the ceramic coating has a thickness of about 5 to 15 μm.

5. A method according to any preceding claim, wherein the step of subjecting the container to oxidizing conditions, nitriding conditions and / or carbonizing conditions comprises: The container is subjected to carbonization conditions such that the ceramic coating comprises carbides of metallic components present in the composition of the container.

6. The method according to any one of claims 1 to 4, wherein the ceramic coating comprises oxides, nitrides and / or carbides of metallic components present in the composition of the container.

7. The method according to any one of claims 1 to 4, wherein the ceramic coating comprises a metal oxide, the method further comprising the steps of: Providing one or more elements in the vicinity of the ceramic coating, the one or more elements having a higher affinity for oxygen than the metal in the metal oxide has for oxygen by: subjecting the ceramic coating to a carrier fluid comprising the one or more elements, Said step thereby replaces said metal oxide in said ceramic coating with an oxide of said one or more elements.

8. A method according to any preceding claim, wherein the container is produced by an additive manufacturing process.

9. A method according to any preceding claim, wherein the bulk density of the powdered material in the container is less than 70%.

10. The method of claim 9, wherein the size distribution of the powdered material is unimodal.

11. A method according to any preceding claim, wherein the compression pressure is isostatic, and the average isostatic pressure is in the range of 50 to 150 MPa, the average temperature is in the range of 1000 to 1300°C, and the length of time at said temperature and said pressure is in the range of 3 to 5 hours.

12. A method according to claim 11 when dependent on any one of claims 9 to 10, wherein the average isostatic pressure, average temperature and length of time result in dynamic grain recrystallisation of the powdered material.

13. The method according to claims 10 to 12, wherein the powdered material is produced by nitrogen or argon atomization.

14. The method according to claims 10 to 13, wherein the powdered material is a pre-alloyed powder comprising an alloy of vanadium with chromium and at least one selected from titanium or zirconium.

15. A method according to any preceding claim, wherein the powdered material comprises any of the following: ODS steel, austenitic stainless steel or reduction-activated ferrite / martensitic steel.

16. A method according to any preceding claim, wherein the container comprises any one or more of: iron, chromium, aluminium, titanium, zirconium or alloys thereof.

17. A component comprising a sintered body, a cladding layer surrounding the sintered body, and a ceramic coating surrounding the cladding layer, wherein: The ceramic coating comprises a metal oxide, a metal nitride and / or a metal carbide of the metal present in the cladding layer.

18. A device comprising an assembly according to claim 17, wherein In use, the apparatus comprises a carrier fluid in contact with the ceramic coating, the carrier fluid comprising one or more gaseous molecules containing carbon, nitrogen and / or oxygen.

19. Use of an assembly according to claim 17 or an apparatus according to claim 18 in a magnetically confined plasma chamber.

20. A tokamak comprising a tritium breeder layer, wherein the tritium breeder layer comprises the assembly of claim 17.

21. The tokamak of claim 20, wherein the tritium breeder layer comprises a carrier fluid in contact with the ceramic coating, wherein the ceramic coating comprises a metal oxide and the carrier fluid comprises one or more elements having a higher affinity for oxygen than the metals in the metal oxide.

22. The tokamak of claim 21 , wherein the carrier fluid further comprises liquid lithium or a lithium-lead eutectic, and wherein the one or more elements are erbium, yttrium, and calcium dissolved in the carrier fluid at a concentration of 5 to 10 wt %.

23. The tokamak according to claim 22, wherein: In use, the tritium breeder layer comprises a carrier fluid in contact with the ceramic coating, the carrier fluid comprising one or more gaseous molecules containing carbon, nitrogen and / or oxygen.

24. A tokamak according to claim 23, wherein the gaseous molecules are any one or more of: nitrogen, nitrogen oxides, carbon monoxide, carbon dioxide, water vapor and oxygen, and wherein the carrier fluid further comprises any one of: a helium-hydrogen mixture; liquid lithium; and a lead-lithium eutectic.

25. Use of a component produced by the method of claim 1 in a device, the component comprising a sintered body and a ceramic coating.

26. The use according to claim 25, wherein the apparatus is a magnetically confined plasma chamber.

27. The use according to claim 25, wherein the device is a system for delivering hydrogen.

28. A method of producing a component having a ceramic coating, the method comprising: at least partially filling the container with a powdered material; subjecting the powdered material to a compressive pressure at a temperature and for a length of time sufficient to at least partially consolidate the powdered material to form the body of the assembly; as well as The outer surface of the container is converted to a ceramic coating such that an unconverted layer of the container remains between the body of the component and the ceramic coating.

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