High temperature interface for ceramic composites

Abstract

The invention is entitled High Temperature Interface for Ceramic Composites. An article for use in a high temperature environment is disclosed, the article comprising a first ceramic composite substrate, a second ceramic composite substrate, and a high temperature interface between a first surface of the first ceramic composite substrate and a second surface of the second ceramic composite substrate. The high temperature interface comprises at least one high temperature interface layer, the at least one high temperature interface layer comprising a ceramic matrix and a plurality of fibers distributed through the ceramic matrix.

Description

Technical Field

[0001] This disclosure relates to high-temperature coatings and interfaces for composite materials. Background Technology

[0002] Carbon-carbon (CC) composites can be used in high-temperature applications. For example, the aerospace industry uses CC composite components as friction materials for commercial and military aircraft, such as brake friction materials. In high-temperature applications, CC composites may be susceptible to oxygen or delamination, which can lead to a deterioration of their physical and mechanical properties. Summary of the Invention

[0003] This disclosure describes a high-temperature coating for a ceramic composite substrate that protects it from oxidation at high temperatures and at the high-temperature interface of the ceramic composite substrate that bonds the substrate together, as well as a technique for manufacturing it using Joule heating.

[0004] In one example, a method includes forming an article comprising a first ceramic composite substrate, a second ceramic composite substrate, and a pre-sintered ceramic interface between the first and second ceramic composite substrates. The pre-sintered ceramic interface comprises a plurality of ceramic particles and a plurality of fibers. The method further includes sintering a portion of the pre-sintered ceramic interface to a sintering temperature of the ceramic interface by heating at least a portion of the pre-sintered ceramic interface to a sintering temperature of the ceramic interface using Joule heating to bond the first and second substrates. The sintering temperature is greater than about 1000 degrees Celsius (°C).

[0005] In another example, the article includes a first ceramic composite substrate, a second ceramic composite substrate, and a high-temperature interface between a first surface of the first ceramic composite substrate and a second surface of the second ceramic composite substrate. The high-temperature interface includes at least one high-temperature interface layer comprising a ceramic matrix and a plurality of fibers distributed through the ceramic matrix.

[0006] In another example, the system for forming a high-temperature ceramic interface includes a sealed chamber and one or more contact electrical elements. The sealed chamber is configured to contain an article and maintain an inert or vacuum atmosphere within the chamber. The article includes a first ceramic composite substrate, a second ceramic composite substrate, and a pre-sintered ceramic interface between the first and second ceramic substrates. The pre-sintered ceramic interface includes multiple ceramic particles and multiple fibers. One or more contact electrical elements are configured to contact a portion of the article, such as the first and / or second substrates, and deliver current to the article to heat a portion of the pre-sintered ceramic interface to the sintering temperature of the multiple ceramic particles to sinter that portion of the pre-sintered ceramic interface. The sintering temperature is greater than about 1000 degrees Celsius (°C).

[0007] Details of one or more examples of this disclosure are set forth in the following drawings and description. Other features, objects, and advantages of this disclosure will be apparent from the description and drawings, as well as from the claims. Attached Figure Description

[0008] Figure 1 This is a schematic diagram illustrating an exemplary aircraft brake assembly including a composite material brake disc formed according to the technology of this disclosure, the composite material brake disc including a high-temperature coating.

[0009] Figure 2 This is a schematic side view of an exemplary article comprising a high-temperature coating formed according to the technology of this disclosure.

[0010] Figure 3 This is a schematic side view of an exemplary article including a high-temperature joint formed according to the technology of this disclosure.

[0011] Figure 4A This is a conceptual side view illustrating an exemplary system for forming a high-temperature coating using a contact heating element according to the technology of this disclosure.

[0012] Figure 4B This is a conceptual side view illustrating another exemplary system for forming a high-temperature coating using contact electrical elements according to the technology of this disclosure.

[0013] Figure 4C This is a flowchart illustrating an exemplary technique for forming a high-temperature coating using contact elements, according to the technology disclosed herein.

[0014] Figure 5A This is a conceptual side view illustrating an exemplary system for forming a high-temperature coating using a non-contact radiative heating element according to the technology of this disclosure.

[0015] Figure 5B This illustrates the technology according to this disclosure. Figure 5A A conceptual side view of an exemplary system.

[0016] Figure 5C This is a flowchart illustrating an exemplary technique for forming a high-temperature coating using a non-contact radiant heating element, according to the present disclosure.

[0017] Figure 6A This is a conceptual diagram illustrating an exemplary system for forming a high-temperature coating using contact elements and a load, according to the technology of this disclosure.

[0018] Figure 6B This is a conceptual diagram illustrating an exemplary system for forming a high-temperature coating using contact elements and a load, according to the technology of this disclosure.

[0019] Figure 6CThis is a flowchart illustrating an exemplary technique for forming a high-temperature coating using contact elements and a load, according to the technology disclosed herein.

[0020] Figure 7A This is a conceptual diagram illustrating an exemplary system for forming a high-temperature joint according to the technology of this disclosure.

[0021] Figure 7B This is a flowchart illustrating an exemplary technique for forming a high-temperature joint according to the present disclosure.

[0022] Figure 8A This is a micrograph of a cross-sectional view of a pre-sintered high-temperature ceramic coating on a silicon carbide / silicon carbide (SiC / SiC) composite substrate.

[0023] Figure 8B This is a micrograph of a cross-sectional view of a partially sintered high-temperature ceramic coating on a SiC / SiC composite substrate.

[0024] Figure 8C This is a micrograph of a cross-sectional view of a sintered high-temperature ceramic coating on a SiC / SiC composite substrate.

[0025] Figure 8D This is a micrograph of a cross-sectional view of a molten high-temperature ceramic coating on a SiC / SiC composite substrate.

[0026] Figure 9 This is a micrograph of a cross-sectional view of a sintered high-temperature ceramic interface including SiC fibers on a SiC / SiC composite substrate. Detailed Implementation

[0027] This disclosure describes high-temperature coatings and bonding interfaces for ceramic composite articles used in high-temperature (e.g., greater than 1000 degrees Celsius (°C)) and / or ultra-high-temperature (e.g., greater than 1500°C) applications. Ceramic composite parts can provide good mechanical properties and have a low mass density relative to other materials, such as metal alloys. However, at high temperatures, ceramic composite parts may be susceptible to oxidation, environmental corrosion, and degradation of their physical and mechanical properties.

[0028] Ceramic-based antioxidant coatings can improve resistance to oxidation and / or environmental erosion at high temperatures experienced in aerospace applications, such as aircraft brakes (e.g., temperatures up to 1600°C or even higher). To form these antioxidant coatings, the coating is applied to the surface of a ceramic-based composite substrate at high temperatures, such as in a slurry, and ceramic particles are sintered at high temperatures to fuse the particles at their melting point. This high-temperature heating heats both the coating and the substrate, and for large components, a large furnace may be required.

[0029] In some examples, the article comprises a ceramic composite substrate and a high-temperature coating on the substrate. To form the high-temperature coating on the substrate, a mixture comprising ceramic particles may be applied to the surface of the substrate and pretreated to form a pre-sintered (e.g., “green” or “brown”) ceramic coating. To sinter the pre-sintered ceramic coating, the ceramic particles may be heated to a sintering temperature and maintained at the sintering temperature for a period of time until the ceramic material of the ceramic particles migrates across the particles to fuse the ceramic particles together. The sintering temperature used to move the ceramic material can be relatively high, and if the sintering temperature is maintained for a long period of time, the substrate beneath the coating may be damaged. For example, the overall heating of the substrate and the ceramic coating for sintering may expose the substrate to high temperatures for a long period of time while the ambient atmosphere reaches the sintering temperature. In some cases, the overall heating furnace may not even be able to achieve the temperatures required for sintering ultra-high temperature ceramic materials or may not be able to accommodate large ceramic composite substrates.

[0030] According to various embodiments of this disclosure, rapid, localized Joule heating can be used to sinter the high-temperature coatings described herein. Joule heating generates conductive or radiant heat from an electric current flowing through one or more conductors. Unlike bulk heating (which convectively heats the coating by maintaining the environment at a uniform temperature), Joule heating can be localized to one or more portions of the pre-sintered ceramic coating. This localized heating allows for the rapid sintering of relatively thin ceramic coatings, such as within seconds or minutes, resulting in a reduced heat load on the underlying substrate compared to bulk heating methods. Localized heat can also be applied discretely and without a large heating environment, allowing large substrates to be coated with high-temperature sintered coatings using relatively little energy. Furthermore, such localized heating can enable the achievement of very high temperatures (e.g., up to 2500°C), temperatures that may not be achievable using conventional furnaces.

[0031] In some cases, one or more contact heating elements can be used to sinter the high-temperature coating described herein. The contact heating element can contact a portion of the pre-sintered ceramic coating and generate Joule heat within the element to conduct heat to the contact portion of the pre-sintered ceramic coating. The contact heating element can use a relatively small amount of energy to rapidly heat to the sintering temperature. Therefore, only a small portion of the underlying substrate near the surface can be heated to the sintering temperature.

[0032] In some cases, one or more contact elements may be used to sinter the high-temperature coating described herein. The contact elements may directly or indirectly (e.g., through the coating) contact a portion of the underlying substrate and generate Joule heating in the underlying substrate to heat that portion of the pre-sintered ceramic coating. The high temperature from the Joule-heated substrate can be concentrated near the surface of the substrate. Therefore, other portions of the substrate can remain at relatively low temperatures.

[0033] In some cases, one or more non-contact radiative heating elements can be used to sinter the high-temperature coatings described herein. The non-contact radiative heating element can be positioned near a portion of the ceramic coating and generate Joule heat to heat adjacent coatings using radiation. The hot zone generated by the non-contact radiative heating element can be relatively constrained by a distance from the volume near the non-contact radiative heating element. The non-contact radiative heating element may include a radiating surface that can be matched to the contour of a radiating surface independently of a specific profile, enabling efficient sintering of non-planar or hard-to-reach coating surfaces.

[0034] In some cases, one or more contact heating elements can be used to sinter the high-temperature coating described herein while it is being compressed. The contact heating elements heat the pre-sintered ceramic coating and apply pressure to it. For example, during heating, the pre-sintered ceramic coating may undergo isotropic shrinkage, which can lead to defects in the coating. As another example, the pre-sintered ceramic coating may be relatively porous, such that the ceramic particles may not bond strongly with adjacent ceramic particles. To counteract this isotropic shrinkage and / or further densify the pre-sintered ceramic coating, the contact heating elements can apply pressure to the pre-sintered ceramic coating, thereby creating relatively extreme temperature and pressure conditions in the underlying substrate through reduced temperatures.

[0035] In some examples, the article comprises two or more ceramic composite substrates and a high-temperature interface between the two or more substrates. To form a high-temperature interface between the substrates, a mixture of ceramic particles and fibers can be applied to the surface of one or both substrates to form a pre-sintered (“green” or “brown”) ceramic interface. To sinter the ceramic interface, the ceramic particles can be heated to a sintering temperature and maintained at the sintering temperature for a period of time until the ceramic material of the ceramic particles migrates across the particles to fuse the ceramic particles together. The ceramic interface can be relatively difficult to heat using localized heating methods. However, the sintering temperature used to move the ceramic material can be relatively high, and if maintained at the sintering temperature for a long period of time, the substrate beneath the coating may be damaged. For example, heating the substrate and ceramic interface using an external heat source, such as bulk heating or a contact heating source, can expose the substrate to a high temperature for a long period of time while the ceramic interface reaches the sintering temperature.

[0036] According to various embodiments of this disclosure, rapid, localized Joule heating (using one or more contact elements) can be used to sinter the high-temperature interfaces described herein. The contact elements can contact a portion of the interface or the underlying substrate and generate Joule heat in the interface or the underlying substrate to heat portions of the pre-sintered ceramic coating. Unlike bulk heating of the interface (which can heat the entire substrate to heat the interface between substrates), the Joule heat generated and transferred by the underlying substrate can be localized to one or more portions of the pre-sintered ceramic coating. This localized heating allows for rapid sintering of relatively thin ceramic coatings, such that the underlying substrate receives less heat compared to bulk heating methods, because the high temperature from the Joule-heated substrate can be concentrated near the surface of the substrate. The localized heat can also be applied discretely and without a large heating environment, allowing a large substrate to be bonded to the high-temperature interface using relatively little energy.

[0037] The high-temperature coatings and interfaces described herein can be formed using localized, inexpensive heating processes that sinter high-temperature ceramics with reduced heating of the underlying components. As explained below, these localized heating processes can be used to form coatings or interfaces on a variety of substrates, including large substrates and substrates with irregular surfaces. As an example, the high-temperature antioxidant coatings described herein can be used in aircraft brakes. Aircraft brakes can withstand relatively high temperatures in oxidizing atmospheres and may include components or features bonded together. Figure 1 This is a schematic diagram illustrating an exemplary aircraft brake assembly including a composite brake disc formed according to the technology of this disclosure, the composite brake disc including a high-temperature coating. For ease of description, examples of this disclosure will be described primarily with respect to aircraft brake assemblies. However, the articles of this disclosure can be used to form brake components other than aircraft brake discs. For example, brake components can be used as friction materials in other types of braking applications and vehicles. Additionally, exemplary articles of this disclosure can be used to form components including high-temperature interfaces formed according to the technology of this disclosure. For example, two parts of a composite brake disc (such as a brake disc with two worn parts) can be bonded together using a high-temperature interface. In other examples, the articles of this disclosure can be used to form high-temperature joints or coatings for hypersonic or other high-temperature structural applications.

[0038] exist Figure 1In the example, the wheel and brake assembly 10 includes a wheel 12, an actuator assembly 14, a brake stack 16, and an axle 18. The wheel 12 includes a hub 20, wheel support flanges 22, bead seals 24A and 24B, lug bolts 26, and lug nuts 28. The actuator assembly 14 includes an actuator housing 30, actuator housing bolts 32, and a plunger 34. The brake stack 16 includes alternating rotor brake discs 36 and stator brake discs 38; the rotor brake discs 36 are configured to move relative to the stator brake discs 38. The rotor brake discs 36 are mounted on the wheel 12, and specifically on the hub 20, via beam keys 40. The stator brake discs 38 are mounted to the axle 18, and specifically on torque tubes 42, via key teeth 44. The wheel and brake assembly 10 can support any kind of private, commercial, or military aircraft or other types of vehicles.

[0039] Wheel and brake assembly 10 includes wheel 12, in Figure 1 In the example, wheel 12 is defined by hub 20 and wheel support flange 22. Wheel support flange 22 is mechanically attached to hub 20 by lug bolts 26 and lug nuts 28. Wheel 12 defines bead seals 24A and 24B. During assembly, an inflatable tire (not shown) can be placed above hub 20 and secured to opposite sides by wheel support flange 22. Thereafter, lug nuts 28 can be fastened to lug bolts 26, and the inflatable tire can be inflated using bead seals 24A and 24B, thereby providing an airtight seal for the inflatable tire.

[0040] The wheel and brake assembly 10 can be mounted to the vehicle via torque tube 42 and axle 18. Figure 1 In the example, torque tube 42 is attached to shaft 18 by a plurality of bolts 46. Torque tube 42 supports actuator assembly 14 and stator brake disc 38. Shaft 18 may be mounted on struts of landing gear (not shown) or other suitable parts of the vehicle to connect wheels and brake assembly 10 to the vehicle.

[0041] During vehicle operation, braking may be required periodically, such as during aircraft landing and taxiing. The wheel and brake assembly 10 is configured to provide braking functionality to the vehicle via actuator assembly 14 and brake stack 16. Actuator assembly 14 includes actuator housing 30 and plunger 34. Actuator assembly 14 may include one or more of different types of actuators, such as, for example, electromechanical actuators, hydraulic actuators, pneumatic actuators, etc. During operation, plunger 34 may extend away from actuator housing 30 to axially compress brake stack 16 against a compression point for braking.

[0042] The brake stack 16 includes alternating rotor brake discs 36 and stator brake discs 38. The rotor brake discs 36 are mounted on the hub 20 for common rotation via a beam key 40. The stator brake discs 38 are mounted to the torque tube 42 via key teeth 44. Figure 1 In the example, brake stack 16 includes four rotors and five stators. However, in other examples, brake stack 16 may include different numbers of rotors and / or stators.

[0043] In some examples, the rotor brake disc 36 and stator brake disc 38 may be mounted in the wheel and brake assembly 10 via beam keys 40 and key teeth 44, respectively. In some examples, the beam keys 40 may be circumferentially spaced around the inner portion of the hub 20. For example, the beam keys 40 may be shaped to have opposing ends (e.g., opposite sides of a rectangle) and may have one end mechanically attached to the inner portion of the hub 20 and an opposing end mechanically attached to the outer portion of the hub 20. The beam keys 40 may be integrally formed with the hub 20, or may be separate from the hub 20 and mechanically attached to it, for example, to provide a thermal barrier between the rotor brake disc 36 and the hub 20. For this purpose, in various examples, the wheel and brake assembly 10 may include a heat shield (not shown) that extends radially outward and surrounds the brake stack 16, for example, to limit heat transfer between the brake stack 16 and the wheel 12.

[0044] In some examples, the key teeth 44 may be circumferentially spaced around the outer portion of the torque tube 42. Accordingly, the stator brake disc 38 may include a plurality of radially inwardly disposed lugs along the inner diameter of the brake disc, the lugs being configured to engage with the key teeth 44. Similarly, the rotor brake disc 36 may include a plurality of radially inwardly disposed lugs along the outer diameter of the brake disc, the lugs being configured to engage with the beam key 40. Thus, the rotor brake disc 36 will rotate with the movement of the wheel, while the stator brake disc 38 remains stationary, allowing the friction surfaces of adjacent stator brake discs 38 and rotor brake discs 36 to engage with each other, thereby slowing the rotation of the wheel 12.

[0045] Rotor brake disc 36 and stator brake disc 38 provide relative friction surfaces for braking an aircraft. As the kinetic energy of a moving aircraft is converted into heat energy in the brake stack 16, the temperature in the brake stack 16 can rise rapidly. Accordingly, the rotor brake disc 36 and stator brake disc 38 forming the brake stack 16 may include coatings capable of operating at very high temperatures and blocking various oxidizing substances.

[0046] In some examples, the articles or components described above (such as...) Figure 1 The brake discs 36 and / or 38 may include a high-temperature coating to protect the underlying substrate from oxidation, such as the non-friction surfaces of the brake discs. Figure 2This is a schematic side view of an exemplary article 50 including a high-temperature coating, formed according to the technology of this disclosure. Article 50 includes a ceramic composite substrate 52. Substrate 52 may include ceramic reinforcing fibers and a ceramic matrix material at least partially surrounding the ceramic-based reinforcing fibers. Examples of ceramic composite materials that can be used for substrate 52 include, but are not limited to, carbon / carbon composites, carbon / silicon carbide composites, silicon carbide / silicon carbide composites, etc. In some examples, substrate 52 may be formed from a porous preform including ceramic fibers or ceramic precursor fibers. Examples of porous preforms that can be used to produce substrate 52 include, but are not limited to: fiber preforms such as woven fiber preforms, nonwoven fiber preforms, chopped fiber and binder preforms, binder-treated random fiber preforms, carbon fiber preforms, or ceramic fiber preforms; foam preforms; porous carbon matrix preforms; or porous ceramic matrix preforms.

[0047] In some examples, the porous preform used to generate substrate 52 includes multiple mechanically bonded layers, which may be, for example, multiple fiber layers, such as multiple woven or nonwoven fabric layers, joined together, for example by an adhesive (such as a resin adhesive) or via needle punching of the multiple layers. In some examples, the layers include one or more tow layers, one or more web layers, or combinations thereof. A tow layer may include one or more fiber tows. The fiber tows may be arranged in any suitable arrangement, including, for example, linear, radial, chordal, etc. A web layer may include web fibers, which may include relatively short, chopped, and tangled fibers. In other examples, the porous preform may not include predefined layers but may be formed from, for example, a bundle of fibers mechanically bonded together via needle punching. In other examples, any combination of porous preforms of the foregoing types may be used.

[0048] The substrate 52 may also include a matrix material that at least partially encapsulates the ceramic fibers. The matrix material can be introduced into the porous preform using one or more of a variety of techniques, including, for example, chemical vapor deposition / chemical vapor infiltration (CVD / CVI), resin transfer molding (RTM), vacuum / pressure infiltration (VPI), high-pressure impregnation / carbonization (PIC), etc.

[0049] In some examples, substrate 52 may be conductive. For example, substrate 52 may include reinforcing fibers that are also electrically conductive and generate Joule heating in response to the current. As will be further described below, this Joule heating allows substrate 52 to heat an overlying coating (such as coating 54) to a high temperature within a relatively short period of time. In some examples, substrate 52 may be non-conductive. For example, substrate 52 may comprise a ceramic matrix and reinforcing fibers that are not electrically conductive.

[0050] The substrate 52 can withstand high temperatures during operation. As an example, a carbon-carbon composite brake disc can withstand temperatures up to about 3,000 degrees Fahrenheit (℉) (about 1,649 °C) during braking events. As another example, a carbon-carbon composite rocket nozzle extension can withstand temperatures up to about 4,500 °C (about 2,482 °C) during rocket engine operation. To protect the substrate 52 from oxidation, the article 50 includes a high-temperature coating 54 on one or more surfaces of the substrate 52. For example, the high-temperature coating 54 may be present on one or more non-frictional or non-contact surfaces of the substrate 52, such as the non-frictional surfaces of a brake disc and / or the non-frictional surfaces of a rocket nozzle.

[0051] The high-temperature coating 54 can be stable at temperatures greater than about 1000°C (such as temperatures greater than about 2000°C). In this context, "stable" can mean that the high-temperature coating 54 does not degrade into its constituent elements, does not react with carbon, and / or does not react (including but not limited to oxidation) with other elements or compounds present in the environment in which the coating 54 is used. The high-temperature coating 54 can have any suitable thickness. In some examples, the thickness of the high-temperature coating 54 can be between about 0.0254 mm and about 10 mm. In some examples, the thickness of the high-temperature coating 54 can correspond to the application or expected service life of the article 50, such that a longer service life can correspond to a higher thickness of the high-temperature coating 54.

[0052] In some examples, the high-temperature coating 54 may include an undercoat 56 on the surface of the substrate 52 (e.g., directly on the substrate 52 or indirectly on the substrate 52 through one or more intermediate layers). The undercoat 56 may include one or more metal carbide layers. In some examples, the undercoat 56 may include at least one of silicon carbide (SiC), titanium carbide (TiC), tungsten carbide (WC), zirconium carbide (ZrC), combinations thereof, or any carbide layer formed using the exemplary process principles described in U.S. Patent 6,555,173 and / or U.S. Patent 4,837,073, the entire contents of which are incorporated herein by reference.

[0053] The primer layer 56 may be configured to reduce delamination, spalling, and / or cracking of the high-temperature coating 54. The primer layer 56 may experience high temperatures, which could exacerbate shear forces caused by differences in the coefficients of thermal expansion between the primer layer 56 and adjacent coatings of the substrate 52 and / or the outer coating 58. To keep these forces relatively low, the primer layer 56 may have a coefficient of thermal expansion that is relatively similar to that of the substrate 52, the outer coating 58, or both. For example, the primer layer 56 may have a coefficient of thermal expansion in the range of about 4 parts per million parts per degree Celsius (ppm / °C) to about 4.5 ppm / °C. In some examples, the primer layer 56 may be chemically compatible with the substrate 52, the outer coating 58, or both. For example, the primer layer 56 may have selected wettability relative to the substrate 52, the outer coating 58, or both.

[0054] In some examples, the base coat 56 may be configured to increase adhesion between the high-temperature coating 54 and the substrate 52. For example, the base coat 56 may be formed by an in-situ process involving a reaction between reactive carbon and a stoichiometric excess of metal. The excess metal may form a metal oxide that can migrate into microcracks in the substrate 52, the base coat 56, and / or the outer coating 58 to provide self-healing functionality. The metal oxide may adhere more strongly to the ceramic matrix of the outer coating 58 and / or may at least partially impregnate into the open pores of the substrate 52. Alternatively or additionally, the base coat 56 may have a relatively low thickness (e.g., less than about 20 micrometers) and / or a uniform thickness (e.g., within about 10 micrometers), controlled by the amount of reactive carbon present on the substrate 52.

[0055] Article 50 includes an outer coating 58 (e.g., directly on the base coating 56 or indirectly on the base coating 56 via one or more intermediate layers) on the surface of the substrate 52 and / or the primer coating 56. The outer coating 58 may be configured to reduce or prevent the migration of reactive oxidizing substances into the substrate 52 at high temperatures. The outer coating 58 includes a ceramic matrix. The ceramic matrix may include any high-temperature refractory ceramic material. High-temperature refractory ceramic materials may include any ceramic material that maintains thermal and chemical stability at temperatures above about 1000°C. The composition of the ceramic matrix may be selected for various properties, including but not limited to the melting point of the ceramic material, the coefficient of thermal expansion of the ceramic material, the thermal conductivity of the ceramic material, etc. For example, during operation of article 50, the melting point of the ceramic matrix in the outer coating 58 may be higher than the expected temperature encountered at the corresponding outer coating 58.

[0056] In some examples, the outer coating 58 may comprise a ceramic material with a relatively low coefficient of thermal expansion (CTE). For example, the CTE of the substrate 52 and / or the undercoat 56 may be relatively low. To reduce interlayer forces between the substrate 52 and / or the undercoat 56, the outer coating 58 may have a CTE relatively similar to that of the substrate 52 and / or the undercoat 56. In some examples, the outer coating 58 may comprise a ceramic material with a relatively high operating temperature (e.g., compared to the substrate 52). A ceramic material with a relatively high operating temperature may have a relatively high melting temperature and / or thermal degradation temperature, allowing the article 50 to operate in environments that would otherwise cause thermal degradation of the substrate 52. In some examples, the outer coating 58 may comprise a ceramic material with high oxidation resistance. A ceramic material with high oxidation resistance may have a relatively high density and / or low porosity, making it less likely for oxidizing substances to migrate through the outer coating 58.

[0057] Although described as a top coating, in some examples, the outer coating 58 may be an intermediate layer, with one or more additional coatings on top of it. For example, the high-temperature coating 54 may include additional abrasive coatings, environmental barrier coatings (EBCs), thermal barrier coatings (TBCs), or other coatings on the outer coating 58. As an example, if the substrate 52 comprises a SiC / SiC substrate, the outer coating 58 may include a composite oxide to protect the substrate 52, wherein additional coatings on the outer coating 58 provide thermal protection (e.g., a more porous coating).

[0058] In some examples, the outer coating 58 may comprise a composite oxide ceramic. The composite oxide ceramic may have a relatively low coefficient of thermal expansion, a relatively high operating temperature, high oxidation resistance, and relatively high resistance to steam erosion at high temperatures. For example, the composite oxide ceramic may have a coefficient of thermal expansion of less than about 10 × 10⁻⁶. -6 The CTE is approximately 1500 °C, and the melting temperature is greater than approximately 1500 °C. Composite oxide ceramics may also include broad classes of materials with a variety of different properties, which can be customized by changing the composition. Exemplary composite oxide ceramic materials may include, but are not limited to, rare earth oxides, such as refractory metal silicates; rare earth monosilicates, such as ytterbium monosilicate or yttrium monosilicate; rare earth disilicates, such as barium disilicate, erbium disilicate, scandium disilicate, molybdenum disilicate, ytterbium disilicate, yttrium disilicate; aluminum titanate; mullite; etc.

[0059] In some examples, the outer coating 58 comprises carbide, boride, or nitride ceramics. Carbide, boride, or nitride ceramics can have relatively high operating temperatures (compared to composite oxide ceramics), relatively low coefficients of thermal expansion, and high oxidation resistance, and can also have relatively high oxidation resistance (e.g., compared to carbon). For example, carbide, boride, and / or nitride ceramics can have a coefficient of thermal expansion of less than about 10 × 10⁻⁶. -6CTE of / ℃ and melting temperature greater than about 2500℃. Exemplary carbide, boride, and nitride ceramic materials may include, but are not limited to, hafnium carbide (HfC), hafnium nitride (HfN), hafnium diboride (HfB2), tantalum carbide (TaC), tantalum diboride (TB2), tantalum nitride (TaN), niobium carbide (NbC), niobium nitride (NbN), niobium diboride (NbB2), zirconium carbide (ZrC), zirconium nitride (ZnN), zirconium diboride (ZrB2), titanium carbide (TiC), titanium nitride (TiN), titanium diboride (TiB2), silicon carbide (SiC), zirconium diboride and silicon carbide (ZrB2-20%SiC), hafnium diboride and silicon carbide (HfB2-20%SiC), tungsten carbide (WC), rhenium carbide (ReC), vanadium carbide (VC), vanadium nitride (VN), combinations thereof, and other refractory ceramic materials.

[0060] As will be further described below, the outer coating 58 can be formed by applying a ceramic mixture as a pre-sintered ceramic coating to the substrate 52, and sintering at least a portion of the pre-sintered ceramic coating by heating a portion of the pre-sintered ceramic coating to the sintering temperature of the ceramic particles in the pre-sintered ceramic coating (such as greater than about 1000°C). This heating can be performed locally using contact or non-contact Joule heating instead of bulk heating. In some cases, these local Joule heating methods may allow the formation of a high-temperature ceramic coating 54 on a relatively large substrate 52 because such local heating methods may not require placement and heating in a furnace as in bulk heating methods.

[0061] In some examples, the articles or components described above (such as...) Figure 1 Brake discs 36 and / or 38 may include high-temperature interfaces to bond two or more substrates. As an example, relatively large composite materials or those with relatively complex shapes may be manufactured into smaller and / or simpler shapes and bonded together. As another example, partially worn composite materials (such as partially worn brake discs) may be bonded together for recycling and / or remanufacturing of the composite material. Figure 3 This is a schematic side view of an exemplary article 60 including a high-temperature interface 64, formed according to the technology of this disclosure. Article 60 includes a first ceramic composite substrate 62A and a second ceramic composite substrate 62B (individually referred to as "substrate 62" and collectively as "substrate 62"). Unless otherwise stated, each substrate 62 may be functionally and / or compositionally similar. Figure 2 The base 52.

[0062] One or both substrates 62 may be subjected to high temperatures during operation. To bond substrates 62A and 62B together, article 60 includes a high-temperature interface 64 between one or more surfaces of substrates 62A and 62B. Interface 64 may have any suitable thickness. The thickness of interface 64 may be related to the roughness of one or more surfaces of substrates 62, the type of material of substrates 62 (e.g., matrix and / or fiber), and other properties that may affect the contact area and / or adhesion of substrates 62. In some examples, the thickness of interface 64 may be between about 0.0254 mm and about 5 mm. In some examples, the thickness of interface 64 may correspond to the surface roughness or tolerance of substrates 62, such that a higher surface roughness corresponds to a higher thickness of interface 64.

[0063] In some examples, interface 64 may include a base coat 66A on the interface surface of substrate 62A (i.e., the surface intended to interface with another component), and / or a base coat 66B on the interface surface of substrate 62B (e.g., directly on substrate 62 or indirectly on substrate 62 via one or more intermediate layers) (referred to individually as "base coat 66" and collectively as "base coat 66"). Unless otherwise specified, each base coat 66 may be functionally and / or compositionally similar to Figure 2 The base coating 56.

[0064] Interface 64 may include the interfacial surfaces of substrates 62A and 62B and / or an interfacial layer 68 between undercoatings 66A and 66B. Interface layer 68 may be configured to bond substrates 62 together to improve adhesion during operation at relatively high temperatures. Interface layer 68 includes a high-temperature ceramic matrix. The ceramic matrix may include any high-temperature refractory ceramic material compatible with substrate 62. The high-temperature refractory ceramic material may include any ceramic material that maintains thermal and chemical stability at temperatures above about 1000°C. Compositions of ceramic matrices may be selected for various properties, including but not limited to the melting point, coefficient of thermal expansion, and thermal conductivity of the ceramic material. For example, during operation of article 60, the melting point of the ceramic matrix in interface layer 68 may be higher than the expected temperature encountered at interface layer 68.

[0065] In some examples, the undercoat 66 may be configured to increase adhesion between the high-temperature interface 64 and the substrate 62. For example, one or both undercoats 66 may be formed by an in-situ process involving a reaction between reactive carbon and a stoichiometric excess of metal. The excess metal may form a metal oxide, which may migrate into the microcracks of the substrate 62, the undercoat 66, and / or the interface layer 68. The metal oxide may adhere strongly to the ceramic matrix of the interface layer 68 and / or may at least partially impregnate the open pores of the substrate 62. Thus, the interface 64 may form a strong bond between the substrates 62.

[0066] In some examples, interface layer 68 may comprise a ceramic material having a relatively low coefficient of thermal expansion (CTE). For example, the CTE of substrate 62 and / or undercoat 66 may be relatively low. To reduce interlayer forces between substrate 62 and / or undercoat 66, interface layer 68 may have a CTE relatively similar to that of substrate 62 and / or undercoat 66. In some examples, interface layer 68 may comprise a ceramic matrix comprising composite oxide ceramics, such as those described above with respect to outer coating 58. For example, as described above with respect to... Figure 2 As explained in section 58, composite oxide ceramics can possess a relatively low coefficient of thermal expansion, a relatively high operating temperature, and high oxidation resistance. For example, composite oxide ceramics can have a coefficient of thermal expansion of less than approximately 10 × 10⁻⁶. -6 The CTE is approximately 1500 °C and the melting temperature is greater than approximately 1500 °C. Exemplary composite oxide ceramic materials may include, but are not limited to, rare earth oxides, such as refractory metal silicates; rare earth monosilicates, such as ytterbium monosilicate or yttrium monosilicate; rare earth disilicates, such as barium disilicate, erbium disilicate, scandium disilicate, molybdenum disilicate, ytterbium disilicate, yttrium disilicate; aluminum titanate; mullite; etc.

[0067] Interface layer 68 may include reinforcing fibers distributed throughout the ceramic matrix to provide mechanical strength to interface layer 68. The fibers may be selected based on electrical conductivity, thermal conductivity, mechanical properties, mechanical / chemical compatibility with the matrix material, etc. Exemplary fibers may include, but are not limited to, carbon / carbon fibers, silicon carbide fibers, etc. In some examples, the fibers may be electrically and / or thermally conductive fibers. For example, as will be further explained below, electrically and / or thermally conductive fibers may be configured to generate Joule heat and / or conduct heat through interface layer 68 in response to an electric current during sintering of the pre-sintered ceramic interface to form interface layer 68. Therefore, the conductive fibers may have a size, shape, composition, and / or concentration sufficient to generate Joule heat and / or conduct Joule heat through interface layer 68 to heat multiple ceramic particles of the ceramic matrix that ultimately form interface layer 68. The conductive fibers may be relatively uniformly distributed and present at a concentration above a percolation threshold, such that the conductive fibers can conduct electricity throughout interface layer 68.

[0068] In some examples, the conductive fibers of interface layer 68 may be configured to generate heat in response to receiving an electric current. For example, as will be further described below, interface layer 68 may be formed by applying a ceramic mixture comprising conductive fibers and a plurality of ceramic particles as a pre-sintered ceramic interface to at least one of substrates 62A and / or 62B, positioning substrate 62 together with the ceramic mixture between the two substrates 62, and sintering at least a portion of the ceramic mixture by heating a portion of the ceramic mixture to the sintering temperature of the plurality of ceramic particles (such as greater than about 1000°C). This heating may be performed locally by applying an electric current to a portion of the ceramic mixture. In response to the electric current, the conductive fibers in the applied mixture may heat and transfer at least a portion of the heat to the surrounding ceramic mixture, thereby reaching the sintering temperature to bond substrate 62.

[0069] In some examples, instead of generating heat through Joule heating, conductive fibers may be configured to conduct heat received from one or both substrates 62A and 62B (e.g., in response to a current received by substrates 62A and / or 62B). For example, as will be further described below, an interface layer 68 may be formed by applying a current to one or both substrates 62 to generate Joule heat in one or both substrates 62. At least a portion of this generated heat may be transferred to a portion of the pre-sintered ceramic interface between the substrates 62 (e.g., as described above) to heat a portion of the pre-sintered ceramic interface to a sintering temperature (such as greater than about 1000°C) of the plurality of ceramic particles, thereby sintering a portion of the pre-sintered ceramic coating. In some cases, conductive fibers may conduct and distribute this generated heat through the plurality of ceramic particles of the pre-sintered ceramic interface to sinter a portion of the pre-sintered ceramic coating in a relatively short time.

[0070] In some examples, the conductive fibers may provide other properties to the interface layer 68. For example, the conductive fibers may have dimensions, shapes, compositions, and / or concentrations that improve the strength of the interface layer 68 or result in a specific coefficient of thermal expansion of the interface layer 68, such as a combination of the properties of the conductive fibers and the ceramic matrix through the interface layer 68.

[0071] The high-temperature coating described herein can be formed from a pre-sintered ceramic coating, which is sintered using rapid, localized Joule heating. Figure 4A -C、 Figures 5A-5C and Figures 6A-6C Describes the use of high-temperature coatings (such as Figure 2 Various systems and techniques for the outer coating (58). Although described individually, these systems and techniques can be used in combination, such as in parallel (e.g., contact and non-contact, heating contact and electrical contact, conduction and radiation, etc.) or sequentially (e.g., the first stage of one heating mechanism and the second stage of another heating mechanism).

[0072] In some examples, the high-temperature coating described herein can be formed as a pre-sintered ceramic coating and sintered by one or more external heating sources that can locally concentrate heat at specific portions of the pre-sintered ceramic coating and expose the underlying substrate to a relatively low heat load compared to a bulk heating method. Figure 4A This is a conceptual diagram illustrating an exemplary system 70 for forming a high-temperature coating on a substrate using a contact heating element according to the technology of this disclosure. Article 80 includes a substrate 82 and a pre-sintered ceramic coating 84 on the surface of the substrate 82. The substrate 82 may be a ceramic composite substrate and, unless otherwise stated, may be functionally and / or compositionally similar to... Figure 2 The substrate 52. The substrate 82 may include an undercoat (not shown), such as Figure 2 The base coating 56. The pre-sintered ceramic coating 84 can represent a high-temperature coating smaller than a fully sintered preform, and can be sintered to form a high-temperature coating, such as... Figure 2 58. Outer coating.

[0073] exist Figure 4A In the example, a pre-sintered ceramic coating 84 may be formed on the surface of a substrate 82. For example, as will be further explained below, a ceramic mixture comprising multiple ceramic particles may be applied to the surface of the substrate 82 and dried to form the pre-sintered ceramic coating 84. Although referred to as "pre-sintered," the pre-sintered ceramic coating 84 may be partially sintered, such that "pre-sintered" may indicate an intermediate state prior to substantial sintering. For example, the pre-sintered ceramic coating 84 may include some degree of particle necking, but may be smaller than fully dense. In some cases, the pre-sintered ceramic coating 84 may have a relative density of less than about 90%, while a fully sintered ceramic coating may have a relative density greater than about 90%.

[0074] The pre-sintered ceramic coating 84 may include multiple ceramic particles configured to withstand the high temperatures experienced during operation of the article 80. The multiple ceramic particles may have a coating corresponding to the high temperature (such as...). Figure 2 The desired composition of the outer coating 58). For example, multiple ceramic particles may include Figure 2 The outer coating 58 described herein is made of any of the ceramic materials, including composite oxide ceramics, carbide ceramics, boride ceramics, and / or nitride ceramics. These ceramic particles may exist as relatively discrete, unbonded, or partially bonded particles. Coating 84 may have a coating corresponding to an antioxidant coating (such as...). Figure 2 The high-temperature coating 54 has any thickness sufficient to protect the substrate 82 from oxidation. In some examples, the coating 84 has a thickness of about 0.05 mm to about 20 mm. In some examples, the pre-sintered ceramic coating 84 has a thickness corresponding to a sintered coating thickness of about 0.0254 mm to about 10 mm.

[0075] System 70 may be configured to sinter one or more portions of a pre-sintered ceramic coating 84. System 70 includes one or more contact heating elements 72. Although the contact heating element 72 is shown as a single contact heating element, any number of contact heating elements may be used. The contact heating element 72 may include any heating element capable of contacting the surface of the pre-sintered ceramic coating 84 and heating a portion of the pre-sintered ceramic coating 84 to the sintering temperature of multiple ceramic particles within the pre-sintered ceramic coating 84. A portion of the pre-sintered ceramic coating 84 may be a discrete portion smaller than the entire surface of the pre-sintered ceramic coating 84, such that sintering can be accomplished by heating the pre-sintered ceramic coating 84 on a partial basis, rather than by heating it all at once as in a whole heating process, when the entire pre-sintered ceramic coating 84 can be finally sintered.

[0076] The contact heating element 72 may include one or more contact surfaces configured to contact the surface of the pre-sintered ceramic coating 84. Although the contact heating element 72 is shown as a flat element, it may include one or more heating surfaces having any profile. As an example, to discretely contact one or more surface portions of the pre-sintered ceramic coating 84, the contact heating element 72 may include a die head whose profile matches at least a portion of the substrate 82 (e.g., a flat surface). As another example, to continuously contact one or more surface portions of the pre-sintered ceramic coating 84, the contact heating element 72 may include a roller configured to roll (e.g., via an actuation system 74) on the substrate 82.

[0077] The contact heating element 72 can be configured to heat a plurality of ceramic particles of the pre-sintered ceramic coating 84 to the sintering temperature of the plurality of ceramic particles. For example, the contact heating element 72 can be configured to contact the pre-sintered ceramic coating 84 for a specific amount of time sufficient to reach and maintain the sintering temperature within the pre-sintered ceramic coating 84, such that substantially all of the plurality of ceramic particles in the volume of the contact portion of the pre-sintered ceramic coating 84 adjacent to the coating 84 are sintered. The sintering temperature can be greater than about 1000°C, such as for composite oxides, or greater than about 2000°C, such as for carbides, nitrides, and / or borides.

[0078] The contact heating element 72 may be a Joule heating element configured to heat a portion of the pre-sintered ceramic coating 84 using indirect Joule heating. The contact heating element 72 may include one or more conductors configured to receive current from a power source 76 and generate resistance heat from the current, such as through the inherent resistivity of the one or more conductors. The contact heating element 72 may be configured to transfer at least a portion of this generated Joule heat to a plurality of ceramic particles in the ceramic mixture via conduction to heat the plurality of ceramic particles at or above the sintering temperature. While a portion of the generated heat may be further transferred to the substrate 82, this portion of the generated heat may be relatively constrained to the surface of the substrate 82.

[0079] The contact heating element 72 may be electrically coupled to a power supply 76. The power supply 76 may be configured to supply power to the contact heating element 72 to generate Joule heat from the contact heating element 72. The power supply 76 may be communicatively coupled to a controller 78. The power supply 76 may be configured to receive control signals from the controller 78 and deliver current to the contact heating element 72 based on the control signals.

[0080] System 70 may include a closed chamber 71 surrounding components of system 70. The closed chamber 71 may be configured to contain article 80 and maintain an inert or vacuum atmosphere within its volume. For example, at high temperatures, substrate 82 may be oxidized by reactants in the air.

[0081] System 70 may include an actuation system 74 configured to generate relative movement between contact heating element 72 and article 80. As an example, contact heating element 72 may be coupled to actuation system 74 and configured to move relative to stationary article 80. As another example, contact heating element 72 may be fixed, and article 80 may be positioned on a conveyor or other component configured to move article 80. Actuation system 74 may be communicatively coupled to controller 78. For example, actuation system 74 may include one or more actuators configured to receive control signals from controller 78 and move one or both of contact heating element 72 and / or article 80 according to various parameters such as the relative speed of movement, the x / y axis position of article 80 relative to planar substrate 82 or the x / y / z axis position of article 80 relative to non-planar substrate 82, or other parameters based on the relative movement between contact heating element 72 and / or article 80, which may be based on the time of heat treatment or a portion of article 80.

[0082] System 70 includes a controller 78. Controller 78 may be configured to control the operation of components of system 70 to sinter one or more portions of the pre-sintered ceramic coating 84. Controller 78 may include any of a wide range of devices, including processors (which include processing circuitry) (e.g., one or more microprocessors, one or more application-specific integrated circuits (ASICs), one or more field-programmable gate arrays (FPGAs), etc.), one or more servers, one or more desktop computers, one or more laptop computers, one or more cloud computing clusters, etc.

[0083] In some examples, controller 78 may be configured to control power supply 76. For example, controller 78 may be configured to send control signals to power supply 76 to control power supply 76 for power contact heating element 72, such as to a specific power level or temperature. In some examples, controller 78 may be configured to control the relative movement between contact heating element 72 and article 80. For example, controller 78 may be configured to send control signals to actuation system 74 to control the relative position of contact heating element 72, thereby heating different portions of pre-sintered ceramic coating 84 and / or heating a portion of pre-sintered ceramic coating 84 for a specific amount of time.

[0084] In some examples, the high-temperature coating described herein can be formed as a pre-sintered ceramic coating and sintered through an adjacent substrate that can locally concentrate heat on the surface of the substrate near the pre-sintered ceramic coating and keep other parts of the substrate at a relatively low temperature compared to a bulk heating method. Figure 4B This is a conceptual diagram illustrating an exemplary system 90 for forming a high-temperature coating using contact electrical elements according to the technology of this disclosure. Figure 4B Compared to the above Figure 4A Article 80 is described, including a substrate 82 and a coating 84. System 90 includes a closed chamber 91, an actuation system 94, a power supply 96, and a controller 98, and may be functionally and / or compositionally similar to those described otherwise. Figure 4A The enclosed chamber 71, the actuation system 74, the power supply 76, and the controller 78.

[0085] System 90 may be configured to sinter one or more portions of a pre-sintered ceramic coating 84 using Joule heat generated in substrate 82. System 90 includes one or more contact elements 92A and 92B (individually referred to as “contact element 92” and collectively as “contact element 92”). Although contact element 92 is shown as two contact elements, any number of contact elements may be used. Contact element 92 may include any electrical element capable of directly contacting substrate 82 and heating a surface portion of substrate 82 to heat the covered pre-sintered ceramic coating 84 to the sintering temperature of a plurality of ceramic particles of coating 84. Contact element 92 may include a surface configured to contact substrate 82, such as directly on the surface of substrate 82. Although contact element 92 is shown as a flat element, contact element 92 may include an electrical contact surface with any profile.

[0086] The contact element 92 may be configured to deliver current directly to the substrate 82 to heat a surface portion of the substrate 82, and accordingly heat a plurality of ceramic particles of the pre-sintered ceramic coating 84 to the sintering temperature of the plurality of ceramic particles. The sintering temperature may be greater than about 1000°C, such as for composite oxides, or greater than about 2000°C, such as for carbides, nitrides and / or borides.

[0087] Contact element 92 may be electrically coupled to power source 96. Power source 96 may be configured to supply or receive power to contact element 92 for use in generating heat from substrate 82. Power source 96 may be communicatively coupled to controller 98 and configured to receive control signals from controller 98 and deliver current to contact element 92 based on the control signals.

[0088] Contact element 92 may include one or more electrical contacts configured to deliver current to a portion of substrate 82. For example, one or more electrical contacts may be configured to contact substrate 82, receive current from power source 96, and deliver current to a portion of substrate 82. Substrate 82 may include a ceramic material (such as ceramic fibers and / or a ceramic matrix) that can generate resistance heat from the current, such as through the inherent resistivity of the ceramic material. This current and the corresponding heating may be concentrated near the surface of substrate 82 in the vicinity of coating 84, such that substrate 82 may be configured to transfer at least a portion of this generated heat to the coating by conduction to heat multiple ceramic particles at or above sintering temperatures. While a portion of the generated heat may be further transferred to other portions of substrate 82, this portion of the generated heat may be relatively low and confined to the vicinity of the surface of substrate 82.

[0089] In some examples, the actuation system 94 may be configured to control the relative movement between contact elements 92A and 92B. The relative distance between contact elements 92A and 92B may be related to the heating rate and / or surface area of ​​a portion of the pre-sintered ceramic coating 84 being heated. The actuation system 94 may include one or more actuators configured to receive control signals from a controller 98 and move one or both of the contact elements 92 and / or the article 80 according to various parameters such as the relative speed of movement, the x / y axis position of the article 80 relative to a planar substrate 82 or the x / y / z axis position of the article 80 relative to a non-planar substrate 82, the distance between the contact elements 92, or other parameters based on the relative movement between the contact elements 92 and / or the article 80, which may be based on the heat treatment time or a portion of the article 80.

[0090] In some examples, controller 98 may be configured to control power supply 96. For example, controller 98 may be configured to send control signals to power supply 96 to control power supply 96, thereby delivering current to substrate 82, such as to a specific temperature. In some examples, controller 98 may be configured to control the relative movement between contact elements 92 and article 80, such that controller 98 can control the relative position of contact elements 92 to heat different portions of pre-sintered ceramic coating 84. In some examples, controller 98 may be configured to control the distance between contact elements 92. For example, the rate of Joule heating may be inversely proportional to the distance between contact elements 92, while the size of the portion heated by Joule heating may be directly proportional to the distance between contact elements 92. Therefore, controller 98 may be configured to control the Joule heating rate and / or the size of the portion of pre-sintered ceramic coating 84 heated based on the distance between contact elements 92, as well as other factors affecting the Joule heating rate and / or the size of the portion of pre-sintered ceramic coating 84, such as the amount of power from power supply 96 and / or the rate of relative movement between contact elements 92 and article 80.

[0091] Figure 4C This illustrates the technology according to this disclosure for using contact elements (such as...) Figure 4A Contact heating element 72 or Figure 4B A flowchart illustrating an exemplary technique for forming a high-temperature coating by using Joule heating to sinter a pre-sintered ceramic coating (contact element 92). (The diagram is related to...) Figure 4A System 70 and Figure 4B System 90 is used to describe Figure 4C However, other systems can be used to achieve this. Figure 4C Examples include systems that achieve another type of heating to locally heat a pre-sintered ceramic coating on a ceramic composite substrate.

[0092] In some examples, Figure 4C The method may include forming an optional undercoat on the surface of the ceramic composite substrate 82, such as... Figure 2 A crystalline metal carbide undercoat 56 (100) is formed. In some examples, a metal-rich combination of one or more carbon coatings and one or more metal coatings can be used to form the undercoat in situ. Forming the undercoat may include cleaning the surface of the substrate 82, applying a reactive carbon coating (e.g., by brushing) to the surface of the substrate 82, and drying the carbon coating. Forming the undercoat may also include applying a metal coating over the carbon coating and drying the metal coating. The metal coating may be metal-rich and applied in stoichiometric excess. Forming the undercoat may also include heating the carbon coating and the metal coating to a heat treatment temperature. The heat treatment temperature may be high enough to allow the metal in the metal coating to move, such as by melting, and to allow the metal to react with the carbon in the carbon coating to form a crystalline metal carbide. The metal carbide may be further heated to further alter the microstructure, phase composition, or other properties or characteristics of the metal carbide. Excess metal from the metal coating may migrate into the pores of the substrate 82. The resulting undercoat may include a metal carbide portion on the surface of the substrate 82 and a metal portion extending into the substrate 82.

[0093] Figure 4C The method may include forming a high-temperature coating on a substrate 82 (or other layers covering the substrate 82, such as an undercoat), such as... Figure 2 High-temperature coating 54 (102). Figure 4C The method may include forming a pre-sintered ceramic coating 84 (104) on the surface of a ceramic composite substrate 82. In some examples, forming the pre-sintered ceramic coating 84 may include applying a ceramic mixture to the surface of the substrate 82. The ceramic mixture may include multiple ceramic particles and a distribution medium, such that the ceramic mixture can be applied as a paste, slurry, or other fluid mixture. The ceramic mixture may be pretreated prior to sintering to form the pre-sintered ceramic coating 84. For example, the ceramic mixture may be dried to remove the distribution medium and pre-baked at a relatively low temperature to burn off volatiles and form a pre-sintered (or partially sintered) ceramic coating 84. In some cases, the ceramic mixture may be partially sintered to form a green or brown preform as the pre-sintered ceramic coating 84.

[0094] Figure 4CThe method may include sintering at least a portion (106) of the pre-sintered ceramic coating 84 by heating a portion of the pre-sintered ceramic coating 84 to its sintering temperature using Joule heating. For example, Joule heating can generate relatively concentrated heat in a conductor compared to bulk heating (where the surrounding gas in the furnace can be heated by convection). This relatively concentrated heat can be controlled such that multiple ceramic particles of the pre-sintered ceramic coating 84 can reach the sintering temperature in a relatively short amount of time, while portions of the substrate 82 not adjacent to the coating 84 can remain at a lower temperature as the coating 84 is sintered. In some examples, the pre-sintered ceramic coating can be sintered in less than about one minute. In some examples, the sintering temperature can be greater than about 1000°C. In some examples, the average overall temperature of the substrate 82 can be at least about 100°C lower than the average overall temperature of the coating 84 during sintering.

[0095] To sinter the pre-sintered ceramic coating 84, multiple ceramic particles can be heated to and maintained at the sintering temperature, allowing sintering to be performed through any of a variety of processes, including but not limited to solid-state sintering, liquid-phase sintering, reactive bonding, or any other type of sintering mechanism or combination of sintering mechanisms. Therefore, the sintering of the pre-sintered ceramic coating 84 can be controlled by operating conditions such as the temperature of the contact heating element 72 or the electrical contact element 92 or the power delivered to it, the temperature of the pre-sintered ceramic coating 84 (e.g., measured by a temperature sensor or determined based on other factors), the amount of contact time between the contact heating element 72 or the contact electrical element 92, and other factors related to the amount and rate of heat delivery to the pre-sintered ceramic coating 84.

[0096] In some examples, a portion of the sintered pre-sintered ceramic coating 84 may include heating the pre-sintered ceramic coating 84 using one or more external heating sources (such as contact heating element 72), which can locally concentrate heat at the pre-sintered ceramic coating 84 and keep the underlying substrate 82 at a relatively lower temperature compared to a bulk heating method. See also... Figure 4A , Figure 4C The method may include bringing a portion of the pre-sintered ceramic coating 84 into contact with a Joule heating element (such as a contact heating element 72) (106). For example, a controller 78 may send a control signal to an actuation system 74 to control the relative movement between the contact heating element 72 and the article 80, such that the contact heating element 72 contacts a specific portion of the pre-sintered ceramic coating 84. Figure 4CThe method may include powering the contact heating element 72 to heat a portion of the pre-sintered ceramic coating to or above the sintering temperature (108). For example, the controller 78 may send a control signal to the power supply 76 to power the contact heating element 72 at a specific power level to reach a specific temperature and / or sustain for a specific amount of time, thereby achieving the sintering temperature in the coating 84 to substantially sinter multiple ceramic particles of the coating 84.

[0097] In some examples, the sintering of a portion of the pre-sintered ceramic coating 84 may include heating the pre-sintered ceramic coating 84 using an adjacent substrate 82, which may locally concentrate heat on the surface of the substrate 82 near the coating 84 and keep other portions of the substrate 82 at relatively lower temperatures compared to a bulk heating method. See also... Figure 4B , Figure 4C The method may include bringing a portion of the pre-sintered ceramic coating 84 into contact with a contact element (such as contact element 92) (106). For example, the controller 98 may send a control signal to the actuation system 94 to control the relative movement between the contact element 92 and the article 80, such that the contact element 92 contacts a specific portion of the substrate 82 corresponding to a desired portion of the pre-sintered ceramic coating 84. Figure 4C The method may include applying an electric current to the substrate 82 to heat a portion of the pre-sintered ceramic coating to or above the sintering temperature (108). For example, the controller 98 may send a control signal to the power supply 96 to deliver current to the contact element 92 to achieve a specific temperature of the substrate 82 and / or sustain it for a specific time, thereby achieving a sintering temperature in the coating 84 to substantially sinter multiple ceramic particles of the coating 84.

[0098] In some examples, heating the pre-sintered ceramic coating 84 may include two or more heating stages. For example, the pre-sintered ceramic coating 84 may be heated to a relatively low temperature (such as between about 500°C and about 1000°C) in a first overall heating stage, such that the substrate 82 may not suffer thermal damage. The pre-sintered ceramic coating 84 may be heated to a relatively high sintering temperature in a second localized heating stage. The first overall heating stage allows the pre-sintered ceramic coating 84 to reach a high sintering temperature (such as greater than about 2000°C), which would not be possible using overall or localized heating.

[0099] In some examples, Figure 4C The method may include sintering one or more other portions of the pre-sintered ceramic coating 84. For example, controllers 78 and / or 98 may control corresponding actuation systems 74 or 94 to control corresponding contact heating elements 72 or contact electrical elements 92 to contact different portions of the coating 84 and / or substrate 82, and heat one or more other portions of the coating 84 to the sintering temperature of the ceramic particles.

[0100] In some examples, the pre-sintered ceramic coating 84 may be sintered in discrete portions. For example, a specific surface area defined by the contact heating element 72 or the contact electrical element 92 may be heated, and then the contact heating element 72 or the contact electrical element 92 may be repositioned relative to the article 80 to heat different portions of the coating 84, such that heating of a specific portion of the coating 84 may be sustained for a specific amount of time corresponding to the amount of contact time between the contact heating element 72 or the contact electrical element 92 and the article 80.

[0101] In some examples, the pre-sintered ceramic coating 84 can be sintered continuously. For example, a specific surface area defined by the contact element 92 can be continuously moved across the surface of the coating 84, such that heating a specific portion of the coating 84 can be sustained for a specific amount of time corresponding to the relative rate of movement between the contact element 92 and the article 80.

[0102] In some examples, the high-temperature coating described herein can be formed as a pre-sintered ceramic coating and sintered using one or more external non-contact radiative heating sources that can locally concentrate heat at the coating and maintain the underlying substrate (including substrates with wavy surfaces) at a relatively lower temperature compared to bulk heating methods and / or with relatively lower contact stress compared to contact heating methods. Figure 5A This is a conceptual side view illustrating an exemplary system 110 for forming a high-temperature coating using a non-contact radiant heating element according to the technology of this disclosure, while Figure 5B This illustrates the technology according to this disclosure. Figure 5A A conceptual front view of an exemplary system 110. Figure 5A and Figure 5B Compared to the above Figure 4A Article 80 is described, including a substrate 82 and a coating 84. System 110 includes a closed chamber 111, an actuation system 114, a power supply 116, and a controller 118, which may be functionally and / or compositionally similar to those described otherwise. Figure 4A The enclosed chamber 71, the actuation system 74, the power supply 76, and the controller 78.

[0103] In some examples, the pre-sintered ceramic coating 84 may include a restricted contact heating method (such as...) Figures 4A-4C The pre-sintered ceramic coating 84 possesses one or more characteristics of its ability to fully sinter the pre-sintered ceramic coating (as described in the text). As an example, the pre-sintered ceramic coating 84 may have a relatively complex shape and / or a relatively complex surface corresponding to the surface of the underlying substrate 82, making contact heating methods potentially unsuitable for heating the pre-sintered ceramic coating on the substrate or uneconomical for this purpose. As another example, the ceramic coating 84 may be relatively brittle, making contact heating methods potentially damaging the coating 84.

[0104] System 110 can be configured to sinter one or more portions of the pre-sintered ceramic coating 84 using radiation from a Joule heat source without contacting the surface of the pre-sintered ceramic coating 84. System 110 includes one or more non-contact radiant heating elements 112. Although the non-contact radiant heating element 112 is shown as a single non-contact radiant heating element, any number of contact elements may be used. The non-contact radiant heating element 112 may include any radiant element capable of heating the pre-sintered ceramic coating 84 to the sintering temperature of the plurality of ceramic particles of the coating 84.

[0105] exist Figure 5A and Figure 5B In the example, the non-contact radiant heating element 112 includes a movement axis 113 through a volume defined by the non-contact radiant heating element 112. The movement axis 113 may define the overall movement path of the article 80 through or past the non-contact radiant heating element 112, but the movement of the article 80 perpendicular to the movement axis 113 may adjust the distance between the pre-sintered ceramic coating 84 and one or more radiant surfaces 115 of the non-contact radiant heating element 112.

[0106] The non-contact radiant heating element 112 may be configured to heat a plurality of ceramic particles of a pre-sintered ceramic coating 84 to a sintering temperature of the plurality of ceramic particles. The sintering temperature may be greater than about 1000°C, such as for composite oxide ceramics, or greater than about 2000°C, such as for carbide, nitride, and / or boride ceramics. The non-contact radiant heating element 112 may be electrically coupled to a power source 116 configured to supply power to the non-contact radiant heating element 112 to generate heat from the non-contact radiant heating element 112.

[0107] In some examples, the non-contact radiant heating element 112 may include one or more radiating surfaces 115 that are radially inward (e.g., toward the movement axis 113) and configured to emit and / or reflect radiation at one or more surfaces of the pre-sintered ceramic coating 84. For example, one or more radiating surfaces 115 may be distributed around or beside the movement axis 113. Although the non-contact radiant heating element 112 is shown as a tubular element, it may include one or more radiating surfaces 115 having any profile or location. For example, the non-contact radiant heating element 112 may include one or more radiating surfaces 115 only on portions of the non-contact radiant heating element 112, such as portions configured to approach the pre-sintered ceramic coating 84 when the article 80 moves along the movement axis 113.

[0108] The non-contact radiant heating element 112 may include one or more infrared heating elements configured to heat a portion of the pre-sintered ceramic coating 84 using radiation generated by Joule heating. For example, the non-contact radiant heating element 112 may include one or more resistors configured to receive current from a power source 116 and generate radiant heat from the current, such as inherent radiation emitted from the one or more resistors or reflected from a reflective surface. The non-contact radiant heating element 112 may be configured to transfer at least a portion of this radiation to a plurality of ceramic particles in the ceramic mixture to heat the plurality of ceramic particles at or above a sintering temperature. While a portion of the generated heat may be further transferred to the substrate 82, this portion of the generated heat may be relatively low due to the short time required for sintering the pre-sintered ceramic coating 84 or the distance between the substrate 82 and the radiating surface 115 of the non-contact radiant heating element 112, and may be relatively constrained to the surface of the substrate 82.

[0109] In some examples, the non-contact radiant heating element 112 may be configured to produce a variable temperature profile along, across, and / or around the axis of the non-contact radiant heating element 112. For example, the non-contact radiant heating element 112 may be configured to produce a relatively hot zone 117 in the vicinity of the non-contact radiant heating element 112. The non-contact radiant heating element 112 may be configured to control the temperature of the relatively hot zone 117 to vary at least one of the movement axis 113 or around the movement axis 113 (e.g., the circumference of the non-contact radiant heating element 112).

[0110] In some examples, the non-contact radiant heating element 112 may be configured to vary the temperature of a relatively hot zone 117 along the axis of movement 113 of the article 80. This variable temperature allows for control over the temperature or heating distribution as the article moves in and out along the axis 113. As an example, sintering may include heating through various temperature ranges that can lead to defects in the article 80, such as cracking, blistering, or other defects. To avoid the formation of these defects, these temperature ranges may be carried out at a slower rate. Correspondingly, the hot zone 117 may have a lower temperature to heat the article 80 at a slower rate through these temperature ranges, such as at the inlet region of the non-contact radiant heating element 112. As another example, sintering may include various post-processing procedures, such as annealing. Correspondingly, after passing through the middle of the hot zone 117, the hot zone 117 may have a lower temperature to produce, for example, a slower annealing step.

[0111] For example, controller 118 may be configured to control power supply 116 to emit a first amount of radiation at a first axial position (such as the proximal end) along the movement axis 113, and to emit a second, different amount of radiation at a second axial position (such as the distal end) along the movement axis 113. The first amount of radiation at the proximal end may be higher, allowing the relatively cool pre-sintered ceramic coating 84 to reach the sintering temperature more quickly, while the second amount of radiation at the distal end may be lower, allowing the now-heated pre-sintered ceramic coating 84 to be maintained at or above the sintering temperature.

[0112] In some examples, the non-contact radiant heating element 112 may be configured to change the temperature of a relatively hot region 117 surrounding or across the axis of movement 113 of the article 80 via (e.g., tubular) or (e.g., planar) means, such that the non-contact radiant heating element 112 can change the temperature in a single plane across the axis 113. Due to the relatively high sintering temperature of the coating 84, it may be difficult to bring the coating 84 to the sintering temperature without at least partially heating the underlying substrate 82, as heat conduction from the coating 84 may be faster than the application of heat radiated to the coating 84. Therefore, the non-contact radiant heating element 112 may be configured to create a heating gradient through the article 80 by heating different portions of the article 80 to different temperatures. For example, to heat the coating 84 to a sintering temperature of about 2000°C, the bottom side of the article 80 may be heated to about 1300°C, while the top side of the article 80 having the coating 84 may be heated to about 2000°C.

[0113] For example, controller 118 may be configured to control power supply 116 to emit a first amount of radiation at a first radial position (such as the top) around the movement axis 113, and a second, different amount of radiation at a second axial position (such as the bottom) around the movement axis 113. The first amount of radiation at the top near coating 84 may be higher, such that coating 84 can receive a relatively high amount of radiation, while the second amount of radiation at the bottom near substrate 82 may be lower or absent, such that substrate 82 can receive a relatively low amount of radiation.

[0114] System 110 may include an actuation system 114 configured to allow relative movement between the non-contact radiant heating element 112 and the article 80, such as axially or radially within the non-contact radiant heating element 112. In some examples, the actuation system 114 may be configured to position a specific portion of the pre-sintered ceramic coating 84 near the radiant surface 115 of the non-contact radiant heating element 112, such as by moving the article 80 relative to the non-contact radiant heating element 112 along a movement axis 113 to sinter another portion of the pre-sintered ceramic coating 84. As an example, the non-contact radiant heating element 112 may be coupled to the actuation system 114 and configured to move relative to the stationary article 80, such as moving along the movement axis 113 to heat different axial portions of the coating 84, or moving perpendicular to the movement axis 113 to increase or decrease the distance between the coating 84 and the non-contact radiant heating element 112. As another example, the non-contact radiant heating element 112 may be fixed and the article 80 may be positioned on a conveyor or frame configured to move the article 80 along a movement axis 113 past the non-contact radiant heating element 112. The actuation system 114 may include one or more actuators configured to receive control signals from a controller 118 and move the non-contact radiant heating element 112 and / or the article 80 according to various parameters such as the relative speed of movement, the axial position on the article 80, the distance between the non-contact radiant heating element 112 and the coating 84, or other parameters based on the relative movement between the non-contact radiant heating element 112 and / or the article 80, which may be based on the heat treatment time or a portion of the article 80.

[0115] Figure 5C This illustrates the technology according to this disclosure for using non-contact radiant heating elements (such as...) Figure 5C A flowchart illustrating an exemplary technique for forming a high-temperature coating using a non-contact radiant heating element 112. (The flowchart is related to...) Figure 5A and Figure 5B System 110 is used to describe Figure 5C However, other systems can be used to achieve this. Figure 5C Examples include systems that achieve another type of non-contact radiative heating to locally heat pre-sintered ceramic coatings on ceramic composite substrates. In some examples, Figure 5C The method may include forming an undercoat on the surface of the ceramic composite substrate 82, such as... Figure 2 Crystalline metal carbide undercoat 56 (120), such as Figure 4C As described in step 100.

[0116] Figure 5C The method may include forming a high-temperature coating on the substrate 82, such as Figure 2High-temperature coating 54 (122). Figure 5C The method may include applying a pre-sintered ceramic coating 84 to the surface (124) of a ceramic composite substrate 82, such as Figure 4C As described in step 104. In some examples, the surface of the substrate 82 may be wavy or difficult to access directly, making contact heating methods insufficient or unable to reach the surface of the pre-sintered ceramic coating 84.

[0117] Figure 5C The method may include sintering at least a portion of the pre-sintered ceramic coating 84 by heating a portion of the pre-sintered ceramic coating 84 to its sintering temperature using radiation generated by Joule heating. For example, radiant heating can generate relatively concentrated heat compared to bulk heating (where the surrounding gas in the furnace can be used to heat the article using convection). This relatively concentrated heat can be spatially controlled using the distance between the article 80 and the non-contact radiant heating element 112 and / or the power / temperature of the non-contact radiant heating element 112, such that multiple ceramic particles of the pre-sintered ceramic coating 84 near the radiant surface 115 can reach the sintering temperature in a relatively short amount of time, while portions of the substrate 82 not near the radiant surface 115 can remain at a lower temperature or be exposed to a higher temperature for a shorter duration relative to bulk heating. Simultaneously, surfaces of the pre-sintered ceramic coating 84 that are relatively difficult to access or contact can still be sintered without heating the surrounding atmosphere (as in bulk heating methods). In some examples, the sintering temperature may be greater than about 1000°C. In some examples, during sintering, the average overall temperature of the substrate 82 may be at least about 100°C lower than the average overall temperature of the coating 84.

[0118] In some examples, a portion of the sintered pre-sintered ceramic coating 84 may include heating the pre-sintered ceramic coating 84 using one or more non-contact radiant heating elements 112. Figure 5C The method may include positioning a portion of the ceramic coating 84 near the non-contact radiant heating element 112 (126). For example, the controller 118 may send a control signal to the actuation system 114 to control the relative movement between the non-contact radiant heating element 112 and the article 80, such that the non-contact radiant heating element 112 positions a specific portion of the pre-sintered ceramic coating 84 at an axial position along the movement axis 113 of the non-contact radiant heating element 112. Figure 5CThe method may include powering the non-contact radiant heating element 112 to heat a portion of the pre-sintered ceramic coating to or above the sintering temperature (128). For example, the controller 118 may send a control signal to the power supply 116 to power the non-contact radiant heating element 112 at a specific power level, to reach a specific temperature of the non-contact radiant heating element 112, to reach a specific temperature of the hot zone 117 generated by the non-contact radiant heating element 112, and / or to sustain for a specific amount of time, thereby achieving a sintering temperature in the coating 84 to substantially sinter multiple ceramic particles of the coating 84.

[0119] To sinter the pre-sintered ceramic coating 84, multiple ceramic particles can be heated to a sintering temperature and maintained at that temperature for a period of time until the ceramic material of the ceramic particles migrates across the particles to fuse them together. Therefore, the sintering of the pre-sintered ceramic coating 84 can be controlled by operating conditions such as the temperature of the non-contact radiant heating element 112 or the power delivered to it, the distance between the pre-sintered ceramic coating 84 and the non-contact radiant heating element 112, the temperature of the pre-sintered ceramic coating 84 (e.g., measured by a temperature sensor or determined based on other factors), the amount of exposure time of the pre-sintered ceramic coating 84 to the non-contact radiant heating element 112, and other factors related to the amount and rate of heat delivery to the pre-sintered ceramic coating 84.

[0120] In some examples, Figure 5C The method may include sintering another portion of the pre-sintered ceramic coating 84. For example, controller 118 may control actuation system 114 to control non-contact radiant heating element 112 to be positioned close to different portions of coating 84 and / or substrate 82, and to heat another portion of coating 84 to a sintering temperature. In some examples, the pre-sintered ceramic coating 84 may be batch-sintered. For example, the entire article 80 may be positioned within non-contact radiant heating element 112 and heated for a specific amount of time. In some examples, the pre-sintered ceramic coating 84 may be continuously sintered as article 80 travels along movement axis 113 past non-contact radiant heating element 112. For example, a specific radiant surface area defined by non-contact radiant heating element 112 may be continuously moved across the surface of coating 84 such that as article 80 travels along movement axis 113 from inlet to outlet, a specific portion of coating 84 may be heated for a specific amount of time corresponding to the relative rate of movement between non-contact radiant heating element 112 and article 80.

[0121] In some examples, Figure 5CThe method may include altering the temperature of a relatively hot region 117 along the axis of movement 113 of the article 80 using a non-contact radiant heating element 112. For example, a controller 118 may control a power supply 116 to emit a first amount of radiation at a first axial position along the axis of movement 113 (such as a proximal end) and a second, different amount of radiation at a second axial position along the axis of movement 113 (such as a distal end). The first amount of radiation at the proximal end may be higher, allowing the relatively cooler pre-sintered ceramic coating 84 to reach the sintering temperature more quickly, while the second amount of radiation at the distal end may be lower, allowing the now-heated pre-sintered ceramic coating 84 to be maintained at or above the sintering temperature.

[0122] In some examples, Figure 5C The method may include changing the temperature of a relatively hot zone 117 surrounding or across the axis of movement 113 of the article 80 by means of (e.g., tubular) or (e.g., planar) non-contact radiant heating elements 112. For example, controller 118 may control power supply 116 to emit a first amount of radiation at a first radial position (such as the top) surrounding the axis of movement 113, and a second, different amount of radiation at a second axial position (such as the bottom) surrounding the axis of movement 113. The first amount of radiation at the top near the coating 84 may be higher, such that the coating 84 receives a relatively high amount of radiation, while the second amount of radiation at the bottom near the substrate 82 may be lower or absent, such that the substrate 82 receives a relatively low amount of radiation.

[0123] In some examples, the high-temperature coatings described herein can be formed as pre-sintered ceramic coatings and sintered by one or more external contact heating sources that can locally apply heat and pressure to the coating to rapidly and efficiently sinter and densify the pre-sintered ceramic coating, thereby avoiding or reducing the exposure of the underlying substrate to extreme temperature and pressure conditions. For example, instead of sintering ceramic coatings in a large furnace under extreme operating conditions and subjecting them to large heat losses, the localized application of heat and pressure can sinter coatings on substrates with a wide range of sizes, shapes, and compositions, including coatings on relatively large or non-conductive substrates. Figure 6A This is a conceptual diagram illustrating an exemplary system 130 for forming a high-temperature coating using contact elements and applied loads according to the technology of this disclosure. Figure 6A Compared to the above Figure 4A Article 80 is described, including a substrate 82 and a pre-sintered ceramic coating 84. System 130 includes a closed chamber 131, an actuation system 134, a power supply 136, and a controller 138, which may be functionally and / or compositionally similar to those described otherwise. Figure 4A The enclosed chamber 71, the actuation system 74, the power supply 76, and the controller 78.

[0124] System 130 may be configured to sinter one or more portions of a pre-sintered ceramic coating 84. System 130 includes one or more contact heating elements 132. Although contact heating element 132 is shown as a single contact heating element, any number of contact heating elements may be used. Contact heating element 132 may include any heating element capable of contacting the pre-sintered ceramic coating 84 and heating the pre-sintered ceramic coating 84 to the sintering temperature of a plurality of ceramic particles. Contact heating element 132 may include a surface configured to contact the pre-sintered ceramic coating 84. Figure 6A In the example, the contact heating element 132 has a substantially planar surface corresponding to the planar surfaces of the coating 84 and the substrate 82, such that the force applied to the coating 84 can be relatively uniform on the planar surface of the pre-sintered ceramic coating 84.

[0125] The contact heating element 132 may be configured to resist relatively high temperatures experienced during the sintering of the ceramic particles and relatively high forces experienced from a load. The contact heating element 132 may be a Joule heating element configured to heat a portion of the ceramic coating using indirect Joule heating. The contact heating element 132 may include one or more conductive high-temperature electrodes (such as graphite, tungsten, rhenium, molybdenum, or tantalum electrodes) configured to receive current from a power source 136 and generate Joule heat from the current (such as through the inherent resistivity of the one or more conductive high-temperature electrodes), and resist compressive forces during the application of a load. For example, a graphite electrode may have a high melting point (e.g., about 3500°C), high removability (e.g., low adhesion potential), high thermal conductivity, low resistance, and high resistance to heat and shock. The contact heating element 132 may be configured to transfer at least a portion of this generated heat to a plurality of ceramic particles in the ceramic mixture via conduction to heat the plurality of ceramic particles at or above the sintering temperature. While a portion of the generated heat may be further transferred to the substrate 82, this portion of the generated heat may be relatively constrained to the surface of the substrate 82.

[0126] The contact heating element 132 may be configured to heat a plurality of ceramic particles of a ceramic mixture to the sintering temperature of the plurality of ceramic particles. For example, the contact heating element 132 may be configured to contact the pre-sintered ceramic coating 84 for a specific amount of time sufficient to reach and maintain the sintering temperature, such that substantially all of the plurality of ceramic particles in the coating 84 are sintered. The sintering temperature may be greater than about 1000°C, such as for composite oxides, or greater than about 2000°C, such as for carbides, nitrides, and / or borides.

[0127] The contact heating element 132 may be electrically coupled to a power source 136. The power source 136 may be configured to supply power to the contact heating element 132 to generate heat from it. The power source 136 may be communicatively coupled to a controller 138. The controller 138 may be configured to control the power source 136. For example, the controller 138 may be configured to send control signals to the power source 136 to control the power source 136 for the power of the contact heating element 132, such as to a specific power level or temperature.

[0128] Before or during sintering, the pre-sintered ceramic coating 84 may undergo one or more physical or chemical processes that can reduce the oxidation resistance or structural integrity of the resulting high-temperature coating. For example, during sintering, the pre-sintered ceramic coating 84 may undergo densification, such as a relative density of about 50% to greater than about 99%. This densification leads to shrinkage, which is generally isotropic and occurs in all directions. In-plane (e.g., xy-direction) shrinkage can be particularly problematic because cracks and other defects may form, making perpendicular-plane (e.g., z-direction) shrinkage preferable. Relatively thin coatings can be sintered such that shrinkage is anisotropic and naturally occurs only in the z-direction due to surface and interface interactions, wetting, liquid phases, and / or other mechanisms. However, in other coating systems, especially thicker coatings, shrinkage may not be anisotropic, and in-plane shrinkage can occur. In-plane shrinkage can lead to various defects, such as slurry cracks, microcracks, voids, etc., which may not be ideal for the protection of the article 80 and for the uniformity and quality of the coating 84. System 130 can be configured to apply pressure in the z-direction, which forces shrinkage to be substantially anisotropic and reduces and / or prevents the formation of in-plane shrinkage defects in the z-direction. In some ceramic systems, especially ultra-high temperature ceramics (UHTC) (such as carbides and borides), temperature alone may not be sufficient for complete densification, making it possible for applied pressure to enhance densification, which would not be possible without pressure.

[0129] System 130 may include a top actuation system component 134A and a bottom actuation system component 134B (collectively referred to as "Actuation System 134") or other components or groups of components configured to locally apply pressure to the pre-sintered ceramic coating 84. Figure 6AIn this example, the contact heating element 132 may be coupled to a top actuation system component 134A, while the article 80 may be positioned on a bottom actuation system component 134B. The top actuation system component 134A and / or the bottom actuation system component 134B may be configured to apply pressure to the article 80 to compress the pre-sintered ceramic coating 84 while simultaneously sintering the pre-sintered ceramic coating 84. The actuation system 134 may be communicatively coupled to a controller 138. The actuation system 134 may include one or more load actuators configured to receive control signals from the controller 138 and apply pressure to the article 80 according to various parameters, such as force / area, x / y axis position on the article 80, desired strain rate, or other parameters.

[0130] Controller 138 may be configured to control the load applied to article 80 by actuation system 134, such that controller 138 can control the amount of pressure applied to ceramic coating 84. For example, controller 138 may be configured to send control signals to actuation system 134 to control one or more load actuators to apply a load to article 80, such as with a specific force / area, a specific strain rate, and / or for a specific duration. When this load is applied, multiple ceramic particles may be compacted during sintering, thereby densifying the ceramic material to form a high-temperature, dense ceramic coating. In some examples, the porosity of the resulting ceramic layer is less than about 5% by volume. Figures 4A to 4C (It describes contact with the pre-sintered ceramic coating 84), such contact can be relatively low and is intended to make thermal or electrical contact with portions of the pre-sintered ceramic coating 84. Conversely, relative to... Figures 6A to 6C The described contacts can be configured to further enhance densification and / or increase z-direction contraction, accompanied by a corresponding reduction in in-plane contraction. In some examples, the load can be as high as approximately 500 MPa.

[0131] In some examples, the high-temperature coating described herein can be formed as a pre-sintered ceramic coating and sintered by one or more external heating sources that can locally apply heat and pressure to the pre-sintered ceramic coating to sinter and densify the coating in a process in which portions of the pre-sintered ceramic coating can be continuously sintered and compressed. Figure 6B This is a conceptual diagram illustrating an exemplary system 140 for forming a high-temperature coating using a contact heating element and a load, according to the technology of this disclosure. System 140 includes an enclosed chamber 141, an actuation system 144, a power supply 146, and a controller 148, which may be functionally and / or compositionally similar to those described herein, unless otherwise stated. Figure 6A The enclosed chamber 131, the actuation system 134, the power supply 136, and the controller 138.

[0132] System 140 may be configured to continuously sinter one or more portions of a pre-sintered ceramic coating 84. System 140 includes a top contact heating element 142A and a bottom contact heating element 142B (collectively, “contact heating element 142”). Although contact heating element 142 is shown as two contact heating elements, any number of contact heating elements may be used. For example, the bottom contact heating element 142B may be absent, such that only the top contact heating element 142A may be configured to heat the top portion of the article 80. Contact heating element 142 may include any heating element capable of contacting the pre-sintered ceramic coating 84 and heating the pre-sintered ceramic coating 84 to the sintering temperature of a plurality of ceramic particles. Contact heating element 142 may include a curved surface configured to contact a first portion of the pre-sintered ceramic coating 84 and proceed to a second portion of the pre-sintered ceramic coating 84 without raising contact heating element 142. Figure 6B In the example, the contact heating element 142 may be a roller configured to advance to sinter another portion of the pre-sintered ceramic coating 84, such that the force applied to the coating 84 can be applied incrementally along the surface of the pre-sintered ceramic coating 84. For example, the pre-sintered ceramic coating 84 may have curvature along its axis, such that a planar surface may not adequately compress the various portions of the coating 84. Instead, the contact heating element 142 with a curved surface may be able to conform to the curved surface.

[0133] The contact heating element 142 may be configured to resist the relatively high temperatures experienced during the sintering of the ceramic particles and the relatively high forces experienced from a load. The contact heating element 142 may be a Joule heating element configured to use indirect Joule heating to heat a portion of the pre-sintered ceramic coating 84. In some examples, the contact heating element 142 may include one or more graphite electrodes configured to receive current from the power source 146 and generate Joule heat from the current, such as through the inherent resistivity of the one or more graphite electrodes, and resist compressive forces during the application of a load.

[0134] The contact heating element 142 may be configured to heat a plurality of ceramic particles of a ceramic mixture to a sintering temperature for the plurality of ceramic particles. For example, the contact heating element 142 may be configured to contact a pre-sintered ceramic coating 84 for a specific amount of time sufficient to reach and maintain the sintering temperature, such that substantially all of the plurality of ceramic particles in the coating 84 are sintered. The contact heating element 142 may be electrically coupled to a power source 136. The power source 146 may be configured to supply power to the contact heating element 142 to generate heat from the contact heating element 142. The power source 146 may be communicatively coupled to a controller 148. The power source 146 may be configured to receive control signals from the controller 148 and deliver power to the contact heating element 142 to generate Joule heat in the contact heating element 142, such as at a desired power level and / or a desired temperature.

[0135] System 130 may include a top actuation system component 144A and a bottom actuation system component 144B (collectively referred to as "Actuation System 144") or other components or groups of components configured to locally apply pressure to the pre-sintered ceramic coating 84. Figure 6A In the example, contact heating element 142A may be coupled to top actuation system component 144A, contact heating element 142B may be coupled to bottom actuation system component 144B, and article 80 may be located between top actuation system component 144A and bottom actuation system component 144B. Top actuation system component 144A and / or bottom actuation system component 144B may be configured to apply pressure to article 80 to compress pre-sintered ceramic coating 84 while sintering pre-sintered ceramic coating 84. Actuation system 144 may be communicatively coupled to controller 148. Actuation system 144 may include one or more load actuators configured to receive control signals from controller 148 and apply pressure to article 80 according to various parameters, such as force / area, x / y axis position of article 80 relative to planar substrate 82 or x / y / z axis position of article 80 relative to non-planar substrate 82, or other parameters.

[0136] In addition to the various functions performed by controller 138, controller 148 can be controlled to control actuation system 144 to advance contact heating element 142 to different portions of pre-sintered ceramic coating 84. For example, controller 148 can be configured to send control signals to actuation system 144 to control the relative movement rate between contact heating element 142 and article 80, thereby heating pre-sintered ceramic coating 84 to a specific temperature or at a specific power level (e.g., corresponding to temperature or heat flux), compressing pre-sintered ceramic coating 84 at a specific pressure or load (including dynamic or static pressure or load), and / or generating relative movement between article 80 and contact heating element 142 to sinter and compress different portions of pre-sintered ceramic coating 84. In this way, system 140 can be configured to continuously and uniformly apply sintering and densify pre-sintered ceramic coating 84 to form a dense high-temperature ceramic coating.

[0137] Figure 6C This illustrates the technology according to this disclosure for using contact elements and loads (such as...) Figure 6A The contact heating element 132 and the actuation system 134 or Figure 6B A flowchart illustrating an exemplary technique for forming a high-temperature coating using a contact heating element 142 and an actuation system 144. (The diagram is in contrast to...) Figure 6A System 130 and Figure 6B System 140 is used to describe Figure 6C However, other systems can be used to achieve this. Figure 6CExamples include systems that achieve another type of heating or loading to locally heat and compress a pre-sintered ceramic coating on a ceramic composite substrate. In some examples, Figure 6C The method may include forming an undercoat on the surface of the ceramic composite substrate 82, such as... Figure 2 Crystalline metal carbide undercoat 56 (150), such as Figure 4C As described in step 100.

[0138] Figure 6C The method may include forming a high-temperature coating on the substrate 82, such as Figure 2 High-temperature coating 54 (152). Figure 6C The method may include forming a pre-sintered ceramic coating 84 (154) on the surface of a ceramic composite substrate 82, such as Figure 4C As described in step 104. Figure 6C The method may include bringing a portion of the pre-sintered ceramic coating 84 into contact with a contact element (such as contact heating element 132 or contact heating element 142) (156). For example, controller 138 or controller 148 may send a control signal to actuation system 134 or 144 to control the relative movement between contact heating element 132 or 142 and article 80, such that contact heating element 132 or 142 can contact a specific portion of the pre-sintered ceramic coating 84.

[0139] In order to form a dense high-temperature ceramic coating, Figure 6C The method may include sintering at least a portion (158) of the pre-sintered ceramic coating 84 by heating a portion of the pre-sintered ceramic coating 84 to a sintering temperature of the pre-sintered ceramic coating 84 using Joule heating, while simultaneously compressing the portion of the pre-sintered ceramic coating 84 (159). In some examples, the sintering temperature may be greater than about 1000°C. In some examples, during sintering, the average overall temperature of the substrate 82 may be at least about 100°C lower than the average overall temperature of the coating 84.

[0140] In some examples, the sintering of a portion of the pre-sintered ceramic coating 84 may include heating the pre-sintered ceramic coating 84 using one or more external heat sources, which can locally concentrate heat at the pre-sintered ceramic coating 84 and keep the underlying substrate 82 at a relatively low temperature compared to a bulk heating method. See also... Figure 6A , Figure 6CThe method may include bringing a portion of the pre-sintered ceramic coating 84 into contact with a Joule heating element (such as contact heating element 132 or contact heating element 142). For example, controller 138 or 148 may send a control signal to actuation system 134 or 144 to control relative planar movement between contact heating element 132 or contact heating element 142 and article 80 (e.g., perpendicular to an applied load of actuation system 134 or actuation system 144), such that contact heating element 132 or contact heating element 142 contacts a specific portion of the pre-sintered ceramic coating 84. Figure 6C The method may include powering the contact heating element 132 to heat a portion of the pre-sintered ceramic coating to or above the sintering temperature (156). For example, the controller 78 may send a control signal to the power supply 76 to power the contact heating element 72 at a specific power level to reach a specific temperature and / or sustain it for a specific amount of time, thereby achieving the sintering temperature in the coating 84 to substantially sinter multiple ceramic particles of the coating 84.

[0141] In some examples, compressing a portion of the pre-sintered ceramic coating 84 may include applying a load to the pre-sintered ceramic coating 84 using an actuation system 134 or 144, while simultaneously concentrating heat locally at that portion of the pre-sintered ceramic coating 84. Reference Figure 6A , Figure 6C The method may include applying a specific load to the pre-sintered ceramic coating 84 using an actuation system 134 to compress a portion of the pre-sintered ceramic coating 84 at a sintering temperature for a specific amount of compression time. For example, the specific load and / or the specific compression time may correspond to forces that can compress and densify the pre-sintered ceramic coating 84 without damaging the pre-sintered ceramic coating 84 and / or the underlying substrate 82. In some examples, the compression load may be as high as about 500 MPa, while the compression time may be between about five seconds and about five minutes.

[0142] In some examples, Figure 6C The method may include sintering another portion of the pre-sintered ceramic coating 84. For example, controllers 138 and / or 148 may control corresponding actuation systems 134 or 144 to control corresponding contact heating elements 132 or 142 to contact different portions of the coating 84 and / or substrate 82, and heat other portions of the coating 84 to the sintering temperature. Figure 6A In the example, the pre-sintered ceramic coating 84 can be sintered in discrete portions. For example, a specific surface area defined by the contact heating element 132 can be heated and compressed, and then the contact heating element 132 is repositioned relative to the article 80 to heat different portions of the coating 84, such that the specific portions of the heatable and compressible coating 84 remain in contact with the heating element 132 for a specific contact time between the heating element 132 and the article 80. Figure 6BIn the example, the pre-sintered ceramic coating 84 can be sintered continuously. For example, a specific surface area defined by the contact heating element 142 can be continuously moved across the surface of the coating 84, such that heating a specific portion of the coating 84 can be sustained for a specific amount of time corresponding to the relative movement rate between the contact heating element 142 and the article 80.

[0143] The high-temperature interface described herein can be formed by a pre-sintered ceramic coating, which is sintered using rapid, localized Joule heating. Figure 7A and Figure 7B Describes the methods for forming high-temperature interfaces (such as Figure 3 Various systems and techniques for the interface layer 68. Although described separately, these systems and techniques can be used in combination, such as in parallel (e.g., electrical contact between two substrates and the interface) or sequentially (e.g., a first stage of one heating mechanism and a second stage of another heating mechanism).

[0144] In some examples, the high-temperature interface described herein may be formed as a pre-sintered ceramic interface between two or more adjacent substrates and sintered to bond the two or more adjacent substrates with a strong bond that reduces the substrates’ exposure to high temperatures. Figure 7A This is a conceptual diagram illustrating an exemplary system 160 for forming a high-temperature interface according to the technology of this disclosure. Article 170 includes a first substrate 172A and a second substrate 172B (individually referred to as "substrate 172" and collectively as "substrate 172") and a pre-sintered ceramic interface 174 between the substrates 172. Each substrate 172 may be a ceramic composite substrate and may be similar to... Figure 3 The substrate 62. The substrate 172 may include an undercoat (not shown), such as Figure 3 The base coating 66. System 160 includes an enclosed chamber 161, an actuation system 164, a power supply 166, and a controller 168, which may be functionally and / or compositionally similar to those described otherwise. Figure 6A The enclosed chamber 131, the actuation system 134, the power supply 136, and the controller 138.

[0145] exist Figure 7A In the example, the pre-sintered ceramic interface 174 may be positioned between the surfaces of the substrate 172. For example, as will be further explained below, a mixture comprising multiple ceramic particles may be applied to the surfaces of substrates 172A and / or 172B and dried to form the pre-sintered ceramic interface 174. Although referred to as “pre-sintered,” the interface 174 may be partially sintered, such that “pre-sintered” can refer to an intermediate state prior to substantially sintering.

[0146] The pre-sintered ceramic interface 174 may include multiple ceramic particles. These multiple ceramic particles may have a corresponding high-temperature interface (such as...). Figure 3The desired composition of the interface layer 68). For example, multiple ceramic particles may include Figure 3 The ceramic material of the interface layer 68 described herein includes any of the following: composite oxide ceramics, carbide ceramics, boride ceramics, and / or nitride ceramics. These ceramic particles may exist as relatively discrete, unbonded, or partially bonded particles. In addition to multiple ceramic particles, the pre-sintered ceramic interface 174 may include multiple fibers, such as… Figure 3 The interface layer 68 describes multiple fibers. Interface layer 68 includes fibers distributed throughout the ceramic matrix to provide enhanced mechanical properties to interface 174, and in some cases, may be electrically and / or thermally conductive to enhance the sintering of interface 174. The pre-sintered ceramic interface 174 may have corresponding interfaces (such as...) Figure 3 The high-temperature interface 64 has any thickness sufficient to bond the substrate 172 together. In some examples, the pre-sintered ceramic interface 174 has a thickness of about 10 micrometers to about five millimeters.

[0147] System 160 may be configured to sinter one or more portions of the pre-sintered ceramic interface 174 using Joule heating generated in the pre-sintered ceramic interface 174 and / or one or both substrates 172. System 160 includes one or more contact elements 162A and 162B (individually referred to as "contact element 162" and collectively as "contact element 162"). Unless otherwise stated, contact element 162 may be functionally and compositionally similar to Figure 4B Contact element 92. Contact element 162 may include any electrical element capable of contacting the pre-sintered ceramic interface 174 and / or substrate 172 to directly (e.g., by Joule heating in the pre-sintered ceramic interface 174) and / or indirectly (e.g., by Joule heating in one or both substrates 172A and 172B) heat the sandwiched pre-sintered ceramic interface 174 to the sintering temperature of the plurality of ceramic particles of the interface 174.

[0148] Contact element 162 may be configured to deliver current to a pre-sintered ceramic interface 174 and / or one or both substrates 172 to heat a plurality of ceramic particles of the pre-sintered ceramic interface 174 to a sintering temperature of the plurality of ceramic particles. The sintering temperature may be greater than about 1000°C, such as for composite oxides, or greater than about 2000°C, such as for carbides, nitrides, and / or borides. In some examples, contact element 162 may include one or more electrical contacts configured to deliver current to a portion of the pre-sintered ceramic interface 174 and / or a portion of substrates 172A and / or 172B.

[0149] The contact element 92 may include one or more electrical contacts configured to receive current from the power source 166 and deliver current to portions of the pre-sintered ceramic interface 174 and / or one or both substrates 172. As an example, the pre-sintered ceramic interface 174 may include conductive fibers that can generate resistance heat from the current and transfer at least a portion of the heat to the surrounding ceramic mixture to heat multiple ceramic particles to a sintering temperature and bond them to the substrate 172. As another example, the substrate 172 may include a ceramic material (such as ceramic fibers and / or a ceramic matrix) that can generate resistance heat from the current and transfer at least a portion of this generated heat to multiple ceramic particles in the pre-sintered ceramic interface 174 via conduction to heat the multiple ceramic particles at or above the sintering temperature.

[0150] Contact element 162 may be electrically coupled to power source 166. Power source 166 may be configured to supply or receive power to contact element 162 for use in generating heat from substrate 172. Power source 166 may be communicatively coupled to controller 168. Power source 166 may be configured to receive control signals from controller 168 and deliver current to contact element 162 based on the control signals.

[0151] Actuation system 164 may be configured to maintain the position of substrate 172, such as by compressing substrate 172. System 160 may include top actuation system component 164A and bottom actuation system component 164B (collectively, “Actuation System 164”) or other components or groups of components configured to position pre-sintered ceramic interface 174 between substrates 172 and locally apply pressure to pre-sintered ceramic interface 174. Unless otherwise specified, actuation system 164 may be functionally and compositionally similar to Figure 6A The actuation system 134.

[0152] System 160 includes a controller 168. The controller 168 may be configured to control the operation of components of system 160 to sinter one or more portions of the pre-sintered ceramic interface 174. The controller 168 may be similar to, for example... Figure 4AThe controller 168. In some examples, the controller 168 may be configured to control the power supply 166. For example, the controller 168 may be configured to send control signals to the power supply 166 to control the power supply 166, thereby delivering current to the substrate 172, such as to a specific temperature. In some examples, the controller 168 may be configured to control the relative movement between the contact element 162 and the article 170, such that the controller 168 can control the relative position of the contact element 162 to heat different portions of the pre-sintered ceramic interface 174. In some examples, the controller 168 may be configured to control the load applied to the article 170 by the actuation system 164, such that the controller 168 can control the amount of pressure applied to the pre-sintered ceramic interface 174. For example, the controller 168 may be configured to send control signals to the actuation system 164 to control one or more load actuators, thereby applying a load to the article 170, such as with a specific force / area, with a specific strain rate, and / or for a specific duration.

[0153] Figure 7B This illustrates the technology according to this disclosure for using one or more contact electrical elements (such as...) Figure 7A A flowchart illustrating an exemplary technique for forming a high-temperature interface by using Joule heating to sinter a pre-sintered ceramic interface (contact element 162). (The remaining text appears to be a fragment and requires further context for accurate translation.) Figure 7A System 160 is used to describe Figure 7B However, other systems can be used to achieve this. Figure 7B Examples include systems that achieve another type of heating to locally heat the pre-sintered ceramic interface between ceramic composite substrates. In some examples, Figure 7B The method may include forming a base coating on the surface of any one or both of the ceramic composite substrates 172A and / or 172B, such as Figure 3 Crystalline metal carbide undercoat 66 (180), such as Figure 4C As described in step 100.

[0154] Figure 7B The method may include forming a high-temperature interface between substrate 172 (or other layers covering substrate 172, such as an undercoat), such as Figure 3 The high-temperature interface 64 (182). Figure 7BThe method may include forming a pre-sintered ceramic interface 174 (184) between the surfaces of ceramic composite substrates 172A and 172B. In some examples, forming the pre-sintered ceramic interface 174 may include first applying a plurality of fibers (such as conductive fibers) to the surface of either or both of the substrates 172A and 172B, and then applying a ceramic mixture to the surface of either or both of the substrates 172A and 172B. The ceramic mixture may include a plurality of ceramic particles and a distribution medium, such that the ceramic mixture can be applied as a paste, slurry, or other fluid mixture. The ceramic mixture may be pretreated prior to sintering to form the pre-sintered ceramic interface 174. For example, the ceramic mixture may be dried to remove the distribution medium and pre-baked at a relatively low temperature to burn off volatiles and form the pre-sintered (or partially sintered) ceramic interface 174. Figure 7B The method may include positioning a second substrate (such as substrate 172B) on a pre-sintered ceramic interface 174 on the surface of substrate 172A.

[0155] Although Figure 7B The method has been described as forming a pre-sintered ceramic interface 174 on a first substrate 172A and positioning a second substrate 172A on the pre-sintered ceramic substrate. However, in other examples, a second substrate 172B may be positioned above the first substrate 172A prior to forming the pre-sintered ceramic interface 174. For example, a ceramic mixture may be applied to either or both surfaces of substrates 172A and / or substrate 172B, and substrate 172B may be positioned on substrate 172A such that the ceramic mixture is positioned between substrates 172. After positioning the substrates 172, the ceramic mixture may be pre-treated, such as by drying or pre-baking at a low temperature, to form the pre-sintered ceramic interface 174 between substrates 172. In this manner, the pre-sintered ceramic interface 174 can adhere more easily to the surfaces of substrates 172, and substrates 172 may only be exposed to the relatively low temperatures involved in pre-sintering or other pre-treatment techniques to form the pre-sintered ceramic interface 174.

[0156] Figure 7B The method may include contacting the article 170, such as a portion of the pre-sintered ceramic interface 174 or one or more portions of the substrate 172, via the contact element 162 (186). For example, the controller 168 may send a control signal to the actuation system 164 to control the relative movement between the contact element 162 and the article 170, such that the contact element 162 may contact a specific portion of the pre-sintered ceramic interface 174.

[0157] Figure 7BThe method may include sintering at least a portion (188) of the pre-sintered ceramic coating 174 by heating a portion of the pre-sintered ceramic interface 174 to the sintering temperature of the pre-sintered ceramic interface 174 using Joule heating. For example, Joule heating within the pre-sintered ceramic interface 174 or within the substrate 172 can generate relatively concentrated heat compared to overall heating in which the surrounding gas in the furnace can heat the adhesive layer by heating adjacent substrates. This relatively concentrated heat can be controlled such that multiple ceramic particles of the pre-sintered ceramic interface 174 can reach the sintering temperature in a relatively short amount of time, while portions of the substrate 172 not adjacent to the pre-sintered ceramic interface 174 can remain at a lower temperature as the pre-sintered ceramic interface 174 is sintered. In some examples, the pre-sintered ceramic interface 174 can be sintered in less than about one minute. In some examples, the sintering temperature can be greater than about 1000°C. In some examples, during sintering, the average overall temperature of the substrate 172 can be at least about 100°C lower than the average overall temperature of the pre-sintered ceramic interface 174.

[0158] In some examples, a portion of the sintered pre-sintered ceramic interface 174 may be heated at a relatively low temperature compared to the overall heating method, using Joule heat generated within the pre-sintered ceramic interface 174 and the substrate 172. See also... Figure 7A , Figure 7B The method may include bringing one or both substrates 172 into contact with a contact element (such as contact electrical element 162). For example, controller 98 may send a control signal to actuation system 164 to control the relative movement between contact electrical element 162 and article 170, such that contact electrical element 162 contacts a specific portion of pre-sintered ceramic interface 174. Figure 7B The method may include applying an electric current to the pre-sintered ceramic interface 174 to generate Joule heat in the pre-sintered ceramic interface 174. For example, conductive fibers in the pre-sintered ceramic interface 174 may be heated in response to the electric current. This heat may be transferred by conduction to heat ceramic particles in one or more portions of the pre-sintered ceramic interface 174 to or above the sintering temperature. For example, a controller 178 may send a control signal to a power supply 176 to deliver current to a contact element 162 to achieve a specific temperature of the pre-sintered ceramic interface 174 and / or sustain it for a specific time, thereby achieving a sintering temperature in the pre-sintered ceramic interface 174 to substantially sinter a plurality of ceramic particles of the pre-sintered ceramic interface 174.

[0159] exist Figure 7AIn some examples not shown, the sintering of a portion of the pre-sintered ceramic interface 174 may include heating the pre-sintered ceramic interface 174 using one or more adjacent substrates 172, which may locally concentrate heat at the surface of the substrate 172 near the pre-sintered ceramic interface 174 and keep other portions of the substrate 172 at a relatively lower temperature compared to a bulk heating method. See also... Figure 7A , Figure 7B The method may include contacting one or both substrates 172 with a contact element (such as contact electrical element 162). For example, controller 98 may send a control signal to actuation system 164 to control the relative movement between contact electrical element 162 and article 170, such that contact electrical element 162 contacts one or more specific portions of substrate 172 corresponding to a desired portion of pre-sintered ceramic interface 174. Figure 7B The method may include applying an electric current to a substrate 172 to generate Joule heat in the substrate 172. This heat can be conducted to one or more portions of the pre-sintered ceramic interface 174 to heat the ceramic particles in one or more portions of the pre-sintered ceramic interface 174 to a sintering temperature or above. For example, a controller 168 may send a control signal to a power supply 166 to deliver current to a contact element 162 to achieve a specific temperature of the substrate 172 and / or sustain it for a specific time, thereby achieving a sintering temperature in the pre-sintered ceramic interface 174 to substantially sinter the plurality of ceramic particles of the coating 84. In some examples, conductive fibers in the pre-sintered ceramic interface 174 may facilitate the conduction of this heat from the substrate 172 through the pre-sintered ceramic interface 174 to rapidly and / or uniformly sinter the ceramic particles of the pre-sintered ceramic interface 174.

[0160] In some examples, Figure 7BThe method may include sintering another portion of the pre-sintered ceramic interface 174. For example, controller 168 may control actuation system 164 to control contact element 162 to contact different portions of the pre-sintered ceramic interface 174 and / or substrate 172, and to heat different portions of the pre-sintered ceramic interface 174 to a sintering temperature. In some examples, the pre-sintered ceramic interface 174 may be sintered in discrete portions. For example, a specific surface area defined by contact element 162 may be heated, followed by repositioning contact element 162 relative to article 170 to heat different portions of the pre-sintered ceramic interface 174, such that heating of a specific portion of the pre-sintered ceramic interface 174 may be sustained for a specific amount of time corresponding to the amount of contact time between contact element 162 and article 170. In some examples, the pre-sintered ceramic coating 84 may be sintered continuously. For example, a specific surface region defined by the contact element 162 can move continuously across the surface of the substrate 172 and / or the pre-sintered ceramic interface 174, such that heating a specific portion of the pre-sintered ceramic interface 174 can be sustained for a specific amount of time corresponding to the relative rate of movement between the contact element 162 and the article 170.

[0161] Experimental methods

[0162] Figures 8A to 8D These are micrographs of high-temperature ceramic coating samples under different degrees of heat treatment. The coating samples were formed on silicon carbide / silicon carbide (SiC / SiC) composite substrates. Each coating sample was subjected to contact heating (such as...) Figures 4A to 4C As described in the text) and non-contact heating (such as...) Figures 5A to 5C It is manufactured (as described in the text) and will be further described below.

[0163] A composite oxide slurry was applied to the surface of a SiC / SiC composite substrate and allowed to dry. The composite oxide slurry was then exposed to air at 600°C to burn off any organic matter. The sample was placed on a moving platform inside a vacuum chamber and moved under a carbon heating element, which was heated to approximately 2000°C using an electric current. The sample was exposed to the heating element for approximately 5 to 10 seconds.

[0164] Depending on the proximity of the coating to the heating element and the temperature gradient of the heating element, different levels of sintering and densification were demonstrated over a short period of time. Figure 8A This is a micrograph of a cross-sectional view of a pre-sintered high-temperature ceramic coating on a SiC / SiC composite substrate. Figure 8B This is a micrograph of a cross-sectional view of a partially sintered high-temperature ceramic coating on a SiC / SiC composite substrate. Figure 8C This is a micrograph of a cross-sectional view of a sintered high-temperature ceramic coating on a SiC / SiC composite substrate; and Figure 8DThis is a micrograph of a cross-sectional view of a molten high-temperature ceramic coating on a SiC / SiC composite substrate. Figure 8A and Figure 8B The coating can be characterized by relatively low density and high volume fraction of pores. Figure 8D The coating can be characterized by pores, bubbles, and other defects that may be caused by overheating, which leads to coating melting. In contrast, Figure 8C The coating can be characterized by a dense and uniform coating.

[0165] Although the system is not optimized for temperature uniformity, control, and / or automation, Figures 8A to 8D The fabrication of the coating samples demonstrates that the coating sintersects within a very short timeframe (e.g., 5–10 seconds). Undesirable reactions present in overall heating are absent due to its slower kinetics and short baking time, and the near-melting or melting temperatures of the ceramic coating can be locally achieved on the surface without the substrate experiencing these extreme temperatures. Figures 8A to 8D As shown, the sintering of the coating can be controlled by temperature, heating time, and proximity to the heating source, allowing for the selection of appropriate times and temperatures to achieve a very dense and uniform coating. Furthermore, a moving hot zone can be used to achieve this type of sintering in a non-contact, linear manner, allowing the coating to be sintered before the actual sintering process. The coating exhibits strong adhesion to the SiC / SiC substrate.

[0166] Figure 9 This is a micrograph of a cross-sectional view of the sintered high-temperature ceramic interface on a SiC / SiC composite substrate. SiC fibers are placed on the surface of the SiC / SiC substrate. A composite oxide slurry is applied to the surface of the SiC / SiC substrate and allowed to dry. Joule heating is used to heat the SiC fibers and the composite oxide slurry, causing the composite oxide to reach near its melting temperature and incorporating the SiC fibers while adhering to the SiC / SiC substrate. Thus, the ceramic interface comprises axially aligned silicon carbide fibers within a carbon matrix. The ceramic interface contacts a silicon carbide undercoat on the carbon substrate. Therefore, the fibers are incorporated into the ceramic interface within a short time (a few seconds), enhancing the mechanical properties of the ceramic interface. Example

[0167] Example 1: A method comprising forming a pre-sintered ceramic coating on a ceramic composite substrate, wherein the pre-sintered ceramic coating comprises a plurality of ceramic particles; and sintering the portion of the pre-sintered ceramic coating by heating at least a portion of the pre-sintered ceramic coating to a sintering temperature of the plurality of ceramic particles using Joule heating, wherein the sintering temperature is greater than about 1000 degrees Celsius (°C).

[0168] Example 2: The method according to Example 1 further includes contacting the portion of the pre-sintered ceramic coating with one or more contact heating elements; and supplying power to the one or more contact heating elements to heat the portion of the pre-sintered ceramic coating.

[0169] Example 3: According to the method described in Example 2, the one or more contact heating elements include one or more high-temperature electrode heating elements.

[0170] Example 4: The method according to any one of Examples 2 and 3 further includes moving the pre-sintered ceramic coating relative to the one or more contact heating elements such that the one or more contact heating elements contact different portions of the pre-sintered ceramic coating.

[0171] Example 5: The method according to any one of Examples 2 to 4 further includes compressing the portion of the pre-sintered ceramic coating while heating the portion of the pre-sintered ceramic coating.

[0172] Example 6: According to the method of Example 5, wherein compressing the portion of the pre-sintered ceramic coating includes using a roller to compress the portion of the pre-sintered ceramic, and wherein the method further includes advancing the roller to heat another portion of the pre-sintered ceramic coating.

[0173] Example 7: The method according to any one of Examples 1 to 6 further includes contacting the portion of the pre-sintered ceramic coating with one or more contact elements; and delivering current through the one or more contact elements to the substrate to heat the portion of the pre-sintered ceramic coating.

[0174] Example 8: The method according to any one of Examples 1 to 7, wherein the plurality of ceramic particles comprises at least one of carbide ceramics, boride ceramics or nitride ceramics.

[0175] Example 9: The method according to any one of Examples 1 to 8, wherein the plurality of ceramic particles comprise rare earth disilicate ceramics.

[0176] Example 10: The method according to any one of Examples 1 to 9 further includes forming a crystalline metal carbide undercoat on the surface of the ceramic composite substrate.

[0177] Example 11: The method according to any one of Examples 1 to 10, wherein forming the pre-sintered ceramic coating further includes applying a ceramic mixture to the surface of the substrate, wherein the ceramic mixture comprises the plurality of ceramic particles.

[0178] Example 12: A system for forming a high-temperature ceramic coating includes a sealed chamber configured to: contain an article comprising a pre-sintered ceramic coating on a ceramic composite substrate, wherein the pre-sintered ceramic coating comprises a plurality of ceramic particles; maintain an inert or vacuum atmosphere in the sealed chamber; and one or more contact elements configured to: contact a portion of the article; and generate Joule heat to heat a portion of the pre-sintered ceramic coating to a sintering temperature of the plurality of ceramic particles to sinter the portion of the pre-sintered ceramic coating, wherein the sintering temperature is greater than about 1000°C.

[0179] Example 13: The system according to Example 12, wherein the one or more contact elements include one or more contact heating elements configured to generate Joule heat in the one or more contact heating elements in response to an electric current, and wherein the system further includes a power source configured to deliver current to the Joule heating elements to heat the portion of the pre-sintered ceramic coating.

[0180] Example 14: The system according to Example 13, wherein the one or more contact heating elements comprise one or more graphite electrode heating elements.

[0181] Example 15: A system according to any one of Examples 12 to 14, wherein the one or more contact elements comprise one or more contact electrical elements configured to deliver current to the substrate to generate the Joule heat in the substrate in response to the current, and wherein the system further comprises a power source configured to deliver the current to the one or more contact electrical elements to heat the portion of the pre-sintered ceramic coating via the substrate.

[0182] Example 16: The system according to any one of Examples 12 to 15 further includes an actuation system coupled to the one or more contact elements and configured to compress the portion of the pre-sintered ceramic coating while the one or more contact elements heat the portion of the pre-sintered ceramic coating.

[0183] Example 17: The system according to Example 16, wherein the one or more contact elements include one or more rollers configured to advance the article to heat another portion of the pre-sintered ceramic coating.

[0184] Example 18: The system according to any one of Examples 12 to 17 further includes an actuation system configured to generate relative movement between the article and the one or more contact elements such that the one or more contact elements contact different portions of the article.

[0185] Example 19: The system according to any one of Examples 12 to 18, wherein the plurality of ceramic particles comprise at least one of carbide ceramics, boride ceramics, or nitride ceramics.

[0186] Example 20: The system according to any one of Examples 12 to 19, wherein the plurality of ceramic particles comprise rare earth disilicate ceramics.

[0187] Example 21: A method comprising forming a pre-sintered ceramic coating on a ceramic composite substrate, wherein the pre-sintered ceramic coating comprises a plurality of ceramic particles; and sintering the portion of the pre-sintered ceramic coating by heating at least a portion of the pre-sintered ceramic coating to a sintering temperature of the pre-sintered ceramic coating using one or more non-contact radiant heating elements, wherein the sintering temperature is greater than about 1000 degrees Celsius (°C).

[0188] Example 22: The method according to Example 21 further includes positioning the portion of the pre-sintered ceramic coating close to the one or more non-contact radiant heating elements; and heating the one or more non-contact radiant heating elements to sinter the portion of the pre-sintered ceramic coating.

[0189] Example 23: The method according to any one of Examples 21 and 22 further includes moving the pre-sintered ceramic coating relative to the one or more non-contact radiant heating elements such that the one or more non-contact radiant heating elements sinter different portions of the pre-sintered ceramic coating.

[0190] Example 24: The method according to any one of Examples 21 to 23 further includes moving the substrate along a moving axis relative to the one or more non-contact radiant heating elements to sinter another portion of the pre-sintered ceramic coating.

[0191] Example 25: According to the method of Example 24, wherein the one or more non-contact radiant heating elements are configured to generate a relatively hot zone near the one or more non-contact radiant heating elements, and wherein the temperature of the relatively hot zone varies along or around the moving axis.

[0192] Example 26: According to the method of any one of Examples 24 and 25, wherein the one or more non-contact radiant heating elements are configured to generate a relatively hot zone near the one or more non-contact radiant heating elements, and wherein the temperature of the relatively hot zone varies about the moving axis.

[0193] Example 27: The method according to any one of Examples 21 to 26, wherein the one or more non-contact radiative heating elements include infrared heating elements.

[0194] Example 28: The method according to any one of Examples 21 to 27, wherein the plurality of ceramic particles comprises at least one of carbide ceramics, boride ceramics, nitride ceramics or rare earth disilicate ceramics.

[0195] Example 29: The method according to any one of Examples 21 to 28 further includes forming a crystalline metal carbide undercoat on the surface of the ceramic composite substrate.

[0196] Example 30: The method according to any one of Examples 21 to 29, wherein forming the pre-sintered ceramic coating further includes applying a ceramic mixture to the surface of the substrate, wherein the ceramic mixture comprises the plurality of ceramic particles.

[0197] Example 31: A system for forming a high-temperature ceramic coating includes a sealed chamber configured to: contain an article comprising a pre-sintered ceramic coating on a ceramic composite substrate; maintain an inert or vacuum atmosphere in the chamber; and one or more non-contact radiative heating elements configured to generate Joule heat to heat a portion of the pre-sintered ceramic coating to a sintering temperature greater than about 1000 degrees Celsius (°C).

[0198] Example 32: The system according to Example 31, wherein the one or more non-contact radiative heating elements include a Joule heating element configured to generate Joule heat in response to an electric current, and wherein the system further includes a power source configured to deliver current to the Joule heating element to heat the portion of the pre-sintered ceramic coating.

[0199] Example 33: The system according to any one of Examples 31 and 32 further includes an actuation system configured to position the portion of the pre-sintered ceramic coating close to the one or more non-contact radiant heating elements.

[0200] Example 34: The system according to Example 33, wherein the actuation system is configured to move the pre-sintered ceramic coating relative to the one or more non-contact radiant heating elements such that the one or more non-contact radiant heating elements sinter different portions of the pre-sintered ceramic coating.

[0201] Example 35: A system according to any one of Examples 33 and 34, wherein the actuation system is configured to move the substrate along a moving axis relative to the one or more non-contact radiant heating elements to sinter another portion of the pre-sintered ceramic coating.

[0202] Example 36: According to the system of Example 35, wherein the one or more non-contact radiant heating elements are configured to generate a relatively hot zone near the one or more non-contact radiant heating elements, and wherein the temperature of the relatively hot zone varies along or around at least one of the moving axis.

[0203] Example 37: The system according to any one of Examples 35 and 36, wherein the one or more radiant heating elements include one or more radiant surfaces oriented radially inward toward the moving axis and configured to emit radiation at one or more surfaces of the pre-sintered ceramic coating.

[0204] Example 38: The system according to any one of Examples 31 to 37, wherein the one or more non-contact radiative heating elements include one or more infrared heating elements.

[0205] Example 39: The system according to any one of Examples 31 to 38, wherein the pre-sintered ceramic coating comprises at least one of carbide ceramic, boride ceramic or nitride ceramic.

[0206] Example 40: The system according to any one of Examples 31 to 39, wherein the pre-sintered ceramic coating comprises rare earth disilicate ceramic.

[0207] Example 41: A method comprising forming an article comprising a first ceramic composite substrate, a second ceramic composite substrate, and a pre-sintered ceramic interface between the first ceramic composite substrate and the second ceramic composite substrate, wherein the pre-sintered ceramic interface comprises a plurality of ceramic particles and a plurality of fibers; and sintering the portion of the pre-sintered ceramic interface to bond the first substrate and the second substrate by heating at least a portion of the pre-sintered ceramic interface to a sintering temperature of the ceramic interface using Joule heating, wherein the sintering temperature is greater than about 1000 degrees Celsius (°C).

[0208] Example 42: According to the method of Example 41, the heating of the portion of the pre-sintered ceramic interface further includes: contacting the article with one or more contact electrical elements; and delivering current to the article to heat the portion of the pre-sintered ceramic interface.

[0209] Example 43: The method according to Example 42, wherein contacting the article comprises contacting at least one of the first substrate or the second substrate with the one or more contact electrical elements, and wherein delivering the current to the article comprises delivering the current to the at least one of the first substrate or the second substrate to generate Joule heating in the at least one of the first substrate or the second substrate.

[0210] Example 44: The method according to any one of Examples 42 and 43, wherein contacting the article comprises contacting the pre-sintered ceramic interface with the one or more contact electrical elements; and wherein delivering the current to the article comprises delivering the current to the pre-sintered ceramic interface to generate Joule heating in the plurality of fibers of the pre-sintered ceramic interface.

[0211] Example 45: The method according to any one of Examples 41 to 44 further includes compressing the portion of the pre-sintered ceramic interface while heating the portion of the pre-sintered ceramic interface.

[0212] Example 46: The method according to any one of Examples 42 to 45 further includes moving the article and the one or more contact elements such that the one or more contact elements contact different portions of the article.

[0213] Example 47: The method according to any one of Examples 41 to 46 further includes forming the pre-sintered ceramic interface on the surface of the first ceramic composite substrate; and positioning the second ceramic composite substrate on the pre-sintered ceramic interface opposite to the surface of the first ceramic composite substrate.

[0214] Example 48: The method according to Example 47, wherein forming the pre-sintered ceramic interface includes applying a ceramic mixture to the surface of the first ceramic composite substrate, and wherein the ceramic mixture includes the plurality of ceramic particles and the plurality of fibers.

[0215] Example 49: The method according to any one of Examples 41 to 48, wherein the plurality of ceramic particles comprise rare earth disilicate ceramics.

[0216] Example 50: The method according to any one of Examples 41 to 49 further includes forming a crystalline metal carbide undercoat on the surface of at least one of the first substrate or the second substrate.

[0217] Example 51: The method according to any one of Examples 41 to 50, wherein the plurality of fibers are conductive.

[0218] Example 52: An article comprising: a first ceramic composite substrate; a second ceramic composite substrate; and a high-temperature interface between a first surface of the first ceramic composite substrate and a second surface of the second ceramic composite substrate, wherein the high-temperature interface comprises at least one high-temperature interface layer, the at least one high-temperature interface layer comprising a ceramic matrix and a plurality of fibers distributed through the ceramic matrix.

[0219] Example 53: The article according to Example 52, wherein the high-temperature interface further includes: a first crystalline metal carbide undercoat on the first surface of the first ceramic composite substrate; and a second crystalline metal carbide undercoat on the second surface of the second ceramic composite substrate, wherein the high-temperature interface layer is positioned between the first metal carbide undercoat and the second metal carbide undercoat.

[0220] Example 54: The article according to Example 53, wherein the ceramic matrix comprises rare earth disilicate ceramic.

[0221] Example 55: An article of any one of Examples 52 to 54, wherein the article is a component of a brake assembly.

[0222] Example 56: The article according to any one of Examples 52 to 55, wherein the plurality of fibers are conductive.

[0223] Example 57: A system for forming a high-temperature ceramic interface, comprising a sealed chamber configured to: contain an article comprising a first ceramic composite substrate, a second ceramic composite substrate, and a pre-sintered ceramic interface between the first ceramic substrate and the second ceramic substrate, wherein the pre-sintered ceramic interface comprises a plurality of ceramic particles and a plurality of fibers; maintain an inert or vacuum atmosphere in the sealed chamber; and one or more contact elements configured to: contact a portion of the article; and deliver current to the article to heat a portion of the pre-sintered ceramic interface to a sintering temperature of the plurality of ceramic particles to sinter the portion of the pre-sintered ceramic interface, wherein the sintering temperature is greater than about 1000 degrees Celsius (°C).

[0224] Example 58: The system according to Example 57, wherein the one or more contact elements are configured to contact at least one of the first substrate or the second substrate, and to deliver the current to the at least one of the first substrate or the second substrate to generate Joule heating in the at least one of the first substrate or the second substrate in response to the current, and wherein the system further includes a power source configured to deliver the current to the one or more contact elements to heat the portion of the pre-sintered ceramic interface via the at least one of the first substrate or the second substrate.

[0225] Example 59: The system according to any one of Examples 57 to 58 further includes an actuation system configured to generate relative movement between the article and the one or more contact elements such that the one or more contact elements contact different portions of the article.

[0226] Example 60: The system according to any one of Examples 57 to 59, wherein the plurality of ceramic particles comprise rare earth disilicate ceramics.

[0227] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

1. A method comprising: An article comprising a first ceramic composite substrate, a second ceramic composite substrate, and a pre-sintered ceramic interface between the first ceramic composite substrate and the second ceramic composite substrate, wherein the pre-sintered ceramic interface comprises a plurality of ceramic particles and a plurality of fibers; A crystalline metal carbide undercoat is formed on the surface of at least one of the first ceramic composite substrate or the second ceramic composite substrate; as well as The pre-sintered ceramic interface is sintered by heating at least a portion of the pre-sintered ceramic interface to a sintering temperature of the ceramic interface using Joule heating to bond the first ceramic composite substrate and the second ceramic composite substrate, wherein the sintering temperature is greater than 1000 degrees Celsius.

2. The method according to claim 1, wherein heating the portion of the pre-sintered ceramic interface further comprises: The article is brought into contact with one or more electrical contact elements; as well as An electric current is delivered to the article to heat the portion of the pre-sintered ceramic interface.

3. The method according to claim 2, Contacting the article includes bringing at least one of the first ceramic composite substrate or the second ceramic composite substrate into contact with the one or more contact electrical elements, and Delivering the current to the article includes delivering the current to at least one of the first ceramic composite substrate or the second ceramic composite substrate to generate Joule heating in the first ceramic composite substrate or the second ceramic composite substrate.

4. The method according to claim 2, Contacting the article includes bringing the pre-sintered ceramic interface into contact with the one or more contact electrical elements; and Delivering the current to the article includes delivering the current to the pre-sintered ceramic interface to generate Joule heating in the plurality of fibers of the pre-sintered ceramic interface.

5. The method according to any one of claims 1 to 4, The plurality of ceramic particles comprise rare-earth disilicate ceramics, and The plurality of fibers are conductive.

6. An article prepared by the method of any one of claims 1 to 5, comprising: First ceramic composite substrate; Second ceramic composite substrate; and A high-temperature interface is located between a first surface of the first ceramic composite substrate and a second surface of the second ceramic composite substrate. The high-temperature interface includes at least one high-temperature interface layer, which includes a ceramic matrix and a plurality of fibers distributed through the ceramic matrix.

7. The article of claim 6, wherein the high-temperature interface further comprises: A first crystalline metal carbide undercoat is applied to the first surface of the first ceramic composite substrate; and A second crystalline metal carbide undercoat is applied to the second surface of the second ceramic composite substrate. The high-temperature interface layer is positioned between the first crystalline metal carbide undercoat and the second crystalline metal carbide undercoat.

8. The article of claim 6 or 7, The ceramic matrix mentioned above comprises rare earth disilicate ceramics, and The plurality of fibers are conductive.

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