Joining ceramic substrates

Abstract

A method of joining ceramic substrates. A first ceramic substrate is positioned adjacent a second ceramic substrate. The first ceramic substrate includes a first adjoining surface and the second ceramic substrate includes a second adjoining surface. The first adjoining surface contacts the second adjoining surface to form a joint. Pores of the first adjoining surface, pores of the second adjoining surface, and the joint, are infiltrated with a preceramic polymer. The preceramic polymer is pyrolyzed in the pores of the first adjoining surface, in the pores of the second adjoining surface, and in the joint.

Description

Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 JOINING CERAMIC SUBSTRATES CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Application No.63 / 527,206, titled “Joining Ceramic Parts for Leak-Tight Connections using Polymer Impregnation and Pyrolysis”, filed July 17, 2023, the contents of which are incorporated by reference herein. This application also claims the benefit of and priority to U.S. Provisional Application 63 / 527,229, titled “Joining Ceramic Parts for Leak-Tight Connections using Chemical Vapor Infiltration”, filed July 17, 2023, the contents of which are incorporated by reference herein. STATEMENT OF GOVERNMENT RIGHTS

[0002] This invention was made with government support under No. DE-AR0001601 and No. DE-EE0009806, awarded by the Department of Energy Advanced Research Projects Agency-Energy and the Department of Energy Solar Energy Technologies Office, respectively. The government has certain rights in this invention. TECHNICAL FIELD

[0003] The subject matter disclosed herein relates to ceramic manufacturing and, in particular, to methods, systems, and components for joining ceramic parts. BACKGROUND

[0004] Ceramics are highly acclaimed in various reactor-based applications due to properties including chemical resistance, high-temperature stability, and high-mechanical strength, etc. However, the processability of ceramics is difficult due to high melting and fusion temperatures, and therefore, the manufacturing of complex and large ceramic components is especially difficult. Furthermore, powder wastage, cost versus effort comparisons, and other manufacturing limitations in conventional production and three dimensional (3D) printing do not allow for full assemblies to be printed in a single pieceClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 which work functionally and to the standards and requirements needed. Some industrial applications require the joining of multiple ceramic components, and in some cases, includes large and / or complex geometries.

[0005] In general, present industrial techniques for joining ceramics include brazing, and the usage of metal sealants. However, these techniques provide weak joining and non-leak- tight joints, eventually leading to failure due to the variations in the coefficient of thermal expansion between dissimilar materials, and mechanical properties. Hence, advances in ceramic joining are very much needed for industrial applications such as large reactor parts and in refractory industry fields, especially where leak-tight and sealed components are required. SUMMARY

[0006] According to one aspect, a method of joining ceramic substrates. A first ceramic substrate is positioned adjacent a second ceramic substrate. The first ceramic substrate includes a first adjoining surface and the second ceramic substrate includes a second adjoining surface. The first adjoining surface contacts the second adjoining surface to form a joint. Pores of the first adjoining surface, pores of the second adjoining surface, and the joint, are infiltrated with a preceramic polymer. The preceramic polymer is pyrolyzed in the pores of the first adjoining surface, in the pores of the second adjoining surface, and in the joint.

[0007] According to another aspect, a method of joining ceramic substrates. A first porous ceramic substrate is positioned adjacent a second porous ceramic substrate. The first porous ceramic substrate includes a first adjoining surface and the second porous ceramic substrate includes a second adjoining surface. The first adjoining surface contacts the second adjoining surface to form a joint. A plurality of polymer impregnation and pyrolysis (PIP) cycles is performed. Each of the PIP cycles includes impregnating pores of the first adjoining surface, pores of the second adjoining surface, and the joint with a preceramic polymer, and pyrolyzing the preceramic polymer in theClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 pores of the first adjoining surface, the pores of the second adjoining surface, and the joint.

[0008] According to another aspect, a ceramic structure. The ceramic structure includes a first ceramic substrate including a first adjoining surface and a plurality of first pores. The first adjoining surface includes a protrusion. A second ceramic substrate includes a second adjoining surface and a plurality of second pores. The second adjoining surface including a recess. The protrusion of the first ceramic substrate is at least partially received within the recess of the second ceramic substrate thereby forming a joint. A pyrolyzed ceramic polymer is disposed in the plurality of first pores and in the plurality of second pores. The pyrolyzed ceramic polymer is disposed between the first adjoining surface and the second adjoining surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG.1A is a diagrammatic view of a first ceramic substrate and a second ceramic substrate, according to some embodiments.

[0010] FIG.1B is a diagrammatic view of a first ceramic substrate joined to a second ceramic substrate, according to some embodiments.

[0011] FIG.2A is an isometric view of a first ceramic substrate positioned adjacent a second ceramic substrate, according to some embodiments.

[0012] FIG.2B is a magnified view of the adjoining surfaces between a first ceramic substrate and a second ceramic substrate, according to some embodiments.

[0013] FIG.3A is an isometric view of a first ceramic substrate, according to some embodiments.

[0014] FIG.3B is an isometric view of a second ceramic substrate, according to some embodiments.

[0015] FIG.4A is a side view of a first ceramic substrate, according to some embodiments.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1

[0016] FIG.4B is a side view of a second ceramic substrate, according to some embodiments.

[0017] FIG.4C is an isometric view of a first ceramic substrate joined to a second ceramic substrate, according to some embodiments.

[0018] FIG.5A is an isometric view of a first ceramic substrate joined to a second ceramic substrate, according to some embodiments.

[0019] FIG.5B is a magnified side view of the adjoining surfaces between a first ceramic substrate and a second ceramic substrate, according to some embodiments.

[0020] FIG.5C is a side view of a joint between a first ceramic substrate and a second ceramic substrate following one or more cycles of polymer impregnation and pyrolysis (PIP), according to some embodiments.

[0021] FIG.5D is a side view of a joint between a first ceramic substrate and a second ceramic substrate including a pyrolyzed ceramic polymer, according to some embodiments.

[0022] FIG.6A is a diagrammatic view of a first ceramic substrate and a second ceramic substrate, according to some embodiments.

[0023] FIG.6B is a diagrammatic view of a first ceramic substrate and a second ceramic substrate with an enlarged section illustrating the porous cavities of the ceramic substrate, according to some embodiments.

[0024] FIG.6C is a diagrammatic view of a porous cavity including a cavity, according to some embodiments.

[0025] FIG.6D is a diagrammatic view of a porous cavity at least partially filled with a preceramic polymer, according to some embodiments.

[0026] FIG.6E is a diagrammatic view of a porous cavity at least partially filled with a pyrolyzed ceramic polymer, according to some embodiments.

[0027] FIG.7A is a diagrammatic view of a first ceramic substrate and a second ceramic substrate, according to some embodiments.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1

[0028] FIG.7B is a diagrammatic view of a first ceramic substrate and a second ceramic substrate with an enlarged section illustrating the porous cavities of the ceramic substrate, according to some embodiments.

[0029] FIG.7C is a diagrammatic view of a porous structure including a cavity and a gap between pores prior to a polymer impregnation and pyrolysis (PIP) process and / or a chemical vapor infiltration (CVI) process, according to some embodiments.

[0030] FIG.7D is a diagrammatic view of a pyrolyzed ceramic polymer filling a cavity following a PIP process, according to some embodiments

[0031] FIG.7E is a diagrammatic view of a porous structure following a CVI process, according to some embodiments.

[0032] FIG.8 is a flow chart of a method of joining ceramic substrates, according to some embodiments. DETAILED DESCRIPTION

[0033] The present disclosure describes systems, methods, and devices for joining ceramic components which yield mechanically robust and leak-tight connections. The joining process includes a polymer impregnation and pyrolysis (PIP) for joining of multiple ceramic parts which utilizes an external agent (e.g., a preceramic polymer) to fill pores of the ceramic parts and the joint between the ceramic parts, and pyrolyzes the preceramic polymer to bind the ceramic compounds of the preceramic polymer with the multiple ceramic parts. In some embodiments, the joining process includes chemical vapor infiltration (CVI), where ceramic matrix particles are suspended in a heated flow gas which infiltrates the pores and the joint of the multiple ceramic parts. The ceramic matrix particles bind with the ceramic parts, the joint, and / or the pyrolyzed ceramic polymer to enhance the mechanical strength and leak-tightness of the joint. The cycles of PIP and / or CVI may be repeated, including up until the pores of the adjoining surfaces are at least 80% filled with pyrolyzed polymer and / or ceramic matrix particles, according to some embodiments.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1

[0034] FIG.1A is a diagrammatic view of a first ceramic substrate 102 and a second ceramic substrate 104, according to some embodiments. The first ceramic substrate 102 includes a first adjoining surface 112 and the second ceramic substrate 104 includes a second adjoining surface 114. The first adjoining surface 112 and the second adjoining surface 114 are urged toward each other (as indicated by arrow 106 and arrow 108) such that the first adjoining surface 112 is adjacent to and / or abuts the second adjoining surface 114.

[0035] FIG.1B is a diagrammatic view of the first ceramic substrate 102 joined to the second ceramic substrate 104, according to some embodiments. The first ceramic substrate 102 is joined to the second ceramic substrate 104 via a ceramic agent 110. The ceramic agent 110 infiltrates (or impregnates) pores in the first adjoining surface 112, pores in the second adjoining surface 114, and any spaces in between the first ceramic substrate 102 and the second ceramic substrate 104 (i.e., the joint), according to some embodiments. Infiltration of the ceramic agent 110 into the pores of the first and second adjoining surfaces 112, 114 and / or the joint is performed via a vacuum, a positive pressure force, capillary action of the pores, and / or gravity, according to some embodiments. In some embodiments, infiltration includes urging the ceramic agent 110 from the first ceramic substrate 102, across the joint, and into the second ceramic substrate 104 (or vice-versa), such that the ceramic agent 110 flows through the porous structure of both the first ceramic substrate 102 and the second ceramic substrate 104. In some embodiments, the ceramic agent 110 infiltrates the first ceramic substrate 102, the second ceramic substrate 104, and the joint simultaneously, e.g., the ceramic agent 110 is urged from a first side of the combined assembly, through the first ceramic substrate 102, the second ceramic substrate 104, and the joint, and to a second side of the combined assembly. It should be noted that FIGS.1A-B are diagrammatic views not drawn to scale. Thus, the porosity of the first ceramic substrate 102, the joint, and the second ceramic substrate 104 is not drawn to scale.

[0036] The ceramic agent 110 is an external agent applied to the first and second ceramic substrates 102, 104 which includes a ceramic compound configured to bond with theClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 substrate. In some embodiments, the ceramic agent 110 includes a preceramic polymer which infiltrates the pores and / or the joint via one or more PIP cycles. In some embodiments, the ceramic agent 110 includes ceramic matrix particles which infiltrates the pores and / or the joint via a CVI process. In some embodiments, the ceramic agent 110 includes a ceramic paste.

[0037] FIG.2A is an isometric view of a first ceramic substrate 202 positioned adjacent a second ceramic substrate 204, according to some embodiments. FIG.2B is a magnified view (section A) of the first ceramic substrate 202 positioned adjacent the second ceramic substrate 204, according to some embodiments. The first ceramic substrate 202 includes a protrusion 216 and the second ceramic substrate 204 includes a recess 218, according to some embodiments. The protrusion 216 is at least partially received within the recess 218. The interface between the first ceramic substrate 202 and the second ceramic substrate 204, i.e., the interface between the protrusion 216 and the recess 218, is defined as a joint 220. Geometrical variation of the joint can be beneficial, as increased joining surface area improves mechanical strength and leak-tightness (and gas-tightness) of the joint. For instance, FIGS.1A-5B illustrate different geometric embodiments of the joint, according to some embodiments. For instance, the embodiment shown in FIG.1A includes the first and second adjoining surfaces 112, 114 which are flat, orthogonally abutting surfaces. The different geometric embodiments of the joint can have between 1 and 25 times the joining surface area of the flat, orthogonally abutting embodiment of FIG.1A, and in some embodiments, the joint can include a joining surface area between 2-10 times the joining surface area of the flat, orthogonally abutting embodiment of FIG. 1A.

[0038] In some embodiments, the first ceramic substrate 202 and the second ceramic substrate 204 include mating features which abut, form, slip fit, or interlock to provide a strong physical connection at the joint 220. The increased surface area and geometric positioning between the components in the joint may increase stability of the physical connection during the PIP and / or CVI process, as movement between the two substrates during these processes can disrupt the seal at the joint.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1

[0039] FIG.3A is an isometric view of a first ceramic substrate 302, and FIG.3B is isometric view of a second ceramic substrate 304, according to some embodiments. The first ceramic substrate 302 includes a first adjoining surface 312 having a protrusion 316 and a recess 322. The second ceramic substrate 304 includes a second adjoining surface 314 having a protrusion 324 and a recess 318. The first adjoining surface 312 of the first ceramic substrate 302 and the second adjoining surface 314 of the second ceramic substrate 304 form an interlocking joint wherein the protrusion 316 of the first ceramic substrate 302 is received within the recess 318 of the second ceramic substrate 304 and the protrusion 324 of the second ceramic substrate 304 is received within the recess 322 of the first ceramic substrate 302, according to some embodiments. In some embodiments, the protrusion 316 includes a secondary mating feature 317 (e.g., a cavity or recess) configured to interlock with a feature of the second ceramic substrate 304.

[0040] FIG.4A is a side view of a first ceramic substrate 402, FIG.4B is a side view of a second ceramic substrate 404, and FIG.4C is an isometric view of the first ceramic substrate 402 positioned adjacent to the second ceramic substrate 404, according to some embodiments. The first ceramic substrate 402 includes a first adjoining surface 412 and a protrusion 416. The second ceramic substrate 404 includes a second adjoining surface 414 and a recess 418 configured to at least partially receive the protrusion 416. The first adjoining surface 412 is disposed on the protrusion 416 and the second adjoining surface 414 is disposed on the recess 418, such that when the protrusion 416 is received with the recess 418, the first adjoining surface 412 abuts the second adjoining surface 414, thereby forming a joint 420, according to some embodiments. The joint 420 may be referred to as a wedge joint, as the protrusion 416 includes a wedge-shaped geometry.

[0041] FIG.5A is an isometric view of a first ceramic substrate 502 positioned adjacent to a second ceramic substrate 504, and FIG.5B is a magnified side view of the interface between the first ceramic substrate 502 and the second ceramic substrate 504, according to some embodiments. The first ceramic substrate 502 and the second ceramic substrate 504 form a joint 520 (i.e., a lap joint), with each substrate including a protrusion and aClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 recess. In some embodiments, a gap 528 (or a micro gap) is present in the joint 520 between the first ceramic substrate 502 and the second ceramic substrate 504.

[0042] FIG.5C is a side view of the first ceramic substrate 502 joined to the second ceramic substrate 504 at the joint 520 after at least one PIP cycle, according to some embodiments. The first ceramic substrate 502 includes a first adjoining portion 530 and the second ceramic substrate 504 includes a second adjoining portion 532. Pores of the first adjoining portion 530 and the second adjoining portion 532 are infiltrated by a preceramic polymer 511. In some embodiments, the preceramic polymer 511 infiltrates pores of the first adjoining portion 530 and the second adjoining portion 532 via a vacuum (e.g., between 0.01 bar and 0.1 bar or between 0.001 psi and 0.1 psi), via a positive pressure pump (e.g., between 1 bar and 10 bar), via gravity, and / or via capillary action. The preceramic polymer 511 is pyrolyzed and converted into a pyrolyzed ceramic polymer, according to some embodiments.

[0043] FIG.5D is a side view of the first ceramic substrate 502 joined to the second ceramic substrate 504 at the joint 520 after a plurality of PIP cycles and / or a CVI process, according to some embodiments. A ceramic agent 510 bonds the first ceramic substrate 502 to the second ceramic substrate 504 across the joint 520. In some embodiments, the ceramic agent 510 includes a pyrolyzed ceramic polymer which infiltrates the pores and / or the joint via one or more PIP cycles. In some embodiments, the ceramic agent 510 includes ceramic matrix particles which infiltrates the pores and / or the joint via a CVI process.

[0044] FIG.6A is a diagrammatic view of a first ceramic substrate 602 and a second ceramic substrate 604, according to some embodiments. The first ceramic substrate 602 includes a first adjoining surface 612 and a protrusion 616. The second ceramic substrate 604 includes a second adjoining surface 614 and a recess 618 configured to at least partially receive the protrusion 616. The first adjoining surface 612 is disposed on the protrusion 616 and the second adjoining surface 614 is disposed on the recess 618, such that when the protrusion 616 is received with the recess 618, the first adjoining surface 612 abuts the second adjoining surface 614, thereby forming a joint, according to someClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 embodiments. In some embodiments, the first ceramic substrate 602 and the second ceramic substrate 604 are formed from the same ceramic material such that the coefficient of thermal expansion is consistent between the first ceramic substrate 602 and the second ceramic substrate 604.

[0045] FIG.6B is a diagrammatic view of the first ceramic substrate 602 positioned adjacent the second ceramic substrate 604 with a magnified section illustrating a porous cavity 634 (or pores) of the ceramic substrates, according to some embodiments. Section B illustrates an enlarged view of the ceramic substrate 602, 604 and a joint 620 positioned between the first ceramic substrate 602 and the second ceramic substrate 604. Section C illustrates an enlarged view of the porous cavity 634 of the ceramic substrate 602, 604 (prior to a PIP or CVI process). In some embodiments, the first ceramic substrate 602 and the second ceramic substrate 604 are positioned adjacent to each other (or abut each other) prior to any pore densification process.

[0046] FIGS.6C-E show diagrammatic views of the porous cavity 634 at various stages of a single PIP cycle, according to some embodiments. For instance, FIG.6C shows a cavity 636 (i.e., a void or unfilled volume) present within the porous cavity 634. FIG.6D shows a preceramic polymer 638 impregnating the porous cavity 634. In some embodiments, the preceramic polymer 638 infiltrates the porous cavity 634 via a vacuum (e.g., between 0.01 bar and 0.1 bar), via a positive pressure pump (e.g., between 1 bar and 10 bar), via gravity, and / or via capillary action. The preceramic polymer 638 is infiltrated such that it is in contact with both of the first ceramic substrate 602 and the second ceramic substrate 604. The micro-viscous forces from the porous cavity 634 support the flow through the pores of the first ceramic substrate 602 and the second ceramic substrate 604 while joining the substrates and the post-processing (pyrolysis) makes the joint permanent.

[0047] FIG.6E shows a pyrolyzed ceramic polymer 640 within the porous cavity 634. The preceramic polymer 638 undergoes a reactive melt process where a transition in the preceramic polymer 638 takes place entrapping the ceramic particles together strongly. The process enables the first ceramic substrate 602 and the second ceramic substrate 604Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 to join together while the mechanical and thermal properties of the substrates remain the same with minimum shrinkage. For example, in the case of SiC, the pyrolyzed ceramic polymer 640 forms C-SiC-C bonds which aid in complementing the SiC substrate’s ability to withstand extreme conditions

[0048] In some embodiments, a portion of the preceramic polymer 638 is vaporized during pyrolysis, resulting in reduced volume of the porous cavity 634 occupied by the pyrolyzed ceramic polymer 640. Thus, the PIP process can be repeated over a plurality of cycles to increase the percentage of the cavity 636 which is filled by the pyrolyzed ceramic polymer 640. The PIP cycle may continue until the porous cavity 634 and mating surfaces are filled to greater than 80%. The number of PIP cycles may be as few as 1 or as many as 100. The number of cycles can be between 2 and 20 PIP cycles, or between 2 and 10 PIP cycles. In some embodiments, the porous cavity 634 becomes supersaturated providing a natural end point for the number of cycles required to complete a joint.

[0049] In some embodiments, the first ceramic substrate 602 and the second ceramic substrate 604 are formed of ceramic materials, including for example, silicon carbide (SiC) with a green density of approximately 40% - 65%, silicon nitride with a green density of 50% - 75%, boron carbide with a green density of 50% - 70%, and aluminum oxide with a green density of 50% - 65%. Other ceramic substrate materials, including but not limited to silicon carbides, silicon nitrides, boron carbides, aluminum oxides, mullites, alumina, and / or cemented carbides can be used.

[0050] In some embodiments, the preceramic polymer 638 includes the same elements as the first ceramic substrate 602 and the second ceramic substrate 604. If, for instance, the first ceramic substrate 602 and the second ceramic substrate 604 are formed of silicon carbide (SiC), the preceramic polymer 638 may include polycarbosilane (PCS) or similar compound including carbon and silicon configured to bond to the silicon carbide. The preceramic polymer 638 can infiltrate the porous cavity 634 in various forms, including for example a suspension, a solution, or pure. The viscosity of the preceramic polymer 638 can be selected based on the pore size and morphology. To more efficiently fill pores during the initial cycle, a lower viscosity preceramic polymer can be selected to fill theClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 pore volume. In some embodiments, the viscosity of the preceramic polymer is within a range of 150-4000 cP.

[0051] In some embodiments, the first ceramic substrate 602 and the second ceramic substrate 604 increase in density (i.e. their pores filled with the pyrolyzed ceramic polymer 640) to greater than 80% density, and in some embodiments, to greater than 95% density which forms the joint. In one example, the joint 620 is mechanically as strong as 50% to 140% of the bulk material of the ceramic subunit. In another example, filling the pores with the pyrolyzed ceramic polymer 640 to greater than 80% density is sufficient for the joint to be mechanically as strong as 50% to 140% of the bulk material of the ceramic subunit.

[0052] FIG.7A is a diagrammatic view of a first ceramic substrate 702 and a second ceramic substrate 704, according to some embodiments. The first ceramic substrate 702 includes a first adjoining surface 712 and a protrusion 716. The second ceramic substrate 704 includes a second adjoining surface 714 and a recess 718 configured to at least partially receive the protrusion 716. The protrusion 716 includes the first adjoining surface 712, and the recess 718 includes the second adjoining surface, such that when the protrusion 716 is received with the recess 718, the first adjoining surface 712 abuts the second adjoining surface 714, thereby forming a joint, according to some embodiments. In some embodiments, the first ceramic substrate 702 and the second ceramic substrate 704 are formed from the same ceramic material such that the coefficient of thermal expansion is consistent between the first ceramic substrate 702 and the second ceramic substrate 704.

[0053] FIG.7B is a diagrammatic view of the first ceramic substrate 702 positioned adjacent the second ceramic substrate 704 with a magnified section illustrating a porous structure 738 (or micro gap) of the ceramic substrates, according to some embodiments. Section D illustrates an enlarged view of the ceramic substrate 702, 704 and a joint 720 positioned between the first ceramic substrate 702 and the second ceramic substrate 704. Section E illustrates an enlarged view of the porous structure 738 of the ceramic substrate 702, 704 (prior to a CVI process). In some embodiments, the first ceramic substrate 702Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 and the second ceramic substrate 704 are positioned adjacent to each other (or abut each other) prior to any pore densification process (e.g. the PIP and / or the CVI process).

[0054] FIGS.7C-E show diagrammatic views of the porous structure 738 at various stages of a PIP and CVI process. For instance, FIG.7C shows the porous structure 738 including a cavity 740 within the porous structure 738 and a gap 736 between pores prior to a PIP or CVI process. FIG.7D shows the a pyrolyzed ceramic polymer 742 filling the cavity 740 following a PIP process (e.g., as described above in FIGS.6A-E).

[0055] FIG.7E shows the porous structure 738 following a CVI process. Ceramic matrix particles 744 fill the gap 736 between pores and bind to the pyrolyzed ceramic polymer 742 within the cavity 740 to form a ceramic agent 746. In some embodiments, the ceramic matrix particles 744 are carried in a heated and / or pressurized flow gas (e.g., helium or hydrogen gas or any inert / carrier gas) and infiltrate the porous structure 738 of the first ceramic substrate 702 and the second ceramic substrate 704. For instance, infiltration of the reactive gas (i.e., the ceramic matrix particles 744 and the non-reactive flow gas) is performed at between 800°C and 1300°C, and / or at between 0.3 bar and 0.000689 bar. In some embodiments, the ceramic matrix particles 744 includes methyltrichlorosilane. The ceramic matrix particles 744 bind with the first ceramic substrate 702, the second ceramic substrate 702, and a pyrolyzed ceramic polymer 742 to enhance the mechanical strength and leak-tightness of the joint. In some embodiments, the first ceramic substrate 702 and the second ceramic substrate 704 are formed of silicon carbonate (SiC), and the a pyrolyzed ceramic polymer 742 and the ceramic matrix particles 744 form C-SiC-C bonds which provide high thermal tolerances for the joint.

[0056] The PIP and / or CVI processes introduce ceramic particles on the first adjoining surface 712 and the second adjoining surface 714, i.e., across the joint 720, thereby providing mechanical stability and a leak-tight seal. As used herein, leak-tight (or gas- tight) is the complete resistance to gas, liquid, or slurry traversing from one side of the substrate to another side of the substrate through any portion of the joint. The chemical reactions at the joint interface enhance chemical bonds between the first ceramicClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 substrate 702 and the second ceramic substrate 704 beyond the mechanical stability of the added joining material itself.

[0057] One benefit of the PIP and / or CVI joint enhancing process is minimum material modification. For processes like PIP, CVI, or similar reaction bonding, the ceramic agent produced is fundamentally similar to the original material of the ceramic substrate. The absence of dissimilar materials makes the mechanical and thermal properties similar to the pure ceramic components, thereby removing structural weak points and / or differences in thermal expansion coefficients.

[0058] FIG.8 is a flow chart of a method 800 of joining ceramic substrates, according to some embodiments. At step 810, the method 800 includes positioning a first ceramic substrate adjacent a second ceramic substrate. The first and second ceramic substrates include any and / or all features of the ceramic substrates 102, 104, 202, 204, 302, 304, 402, 404, 502, 504, 602, 604, 702, 704 described above. Positioning the first ceramic substrate adjacent the second ceramic substrate includes any and or all of abutting, forming, slip fitting, interlocking, mating, etc. between the adjoining surfaces.

[0059] At step 820, the method 800 includes infiltrating pores of the first adjoining surface of the first ceramic substrate, pores of the second adjoining surface of the second ceramic substrate, and the joint therebetween with a preceramic polymer. The preceramic polymer includes any and / or all features of the preceramic polymer described above in relation to FIGS.1A-7E. In some embodiments, infiltration includes urging the preceramic polymer from within the first ceramic substrate, across the joint, and into the second ceramic substrate (or vice-versa), such that the preceramic polymer flows through the porous structure of both the first ceramic substrate and the second ceramic substrate. In some embodiments, the preceramic polymer infiltrates the first ceramic substrate, the second ceramic substrate, and the joint simultaneously, e.g., the preceramic polymer is urged from a first side of the combined assembly, through the first ceramic substrate, the second ceramic substrate, and the joint, and to a second side of the combined assembly.

[0060] In some embodiments, the preceramic polymer is urged via a vacuum providing an infiltration force. For instance, the infiltration force is between 0.01 bar and 0.9 bar inClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 one embodiment, and in one embodiment, between 0.5 bar and 0.01 bar, and in another embodiment, between 0.05 bar and 0.3 bar. The infiltration force is selected based on viscosity of the preceramic polymer, size and shape of the porous structure, and desired PIP cycle time. In some embodiments, an infiltration force of between 0.05 bar and 0.15 bar is beneficial to achieve full infiltration of the preceramic polymer.

[0061] In some embodiments, the preceramic polymer is urged via a pressure source providing a positive infiltration force. For instance, the infiltration force is between 1.1 bar and 100 bar in one embodiment, and between 1.1 bar and 50 bar in one embodiment, and between 5 bar and 20 bar in another embodiment. The infiltration force is selected based on viscosity of the preceramic polymer / slurry, size and shape of the porous structure, and desired PIP cycle time. In some embodiments, an infiltration force of between 5 bar and 15 bar is beneficial to achieve full infiltration of the preceramic polymer.

[0062] At step 830, the method 800 includes pyrolyzing the preceramic polymer. In some embodiments, the pyrolysis occurs at temperatures greater than 400°C, and in some cases (e.g., for silicon carbide), the pyrolysis temperature range is between 600°C and 1000°C. Pyrolysis of the preceramic polymer provides a reactive melt process where a transition in the preceramic polymer takes place, entrapping the ceramic particles together strongly, according to some embodiments. The temperature of the pyrolysis can be selected based on the composition of the preceramic polymer, the desired vaporization of the preceramic polymer, and / or the composition of the ceramic substrate.

[0063] In some embodiments, a portion of the preceramic polymer is vaporized during pyrolysis, resulting in reduced volume of the porous cavity occupied by the pyrolyzed ceramic polymer. Thus, the steps 820 and 830 can be sequentially repeated over a plurality of cycles to increase the percentage of the cavity which is filled by the pyrolyzed ceramic polymer. The cycle may continue until the porous cavity and mating surfaces are filled to greater than 80%. The number of cycles may be as few as 1 or as many as 100. In one embodiment, the number of cycles is between 2 and 20 PIP cycles, and in another embodiment, between 2 and 10 PIP cycles. In some embodiments, theClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 porous cavity becomes supersaturated providing a natural end point for the number of cycles required to complete a joint.

[0064] At step 840, the method 800 includes infiltrating pores of the first adjoining surface of the first ceramic substrate, pores of the second adjoining surface of the second ceramic substrate, and the joint therebetween with a non-reactive gas. The non-reactive gas includes any and / or all features of the reactive gas described above in relation to FIGS.1A-7E. For instance, the reactive gas may include ceramic matrix particles and a flow gas. In some embodiments, the infiltration occurs at temperatures greater than 400°C, and in some cases (e.g., for silicon carbide), the CVI temperature range is between 800°C and 1300°C, and in one embodiment the CVI temperature range is between 1000°C and 1200°C.

[0065] In some embodiments, the reactive gas is urged via a vacuum providing an infiltration force. For instance, the infiltration force is between 0.0005 bar and 0.5 bar in one embodiment, and in another embodiment, between 0.0006 bar and 0.04 bar, and in another embodiment, between 0.000689 bar and 0.3 bar. The infiltration force is selected based on the composition of ceramic matrix particles, size and shape of the porous structure, and desired CVI cycle time. In some embodiments, an infiltration force of between 0.000689 bar and 0.3 bar is beneficial to achieve full infiltration of the reactive gas.

[0066] In some embodiments, the step 840 (i.e., the CVI process) is repeated until the porous cavity and mating surfaces are filled to greater than 80%, and in some embodiments, to greater than 95%. In some embodiments, the porous cavity and mating surfaces are filled to between 96% - 98% with the CVI and / or PIP process. In some embodiments, the CVI process may be followed by a PIP cycle.

[0067] While the invention has been described with reference to an exemplary embodiment(s), it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing fromClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment(s) disclosed, but that the invention will include all embodiments falling within the scope of the appended claims. Discussion of Possible Embodiments

[0068] The following are non-exclusive descriptions of possible embodiments of the present invention.

[0069] In some aspects, the techniques described herein relate to a method of joining ceramic substrates, the method including: positioning a first ceramic substrate adjacent to a second ceramic substrate, the first ceramic substrate including a first adjoining surface and the second ceramic substrate including a second adjoining surface, wherein the first adjoining surface contacts the second adjoining surface to form a joint; infiltrating pores of the first adjoining surface, pores of the second adjoining surface, and the joint with a preceramic polymer; and pyrolyzing the preceramic polymer in the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint.

[0070] In some aspects, the techniques described herein relate to a method, wherein infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with the preceramic polymer includes providing an infiltration force via a first vacuum between 0.5 bar and 0.01 bar.

[0071] In some aspects, the techniques described herein relate to a method, wherein infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with the preceramic polymer includes providing an infiltration force via a first pressure between 1.1 bar and 50 bar.

[0072] In some aspects, the techniques described herein relate to a method, wherein pyrolyzing the preceramic polymer includes thermally processing the preceramic polymer at 400°C or above.

[0073] In some aspects, the techniques described herein relate to a method, wherein the first adjoining surface includes a protrusion and the second adjoining surface includes aClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 recess, wherein the protrusion is at least partially received within the recess to form the joint.

[0074] In some aspects, the techniques described herein relate to a method, wherein steps of (1) infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with the preceramic polymer, and (2) pyrolyzing the preceramic polymer in the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint, are sequentially repeated for a plurality of cycles.

[0075] In some aspects, the techniques described herein relate to a method, further including: infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with a reactive gas including ceramic matrix particles.

[0076] In some aspects, the techniques described herein relate to a method, wherein infiltration of the reactive gas is performed until the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are at least 80% filled, and wherein the joint is a gas-tight barrier.

[0077] In some aspects, the techniques described herein relate to a method, wherein infiltration of the reactive gas is performed at between 800°C and 1300°C, and at between 0.3 bar and 0.000689 bar.

[0078] In some aspects, the techniques described herein relate to a method, wherein the ceramic matrix particles of the reactive gas includes MethylTrichloroSilane and wherein the reactive gas includes a helium or hydrogen flow gas.

[0079] In some aspects, the techniques described herein relate to a method, wherein the ceramic matrix particles of the reactive gas bind with the first ceramic substrate, the second ceramic substrate, and a pyrolyzed ceramic polymer.

[0080] In some aspects, the techniques described herein relate to a method of joining ceramic substrates, the method including: positioning a first porous ceramic substrate adjacent a second porous ceramic substrate, the first porous ceramic substrate including a first adjoining surface and the second porous ceramic substrate including a second adjoining surface, wherein the first adjoining surface contacts the second adjoining surface to form a joint; and performing a plurality of polymer impregnation and pyrolysisClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 (PIP) cycles, each of the PIP cycles including: impregnating pores of the first adjoining surface, pores of the second adjoining surface, and the joint with a preceramic polymer, and pyrolyzing the preceramic polymer in the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint.

[0081] In some aspects, the techniques described herein relate to a method, wherein the plurality of PIP cycles is performed until the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are at least 80% filled with pyrolyzed polymer.

[0082] In some aspects, the techniques described herein relate to a method, wherein the first porous ceramic substrate and the second porous ceramic substrate is SiC, and wherein the preceramic polymer is polycarbosilane.

[0083] In some aspects, the techniques described herein relate to a method, wherein the first adjoining surface includes a protrusion and the second adjoining surface includes a recess, wherein the protrusion is at least partially received within the recess to form the joint.

[0084] In some aspects, the techniques described herein relate to a method, further including: infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with a reactive gas including ceramic matrix particles.

[0085] In some aspects, the techniques described herein relate to a method, wherein infiltration of the reactive gas is performed at between 800°C and 1300°C, and at between 0.3 bar and 0.000689 bar.

[0086] In some aspects, the techniques described herein relate to a method, wherein infiltration of the reactive gas is performed until the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are at least 95% filled and gas- tight.

[0087] In some aspects, the techniques described herein relate to a ceramic structure, including: a first ceramic substrate including a first adjoining surface and a plurality of first pores, the first adjoining surface including a protrusion; a second ceramic substrate including a second adjoining surface and a plurality of second pores, the second adjoiningClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 surface including a recess, wherein the protrusion of the first ceramic substrate is at least partially received within the recess of the second ceramic substrate thereby forming a joint; and a pyrolyzed ceramic polymer disposed in the plurality of first pores and in the plurality of second pores, and wherein the pyrolyzed ceramic polymer is disposed between the first adjoining surface and the second adjoining surface.

[0088] In some aspects, the techniques described herein relate to a ceramic structure, wherein the pyrolyzed ceramic polymer disposed between the first adjoining surface and the second adjoining surface provides a gas-tight seal for the joint.

[0089] In some aspects, the techniques described herein relate to a ceramic structure, wherein the plurality of first pores and the plurality of second pores are at least 80% filled with the pyrolyzed ceramic polymer.

[0090] In some aspects, the techniques described herein relate to a ceramic structure, further including a ceramic matrix material disposed in the plurality of first pores, in the plurality of second pores, and between the first adjoining surface and the second adjoining surface, wherein the ceramic matrix material is non-identical to the pyrolyzed ceramic polymer.

Claims

Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 CLAIMS:

1. A method of joining ceramic substrates, the method comprising: positioning a first ceramic substrate adjacent a second ceramic substrate, the first ceramic substrate including a first adjoining surface and the second ceramic substrate including a second adjoining surface, wherein the first adjoining surface contacts the second adjoining surface to form a joint; infiltrating pores of the first adjoining surface, pores of the second adjoining surface, and the joint with a preceramic polymer; and pyrolyzing the preceramic polymer in the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint.

2. The method of claim 1, wherein infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with the preceramic polymer includes providing an infiltration force via a first vacuum between 0.5 bar and 0.01 bar.

3. The method of claim 1, wherein infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with the preceramic polymer includes providing an infiltration force via a first pressure between 1.1 bar and 50 bar.

4. The method of claim 1, wherein pyrolyzing the preceramic polymer includes thermally processing the preceramic polymer at 400°C or above.

5. The method of claim 1, wherein the first adjoining surface includes a protrusion and the second adjoining surface includes a recess, wherein the protrusion is at least partially received within the recess to form the joint.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 6. The method of claim 1, wherein steps of (1) infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with the preceramic polymer, and (2) pyrolyzing the preceramic polymer in the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint, are sequentially repeated for a plurality of cycles.

7. The method of claim 1, further comprising: infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with a reactive gas including ceramic matrix particles.

8. The method of claim 7, wherein infiltration of the reactive gas is performed until the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are at least 80% filled, and wherein the joint is a gas-tight barrier, wherein infiltration of the reactive gas is performed at between 800°C and 1300°C, and at between 0.3 bar and 0.000689 bar.

9. The method of claim 7, wherein the ceramic matrix particles of the reactive gas includes MethylTrichloroSilane and wherein the reactive gas includes a helium or hydrogen flow gas.

10. The method of claim 7, wherein the ceramic matrix particles of the reactive gas bind with the first ceramic substrate, the second ceramic substrate, and a pyrolyzed ceramic polymer.

11. The method of claim 1, wherein the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are infiltrated by a ceramic paste, wherein infiltrating the pores of the first adjoining surface, the pores of the second adjoiningClient Docket No. DE-10A / B B&A Docket No.4114.008PCT1 surface, and the joint with the ceramic paste includes providing an infiltration force via a vacuum between 0.001 psi and 0.1 psi.

12. A method of joining ceramic substrates, the method comprising: positioning a first porous ceramic substrate adjacent a second porous ceramic substrate, the first porous ceramic substrate including a first adjoining surface and the second porous ceramic substrate including a second adjoining surface, wherein the first adjoining surface contacts the second adjoining surface to form a joint; and performing a plurality of polymer impregnation and pyrolysis (PIP) cycles, each of the PIP cycles including: impregnating pores of the first adjoining surface, pores of the second adjoining surface, and the joint with a preceramic polymer, and pyrolyzing the preceramic polymer in the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint.

13. The method of claim 12, wherein the plurality of PIP cycles is performed until the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are at least 80% filled with pyrolyzed polymer.

14. The method of claim 12, wherein the first porous ceramic substrate and the second porous ceramic substrate is SiC, and wherein the preceramic polymer is polycarbosilane.

15. The method of claim 12, wherein the first adjoining surface includes a protrusion and the second adjoining surface includes a recess, wherein the protrusion is at least partially received within the recess to form the joint.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 16. The method of claim 12, further comprising: infiltrating the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint with a reactive gas including ceramic matrix particles.

17. The method of claim 16, wherein infiltration of the reactive gas is performed at between 800°C and 1300°C, and at between 0.3 bar and 0.000689 bar.

18. The method of claim 16, wherein infiltration of the reactive gas is performed until the pores of the first adjoining surface, the pores of the second adjoining surface, and the joint are at least 95% filled and gas-tight.

19. A ceramic structure, comprising: a first ceramic substrate including a first adjoining surface and a plurality of first pores, the first adjoining surface including a protrusion; a second ceramic substrate including a second adjoining surface and a plurality of second pores, the second adjoining surface including a recess, wherein the protrusion of the first ceramic substrate is at least partially received within the recess of the second ceramic substrate thereby forming a joint; and a pyrolyzed ceramic polymer disposed in the plurality of first pores and in the plurality of second pores, and wherein the pyrolyzed ceramic polymer is disposed between the first adjoining surface and the second adjoining surface.

20. The ceramic structure of claim 19, wherein the pyrolyzed ceramic polymer disposed between the first adjoining surface and the second adjoining surface provides a gas-tight seal for the joint.Client Docket No. DE-10A / B B&A Docket No.4114.008PCT1 21. The ceramic structure of claim 19, wherein the plurality of first pores and the plurality of second pores are at least 80% filled with the pyrolyzed ceramic polymer.

22. The ceramic structure of claim 19, further comprising a ceramic matrix material disposed in the plurality of first pores, in the plurality of second pores, and between the first adjoining surface and the second adjoining surface, wherein the ceramic matrix material is non-identical to the pyrolyzed ceramic polymer.

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