Parts manufactured using an infiltration process, devices including the parts, and infiltration processes for manufacturing the parts

Abstract

The invention relates to a part (1) comprising a part body (2) in which at least one cavity (3) is formed, at least a portion of the wall surface (4) of the part body (2) that defines the cavity (3) is coated with a coating (10). The design of the part (1) is based on (a) a porous precursor body (5) made in one or more parts from an inorganic matrix (M1), the precursor body (5) having the cavity (3), (b) a porous precursor coating (11) made from an inorganic matrix (M2) that coats at least a portion of the wall surface (4) of the precursor body (5), the wall surface defining the cavity (3), and (c) infiltrating the porous precursor body (5) and the porous precursor coating (11) with an inorganic infiltrate (M3). The infiltrated precursor body (5) forms the part body (2) and the infiltrated precursor coating (11) forms the coating (10). The invention also relates to a method for producing a part (1), in which a precursor body (5) and a precursor coating (11) are infiltrated to produce a part body (2) provided with a coating (10).

Description

[Technical Field]

[0001] The invention relates to a component according to claim 1, to an apparatus comprising a component according to claim 13, and to a process for manufacturing a component according to claim 14. [Background technology]

[0002] The manufacture of various components, such as ceramic support elements (e.g., chucks) for holding semiconductor wafers during lithography processing, can employ infiltration techniques in which a molten mass infiltrates a preform / precursor body made of a porous material. A well-known example of such an infiltration technique involves infiltrating a silicon melt into a precursor body made of a porous ceramic material, such as silicon carbide. During infiltration, the infiltrate reacts with carbon within the porous ceramic material to form secondary silicon carbide (SiC or in-situ SiC). This secondary silicon carbide grows epitaxially on the primary silicon carbide grains, as described, for example, in JN Ness, T.F. Page, Microstructural Evolution in Reaction-Bonded Silicon Carbide, Journal of Materials Science 21 (1986) 1377-1397.

[0003] A wide variety of carbon-containing precursor body materials can be used to introduce carbon into the precursor body prior to infiltration, including, for example, pitch, phenol, furfuryl alcohol, and carbohydrates such as sugar. The precursor body, made of a carbon-containing precursor body material, is first heated to above 600°C in an inert atmosphere to convert the carbon-containing precursor body material to carbon before infiltration. The precursor body is then contacted with silicon metal or a silicon alloy in an inert or vacuum atmosphere and heated above the melting point of the infiltration material. The precursor body is completely infiltrated through self-wetting and reaction between the carbon and molten silicon (Si). The carbon in the precursor body reacts with the Si to form in situ SiC, which forms a scaffold within the porous preform. A dense composite with all pores filled, including those where in situ SiC does not form, is generally desired. Therefore, excess silicon is present. The resulting composite, containing silicon carbide and unreacted silicon, is sometimes referred to as Si / SiC for short.

[0004] U.S. Patent No. 5,509,555 describes the production of silicon carbide composites by infiltrating a porous precursor body containing carbon and / or silicon carbide with a silicon alloy containing, in addition to silicon, other metals, such as aluminum, copper, zinc, nickel, or combinations thereof. Silicon has a melting anomaly and expands upon cooling. Some of the silicon remains on the surface of the porous precursor body and adheres firmly thereto, requiring subsequent removal. For this reason, U.S. Patent No. 5,509,555 proposes, for example, powders and etching baths that are said to react with the adhered infiltrate to remove it from the surface. However, this is costly, inconvenient, and generates hazardous waste.

[0005] U.S. Pat. No. 5,205,970 describes the production of reaction-bonded silicon carbide composites by a melt infiltration process, in which a porous precursor body is infiltrated with an infiltrate. After the production process, excess silicon remains on the surface of the precursor body in the form of a surface melt exudate, particularly in the form of droplets. This is due in particular to silicon melt anomalies, which cause some of the silicon to re-flow from the porous precursor body upon cooling. The silicon solidifies and adheres firmly to the surface of the porous precursor body, so it must be removed in a subsequent process to obtain dimensionally accurate parts. Therefore, U.S. Pat. No. 5,205,970 describes the removal of excess silicon by contacting the part surface with a carbon-based hygroscopic material. This process requires a second high-temperature cycle in which the liquidus temperature of the infiltrate is exceeded, at least in the region of the surface melt exudate. The hygroscopic material can be, for example, a carbon-based felt, whose capillaries must be at least as large as those of the silicon carbide composite after the reaction bonding process. The capillary action of silicon carbide composites is stronger than that of hygroscopic materials, so it is said that only excess silicon that leaks onto the surface of the part is absorbed by the felt, and no silicon is drawn out from the bulk of the part.

[0006] U.S. Patent No. 3,857,744 discloses applying boron nitride powder to a porous precursor body before infiltration. This boron nitride powder is said to reduce silicon deposition and adhesion to the powder-coated part. A drawback is that the boron nitride powder must be removed again, otherwise it will be released into the environment during subsequent use of the part. This results in the generation of hazardous waste containing boron nitride and flaked infiltrate. Furthermore, removal is only possible on accessible surfaces, often not in cavities. Since the boron nitride powder is clearly not always sufficient, the boron nitride and any remaining silicon are removed from the part by sandblasting. This is costly, laborious, and requires additional work steps. Furthermore, this method is only feasible to a limited extent, if at all, in difficult-to-access sites.

[0007] PCT International Application Publication No. 2005 / 037726 describes a method for producing a part comprising a cavity and made of a metal-ceramic composite material produced by melt infiltration, where closure of the cavity due to melt seepage of the infiltrate into the cavity is prevented by filling the cavity with a temporary filler material that cannot be infiltrated by the infiltrate.

[0008] According to PCT International Application Publication No. 2005 / 037726, contacting the non-wetting material with the entire cavity wall prevents the material from infiltrating the cavity and thus the cavity. This contact is achieved by lining the cavity or filling the entire cavity. Therefore, the non-wetting material can be easily removed after infiltration of the porous precursor body, because the non-wetting material is in the form of loosely bound or free-flowing particle agglomerates both before and after the infiltration process. According to PCT International Application Publication No. 2005 / 037726, removal of loosely bound or free-flowing particle agglomerates is easily carried out after the infiltration process using compressed air, water, shaking, or suction. However, for this purpose, it may be necessary to introduce additional holes into the cavity to allow access for removal of the filler material. These holes must then be reclosed. The costs and complexity are correspondingly high, and there is a risk that residues of the non-wetting material will cause problems and damage in subsequent applications of the part.

[0009] The object of the present invention is therefore to provide a cheaper and less complex solution for providing parts with cavities that are free of infiltrating material, especially in the case of surface melt exudates, and also to reduce the risk of impurities remaining in the cavities. Summary of the Invention

[0010] The main features of the present invention are specified in claims 1 and 14. Embodiments are specified in claims 2 to 13 and claim 15.

[0011] The present invention relates to a component having a component body with at least one cavity, wherein the wall surfaces of the component body defining the cavity are at least partially or completely covered by a coating, the component comprising: - a single-piece or multi-piece porous precursor body made of an inorganic matrix, the porous precursor body comprising / containing a cavity; - a porous precursor coating made of an inorganic matrix, the porous precursor coating at least partially coating the wall surfaces of the precursor body that define the cavity; - infiltration of the porous precursor body and the porous precursor coating with an inorganic infiltrate; is formed based on The infiltrated precursor body forms the part body, and the infiltrated precursor coating forms the coating.

[0012] The infiltration of the precursor coating and the precursor body forms a material bond between the precursor body and the precursor coating, i.e., between the component body and the coating. This results in a strongly adherent and durable coating that does not need to be removed. In particular, a material bond can be formed between the coating and the component body, preferably at least partially formed by ionic bonding. Furthermore, the solidified infiltrate can extend from the component body into the coating, thus forming a continuous scaffold between the precursor body and the precursor coating, which also results in a stable bond. From a process engineering perspective, the interaction between the precursor coating and the infiltrate makes it possible to employ a permanent coating, particularly as an alternative to temporary auxiliary materials used in the prior art to prevent surface melt exudation. Thus, the precursor coating can provide properties, particularly in the cavity region, that deviate from the infiltration characteristics of the precursor body. While it is important that the infiltrate is sufficiently dispersed in the component body region, it is sufficient in the precursor coating region to achieve a permanent bond of the precursor coating to the component body.

[0013] The infiltrate preferably forms a (fluid) impermeable coating in the porous precursor coating, which can prevent any impurities from subsequently settling in the coating or the colonization of the coating by microorganisms.

[0014] Because different inorganic matrices are selected for the precursor body and the precursor coating, the material properties of the coating and the material properties of the remaining part can be clearly defined relative to one another. In particular, the matrix of the precursor coating may differ from the matrix of the precursor body, for example, in terms of its micrograin size, microstructural density and / or material / material alloy.

[0015] The microstructure of the porous precursor body and porous precursor coating is unchanged by infiltration or the temperature cycles completed during infiltration. The post-infiltration microstructure can also be identified by taking polished sections and examining them microscopically, particularly by optical or scanning electron microscopy. The infiltrate can be separately identified within the previously empty pores. Energy dispersive X-ray spectroscopy (EDX) can also identify different materials in the microstructure, particularly the precursor body material, precursor coating material, infiltrate material, and materials formed by reaction.

[0016] The precursor body should have at least one free surface that is free of such a precursor coating (especially functionally equivalent during infiltration). Therefore, the part should have at least one free surface that is free of such a coating (especially formed by infiltration of a porous precursor coating). Optimization in terms of infiltration of the precursor body may therefore be carried out in the region of the free surface. It is preferred that a maximum of 30% of the entire surface of the precursor body is covered by the precursor coating. Likewise, it is preferred if at least 70% of the entire surface of the precursor body is a free surface that is free of such a precursor coating, which is particularly suitable for surface melt exudation of the infiltrate.

[0017] In more specific embodiments, the precursor coating is less wettable to the infiltrant than the precursor body, and / or the precursor coating matrix and the precursor body matrix are each formed from a microstructure, with the microstructure of the precursor coating matrix being finer than the microstructure of the precursor body matrix. When wettability is poor, the infiltrant is less strongly induced to infiltrate the precursor coating material. Thus, infiltration occurs primarily within the precursor body. In contrast, infiltration into the precursor coating tends to be slower from both the free outer surface and the side facing the precursor body.

[0018] At the same time, infiltrates that unintentionally reach the free surface of the precursor coating adhere less strongly to the coating than to the precursor body, i.e., are less strongly absorbed into the coating's pores. This prevents the infiltrate from remaining strongly attached to the coating after solidification. The finer microstructure creates a mechanical barrier for the infiltrate, and the infiltrate's viscosity is usually matched to the porosity of the precursor body being infiltrated. Furthermore, the finer capillaries hold the already infiltrated infiltrate more tightly in the pores of the precursor coating than in the pores of the precursor body. Thus, during melting, the infiltrate seeks a path outward beyond the precursor coating. The precursor coating reduces or even prevents the seepage of surface melt into cavities.

[0019] In a particular variant, the matrix microstructure of the precursor coating has a primary particle size of 0.1 μm to 100 μm, preferably 0.2 μm to 60 μm, more preferably 0.5 μm to 30 μm, even more preferably 0.8 μm to 8 μm, and especially preferably 1 μm to 6 μm. Due to the small particle size of the microstructure (also known as crystallites) and the resulting small interparticle spaces, infiltrates have a lower tendency to infiltrate into the precursor coating than into the precursor body.

[0020] Furthermore, the microstructure of the matrix of the precursor body optionally has a primary particle size of 0.1 μm to 500 μm, preferably 0.2 μm to 400 μm, more preferably 0.5 μm to 300 μm, even more preferably 1 μm to 250 μm, and particularly preferably 2 μm to 200 μm. This particle size still ensures sufficient capillary action to promote infiltration. The optional use of additional particulate carbon in the precursor body in combination with this primary particle size also achieves high wetting on and within the precursor body.

[0021] The primary particle sizes should be combined with respect to the ranges of values, particularly when the overlapping ranges of values ​​coincide, such that the matrix microstructure of the precursor coating is finer than the matrix microstructure of the porous precursor body.

[0022] The primary particle size may be determined in advance by laser diffraction particle size analysis / laser particle size measurement of the raw material. The primary particle size may also be determined after fabrication of the precursor body and precursor coating, or on subsequent parts, by taking polished sections and examining them with an optical or electron microscope.

[0023] In particular, the precursor coating has a lower tendency for infiltrants to infiltrate than the precursor body, particularly due to its poorer wetting properties and / or finer microstructure. Therefore, infiltrant deposits on the coating can be easily removed. Furthermore, the infiltrant disperses more freely within the precursor body, and therefore, any changes in the infiltrate's thermal volume during infiltration and cooling will primarily seek a path through the precursor body, i.e., through the precursor coating.

[0024] Surface melting and exudation of the infiltrate after infiltration is thus reduced, primarily on the free surface of the component that is not coated with the corresponding precursor coating. For one thing, the low wetting tendency of the precursor coating partially blocks surface exudation from the interior to the exterior, for example. If an infiltrate reaches the wall surface coated with the precursor coating from the exterior, the low wetting tendency means that in any case it will only bond weakly to the coating, and the cooled infiltrate can be removed by methods with a moderate material removal force, such as shaking, vibration, the introduction of compressed air or water, etc.

[0025] The entire wall surface defining the cavity is optionally covered with the precursor coating.

[0026] The precursor bodies, infiltrates, and precursor coatings are identifiable in the part by taking polished sections and examining them microscopically, for example, by optical or electron microscopy.

[0027] Preferably, the component is composed of a metal-ceramic composite and coating produced by melt infiltration and optional reaction bonding. The metal-ceramic composite may be silicon-infiltrated and reaction-bonded silicon carbide (SiC) (also known as SiSiC or RBSiC). The process chain for producing SiC typically involves the following steps: First, a porous precursor body, typically consisting essentially of silicon carbide, carbon, and / or other organic auxiliary substances, is produced using a suitable molding method (pressing, (pressure) slip casting, film casting, injection molding, extrusion, stamping, 3D printing). This precursor body is then infiltrated with molten silicon or its alloys during a subsequent high-temperature treatment under vacuum and / or protective gas atmosphere. The infiltrated silicon reacts with carbon by dissolution and reprecipitation, forming so-called secondary silicon carbide, which grows epitaxially on the primary silicon carbide grains. This is described, for example, in JN Ness, TF Page, Microstructural Evolution in Reaction-Bonded Silicon Carbide, Journal of Materials Science 21 (1986), 1377-1397. The pores of the precursor body remaining after the reaction are filled with unreacted free silicon, and excess silicon is used to ensure complete filling of the pores. However, this excess silicon has the disadvantage of forming a silicon surface melt exudate when the temperature drops below the liquidus temperature during cooling, and silicon exhibits a volume expansion of approximately 10% upon solidification. This silicon melt exudate forms on the surface of the part with little control and aggregates in geometrically sensitive volumes (e.g., depressions, internal cavities, etc.). Subsequent removal of the silicon melt exudate, for example by sandblasting, is only possible in suitably accessible areas. The precursor coating of the present invention ensures that the silicon melt exudate forms primarily on the surface of the part body that does not have such a precursor coating. Therefore, the melt exudate can be concentrated in non-critical areas.

[0028] The coating is particularly preferred in embodiments where the infiltrate exhibits a melt anomaly, such that the infiltrate expands upon solidification. Surface melt exudates are concentrated at the free surface. The infiltrate, in particular, cannot penetrate the precursor coating, or at least cannot penetrate the precursor coating without strong internal counterpressure, and as a result, cannot solidify and form a strong bond with the coating within the cavity. In this way, an empty cavity can be achieved without significant cost and complexity.

[0029] In more specific embodiments, the precursor body includes a higher proportion of a reaction partner (e.g., carbon) of the infiltrant than the precursor coating, particularly to provide a resulting part in which the proportion of free infiltrant reacted with the reaction partner is greater within the matrix of the precursor body than within the matrix of the precursor coating. For example, a reaction partner such as carbon can particularly increase the wettability of the precursor body, and conversely, a lack of such a reaction partner in the precursor coating can keep the wettability therein low.

[0030] In a more specific embodiment of the part, the cavities form channels or channel structures, which makes the part suitable, for example, as a heat sink. This coating makes it possible to produce heat sinks with small channel diameters and complex shapes without the risk of blockage due to surface melt seepage. The channels may therefore be cooling channels, in particular for the flow of a cooling medium. Alternatively, the channels may be drainage channels, in particular for the attachment of workpieces, such as silicon wafers.

[0031] Preferably, the inorganic matrix of the precursor body is formed at least substantially or entirely from the group of materials silicon carbide, boron carbide, diamond, or combinations of these materials, which are particularly suitable for forming infiltrable precursor bodies.

[0032] In one embodiment, the inorganic matrix of the precursor body is at least substantially or completely formed from the group of materials silicon carbide, boron carbide, diamond, molybdenum disilicide, silicon nitride, titanium carbide, zirconium carbide, aluminum nitride, tungsten carbide, or combinations of these materials. Impurities that are unavoidable as a result of manufacturing are also included and are included in this feature. This also applies to the definition of material in this document.

[0033] For example, the infiltrate may be silicon or an alloy of silicon with, in particular, aluminum and / or boron and / or copper. This characteristic also includes impurities that are unavoidable as a result of production. This infiltrate allows particularly good infiltration of the porous precursor body, including reaction with any carbon in the inorganic matrix, to produce secondary silicon carbide.

[0034] The silicon alloy may contain, for example, one or more metals, particularly selected from the group consisting of aluminum, copper, titanium, nickel, magnesium, zinc, cobalt, chromium, silver, gold, or alloys of these metals. Such silicon alloys have a lower melting anomaly than pure silicon, i.e., they can reduce volume expansion during solidification. Therefore, the stress and surface bleed of the part are lower.

[0035] The infiltrate is particularly preferably an alloy comprising silicon and at least one of the materials aluminum and / or boron.

[0036] Particularly preferred is an embodiment in which the inorganic matrix of the precursor body is based on a first silicon carbide, the precursor coating is based on a second silicon carbide, and the infiltrate is based on silicon. It is also possible for the precursor body to contain carbon as a reaction partner for the silicon infiltration, resulting in secondary silicon carbide.

[0037] The inorganic matrix of the precursor body may be formed, for example, from one or more of silicon carbide, boron carbide, and / or carbon, or a combination thereof, and one or more metals. Again, in particular, the metals may be selected from the group consisting of silicon, aluminum, copper, titanium, nickel, magnesium, zinc, cobalt, chromium, silver, gold, or alloys of these metals. The metals may be particularly capable of reducing melting anomalies.

[0038] In a preferred embodiment, a material bond is formed between the coating and the component body, preferably to an extent of at least 30%, more preferably primarily by ionic bonding. This results in a strong, durable coating that is not or does not need to be removed during or after manufacturing. For this purpose, the proportion of ionic bonds should predominate over the proportion of covalent bonds. Ionic bonds (also known as heteropolar or electrovalent bonds) are chemical bonds based on the electrostatic attraction of positively and negatively charged ions.

[0039] Another feature is that the precursor coating is formed by casting a slip formed on the wall surface that defines the cavity. The cast thus grown forms an initial microporous surface with a relatively uniform layer thickness, and this is achieved with particularly low technical complexity. In slip casting, casting is understood to mean, in particular, that a solidified deposit of the slip has been achieved.

[0040] The formation of the cast is based on the porosity of the precursor body and the resulting capillary forces that remove the dispersant (preferably water) from the slip and cause the accumulation of solid particles from the slip on the wall surface ("cast formation").

[0041] Alternatively, the precursor coating can be deposited on the wall surfaces defining the cavity by a vapor phase method. This also allows for a uniform application. Drying of the precursor body, which is necessary from a process engineering point of view when using slip / slip casting methods, is not required here. The vapor phase method can be carried out, for example, by a CVD (chemical vapor deposition) process or a PVD (physical vapor deposition) process. These processes allow for the achievement of thin coatings of uniform thickness.

[0042] Specifically, the precursor coating is formed from or consists of a coating material that at least substantially corresponds to the material of the precursor body. This material is thus specific to the matrix material of the precursor body. Therefore, it does not need to be removed from the wall surface after infiltration. During both manufacturing and application, the coating has at least part of the same material properties as the matrix of the precursor body. Thermal expansion stresses between the coating and the precursor body are also low, allowing the coating to remain intact.

[0043] An advantageous embodiment provides that the coating contains a low proportion of carbon or no carbon prior to infiltration, so that, particularly after infiltration of the precursor body with the infiltrate, there is proportionally less reactant in the coating that reacts with the infiltrate to form carbides than in the precursor body.

[0044] The precursor coating may have a thickness of 0.01 mm to 1.0 mm, preferably 0.02 mm to 0.5 mm, and particularly preferably 0.05 mm to 0.2 mm. These coating thicknesses serve as a barrier to infiltrants, but still allow for very small cavities that can be positioned very close together. The smaller the layer thickness, the closer the cavities can be positioned within the precursor body prior to application of the precursor coating.

[0045] The cavity diameter is preferably 2 mm to 25 mm. Therefore, it is difficult to reprocess the cavity from the inside because it is difficult to insert hands, people, or large tools. At the same time, such a small diameter makes it particularly susceptible to closure due to exudation of the surface melt.

[0046] In one possible embodiment, the component is configured as a wafer chuck. A wafer is a thin slice that serves as the blank from which electronic components such as integrated circuits ("chips") are fabricated in a multi-stage process. The wafer chuck holds the wafer during processing by vacuum and / or electrostatic attraction.

[0047] The invention further relates to an apparatus including a part as described above and below, and a fluid conveying device connected to a cavity of the part via a fluid conduit, so that the cavity can be used for cooling or for suction gripping of a workpiece, in which the part can take advantage of a small, unobstructed and inexpensively manufacturable cavity, for example in the form of a carrier / holder with cooling or drainage channels.

[0048] In a more specific embodiment of the apparatus of the present invention, the apparatus comprises a processing device, and the part forms a workpiece holder for holding a workpiece in the processing device. The cavity, which may be configured, for example, as a channel, allows for the conduction of a coolant into or through the cavity, thereby enabling, for example, accurate mounting of the workpiece without thermal deformation. However, the cavity may optionally be open to the workpiece receiving surface of the workpiece holder, whereby the workpiece can be fixed by evacuation of the cavity by a fluid transport device.

[0049] Finally, the present invention provides a method for manufacturing a component having a component body with at least one cavity, comprising: a) providing a single-piece or multi-piece porous precursor body made of an inorganic matrix comprising cavities; b) forming a porous precursor coating comprising an inorganic matrix on a wall surface of the precursor body that defines the cavity; c) infiltrating the porous precursor body and the porous precursor coating with an inorganic infiltrant at a temperature equal to or greater than the liquidus temperature of the infiltrant; d) cooling the infiltrated precursor body and the infiltrated precursor coating below a solidus temperature of the infiltrate, whereby a coating is formed from the precursor coating and the infiltrate, a part body is formed from the precursor body and the infiltrate, and a material compound is formed between the coating and the part body, among other things; The present invention also relates to a method comprising:

[0050] The advantage of the present invention is that the coating is reliably adhered to the part body and does not need to be removed. The precursor body matrix can be optimized for infiltration via the infiltrant, while the precursor coating matrix can be optimized for preventing surface melt exudation. This avoids cavity blockage and the cost and complexity of keeping the cavity free of surface melt exudation and / or auxiliary materials for its prevention.

[0051] In forming the porous precursor coating, the inorganic matrix can optionally include temporary organic components, such as plasticizers, binders, etc., which may aid in better application of the porous precursor coating. Such organic components are typically burned off during infiltration.

[0052] In a more particular method configuration: - the precursor coating is less wettable to the infiltrate than the porous precursor body; and / or - the matrix of the precursor coating and the matrix of the precursor body are each formed from a microstructure, and the microstructure of the matrix of the precursor coating is finer than the microstructure of the matrix of the porous precursor body; Things are provided.

[0053] The infiltrate exhibits melt anomalies such that it expands upon solidification, and during cooling a surface melt exudate forms at least substantially exclusively on the free surfaces not covered by the precursor coating.

[0054] If there is no surface melt exudate in the area of ​​the coating, then (partial) blockage of the cavity does not occur here, and instead the surface melt exudate is directed to the free uncoated surface, which tends to be less problematic or at least easier to remove.

[0055] All the features described with respect to the components may also, individually or in combination, form part of the subject matter of the process, as long as this is necessary or expedient. The advantages therefore correspond to those described with respect to the device features. In particular, optional developments of the process may, for example, comprise the following features, individually or in combination:

[0056] The low wetting tendency of the precursor coating partially inhibits surface leaching, for example, in the inside-out route. Any external infiltration of the precursor-coated wall surface may optionally be removed by shaking, vibrating or introducing compressed air or water into the cavity. The precursor body may be made up of two or more separate parts. Any individual part of the precursor body may each adjoin a cavity and in particular form a wall of the cavity. - The precursor coating should already be applied before infiltration of the precursor body. Infiltration may be continued until the infiltrate protrudes from the interior into the precursor coating, preferably infiltrating the precursor coating from the interior. The part may be silicon infiltrated and reaction bonded silicon carbide (SiC) (also known as SiSiC or RBSiC). The precursor body may contain a higher proportion of the infiltrant's reaction partner (e.g., carbon) than the precursor coating. The reaction partners may be present in a configuration such that they are dispersed / incorporated into the precursor body prior to application of the precursor coating. - initially, a suitable forming process (pressing, (pressure) slip casting, film casting, injection molding, extrusion, stamping, 3D printing) may be used to produce a porous precursor body, for example consisting essentially of silicon carbide, carbon and / or other organic auxiliary substances. The precursor body and the precursor coating may be infiltrated with molten silicon in a subsequent high temperature treatment under vacuum and / or protective gas atmosphere. - The infiltrated silicon can react with carbon by dissolution and reprecipitation to form so-called secondary silicon carbide, which grows epitaxially on the primary silicon carbide grains. The pores of the precursor body remaining after the reaction is complete may be filled with unreacted free silicon, or excess silicon may be used to ensure complete pore filling. - Surface melt exudates may be formed by silicon, which exhibits a volume expansion of about 10% upon solidification. The precursor coating may be formed with a poorer wettability to the infiltrant than the precursor body. The coating of the precursor body may be formed from a finer microstructure than the porous precursor body. The viscosity of the infiltrant may be adapted to the porosity of the precursor body to be infiltrated, or vice versa, the porosity may be adapted to the viscosity of the infiltrant, in order to achieve optimal infiltration, in particular by capillary action. The microstructure of the precursor coating may have a primary particle size of 0.1 μm to 100 μm, preferably 0.2 μm to 60 μm, more preferably 0.5 μm to 30 μm, even more preferably 0.8 μm to 8 μm, and particularly preferably 1 μm to 6 μm. The microstructure of the precursor body may have a primary particle size of 0.1 μm to 500 μm, preferably 0.2 μm to 400 μm, more preferably 0.5 μm to 300 μm, even more preferably 1 μm to 250 μm, and particularly preferably 2 μm to 200 μm. The precursor coating may be less prone to infiltration by infiltrants than the porous precursor body, in particular due to poorer wetting and / or a finer microstructure. The cavity may be formed in the form of a channel or a channel structure. The inorganic matrix of the precursor body may be at least substantially or completely formed from the group of materials silicon carbide, boron carbide, diamond, molybdenum disilicide, silicon nitride, titanium carbide, zirconium carbide, aluminium nitride, tungsten carbide, or combinations of these materials. Infiltration may be carried out by contacting the precursor body with an infiltrate, the precursor body, precursor coating and infiltrate completing a common temperature cycle. The infiltrate may be silicon or an alloy thereof. The silicon alloy may, for example, contain one or more metals. The metal may in particular be chosen from the group of aluminium, copper, titanium, nickel, magnesium, zinc, cobalt, chromium, silver, gold or alloys thereof. The inorganic matrix of the precursor body may be based on a first silicon carbide, a precursor coating on the second silicon carbide, and an infiltrate on the silicon. Carbon may preferably be introduced into the precursor body as a reaction partner for the infiltration of silicon, in order to obtain a second silicon carbide prior to application of the precursor coating. The inorganic matrix may be formed from one or more of the primary materials silicon carbide, boron carbide and / or carbon, or a combination thereof, together with one or more metals, which may in particular be selected from the group consisting of aluminum, copper, titanium, nickel, magnesium, zinc, cobalt, chromium, silver, gold, or alloys of these metals. A material bond may be formed between the coating and the precursor body, the material bond between the coating and the infiltrated precursor body being preferably formed to an extent of at least 30%, more preferably predominantly, by ionic bonding. The coating may be formed as a solid and durable coating that is not removed during or after manufacture. - The precursor coating may be formed by slip casting (where the porous precursor body replaces the plaster often used in slip casting and no demolding is performed). The precursor coating may be formed by casting, consisting of a slip formed on the wall surfaces that define the cavity. The precursor coating may be deposited on the wall surface by a gas phase process. The gas phase method may be carried out, for example, by a CVD (Chemical Vapour Deposition) process or a PVD (Physical Vapour Deposition) process. The precursor body may be dried after application of the precursor coating. The precursor coating may be formed from or consist of a coating material that at least substantially corresponds to the material of the precursor body. The precursor coating may be formed with a low or no carbon percentage prior to infiltration. The introduction of carbon into the precursor body may be carried out before the application of the precursor coating. The precursor coating may be applied in a thickness of 0.01 mm to 1.0 mm, preferably 0.02 mm to 0.5 mm, particularly preferably 0.05 mm to 0.2 mm. The cavity may be formed with a diameter of 2 mm to 25 mm. [Brief explanation of the drawings]

[0057] Further features, details and advantages of the invention are apparent from the following description of exemplary embodiments, based on the claims and the drawings.

[0058] [Figure 1] 1 is a perspective view of an apparatus including components, seen from diagonally above, and a schematic diagram of a fluid transport device; [Figure 2] 2 is a perspective view of the component according to FIG. 1, including a partial cross section, seen obliquely from below. [Figure 3] 1 shows a perspective view from above of an apparatus with components and a schematic diagram of a fluid transport device, the components being shown as partially transparent. [Figure 4] 1 shows a schematic detail cross section through the part. [Figure 5] 1 is a polished cross-section photomicrograph taken by an optical microscope showing a cavity in a part in cross section. [Figure 6] FIG. 6 is a detailed optical microscope image of FIG. 5 revealing the microstructure of the precursor body and precursor coating. [Figure 7] Electron microscope detail image of Figure 6, in which the distinction between primary silicon carbide, secondary silicon carbide, and free silicon is clear. [Figure 8a] 1 is a detailed black and white optical microscope image revealing the microstructure of the precursor body and precursor coating. [Figure 8b] 1 is a detailed black and white optical microscope image revealing the microstructure of the precursor body and precursor coating. DETAILED DESCRIPTION OF THE INVENTION

[0059] Figure 1 is a perspective view from diagonally above, which shows a schematic representation of an apparatus 20 comprising a part 1 and a fluid transport device 21. Figure 2 shows part 1 again in a perspective view, this time from diagonally below, including a partial cross section (this partial cross section is also included in Figure 1 but is barely discernible). Figures 1 and 2 show a part body 2 comprising three part-annular cavities 3, each forming a channel between two openings. The openings are located on the periphery and on the top surface of the part body 2.

[0060] The component body 2 is produced on the basis of a porous precursor body 5 consisting of an inorganic matrix M1, which consists of two bonded preforms of SiC-carbon material (with an average grain size of 20 μm and a carbon content of 10%). The cavities 3 / channels of the precursor body 5 extend along the bonded surfaces of the preforms and are produced by incorporating the bottom and / or top of the channels into the respective preforms. The preforms may be produced by subtractive manufacturing, for example, sheet pressing or milling. The preforms are quasi-monolithically bonded together using modern finishing methods of the same material. The precursor body 5 thus obtained has a number of channels (cavities 3) with diameters of 2-5 mm.

[0061] The porous precursor coating 11 on the wall surface 4 of the cavity 3 is applied through two openings in the channel (cavity 3) in the form of an additional inorganic matrix M2. The surface visible on the outside does not receive this porous precursor coating and forms a free surface 6. The precursor coating 11 on the wall surface 4 is produced, in particular, by a slip casting method. A SiC slip (in particular, aqueous) with a primary particle size of approximately 5 μm and a solids content of 50% by weight is used as the coating slip. The slip is filled into the channel (cavity 3) through the openings and then ejected after a specified time to allow sufficient cast formation. Due to the inherent porosity of the precursor body 5, a cast of 0.05 mm to 1 mm is formed on the wall surface 4, which serves as the precursor coating 11. The precursor body 5 with the coated channel (cavity 3) is then dried at room temperature to remove residual moisture from the intermediate product.

[0062] The precursor bodies 5 are then contacted with silicon and heated in a vacuum oven until the silicon liquefies and infiltrates the porous precursor bodies 5 and the porous precursor coating 11. This result is also evident from the detailed schematic cross section of FIG.

[0063] The infiltration of the precursor coating 11 results in a permanent coating 10 firmly bonded to the component body 2 resulting from the precursor body 5 and the infiltrate M3 (see FIG. 4). This results in a material compound in particular.

[0064] After the precursor body 5 is completely infiltrated with silicon, the part 1 is cooled, and a surface melt exudate forms in the free surface 6 due to the silicon melt anomalies. In this case, the surface melt exudate can be removed by sandblasting. Due to the coating 10 on the wall surface 4 of the cavity 3, typically only a few small silicon beads, if any, are present within the cavity 3, which can be removed, for example, by introducing air or water. Furthermore, the matrices M1 and M2 of the precursor body 5 and the precursor coating 11 are different. In particular, the precursor coating 11 has poorer wettability with the infiltrate M3 (see FIG. 4 ) than the precursor body 5. Furthermore, the matrix M2 of the precursor coating 11 and the matrix M1 of the precursor body 5 each have a microstructure, with the microstructure of the matrix M2 of the precursor coating 11 being finer than the microstructure of the matrix M1 of the precursor body 5.

[0065] The microstructure of the matrix M2 of the precursor coating 11 may have a primary particle size of, for example, 0.1 μm to 100 μm, preferably 0.2 μm to 60 μm, more preferably 0.5 μm to 30 μm, even more preferably 0.8 μm to 8 μm, and particularly preferably 1 μm to 6 μm. The microstructure of the matrix M1 of the precursor body 5 is coarser than the microstructure of the precursor coating 11 and has a primary particle size of 0.1 μm to 500 μm, preferably 0.2 μm to 400 μm, more preferably 0.5 μm to 300 μm, even more preferably 1 μm to 250 μm, and particularly preferably 2 μm to 200 μm. Therefore, the precursor coating 11 has a lower tendency to infiltrate with the infiltrant M3 (see FIG. 4 ) than the precursor body 5.

[0066] The precursor coating does not incorporate carbon (except for small impurities, etc.) that can be used as a reaction partner for the infiltrant M3 (see FIG. 4). As a result, the matrix M1 of the precursor body 5 has a greater ratio of free infiltrant M3 (see FIG. 4) to reacted infiltrant M3 with a reaction partner (see FIG. 4) than the matrix M2 of the precursor coating 11.

[0067] 3 is a perspective view of an apparatus 20 including a part 1 and a fluid transport device 21, seen obliquely from above, with the part 1 shown partially transparent. Unlike in FIGS. 1 and 2, the cavity 3 is formed as a complex channel structure. The channel (cavity 3) is not formed on a single plane but is formed three-dimensionally in space.

[0068] The precursor body 5 is fabricated similarly to Figures 1 and 2 by quasi-monolithic bonding of two pre-fabricated SiC-carbon materials with internal channel structures. However, the pre-fabricated bodies are fabricated by 3D printing, in this case, binder jetting. In binder jetting, powder is applied layer by layer on a platform, and a binder is introduced point-by-point into each layer to locally bind the powder, building a three-dimensional body and enabling the removal of the 3D precursor body from a loose powder bed. The SiC powder used forms a matrix M1 with an average particle size of 50–250 μm. The channel portion of the cavity 3 of the pre-fabricated body must be sufficiently accessible to allow the removal of unbound powder from the channel. Therefore, the precursor body 5 again has a multi-component structure. After the cavity 3 is completely removed from the 3D printing powder, the pre-fabricated bodies are bonded together so that each channel is connected by a complex duct system. The channels (cavity 3) within the precursor body 5 have a channel diameter of 5 mm, and at the end of each channel there are two channel openings for applying a precursor coating 11 that continues to the wall 4 of the cavity 3.

[0069] The application and further processing of the precursor coating 11 may be carried out similarly to FIGS. 1 and 2 in conjunction with FIG.

[0070] However, any single-piece configuration of the precursor body 5 is equally conceivable, especially if it allows sufficient powder evacuation during 3D printing. For this purpose, the precursor body 5 can be produced as a monolith by binder jetting. This allows for maximum geometric freedom in the channel geometry (cavity 3 geometry). The limiting factor here is the removal of unbound powder from the intended channels / cavities 3, which is particularly influenced by the channel diameter and the powder flowability. The channel diameter of monolithically produced channel structures (cavities 3) is, for example, 10 mm. These are suitable, for example, as classical water-conducting cooling channels.

[0071] Application of the precursor coating 11 to the wall surfaces 4 of the cavity 3 may be carried out according to the application process described with reference to Figures 1 and 2. For a channel diameter of 10 mm, this may be done using a coating slip with a solids content of 65 wt%. Subsequent processing of the precursor body 5 with the precursor coating 11 may be carried out according to Figures 1 and 2 in conjunction with Figure 4.

[0072] Considering the schematic detailed cross-section of Figure 4, Figure 5 shows an actual polished cross-section photomicrograph taken with an optical microscope, showing a cross-section of a cavity 3 of part 1. The cavity 3 is formed in a precursor body 5, and the wall surface 4 of the cavity 3 is coated with a precursor coating 11. The precursor body 5 is composed of a first matrix M1 having a coarser microstructure K1 than the microstructure K2 of the second matrix M2 forming the precursor coating 11. The free surface 6 of the precursor body 5, free of any coating, is also evident. Co-infiltration of the precursor body 5 and precursor coating 11 with infiltrate M3 results in a part body 2 composed of the precursor body 5 and infiltrate M3 coated with a coating 10 of the precursor coating 11 and infiltrate M3. The thickness of the coating 10 is 550.940 μm at the 2 o'clock direction, 704.762 μm at the 5 o'clock direction, 652.110 μm at the 8 o'clock direction, and 719.315 μm at the 11 o'clock direction.

[0073] The detailed optical microscope image in FIG. 6 shows the boundary region between the component body 2 and the coating 10. Along the wall surface 4, coarse grains K1 of the inorganic matrix M1 of the precursor body 5 are adjacent to finer grains K2 of the inorganic matrix M2 of the precursor coating 11. As a result, the infiltrate M3 is much more finely distributed in the inorganic matrix M2 of the precursor coating 11 than in the inorganic matrix M1 of the precursor body 5. It is clear that the infiltrate M3 extends, in individual regions of the wall surface 4, from the gaps between the grains K1 of the matrix M1 of the precursor body 5 to the gaps between the grains K2 of the matrix M2 of the precursor coating 11. In this way, a kind of framework or scaffold of the infiltrate M3 exists, extending through the precursor body 5 and the precursor coating 11.

[0074] An even larger magnification of Figure 7 is a detailed electron microscope image of Figure 6. Here, the material grains K1 that form the matrix M1 of the porous precursor body 5 are first apparent. Infiltrate M3 has infiltrated into the voids of matrix M1 and is now present in two different forms. Infiltrate M3.1 has reacted with its reaction partner and grown epitaxially on the material grains K1 of the matrix M1 of the precursor body 5. The remaining voids are filled with free infiltrate M3.2.

[0075] In this example, the material grains M1 of the matrix M1 of the porous precursor body 5 are silicon carbide, and the infiltrate M3 is silicon, so that in-situ silicon carbide exists as the reacted infiltrate M3.1 and silicon exists as the free infiltrate M3.2, and therefore carbon exists in the precursor body 5 as a reaction partner for the infiltrate M3.

[0076] 7, the microstructure of the matrix M2 of the precursor coating 11 is very similar in some microscopic form, however, due to the absence of a reaction partner incorporated in the precursor coating 11, the ratio of free infiltrate M3.2 to reacted infiltrate M3.1 predominates much more strongly here than in the region of the precursor body 5.

[0077] 8a and 8b show additional detailed black and white optical microscope images of a polished cross section of part 1. A part body 2 is evident, consisting of a porous precursor body 5 made of a porous matrix M1 and an infiltrate M3. A coating 10 is disposed on the wall surface 4 of a cavity 3 of the porous precursor body 5. The coating 10 is composed of a porous precursor coating 11 made of a matrix M2 and an infiltrate M3. In both cases, it is apparent that the microstructure in the area of ​​part body 2 is coarser than in the area of ​​coating 10. Furthermore, although reference is made above with respect to FIGS. 5, 6, and 7, these individual features may also be realized individually here.

[0078] Those skilled in the art will appreciate that the individual steps of the described exemplary embodiments may also be individually incorporated into the described methods or components.

[0079] The invention is not limited to any of the embodiments described above, but can be varied in a wide variety of ways.

[0080] All of the features and advantages apparent from the claims, description and drawings, including structural details, spatial arrangements and method steps, can be essential to the invention both individually and in very various combinations. [Explanation of symbols]

[0081] 1 part 2. Part body 3 Cavity 4 Wall surface 5. Porous precursor body 6 Free surface 10 Coating 11 Porous precursor coating 20 equipment 21 Fluid transport device K1 Material grain (precursor body) K2 Material Granules (Coating) M1 Inorganic matrix (precursor body) M2 Inorganic matrix (precursor coating) M3 Infiltration

Claims

1. A component body (2) having at least one cavity (3) and a coating (10) at least partially covering a wall surface (4) of the component body (2) that defines the cavity (3), the component body (2) is composed of a single or multiple pieces of a porous precursor body (5) made of an inorganic matrix (M1) having the cavity (3), and an inorganic infiltrate (M3) that infiltrates the porous precursor body (5) and exhibits a melting abnormality such as expanding upon solidification, The coating (10) is composed of a porous precursor coating (11) made of an inorganic matrix (M2) that at least partially covers the wall surface (4) of the precursor body (5) that defines the cavity (3), and an inorganic infiltrate (M3) that infiltrates the precursor coating (11) and exhibits a melting anomaly that expands upon solidification.

2. a) the precursor coating (11) is less wettable by the infiltrate (M3) than the precursor body (5), and / or b) the component (1) according to claim 1, wherein the matrix (M2) of the precursor coating (11) and the matrix (M1) of the precursor body (5) are formed from microstructures (K1, K2), respectively, and the microstructure (K2) of the matrix (M2) of the precursor coating (11) is finer than the microstructure (K1) of the matrix (M1) of the precursor body (5).

3. Component (1) according to claim 2, wherein the microstructure (K2) of the matrix (M2) of the precursor coating (11) is constituted by primary grain sizes of 0.1 μm to 100 μm, preferably 0.2 μm to 60 μm, more preferably 0.5 μm to 30 μm, even more preferably 0.8 μm to 8 μm, and particularly preferably 1 μm to 6 μm.

4. 4. The component (1) according to claim 2 or claim 3, wherein the microstructure (K1) of the matrix (M1) of the precursor body (5) is constituted by primary particle sizes of 0.1 μm to 500 μm, preferably 0.2 μm to 400 μm, more preferably 0.5 μm to 300 μm, even more preferably 1 μm to 250 μm, particularly preferably 2 μm to 200 μm.

5. 5. The component (1) according to any one of claims 1 to 4, wherein the precursor coating (11) has a lower tendency to weep with the infiltrant (M3) than the precursor body (5).

6. A part (1) described in any one of claims 1 to 5, wherein the solidified infiltrate (M3) extends from the part body (2) into the coating (10) and forms a continuous scaffold between the precursor body (5) and the precursor coating (11).

7. A part (1) described in any one of claims 1 to 6, wherein the proportion of infiltrates (M3) that have reacted with a reaction partner and been released is greater in the matrix (M1) in the precursor body (5) than in the matrix (M2) of the precursor coating (11).

8. 8. The component (1) according to any one of the preceding claims, wherein the cavity (3) forms a channel or a channel structure.

9. 9. The component (1) according to any one of claims 1 to 8, wherein the inorganic matrix (M1) of the precursor body (5) is at least substantially or completely formed from the group of materials: silicon carbide, boron carbide, diamond, molybdenum disilicide, silicon nitride, titanium carbide, zirconium carbide, aluminum nitride, tungsten carbide, or combinations of these materials.

10. Component (1) according to any one of claims 1 to 9, wherein the infiltrate (M3) is silicon or an alloy of silicon.

11. A part (1) described in any one of claims 1 to 10, wherein the precursor coating (11) has a thickness of 0.01 mm to 1.0 mm.

12. Component (1) according to any one of claims 1 to 11, wherein the precursor coating (11) is formed from a coating material corresponding to the material of the precursor body (5).

13. An apparatus (20) comprising a component (1) according to any one of claims 1 to 12, and comprising a fluid conveying device (21) connected to the cavity (3) of the component (1) via a fluid conduit.

14. A method for manufacturing a component (1) having a component body (2) with at least one cavity (3), comprising: e) providing a single-piece or multi-piece porous precursor body (5) made of an inorganic matrix (M1) constituting said cavity (3); f) forming a porous precursor coating (11) made of an inorganic matrix (M2) on the wall surfaces (4) of said precursor body (5) that define said cavity (3); g) infiltrating the porous precursor body (5) and the porous precursor coating (11) with an inorganic infiltrant (M3) at a temperature equal to or greater than the liquidus temperature of the infiltrant (M3) that exhibits a melt anomaly such that it expands upon solidification; h) cooling the infiltrated precursor body (5) and the infiltrated precursor coating (11) below a solidus temperature of the infiltrate (M3), wherein a coating (10) is formed from the precursor coating (11) and the infiltrate (M3), a component body (2) is formed from the precursor body (5) and the infiltrate (M3), and a material compound is formed between the coating (10) and the component body (2).

15. - said precursor coating (11) is less wettable by said infiltrate (M3) than said porous precursor body (5); the matrix (M2) of the precursor coating (11) and the matrix (M1) of the precursor body (5) are each formed from a microstructure (K1, K2), the microstructure (K2) of the matrix (M2) of the precursor coating (11) being finer than the microstructure (K1) of the matrix (M1) of the porous precursor body (5), The infiltrate (M3) exhibits melting anomalies such as expansion upon solidification, 15. The method according to claim 14, wherein during cooling a surface melt exudate is formed exclusively on the free surfaces (6) not covered by the precursor coating (11).

16. The precursor coating (11): a) formed by casting of a slip formed on the wall surfaces (4) defining the cavity (3), or 16. The method according to claim 14 or 15, wherein b) the material is deposited on the wall surfaces (4) defining the cavity (3) by a vapor phase method.

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