COMPONENT PRODUCED USING AN INFILTRATION PROCESS, DEVICE COMPRISING SAID COMPONENT, AND INFILTRATION PROCESS FOR PRODUCING A COMPONENT

Abstract

A component includes a component body in which at least one cavity is formed, wherein a wall surface of the component body, which wall surface delimits the cavity, is at least partially coated with a coating. The design of the component is based on a porous preform made in one or more parts from an inorganic matrix (M1), the preform having the cavity and a porous pre-coating made from an inorganic matrix (M2), the pre-coating coating at least part of a wall surface of the preform that delimits the cavity The porous preform and the porous pre-coating are infiltrated with an inorganic infiltrate (M3). The infiltrated preform forms the component body, and the infiltrated pre-coating forms the coating. A method for producing the component, wherein the preform and the pre-coating are infiltrated so as to produce the component body comprising the coating is also disclosed.

Claims

1. A component (1) having a component body (2) comprising at least one cavity (3), wherein a wall surface (4) of the component body (2) delimiting the cavity (3) is at least partially coated with a coating (10), wherein the component (1) is formed on the basis of a one-piece or multi-piece porous precursor body (5) composed of an inorganic matrix (M1), wherein the precursor body (5) comprises the cavity (3), a porous precursor coating (11) composed of an inorganic matrix (M2), with which a wall surface (4) of the precursor body (5) delimiting the cavity (3) is at least partially coated, and infiltration of the porous precursor body (5) and the porous precursor coating (11) with an inorganic infiltrate (M3), wherein the infiltrated precursor body (5) forms the component body (2) and the infiltrated precursor coating (11) forms the coating (10).

2. The component (1) as claimed in claim 1, characterized in that a) the precursor coating (11) has a poorer wettability with respect to the infiltrate (M3) than the precursor body (5) and/or b) 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), wherein 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. The component (1) as claimed in claim 2, characterized in that the microstructure (K2) of the matrix (M2) of the precursor coating (11) has a primary grain size of 0.1 m to 100 m, preferably of 0.2 m to 60 m, more preferably of 0.5 m to 30 m, yet more preferably of 0.8 m to 8 m and particularly preferably of 1 m to 6 m.

4. The component (1) as claimed in claim 2, characterized in that the microstructure (K1) of the matrix (M1) of the precursor body (5) has a primary grain size of 0.1 m to 500 m, preferably of 0.2 m to 400 m, more preferably of 0.5 m to 300 m, yet more preferably of 1 m to 250 m and particularly preferably of 2 m to 200 m.

5. The component (1) as claimed in claim 1, characterized in that the precursor coating (11) has a lower infiltration tendency with respect to the infiltrate (M3) than the precursor body (5).

6. The component (1) as claimed in claim 1, characterized in that the infiltrate (M3) exhibits a melting anomaly such that it expands upon solidification.

7. The component (1) as claimed in claim 1, characterized in that the precursor body (5) comprises a higher proportion of a reaction partner for the infiltrate (M3) than the precursor coating (11) and in particular the proportion of infiltrate (M3) that has reacted with the reaction partner to free infiltrate (M3) is greater within the matrix (M1) in the precursor body (5) than within the matrix (M2) of the precursor coating (11).

8. The component (1) as claimed in claim 1, characterized in that the cavity (3) forms a channel or a channel structure.

9. The component (1) as claimed in claim 1, characterized in that the inorganic matrix (M1) of the precursor body (5) is at least substantially or completely formed from the material group of silicon carbide, boron carbide, diamond, molybdenum disilicide, silicon nitride, titanium carbide, zirconium carbide, aluminum nitride, tungsten carbide or combinations of these materials.

10. The component (1) as claimed in claim 1, characterized in that the infiltrate (M3) is silicon or an alloy of silicon in particular with aluminum and/or boron and/or copper.

11. The component (1) as claimed in claim 1, characterized in that the precursor coating (11) a) is formed by a cast composed of a slip that is formed on the wall surface (4) delimiting the cavity (3); or b) is deposited on the wall surface (4) delimiting the cavity (3) by a gas phase process.

12. The component (1) as claimed in claim 1, characterized in that the precursor coating (11) is formed of a coating material which corresponds at least substantially to the material of the precursor body (5).

13. An apparatus (20) comprising a component (1) according to claim 1 and comprising a fluid conveying apparatus (21) which is connected to the cavity (3) of the component (1) via a fluid conduit.

14. A process for producing a component (1) having a component body (2) comprising at least one cavity (3) comprising the steps of: e) providing a single-piece or multi-piece porous precursor body (3) composed of an inorganic matrix (M1) comprising a cavity (3); f) forming a porous precursor coating (11) composed of an inorganic matrix (M2) on a wall surface (4) of the precursor body (5) delimiting the cavity (3); g) infiltrating the porous precursor body (5) and the porous precursor coating (11) with an inorganic infiltrate (M3) at a temperature above the liquidus temperature of the infiltrate (M3); h) cooling the infiltrated precursor body (5) and the infiltrated precursor coating (11) below the solidus temperature of the infiltrate (M3), wherein a coating (10) is formed from the precursor coating (11) and the infiltrate (M3) and a component body (2) is formed from the precursor body (5) and the infiltrate (M3), wherein a material compound is especially formed between the coating (10) and the component body (2).

15. The process as claimed in claim 14, characterized in that the precursor coating (11) has a poorer wettability with respect to the infiltrate (M3) than the porous precursor body (5) and/or the matrix (2) of the precursor coating (11) and the matrix (M1) of the precursor body (5) are each formed from a microstructure (K1, K2), wherein the microstructure (K2) of the matrix (2) of the precursor coating (11) is finer than the microstructure (K1) of the matrix (M1) of the porous precursor body (5), wherein the infiltrate (M3) exhibits a melting anomaly such that it expands as it solidifies, wherein during cooling surface melt exudations are formed at least substantially exclusively on free surfaces (6) not covered by the precursor coating (11).

Description

[0108] Further features, details and advantages of the invention are apparent from the wording of the claims and from the following description of exemplary embodiments on the basis of the drawings. In the figures:

[0109] FIG. 1 shows a perspective view from obliquely above of an apparatus comprising a component and a schematic diagram of a fluid conveying apparatus;

[0110] FIG. 2 shows a perspective view from obliquely below of the component according to FIG. 1 including a partial section;

[0111] FIG. 3 shows a perspective view from obliquely above of an apparatus comprising a component and a schematic diagram of a fluid conveying apparatus, wherein the component is shown as partially transparent;

[0112] FIG. 4 shows a schematic detail section through a component;

[0113] FIG. 5 shows a polished section micrograph from an optical microscope showing a cavity in a component in cross section;

[0114] FIG. 6 shows a detail image from an optical microscope of FIG. 5 from which the microstructure of the precursor body and the precursor coating is apparent;

[0115] FIG. 7 shows a detail image from an electron microscope of FIG. 6 from which the differentiation between primary silicon carbide, secondary silicon carbide and free silicon is apparent; and

[0116] FIGS. 8a and 8b show a black-and-white detail image from an optical microscope from which the microstructure of the precursor body and the precursor coating is apparent.

[0117] FIG. 1 shows in a perspective view, from obliquely above, an apparatus 20 comprising a component 1 and a fluid conveying apparatus 21 included in schematic form. FIG. 2 again shows component 1 in a perspective view, now from obliquely below, including a partial section (this partial section is also included in FIG. 1 but hardly discernible). FIGS. 1 and 2 show a component body 2 comprising three part-annular cavities 3 which each form a channel between two openings. The openings are located on the circumference of the component body 2 and on the top surface of the component body 2.

[0118] The component body 2 is produced on the basis of a porous precursor body 5 composed of an inorganic matrix M1 composed of two joined semifinished products of SiC-carbon material (having an average particle size of 20 m and a carbon content of 10%). The cavities 3/channels of the precursor body 5 run along the joining surface of the semifinished products and are produced by incorporating the channel bottom and/or top into the respective semifinished product. The semifinished products may be produced by subtractive manufacturing for example, by pressing or milling of sheets. The semifinished products are joined in a quasi monolithic manner with material of the same kind using state-of-the-art finishing methods. The resulting precursor body 5 thus has a plurality of channels (cavities 3) having diameters of 2 to 5 mm.

[0119] A porous precursor coating 11 of the wall surfaces 4 of the cavities 3 is applied in the form of a further inorganic matrix M2 through the two openings of the channels (cavities 3). The surfaces visible on the outside do not receive such a porous precursor coating and form free surfaces 6. The precursor coating 11 of the wall surfaces 4 is especially produced via a slip casting process. A SiC slip (especially water-based) having a primary grain size of about 5 m and a solids content of 50% by weight is used as the coating slip. The slip is filled into the channels (cavities 3) via the openings and, after a defined time which allows for sufficient cast formation, is discharged therefrom. Due to the inherent porosity of the precursor body 5 a cast of 0.05 mm to 1 mm is thus formed at the wall surface 4 and functions as precursor coating 11. The precursor body 5 comprising the coated channels (cavities 3) is then dried at room temperature to remove the residual moisture from the intermediate product.

[0120] The precursor body 5 is then brought into contact with silicon and heated in a vacuum oven until the silicon liquefies and infiltrates the porous precursor body 5 and the porous precursor coating 11. The result of this is also apparent from the schematic detail section of FIG. 4.

[0121] The infiltration of the precursor coating 11 results in a permanent coating 10 which is firmly bonded to the component body 2 resulting from the precursor body 5 and the infiltrate M3 (see FIG. 4). This especially results in a material compound.

[0122] After complete infiltration of the precursor body 5 with silicon the component 1 is cooled and surface melt exudations are formed in the region of the free surfaces 6 due to a melting anomaly of the silicon. In the present case the surface melt exudations are removable by sandblasting. Due to the coating 10 of the wall surfaces 4 of the cavities 3 there are usually just a few, if any, small silicon beads in the cavities 3 which are removable for example by introduction of air or water. In addition the matrices M1 and M2 of the precursor body 5 and the precursor coating 11 differ. The precursor coating 11 especially has a poorer wettability with respect to the infiltrate M3 (see FIG. 4) than the precursor body 5. In addition the matrix M2 of the precursor coating 11 and the matrix M1 of the precursor body 5 are each formed from a microstructure, wherein the microstructure of the matrix M2 of the precursor coating 11 is finer than the microstructure of the matrix M1 of the precursor body 5.

[0123] The microstructure of the matrix M2 of the precursor coating 11 may have for example a primary grain size of 0.1 m to 100 m, preferably of 0.2 m to 60 m, more preferably of 0.5 m to 30 m, yet more preferably of 0.8 m to 8 m and particularly preferably of 1 m to 6 m. The microstructure of the matrix M1 of the precursor body 5 is coarser than that of the precursor coating 11 and has a primary grain size of 0.1 m to 500 m, preferably of 0.2 m to 400 m, more preferably of 0.5 m to 300 m, yet more preferably of 1 m to 250 m and particularly preferably of 2 m to 200 m. The precursor coating 11 thus has a poorer infiltration tendency with respect to the infiltrate M3 (see FIG. 4) than the precursor body 5.

[0124] The precursor coating has had no carbon introduced into it to be available therein as a reaction partner for the infiltrate M3 (see FIG. 4) (with the exception of small impurities and the like). As a result the matrix M1 in the precursor body 5 has a proportion of infiltrate M3 reacted with the reaction partner (see FIG. 4) to free infiltrate M3 (see FIG. 4) which is greater than in the matrix M2 of the precursor coating 11.

[0125] FIG. 3 shows a perspective view of an apparatus 20 comprising a component 1 and a fluid conveying apparatus 21 from obliquely above, wherein the component 1 is shown partially transparent. In a departure from FIGS. 1 and 2, the cavities 3 are formed as complex channel structures. The channels (cavities 3) are not only in one plane but are formed three-dimensionally in space.

[0126] The precursor body 5 is produced analogously to FIGS. 1 and 2 by the quasi-monolithic joining of two semifinished products composed of SiC-carbon material having an internal channel structure. However, the semi-finished products are produced by 3D printing, in this case the binder jet technology. In the binder-jet process a three-dimensional body is built up by applying powder layerwise on a platform and in each layer introducing binder on a point-by-point basis which effects local binding of the powder and, once printing is complete, allows removal of a 3D precursor body from the loose powder bed. The SiC powder used forms a matrix M1 having an average grain size of 50 to 250 m. The present channel sections of the cavities 3 in the semifinished products must have sufficient accessibility to allow removal of unbound powder from the channels. The precursor body 5 therefore has a multi-part configuration here too. After complete depowdering of the cavities 3 from the 3D printing powder the semifinished products are joined in such a way that the individual channels are connected in a complex duct system. The channels (cavities 3) in the precursor body 5 have a channel diameter of 5 mm and each have two channel openings at the ends of the channels to implement the subsequent precursor coating 11 of the walls 4 of the cavities 3.

[0127] The application of the precursor coating 11 and the further processing may be carried out analogously to FIGS. 1 and 2 in conjunction with FIG. 4.

[0128] However, if sufficiently emptiable, in particular of the powder during 3D printing, an optional one-piece configuration of the precursor body 5 is likewise contemplated. To this end the precursor body 5 is producible as a monolith by the binder jet process. This allows maximum geometric freedom of the channel geometry (the geometry of the cavities 3). The removal of unbound powder from the intended channel/cavity 3, which is influenced especially by the channel diameter and the flowability of the powder, is the limiting factor here. A monolithically manufactured channel structure (cavities 3) may have a channel diameter of 10 mm for example. These are suitable for example as classical water-conducting cooling channels.

[0129] The application of the precursor coating 11 on the wall surfaces 4 of the cavity 3 may be performed according to the coating process described for FIGS. 1 and 2. At a channel diameter of 10 mm this may be done using a coating slip having a solids content of 65 wt %. The subsequent processing of the precursor body 5 with precursor coating 11 may be implemented as per FIGS. 1 and 2 in conjunction with FIG. 4.

[0130] Having regard to the schematic detail section of FIG. 4, FIG. 5 shows a real polished section micrograph from an optical microscope which shows the cavity 3 in a component 1 in cross-section. The cavity 3 is formed in a precursor body 5 and a 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 microstructure K1 which is coarser than the microstructure K2 of a second matrix M2 which forms the precursor coating 11. A free surface 6 of the precursor body 5 without coating is also apparent. Joint infiltration of the precursor body 5 and the precursor coating 11 with an infiltrate M3 results in a component body 2 composed of precursor body 5 and infiltrate M3 which is coated with a coating 10 of precursor coating 11 and infiltrate M3. In the image direction the layer thicknesses of the coating 10 are 550.940 m at 2 o'clock, 704.762 m at 5 o'clock, 652.110 m at 8 o'clock and 719.315 m at 11 o'clock.

[0131] The detail image from an optical microscope of FIG. 6 shows the boundary zone between the component body 2 and the coating 10. Along the wall surface 4 the coarse material grains K1 of the inorganic matrix M1 of the precursor body 5 and the finer material grains K2 of the inorganic matrix M2 of the precursor coating 11 are adjacent to one other. As a result the infiltrate M3 is also 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 apparent that the infiltrate M3 extends in individual regions of the wall surface 4 from interspaces between the material grains K1 of the matrix M1 of the precursor body 5 to the interspaces between the material grains K2 of the matrix M2 of the precursor coating 11. There is thus a sort of skeleton or scaffold composed of infiltrate M3 which extends through precursor body 5 and precursor coating 11.

[0132] The even stronger enlargement of FIG. 7 shows a detail image from an electron microscope of FIG. 6. Initially apparent here are the material grains K1 which form the matrix M1 of the porous precursor body 5. Infiltrate M3 has penetrated into the interspaces of the matrix M1 and is now present in two different forms. The infiltrate M3.1 has reacted with a reaction partner and has grown epitaxially on the material grains K1 of the matrix M1 of the precursor body 5. The rest of the interspaces are filled with free infiltrate M3.2.

[0133] In the present case the material grains M1 of the matrix M1 of the porous precursor body 5 are silicon carbide, the infiltrate M3 is silicon and as a result in-situ silicon carbide is present as reacted infiltrate M3.1 and silicon is present as free infiltrate M3.2. To this end carbon was present in the precursor body 5 as a reaction partner for the infiltrate M3.

[0134] According to FIG. 7 the microstructure of the matrix M2 of the precursor coating 11 is very similar in somewhat finer form. However, due to the lack of incorporation of a reaction partner in the precursor coating 11 the proportion of free infiltrate M3.2 relative to reacted infiltrate M3.1 predominates much more strongly here than in the region of the precursor body 5.

[0135] The illustrations of FIGS. 8a and 8b show additional detail images from an optical microscope of a polished section of a component 1 in black-and-white. A component body 2 composed of a porous precursor body 5 composed of a porous matrix M1 and infiltrate M3 is apparent. A coating 10 is arranged on a wall surface 4 of a cavity 3 of the porous precursor body 5. The coating 10 is composed of a porous precursor coating 11 composed of a matrix M2 and also infiltrate M3. It is apparent in each case that the microstructure in the region of the component body 2 is coarser than in the region of the coating 10. Reference is moreover made to the foregoing in respect of FIGS. 5, 6 and 7, the individual features of which may also be realized individually here.

[0136] It will be appreciated that a person skilled in the art can also incorporate each individual step of the recited exemplary embodiments individually into the described process or component.

[0137] The invention is not restricted to any of the above-described embodiments but may be modified in a very wide variety of ways.

[0138] All of the features and advantages apparent from the claims, the description and the drawing, including structural details, spatial arrangements and process steps, may be essential to the invention both individually and in a very wide variety of combinations.

LIST OF REFERENCE SIGNS

[0139] 1 Component [0140] 2 Component body [0141] 3 Cavity [0142] 4 Wall surface [0143] 5 Porous precursor body [0144] 6 Free surface [0145] 10 Coating [0146] 11 Porous precursor coating [0147] 20 Apparatus [0148] 21 Fluid conveying apparatus [0149] K1 Material grains (precursor body) [0150] K2 Material grains (coating) [0151] M1 Inorganic matrix (precursor body) [0152] M2 Inorganic matrix (precursor coating) [0153] M3 Infiltrate