METHOD FOR PRODUCING A WORKPIECE BY COATING AND ADDITIVE MANUFACTURING; CORRESPONDING WORKPIECE

Abstract

A method for producing a workpiece, includes providing a substrate having a predetermined surface structure; coating the surface structure with a coating material, wherein the coating material is resistant to a production temperature of an additive production method; the additive production of a material for the workpiece on the coated surface structure using the additive production method such that the coated surface structure defines a base surface of the workpiece to be produced, and the detachment of the substrate. A workpiece is produced by the described method.

Claims

1.-10. (canceled)

11. A method for producing a workpiece, comprising: providing a substrate having a predetermined surface structure, coating the surface structure with a coating material by a thermal coating method, the coating material being resistant to a production temperature of an additive manufacturing process, additively manufacturing a material for the workpiece on the coated surface structure by deposition welding, so that the coated surface structure defines a base surface of the workpiece to be produced, the material being a nickel-based or cobalt-based superalloy or a starting material therefor, and detaching the substrate in such a way that the structure of the substrate is transferred to the base surface of the workpiece to be produced.

12. The method as claimed in claim 11, wherein the base surface is a surface of the workpiece that is at least partially inner-lying with respect to a contour of the workpiece to be produced.

13. The method as claimed in claim 11, wherein the surface structure is roughened or pretreated before the coating with the coating material, in order to improve an adhesive bond of the coating material on the surface structure.

14. The method as claimed in claim 11, wherein the coating material is a metal and/or a ceramic-metal composite.

15. The method as claimed in claim 11, wherein the workpiece is a high-temperature-resistant component.

16. The method as claimed in claim 11, wherein the coating material and the material for the workpiece are identical, at least in constituent parts.

17. The method as claimed in claim 11, wherein the coated surface structure has a roughness of less than 60 m.

18. The method as claimed in claim 11, wherein the substrate comprises a ceramic that forms the surface structure.

19. A workpiece produced by the method according to claim 11, wherein the material of the workpiece is a nickel-based or cobalt-based superalloy or a starting material therefor.

20. The method as claimed in claim 11, wherein the thermal coating method comprises thermal spraying.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Further details of the invention are described below on the basis of the drawing. The same or corresponding elements of the drawing are respectively provided with the same designations in the individual figures.

[0051] FIG. 1 schematically indicates the sequence of a method for producing a workpiece.

[0052] FIG. 2 schematically shows a workpiece that has been produced by means of the method indicated in FIG. 1.

[0053] FIG. 3 schematically shows the workpiece from FIG. 2, a substrate having been detached.

DETAILED DESCRIPTION OF INVENTION

[0054] FIG. 1 schematically shows the sequence of a method for the additive manufacturing of a workpiece or component (compare designation 100 in FIG. 2), for example a component for a turbomachine, such as a gas turbine. The workpiece 100 is advantageously a high-temperature-resistant workpiece that is used in connection with a hot air path of a gas turbine. The workpiece advantageously consists of a nickel-based or cobalt-based superalloy or comprises a corresponding material.

[0055] The method comprises the provision of a substrate 1, which in FIG. 1 and FIG. 2 is indicated in a side view or sectional view. The substrate 1 comprises a predetermined surface structure 2. The predetermined surface structure 2 may be for example a rib structure and/or a turbulator structure or be defined thereby.

[0056] The predetermined surface structure 2 is advantageously a surface structure with surface structure elements 10, as shown in FIGS. 1 and 2. The surface structure elements 10 have (shown by way of example) in each case a rectangular cross section.

[0057] The surface structure elements 10, advantageously each individual or at least one of the surface structure elements 10, may have an outer dimension of some or a few millimeters, for example up to 3 millimeters. Alternatively, the surface structure elements 10 may have a dimension in the micrometer range, advantageously less than 100 m, particularly advantageously less than 80 m or still smaller (compare dimension a further below).

[0058] The surface structure 2 is advantageously predetermined or defined for the production of the workpiece. In other words, the topography of the surface structure is defined.

[0059] Although not explicitly shown in the figures, the surface structure elements or else only some of them may be different and/or have dimensions that are different from one another.

[0060] The method also comprises the coating of the surface structure 2 with a coating material 9. In FIG. 1, the coating material 9 is shown already deposited completely on the surface structure 2 by the method according to the invention for producing the workpiece. The coating material 9 has also been applied to the surface structure with a layer thickness b, to be precise in such a way that the coated surface structure 2 defines a base surface 3 of the workpiece 100 (to be produced). This is indicated in FIG. 1 by showing that the surface structure 2 forms a negative and the base surface 3 or its surface structure (not explicitly depicted) forms a corresponding positive. In other words, the surface structure 2 (coated with the coating material) of the substrate 1 is determinative for the form of the base surface of the workpiece 100. The finished workpiece (compare FIGS. 2 and 3) accordingly has the base surface 3.

[0061] The coating material 9 is also advantageously chosen and/or formed in such a way that it is resistant, at least for a short time, to a production temperature of the additive manufacturing process with which the workpiece is produced (cf. further below). In particular, the coating material 9 is resistant to and/or thermally stable at temperatures above 1000 C., advantageously above 1200 C., 1400 C. or still higher temperatures; at least for a period of several seconds or minutes, during which the coating material is for example exposed directly to a laser beam or electron beam.

[0062] The coating with the coating material 9 is advantageously performed within the scope of the method according to the invention in such a way that the coating material 9 is coated or deposited on the surface structure 2 of the substrate 1 with a layer thickness of b, particularly advantageously by means of a thermal coating process. Preferably, other methods, in particular methods of physical vapor deposition, for example electron-beam evaporation or pulsed laser deposition, may be used for the coating. Other possible methods are thermal spraying, for example high-speed flame spraying, or else cold-gas spraying, a dip coating method or a galvanic coating method.

[0063] The coating material 9 is advantageously a metal or a ceramic-metal composite, for example a ceramic compound in a metal matrix, such as a CERMET material.

[0064] Accordingly, thermal coating methods, such as thermal spraying, are used particularly advantageously for the coating. Alternatively, howeveradvantageously in the case of low-melting substrate materials, i.e. structures that have the surface structure such as polymers or low-melting metalscold coating methods may be used for the coating of the surface structure.

[0065] Although not explicitly shown in the figures, an adhesion promoter for improving the adhesive bond of the coating material 9 may be applied before the coating of the surface structure 2 with the coating material 9.

[0066] Particularly advantageously, the coating material 9 is also applied in such a way that it is arranged as far as possible, advantageously completely, uniformly and/or homogeneously on the surface structure 2. Particularly advantageously, likewise on vertical or inclined portions of the surface structure, the layer thickness of the coating material 9 is likewise b.

[0067] Preferably, the coating material 9 is of a material that is chemically and/or physically related to the material from which the workpiece 100 is produced.

[0068] Particularly advantageously, the coating material 9 is also of the same material as the workpiece 100, for example a nickel-based or cobalt-based superalloy.

[0069] The method also comprises the additive manufacturing of a material 5 for the workpiece on the surface structure 2.

[0070] The coating material 9 and the material 5 for the workpiece 100 are advantageously identical, at least in part, for example main constituent parts and/or alloying constituents. The coating material 9 may also be completely identical to the material 5.

[0071] In FIG. 1, the workpiece (compare designation 100 in the figure) has not yet been produced completely. Therefore, reference can be made hereafter to the material 5 as synonymous to the workpiece 100. The material may in particular be a starting material for the workpiece.

[0072] Furthermore, the method for producing the workpiece may comprise one or more heat treatments, for example for setting certain phase precipitates. These may be in particular expedient phase precipitates or settings of the or phases of the respective material to be produced of the superalloy.

[0073] The additive manufacturing of the workpiece is advantageously performed by means of deposition welding, for example laser deposition welding (LMD), in particular laser powder-deposition welding or electron-beam welding. Said methods or techniques for deposition welding are advantageously performed in a CAD-aided and/or robot-assisted manner or can be correspondingly controlled. A corresponding laser deposition welding device is indicated in FIG. 1 by the designation 6.

[0074] The material 5 for producing the workpiece 100 is advantageously produced or manufactured according to the described method by laser powder-deposition welding. In this case, within the described method for producing the workpiece, it is advantageously produced in accordance with the material properties that are expedient for the desired (3D) structure. This may involve setting process parameters, such as the laser power, the time of exposure to the laser or other parameters in accordance with the desired material phase. Furthermore, a longer exposure time may be required for example at difficultly accessible locations or edges of the workpiece to be produced than at other locations. It is also possible when scanning during the material build-up for an apparatus head of the deposition welding device to be guided by way of or with the aid of a feedback loop.

[0075] FIG. 2 shows inter alia the completely produced workpiece or component 100 that has been produced can be produced by means of the described method. The workpiece 100 is connected in one piece to the substrate 1 by way of the coating material 9 and optionally by way of an adhesion-promoting material. Accordingly, the base surface 3 of the coating material 9 represents or comprises an imprint of the coated surface structure 2. Advantageously, by the described methodby prescribing the surface structure on the substratethe base surface of the coating material 9, but advantageously also the workpiece 100 to be produced, is defined, replicated or molded, in order to transfer the surface structure onto the workpiece, and consequently to create a particularly high-resolution and/or microscopically structured base surface of the workpiece.

[0076] The workpiece 100 in FIG. 2 has a contour 4, which encloses or envelops the workpiece 100 including its surface structure elements. The contour 4 is shown in FIG. 2 by the dashed line and is also shown in FIG. 1 in conjunction with the material 5. With respect to the contour 4 of the workpiece 100 to be produced, the base surface 3 is an at least partially inner-lying surface of the workpiece 100.

[0077] The surface structure elements 10 shown in FIGS. 1 and 2, or at least one of them, has/have for example a dimension a of less than 100 m. The dimension advantageously relates to a width (compare the horizontal direction in FIGS. 1 and 2) of the respective surface structure elements 10, but may also relate to a corresponding depth or height. The width may accordingly refer to a direction along the contour.

[0078] Therefore, the smaller the width or dimension a of the surface structure elements 10 of the substrate 1, the smaller, finer or more filigree the base surface 3 of the workpiece can also be structured.

[0079] According to one embodiment of the present invention, the substrate 1 is a ceramic or a casting component or comprises for example a ceramic at least on the surface structure 2. The substrate 1 may for example be produced or provided by precision casting with the aid of ceramic casting cores. Preferably, the surface structure 2 has been or is formed by a ceramic casting core. The casting core consists for example of alumina, for example Al.sub.2O.sub.3, or silica (SiO.sub.2) or comprises one of these materials. In other words, the provision of the substrate is carried out according to the described method.

[0080] Furthermore, the casting core advantageously has on the outer side a very fine powder grain size, in order to be expediently able to resolve a fine, for example microscopically small, surface structure. With increasing distance from the surface structure, the material of the substrate (of the casting core) may comprise an ever more porous or coarser grain size or grading, in order at the same time also to have a sufficient (thermal) shock resistance. Such a graded component advantageously has a particularly small and technologically desired surface roughness of merely 50 m or less, for example 30 m.

[0081] The term roughness may be an average roughness, a root-mean-square roughness or a mean roughness value.

[0082] According to a refinement, the substrate comprises at least on the surface structure or as the surface structure 2 a refractory metal, for example tantalum, zirconium, molybdenum or tungsten or some other high-melting, for example base, metal of the fourth, fifth or sixth auxiliary group of the periodic system. According to this refinement, the surface structure has been or is advantageously produced by electron-beam melting.

[0083] Although not explicitly shown in the figures, the method also comprises the detachment of the substrate 1 from the workpiece 100 after the additive manufacturing of the same (cf. FIG. 3). For all of the embodiments described, the detachment of the substrate 1 may be performed selectively by thermal or chemical means. For example, irrespective of whether the substrate or the surface structure is metallic or ceramic, the workpiece 100 can be chemically detached.

[0084] For example, in the case of a substrate with an aluminum surface structure, the detachment may be performed by means of concentrated hydrochloric acid and at temperatures between 50 C. and 80 C.

[0085] FIG. 3 schematically indicates that the substrate 1 has been removed for example by chemical or thermal detachment after the additive manufacturing of the workpiece 100.

[0086] As an alternative to the representation of FIG. 3, the substrate may likewise be detached from the workpiece 100 by the coating material 9 being separated from the substrate 1 by suitable means (selective thermal and/or chemical detachment).

[0087] The invention is not restricted to the exemplary embodiments by being described with reference to them, but in particular comprises any combination of features in the patent claims, even if this feature or this combination is not itself explicitly specified in the patent claims or exemplary embodiments.