Method of producing a hot gas component of a turbomachine including an embedded channel
A component, especially a hot gas component of a turbomachine, has at least one passage ( 7, 7 ′), especially a cooling passage, which is embedded in an outer wall ( 5 ) of the component ( 1 ) of the turbomachine and basically extends parallel to the surface ( 6 ) of the component ( 1 ). The component ( 1 ) has a basic body ( 8 ) and at least one coating ( 9 ) which is applied to the basic body on the outside, and the passage ( 7, 7 ′) on one hand is formed by a cavity which is formed in the basic body ( 8 ), and on the other hand is closed off towards the surface ( 6 ) of the component ( 1 ) by the coating ( 9 ).
1. A method for producing a hot gas component of a turbomachine, the component having at least one passage embedded in an outer wall of the component, the method comprising:
forming at least one passage-like cavity in a basic body of the component;
covering the at least one passage-like cavity by applying a coating material to the basic body;
locally surface melting the basic body at least on two sides of the cavity simultaneous with said applying and with melting the coating material at least in the region of the cavities, wherein the coating material, a process temperature, and the width of the cavity are matched to each other so that the molten coating material does not penetrate into the cavity on account of surface tension; and
cooling and hardening the molten coating material so that the coating material is epitaxially built up on the basic body, achieving a metallurgical connection to the basic body on the two sides of the cavity.
2. The method as claimed in claim 1 , wherein said simultaneous melting of the basic body and said applying of the coating material comprises a process selected from the group consisting of plasma spraying, electron beam evaporation, lasering, and combinations thereof.
3. The method as claimed in claim 2 , further comprising:
feeding the coating material in the form of powder or wire.
4. The method as claimed in claim 2 , wherein lasering comprises an epitaxial laser metal forming process.
5. The method as claimed in claim 1 , wherein forming at least one passage-like cavity comprises a process selected from the group consisting of precision investment casting, mechanically forming, electrochemically forming, photochemically forming, laser forming, and combinations thereof.
6. The method as claimed in claim 1 , wherein:
a first phase of the hardening of the coating material is of the γ-type, or
in the coating, a transition from the monocrystal structure to the equiaxial structure is avoided, or
in the coating, the formation of new crystallization germs is avoided, or
combinations thereof.
7. The method as claimed in claim 1 , further comprising:
smoothing the surface of the coating after said cooling and hardening by laser melting.
8. The method as claimed in claim 1 , further comprising:
heating the basic body before and/or during said coating, to reduce stresses which occur by the hardening and/or cooling of the coating.
9. The method as claimed in claim 1 , wherein applying the coating comprises applying so that the coating contains a monocrystalline structure and/or is epitaxially connected to the basic body.
10. The method as claimed in claim 1 , further comprising:
additionally melting the coating material so that a monocrystal structure of the basic body is reproduced in the coating and/or a polycrystalline structure of the coating is transformed into a monocrystal structure.
11. The method as claimed in claim 1 , further comprising:
processing the coating after said cooling and hardening so that the coating contains a monocrystalline structure and/or is epitaxially connected to the basic body.