Casting mold and methods for production

Abstract

The invention relates to a method for producing a casting mold as well as to a casting mold (10), in particular a continuous casting mold or similar. Said casting mold is made of a material which is essentially made of carbon and the casting mold is coated with pyrolytic carbon and/or boron nitride.

Claims

1. A method for producing a casting mold for metal casting, comprising the steps of: producing a casting mold of a material made essentially of carbon, and coating the casting mold with at least one of pyrolytic carbon and boron nitride, wherein the step of coating the casting mold is performed at a temperature between 500 C. and 1900 C., wherein the step of coating the casting mold comprises the steps of applying the coating during a first process phase (P1) using a CVI method at a first temperature (T1) and subsequently applying the coating during a second process phase (P2) using a CVD method at a second temperature (T2), the first process phase being chosen to be at least one of longer than the second process phase and at a first temperature chosen to be lower than a second temperature during the second process phase.

2. The method according to claim 1, wherein the casting mold is made entirely of carbon.

3. The method according to claim 2, wherein the casting mold is made of graphite.

4. The method according to claim 3, wherein the step of coating the casting mold further comprising the step of sealing the pores in the graphite of the casting mold.

5. The method according to claim 1, wherein the step of coating the casting mold comprises coating the casting mold with a surface coating of pyrolytic carbon.

6. The method according to claim 1, further comprising the step of infiltrating the casting mold with pyrolytic carbon.

7. The method according to claim 1, wherein no thermal post-processing is performed after the step of applying the coating.

8. The method according to claim 1, wherein the step of forming said casting mold comprises applying a casting mold that comprises one or more piece.

9. The method according to claim 1, wherein the step of coating at least a portion of the casting mold comprises coating an entire surface of the casting mold.

10. The method according to claim 1, wherein the step of coating at least a portion of the casting mold comprises coating at least a portion of the casting mold to a thickness of 5 m to 500 m.

11. The method according to claim 1, wherein the step of coating at least a portion of the casting mold comprises applying a surface coating of the casting mold comprising anisotropic carbon.

12. The method according to claim 1, wherein the step of coating at least a portion of the casting mold comprises applying an infiltration coating, and the infiltration coating of the casting mold has a coating thickness between 1 m and 100 m.

13. The method according to claim 1, wherein the step of coating the casting molding comprises forming an infiltration coating of the casting mold and a surface coating of the casting mold, and wherein the infiltration coating has finer crystals than the surface coating of the casting mold.

14. The method according to according to claim 1, wherein the coating has a porosity of lesser than 1%.

15. The method according to according to claim 1, wherein the coating comprises an anti-corrosion layer.

Description

(1) In the figures,

(2) FIG. 1 shows a longitudinal section view of a continuous casting mold;

(3) FIG. 2 shows a detailed view of a coating;

(4) FIG. 3 shows a diagram representation of a coating process.

(5) FIG. 1 shows a continuous casting mold 10 as regularly used for producing semi-finished products made of non-ferrous metals in the continuous casting process. The continuous casting mold 10 is made in one piece from a body 11 made of graphite. The body 11 is formed rotationally symmetric and has a through opening 12. At a crucible end 13 of the body 11, an inner thread 14 is formed in the through opening 13, said continuous casting mold 10 being able to be tightly mounted to a crucible, not shown, by means of the inner thread 14. A drawing end 15 of the body 11 is unattached, meaning it cannot be attached. The body 11 has a conically tapered wall 16. A surface 17 of the continuous casting mold 10 is coated in particular with pyrolytic carbon.

(6) For producing a round bar made of non-ferrous metal such as brass or bronze, for example, not shown, molten metal now flows into the through opening 12 at the crucible end 13 and solidifies within the body 11 of the continuous casting mold so that the plasticized metal can be drawn out of the continuous casting mold 10 at the drawing end 15.

(7) FIG. 2 shows an enlarged view of a coating 18 of the continuous casting mold 10 or rather the body 11 in the area of the surface 17. The coating 18 comprises a surface coating 19 and an infiltration coating 20. The body 11 comprises a plurality of pores 21, which would enable a diffusion of molten metal or molten components in the body 11 when uncoated. Within the infiltration coating 20, the body 11 is or rather the no longer visible pores arranged thereon are infiltrated by pyrolytic carbon as a result of a conducted coating method, with the pores essentially filled entirely. The surface coating 19 is applied on the body 11 or a surface 22 formed on the body 11 before having been coated, respectively. For this purpose, the surface coating 19 is realized anisotropic and comprises a porosity of essentially 0%. The infiltration coating 20 is realized having finer crystals with respect to the surface coating 19.

(8) FIG. 3 shows a diagram of a process for coating the continuous casting mold 10. During a process time t of the coating process of the continuous coating mold 10 or rather the body 11, the temperature T1 is 600 C., for example, during a first process phase P1, a second process phase P2 taking place after the first process phase P1, a second temperature T2 of 1700 C. being applied during the second process phase P2, for example. The infiltration coating 20 is formed during the first process phase P1, the surface coating 19 being formed during the second process phase P2. The coating process is either a CVI method or a CVD method.