Turbomachine component with a parting joint, and a steam turbine comprising said turbomachine component

1. A turbomachine component, comprising:

at least two sub-components which are separated by means of a parting joint and have in each case a sealing surface at the parting joint,

wherein at least one of the two sealing surfaces is convex, such that in an assembled state of the two sub-components, the sealing surfaces form a contact line at those points at which they abut against one another so as to form a linear contact between the two sealing surfaces, and

wherein at least one of the sealing surfaces is provided with a coating which has a hard material, is at most 30 μm thick and which is applied by a gas phase deposition method, or a coating which has a chromium-containing alloy, which is at most 30 μm thick and is applied by a gas phase deposition method, or a coating which is at most 300 μm thick and is applied by a thermal spraying method,

wherein the coating is formed such that it is not porous; and

wherein the turbomachine component is a split steam turbine housing.

2. The turbomachine component as claimed in claim 1 ,

without an additional lubricating film between the coating and the sub-component.

3. The turbomachine component as claimed in claim 1 ,

wherein the chromium fraction in the chromium-containing alloy is greater than 10% by mass.

4. The turbomachine component as claimed in claim 1 ,

wherein the chromium-containing alloy comprises nickel.

5. The turbomachine component as claimed in claim 1 ,

wherein the coating which is to be applied by the thermal spraying method comprises particles of an additional hard material.

6. The turbomachine component as claimed in claim 5 ,

wherein the particles are ceramic particles.

7. The turbomachine component as claimed in claim 5 ,

wherein the additional hard material comprises a carbide.

8. The turbomachine component as claimed in claim 5 ,

wherein the additional hard material has a proportion by mass of 70 to 80% by mass in the coating.

9. The turbomachine component as claimed in claim 1 ,

wherein the thermal spraying method is high velocity oxygen fuel spraying, cold gas spraying or detonation spraying.

10. The turbomachine component as claimed in claim 1 ,

wherein the hard material comprises a nitride or a boride.

11. The turbomachine component as claimed in claim 1 ,

wherein the gas phase deposition method is a method from the group PVD (physical vapor deposition) or CVD (chemical vapor deposition).

12. The turbomachine component as claimed in claim 3 , wherein the chromium fraction in the chromium-containing alloy is between 15 and 25% by mass.

13. The turbomachine component as claimed in claim 4 , wherein the chromium-containing alloy comprises 75 to 85% by mass of nickel.

14. The turbomachine component as claimed in claim 7 , wherein the carbide comprises tungsten carbide, titanium carbide and/or chromium carbide.

15. The turbomachine component as claimed in claim 10 , wherein the nitride comprises chromium nitride, titanium nitride, and/or titanium aluminum nitride.

16. The turbomachine component as claimed in claim 10 , wherein the boride comprises titanium boride.

17. A turbomachine component, comprising:

a turbine housing comprising a lower part and an upper part, each part comprising a respective sealing surface, the sealing surfaces joined at a parting joint in an assembled state of the turbine housing;

wherein at least one of the sealing surfaces is convex, such that in the assembled state of the turbine housing, the sealing surfaces form a contact line at those points at which they abut against one another so as to form a linear contact between the two sealing surfaces;

wherein at least one of the sealing surfaces is provided with a coating material; and

wherein the coating material comprises a material which withstands wear and/or corrosion better than a material of construction of the turbine housing.

18. The turbomachine component of claim 17 , wherein the coating material comprises greater than 10% by mass of chromium.

19. The turbomachine component of claim 17 , wherein the coating material comprises 75-85% by mass of nickel.

20. The turbomachine component of claim 17 , wherein the coating material comprises ceramic particles.