Method of protecting a component of a turbomachine from liquid droplets erosion, component and turbomachine
The method of protecting a component of a turbomachine from liquid droplets erosion provides covering at least one region of a component surface exposed to a flow of a fluid containing a liquid phase to be processed by the turbomachine with a protective layer. The protective layer consists of a plurality of adjacent sub-layers of different materials having high hardness in the range of 1000-3000 HV and low fracture toughness below 20 MPam 1/2 . The materials are typically nitrides or carbides of titanium or aluminum or chromium or tungsten. In an embodiment, the covering is carried out by a PVD technique, in particular by Cathodic Arc PVD, or a CVD technique. The method may be applied to any component of turbomachines, but it may be particularly beneficial for parts of centrifugal compressors.
1. A method of protecting a component of a turbomachine from liquid droplets erosion, the method comprising:
covering at least one region of a component surface exposed to a flow of a fluid containing a liquid phase to be processed by the turbomachine with a protective layer,
wherein the protective layer comprises a plurality of adjacent sub-layers of two materials in alternate position,
wherein the materials have high hardness in the range of 1000-3000 HV and low fracture toughness below 20 MPam 1/2 , and
wherein a first material of the two materials is a stoichiometric nitride or carbide or boride of titanium or zirconium or chromium or tungsten or aluminum or vanadium, and a second material of the two materials is a non-stoichiometric nitride or carbide or boride of titanium or zirconium or chromium or tungsten or aluminum or vanadium.
2. The method of claim 1 , wherein the materials are Titanium Nitride (TiN).
3. The method of claim 1 , wherein the covering is carried out by a CVD technique.
4. The method of claim 1 , wherein the covering is carried out by a PVD technique.
5. The method of claim 4 , wherein “targets” for the Cathodic Arc PVD are located and/or shaped so that at least the targets see directly or indirectly parts of the at least one region of the component surface to be covered.
6. A component of a centrifugal compressor having a surface exposed to a flow of a fluid containing a liquid phase to be compressed by the centrifugal compressor, the component comprising:
at least one region of the surface covered with a protective layer,
wherein the protective layer comprises a plurality of adjacent sub-layers of two materials in alternate position,
wherein the materials have high hardness in the range of 1000-3000 HV and low fracture toughness below 20 MPam 1/2 , and
wherein a first material of the two materials is a stoichiometric nitride or carbide or boride of titanium or zirconium or chromium or tungsten or aluminum or vanadium, and a second material of the two materials is a non-stoichiometric nitride or carbide or boride of titanium or zirconium or chromium or tungsten or aluminum or vanadium.
7. The component of claim 6 , wherein the component is a diaphragm, and wherein the surface exposed to fluid flow is covered by the protective layer entirely.
8. The component of claim 6 , wherein the component is\an open impeller, and wherein the surface exposed to fluid flow is covered by the protective layer entirely.
9. The component of claim 6 , wherein the component is a closed impeller, and wherein the surface exposed to fluid flow is covered by the protective layer only at the inlet zone of the channels and/or at the outlet zone of the channels.
10. The component of claim 6 , wherein the component is an inlet guide vane, and wherein the surface exposed to fluid flow is covered by the protective layer entirely.
11. A centrifugal compressor, the centrifugal compressor comprising:
a component having a surface exposed to a flow of a fluid containing a liquid phase to be compressed by the centrifugal compressor, the component comprising:
at least one region of the surface covered with a protective layer,
wherein the protective layer comprises a plurality of adjacent sub-layers of two materials in alternate position,
wherein the materials have high hardness in the range of 1000-3000 HV and low fracture toughness below 20 MPam 1/2 , and
wherein a first material of the two materials is a stoichiometric nitride or carbide or boride of titanium or zirconium or chromium or tungsten or aluminum or vanadium, and a second material of the two materials is a non-stoichiometric nitride or carbide or boride of titanium or zirconium or chromium or tungsten or aluminum or vanadium.
12. The centrifugal compressor of claim 11 , wherein the centrifugal compressor comprising a combination of components.
13. The centrifugal compressor of claim 11 ,
wherein the bulk material of the or each component is martensitic stainless steel or nickel-base alloy or cobalt-base alloy.
14. An axial compressor, wherein at least the blades of the first stage or stages have a protective layer for their protection according to claim 1 .
15. A steam turbine, wherein at least the blades of the last stage or stages have a protective layer for their protection according to claim 1 .
16. The centrifugal compressor of claim 12 ,
wherein the bulk material of the or each component is martensitic stainless steel or nickel-base alloy or cobalt-base alloy.
17. The method of claim 1 , wherein the covering is carried out by a Cathodic Arc PVD.
18. The centrifugal compressor of claim 11 , wherein the component is a diaphragm, and wherein the surface exposed to fluid flow is covered by the protective layer entirely.
19. The centrifugal compressor of claim 11 , wherein the component is an open impeller, and wherein the surface exposed to fluid flow is covered by the protective layer entirely.
20. The centrifugal compressor of claim 11 , wherein the component is a closed impeller, and wherein the surface exposed to fluid flow is covered by the protective layer only at the inlet zone of the channels and/or at the outlet zone of the channels.
21. The centrifugal compressor of claim 11 , wherein the component is an inlet guide vane, and wherein the surface exposed to fluid flow is covered by the protective layer entirely.