Abradable coating
An abradable coating for a turbomachine, as well as a turbomachine module and a turbomachine including such an abradable coating, the abradable coating including, with a content of greater than 50% by volume, an inorganic compound whose Mohs hardness is less than 6 and whose melting temperature is greater than 900° C.
1. An abradable track suitable for a turbomachine, the abradable track comprising:
a substrate; and
abradable coating, provided on the substrate;
wherein the abradable coating comprises, in a content of greater than 95 vol. %, Ca 10 (PO 4 ) 6 (OH) 2 , LaPO 4 , or diatomaceous earth, and
wherein the abradable coating has a surface roughness Ra of less than 3 μm.
2. The abradable track of claim 1 , wherein the abradable coating has a porosity of less than 15%.
3. The abradable track of claim 1 , wherein the abradable coating further comprises a metal compound.
4. The abradable track of claim 3 , wherein the metal compound is based on nickel, cobalt, or iron.
5. The abradable track of claim 3 , wherein the metal compound is NiAl.
6. The abradable track of claim 3 , wherein the Ca 10 (PO 4 ) 6 (OH) 2 and the metal compound together constitute at least 99 vol. % of total abradable coating material.
7. A turbomachine module, comprising:
a rotor, provided with a plurality of moving blades;
a stator; and
the abradable track of claim 1 , provided at the interface between a portion of the rotor and a portion of the stator.
8. A turbomachine, comprising:
a module of claim 7 .
9. A process for manufacturing the abradable track of claim 1 , the process comprising:
depositing the Ca 10 (PO 4 ) 6 (OH) 2 , LaPO 4 , or diatomaceous earth by thermal spraying from a powder having a particle size in a range of from 45 to 90 μm; and
surface machining the abradable coating.
10. The abradable track of claim 1 , wherein the abradable coating further comprises NiCrAl.
11. The abradable track of claim 1 , wherein the abradable coating further comprises CoNiCrAlY.
12. The abradable track of claim 1 , wherein the abradable coating further comprises FeCrAlY.
13. The abradable track of claim 1 , wherein the abradable coating comprises the LaPO 4 .
14. The abradable track of claim 1 , wherein the abradable coating comprises the diatomaceous earth.
15. The abradable track of claim 1 , wherein the Ca 10 (PO 4 ) 6 (OH) 2 is at least 99 vol. % of the abradable coating.
16. The abradable track of claim 1 , wherein the abradable coating consists of the Ca 10 (PO 4 ) 6 (OH) 2 and possible impurities.
17. The abradable track of claim 1 , wherein the LaPO 4 is at least 99 vol. % of the abradable coating.
18. The abradable track of claim 1 , wherein the abradable coating consists of the LaPO 4 and possible impurities.
19. The abradable track of claim 1 , wherein the diatomaceous earth is at least 99 vol. % of the abradable coating.
20. The abradable track of claim 1 , wherein the abradable coating consists of the diatomaceous earth and possible impurities.
21. The abradable track of claim 1 , wherein the abradable coating has a porosity of less than 15%, and
wherein the Ca 10 (PO 4 ) 6 (OH) 2 is greater than 95 vol. % of the abradable coating.