Turbine engine abradable systems
In a method for forming an abradable material ( 36 ), the abradable material has at least 20% by volume rutile titania ( 44 ) and hBN ( 46 ). The method includes: blending a first titania powder having an oxygen debit of at least 5.0% with a second titania powder having an oxygen debit, if any, of less than 1.0%. The blend is thermal sprayed. The sprayed blend is then oxidized.
1. A method for forming an abradable material, the abradable material comprising:
at least 20% by volume rutile titania; and
hBN,
the method comprising:
blending a first titania powder having an oxygen debit of at least 5.0% with a second titania powder having an oxygen debit, if any, of less than 1.0%;
thermal spraying the blend; and
oxidizing the sprayed blend,
wherein oxygen debit in an oxide of an element is measured relative to a fully oxidized element.
2. The method of claim 1 , wherein the abradable material further comprises:
bentonite binding said hBN wherein by weight the bentonite is between 5.0% and 25.0% of the combined bentonite and hBN.
3. The method of claim 2 , wherein:
the hBN is agglomerated with the bentonite and the agglomerate is co-sprayed with the first titania powder and the second titania powder.
4. The abradable material of claim 1 comprising:
at least 10% by volume said hBN.
5. The abradable material of claim 1 comprising:
at least 35% by volume said hBN.
6. The method of claim 1 wherein:
the blending is a pre-blending.
7. The method of claim 1 wherein:
the hBN is pre-blended with the first titania powder and the second titania powder.
8. The method of claim 1 wherein:
the blend is co-sprayed with a fugitive porosity-former.
9. The method of claim 1 wherein:
the abradable material is sprayed on an inner diameter surface of a blade outer airseal substrate optionally atop a bond coat.
10. A method for coating a substrate, the method comprising:
blending a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%; and
thermal spraying the blend; and
oxidizing the sprayed blend to reduce a net oxygen debit by at least 50%;
or;
co-thermal spraying a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%, the co-thermal spraying forming a blend of the first ceramic powder and the second ceramic powder; and
oxidizing the sprayed blend to reduce a net oxygen debit by at least 50%,
wherein oxygen debit in an oxide of an element is measured relative to a fully oxidized element.
11. The method of claim 10 comprising:
said blending the first ceramic powder with the second ceramic powder; and
said thermal spraying the blend; and
said oxidizing the sprayed blend.
12. The method of claim 10 wherein:
the first ceramic powder forms 5% to 50% by weight of the combined first ceramic powder and second ceramic powder in the blend; and
the second ceramic powder forms 50% to 95% by weight of the combined first ceramic powder and second ceramic powder in the blend.
13. The method of claim 10 wherein:
the first ceramic powder and the second ceramic powder combine to form at least 40% by volume of a layer sprayed from the blend.
14. The method of claim 10 wherein:
the first ceramic powder is Magnéli phase titania; and
the second ceramic powder is TiO 2 .
15. A method for coating a substrate, the method comprising:
blending a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%; and
thermal spraying the blend;
or;
co-thermal spraying a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%, the co-thermal spraying forming a blend of the first ceramic powder and the second ceramic powder,
wherein:
oxygen debit in an oxide of an element is measured relative to a fully oxidized element; and
the first ceramic powder forms 5% to 75% by volume of the as-sprayed blend.
16. A method for coating a substrate, the method comprising:
blending a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%; and
thermal spraying the blend;
or;
co-thermal spraying a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%, the co-thermal spraying forming a blend of the first ceramic powder and the second ceramic powder,
wherein:
oxygen debit in an oxide of an element is measured relative to a fully oxidized element; and
the first ceramic powder and the second ceramic powder are oxides or silicates of different elements.
17. The method of claim 16 wherein:
the first ceramic powder is a zirconia and the second ceramic powder is an alumina.
18. A method for coating a substrate, the method comprising:
blending a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%; and
thermal spraying the blend;
or;
co-thermal spraying a first ceramic powder having an oxygen debit of at least 5.0% with a second ceramic powder having an oxygen debit, if any, of less than 1.0%, the co-thermal spraying forming a blend of the first ceramic powder and the second ceramic powder,
wherein:
oxygen debit in an oxide of an element is measured relative to a fully oxidized element; and
the first ceramic powder and the second ceramic powder are oxides or silicates of the same element.
19. The method of claim 18 wherein:
the first ceramic powder is a silicate; and
the second ceramic powder is a silicate.
20. The method of claim 19 wherein:
the first ceramic powder is a yttrium silicate; and
the second ceramic powder is a yttrium silicate.