Machinable coatings fabricated by slurry methods for use on ceramic matrix composites
A blade outer air seal has at least one internal surface and a layer atop the at least one internal surface. The layer has: a matrix comprising at least one of hafnium silicate (HfSiO 4 ) and zirconium silicate (ZrSiO 4 ), ytterbium disilicate (Yb 2 Si 2 O 7 ); and barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate.
1. A blade outer air seal comprising:
at least one internal surface formed within said blade outer air seal; and
a layer atop the at least one internal surface, the layer is an outermost layer comprising:
a matrix comprising at least one of hafnium silicate (HfSiO 4 ), zirconium silicate (ZrSiO 4 ), and ytterbium disilicate (Yb 2 Si 2 O 7 ); and
barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate.
2. The blade outer air seal of claim 1 wherein:
the at least one internal surface comprises a ceramic matrix composite.
3. The blade outer air seal of claim 2 wherein:
the ceramic matrix composite is a Si/SiC ceramic matrix composite.
4. The blade outer air seal of claim 1 wherein:
the at least one internal surface comprises at least one of a forward internal surface, an aft internal surface and a ramped internal surface.
5. The blade outer air seal of claim 1 wherein:
the layer has a thickness of 0.05 mm to 0.50 mm.
6. The blade outer air seal of claim 1 wherein:
the layer has a BMAS or other alkaline earth aluminosilicate concentration of 0.8% to 10.0% by weight.
7. A gas turbine engine including the blade outer air seal of claim 1 .
8. A method for using the blade outer air seal of claim 1 , the method comprising:
exposing the blade outer air seal to a calcium magnesium aluminosilicate (CMAS)-forming environment.
9. A blade outer air seal comprising:
at least one internal surface formed within said blade outer air seal; and
a layer atop the at least one internal surface comprising:
a matrix comprising at least one of hafnium silicate (HfSiO 4 ), zirconium silicate (ZrSiO 4 ), and ytterbium disilicate (Yb 2 Si 2 O 7 ); and
barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate including a concentration of 0.8% to 10.0% by weight.
10. The blade outer air seal of claim 9 wherein:
the at least one internal surface comprises a ceramic matrix composite.
11. The blade outer air seal of claim 10 wherein:
the ceramic matrix composite is a Si/SiC ceramic matrix composite.
12. The blade outer air seal of claim 9 wherein:
the at least one internal surface comprises at least one of a forward internal surface, an aft internal surface and a ramped internal surface.
13. The blade outer air seal of claim 9 wherein:
the layer is an outermost layer.
14. The blade outer air seal of claim 9 wherein:
the layer has a thickness of 0.05 mm to 0.50 mm.