Machinable coatings fabricated by slurry methods for use on ceramic matrix composites
View Patent ↗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 method for coating a blade outer air seal, the method comprising:
applying to at least one inner surface of said blade outer air seal a combination of:
at least one of hafnium oxide (HfO 2 ), zirconium oxide (ZrO 2 ) and ytterbium oxide (Yb 2 O 3 );
silicon carbide (SiC) or silicon (Si) and
barium magnesium aluminosilicate (BMAS) or other alkaline earth aluminosilicate, wherein said barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate includes a concentration of 0.8% to 10.0% by weight; and
heating the combination applied to the blade outer air seal.
2. The method of claim 1 wherein:
the applying is of one or more slurries.
3. The method of claim 2 wherein:
the weight concentration of the BMAS or other alkaline earth aluminosilicate relative to the concentration in the one or more slurries is 0.8% to 10.0%.
4. The method of claim 2 wherein:
the applying is via ultrasonic spray.
5. The method of claim 1 wherein:
the heating is in an oxidizing environment; and
the heating is to a peak temperature of at least 1450° C.