A gas turbine engine article includes a substrate and a silicate-resistant barrier coating disposed on the substrate. The silicate-resistant barrier coating has an engineered microstructure that includes a refractory matrix formed of grains and calcium aluminosilicate additive (CAS additive) dispersed in grain boundaries between the grains.

A gas turbine engine article includes a substrate and a silicate-resistant barrier coating disposed on the substrate. The silicate-resistant barrier coating has an engineered microstructure that includes a refractory matrix formed of grains and calcium aluminosilicate additive (CAS additive) dispersed in grain boundaries between the grains.

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.sub.4) and zirconium silicate (ZrSiO.sub.4), ytterbium disilicate (Yb.sub.2Si.sub.2O.sub.7); and barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate.

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.sub.4) and zirconium silicate (ZrSiO.sub.4), ytterbium disilicate (Yb.sub.2Si.sub.2O.sub.7); and barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate.

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.sub.4) and zirconium silicate (ZrSiO.sub.4), ytterbium disilicate (Yb.sub.2Si.sub.2O.sub.7); and barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate.

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.sub.4) and zirconium silicate (ZrSiO.sub.4), ytterbium disilicate (Yb.sub.2Si.sub.2O.sub.7); and barium magnesium alumino silicate (BMAS) or other alkaline earth aluminosilicate.

A method for coating a substrate includes spraying a combination of powders. The combination of powders includes: Hf.sub.0.5Si.sub.0.5O.sub.2; Zr.sub.0.5Si.sub.0.5O.sub.2; and, optionally, at least one of HfO.sub.2 and ZrO.sub.2. A molar ratio of said Hf.sub.0.5Si.sub.0.5O.sub.2 and HfO.sub.2 combined to said Zr.sub.0.5Si.sub.0.5O.sub.2 and ZrO.sub.2 combined is from 2:1 to 4:1. A molar ratio of said Hf.sub.0.5Si.sub.0.5O.sub.2 to said HfO.sub.2 is at least 1:3.

A method for coating a substrate includes spraying a combination of powders. The combination of powders includes: Hf.sub.0.5Si.sub.0.5O.sub.2; Zr.sub.0.5Si.sub.0.5O.sub.2; and, optionally, at least one of HfO.sub.2 and ZrO.sub.2. A molar ratio of said Hf.sub.0.5Si.sub.0.5O.sub.2 and HfO.sub.2 combined to said Zr.sub.0.5Si.sub.0.5O.sub.2 and ZrO.sub.2 combined is from 2:1 to 4:1. A molar ratio of said Hf.sub.0.5Si.sub.0.5O.sub.2 to said HfO.sub.2 is at least 1:3.

The invention relates to a process of selectively treating parts of the surface of a porous dental ceramic comprising the steps of a) providing a composition and a porous dental ceramic having an outer surface, b) applying the composition to only a part of the outer surface of the porous dental ceramic, c) optionally drying the porous dental ceramic, and d) optionally firing the porous dental ceramic, wherein the composition comprises—a liquid being miscible with water, but not being water, —a whitening agent comprising nano-sized metal oxide particles, metal ion containing components or mixtures thereof which precipitate if the composition is adjusted to a pH above 5, —acid, complexing agent or mixture thereof. The invention also relates to a dental ceramic article obtainable by a process.

The invention relates to a process of selectively treating parts of the surface of a porous dental ceramic comprising the steps of a) providing a composition and a porous dental ceramic having an outer surface, b) applying the composition to only a part of the outer surface of the porous dental ceramic, c) optionally drying the porous dental ceramic, and d) optionally firing the porous dental ceramic, wherein the composition comprises—a liquid being miscible with water, but not being water, —a whitening agent comprising nano-sized metal oxide particles, metal ion containing components or mixtures thereof which precipitate if the composition is adjusted to a pH above 5, —acid, complexing agent or mixture thereof. The invention also relates to a dental ceramic article obtainable by a process.