Environmental barrier coating
An article according to an exemplary embodiment of this disclosure, among other possible things includes a substrate and a barrier layer on the substrate. The barrier layer includes a bond coat comprising a matrix, diffusive particles disposed in the matrix, and gettering particles disposed in the matrix; a topcoat; and a porous interlayer disposed between the topcoat and the bond coat. The porous interlayer has a porosity that is greater than a porosity of the topcoat. A slurry composition for applying an interlayer to an article and method of applying a top coat to an article are also disclosed.
1 . An article, comprising:
a substrate; and
a barrier layer on the substrate, the barrier layer including:
a bond coat comprising a matrix, diffusive particles disposed in the matrix, and gettering particles disposed in the matrix,
a topcoat, and
a porous interlayer disposed between the topcoat and the bond coat, the porous interlayer having a porosity that is greater than a porosity of the topcoat:
wherein the topcoat and the porous interlayer include at least one of hafnia, hafnium silicate, yttrium monosilicate, yttrium disilicate, ytterbium monosilicate, ytterbium disilicate, yttria stabilized zirconia, gadolinia stabilized zirconia, calcium aluminosilicates, mullite, and barium strontium aluminosilicate.
2 . The article of claim 1 , wherein the porous interlayer and the topcoat include a common material.
3 . The article of claim 2 , wherein the common material includes at least one of hafnia, hafnium silicate, yttrium monosilicate, yttrium disilicate, ytterbium monosilicate, ytterbium disilicate, yttria stabilized zirconia, gadolinia stabilized zirconia, calcium aluminosilicates, mullite, and barium strontium aluminosilicate.
4 . The article of claim 2 , wherein the common material includes at least one of hafnia and hafnium silicate.
5 . The article of claim 2 , wherein the common material includes at least one of yttrium monosilicate and yttrium disilicate.
6 . The article of claim 2 , wherein the common material includes at least one of ytterbium monosilicate and ytterbium disilicate.
7 . The article of claim 2 , wherein the common material includes at least one of yttria stabilized zirconia and gadolinia stabilized zirconia.
8 . The article of claim 2 , wherein the common material includes at least one of calcium aluminosilicates and mullite.
9 . The article of claim 1 , wherein a ratio of a thickness of the porous interlayer to a thickness of the top coat is between about 0.5 to about 1.
10 . The article of claim 1 , wherein a ratio of a thickness of the porous interlayer to a thickness of the bond coat is between about 0.1 and 0.5.
11 . The article of claim 1 , wherein a porosity of the porous interlayer is between about 5 and 50 percent.
12 . The article of claim 11 , wherein a porosity of the porous interlayer is about 25 percent.
13 . The article of claim 11 , wherein a porosity of the top coat is less than about 10 percent.
14 . The article of claim 1 , wherein the porous interlayer includes pores, and wherein a porosity of the interlayer is between about 5% and about 25%.
15 . The article of claim 1 , wherein the porous interlayer includes silica.
16 . The article of claim 15 , wherein the porous interlayer includes more silica than the topcoat.