Solvent based environmental barrier coatings for high temperature ceramic components

An environmental barrier coating for high temperature ceramic components, the barrier coating comprising:

• a bond coat layer comprising silicon;
• a silica layer;
• at least one transition layer including:
• from about 85% to about 99% by volume of a primary transition material comprising a doped rare earth disilicate containing a doping composition selected from the group consisting of iron, aluminum, titanium, gallium, nickel, boron, an alkali, and alkali earth the doped rare earth disilicate being a rare earth disilicate in which is dissolved at least one slurry sintering aid containing the doping composition;
• and
• from 1% to about 15% by volume of a secondary material containing the doping composition of the primary transition material, the secondary material being selected from the group consisting of Fe2O3, iron silicates, rare earth iron oxides, Al2O3, mullite, rare earth aluminates, rare earth aluminosilicates, TiO2, rare earth titanates, GaO3, rare earth gallates, NiO, nickel silicates, rare earth nickel oxides, borosilicate glass, alkaline earth silicates, alkaline earth rare earth oxides, alkaline earth rare earth silicates, and mixtures thereof;
• and
• an outer layer including:
• from about 85% to about 99% by volume of a primary outer material comprising a rare earth monosilicate or a doped rare earth monosilicate, and from 1% to about 15% by volume of the secondary material;
• an intermediate layer comprising the primary outer material;
• and
• a compliant layer including:
• from about 85% to about 99% by volume of a primary compliant material selected from BSAS, and a rare earth doped BSAS, and from about 1% to about 15% of a secondary compliant material selected from the group consisting of Ln2O3, Ln2Si2O7, Ln2SiO5, Ln3Al5O12, Al2O3, mullite, and combinations thereof;
• wherein the transition layer, the outer layer, and the compliant layer are applied to the component as a slurry, the slurry for each of the transition layer, the outer layer, and the compliant layer comprises an organic solvent, the slurry sintering aid, and a corresponding one of the primary transition material, the primary outer material, or the primary compliant material;
• wherein the transition layer has a porosity of from 0.01% to about 15% by volume of the transition layer, the outer layer has a porosity of from about 0.01% to about 30% by volume of the outer layer, and the compliant layer has a porosity of from about 0.01% to about 15% by volume of the compliant layer.