Methods for making environmental barrier coatings using sintering aids

A method for making an environmental barrier coating using a sintering aid, the method comprising:

• applying a bond coat layer to a ceramic component;
• combining at least water, a primary transition material comprising a rare earth disilicate, and at least two slurry sintering aids each containing at least one doping composition to produce a transition layer slurry;
• combining at least water and a primary outer material comprising a rare earth monosilicate to produce an outer layer slurry;
• combining at least water and a primary compliant material comprising BSAS to produce a compliant layer slurry;
• applying the transition layer slurry, the outer layer slurry, and the compliant layer slurry to the cermaic component;
• and
• sintering the ceramic component to produce the environmental barrier coating having at least the bond coat layer, a transition layer formed by the transition layer slurry, an outer layer formed by the outer layer slurry, and a compliant layer formed by the compliant layer slurry, the sintering step causing the at least two slurry sintering aids to dissolve into at least one of the primary transition, primary outer and primary compliant materials to form at least one of a doped rare earth disilicate containing the at least one doping composition in the transition layer, a doped rare earth monosilicate containing the at least one doping composition in the outer layer, and a rare earth doped BSAS containing the at least one doping composition in the compliant layer, the transition layer containing 0% to about 15% by volume of porosity, and/or the outer layer containing 0% to about 30% by volume of porosity, and/or the compliant layer containing 0% to about 30% by volume of porosity.

A method for making an environmental barrier coating using a sintering aid, the method comprising:

• applying a bond coat layer to a ceramic component;
• combining at least water and a primary transition material comprising a rare earth disilicate to produce a transition layer slurry;
• combining at least water and a primary outer material comprising a rare earth monosilicate to produce an outer layer slurry;
• combining at least water and a primary compliant material comprising BSAS to produce a compliant layer slurry;
• applying at least the transition layer slurry, the outer layer slurry, and the compliant layer slurry to the ceramic component;
• and
• sintering the ceramic component to produce the environmental barrier coating having at least the bond coat layer, a transition layer formed by the transition layer slurry, an outer layer formed by the outer layer slurry, and a compliant layer formed by the compliant layer slurry, at least the transition layer further comprising at least one slurry sintering aid containing at least one doping composition chosen from the group consisting of iron, aluminum, titanium, gallium, nickel, boron, alkali metals, alkaline-earth metals, and Lnb rare earth metals, the sintering step causing the at least one slurry sintering aid to dissolve into the primary transition material to form a doped rare earth disilicate containing the at least one doping composition, the transition layer containing 0% to about 15% by volume of porosity, and/or the outer layer containing 0% to about 30% by volume of porosity, and/or the compliant layer containing a combined amount of about 0% to about 30% by volume of porosity.