Method for making solvent based environmental barrier coatings using sintering aids

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

• combining at least an organic solvent and a primary transition material comprising a rare earth disilicate of to produce a transition layer slurry;
• combining at least an organic solvent and a primary outer material comprising a rare earth monosilicate to produce an outer layer slurry;
• combining at least an organic solvent and a primary compliant material comprising BSAS or a rare earth doped BSAS to produce a compliant layer slurry;
• applying the transition layer slurry, the outer layer slurry, and the compliant layer slurry to the component;
• drying the transition layer slurry, the outer layer slurry, and, the compliant layer slurry on the component to form a dried transition layer, a dried outer layer, and a dried compliant layer;
• infiltrating a sol-gel solution into the dried transition layer, the dried outer layer, and the dried compliant layer, the sol-gel solution comprising a sintering aid chosen from the group consisting of aqueous solutions of a water-soluble salt sintering aid and organic solvent solutions of a solvent-soluble salt sintering aid;
• and then
• sintering the dried transition layer, the dried outer layer, and the dried compliant layer to produce the environmental barrier coating having a transition layer formed by the dried transition layer, an outer layer formed by the dried outer layer, and a compliant layer formed by the dried compliant layer;
• wherein the sintering aid dissolves into the primary transition material and the primary outer material during sintering to form a doped rare earth disilicate in the transition layer and form a doped rare earth monosilicate in the outer layer.

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

• combining at least an organic solvent and a primary transition material comprising a rare earth disilicate to produce a transition layer slurry;
• combining at least an organic solvent and a primary outer material comprising a rare earth monosilicate to produce an outer layer slurry;
• combining at least an organic solvent and a primary compliant material comprising BSAS or a rare earth doped BSAS to produce a compliant layer slurry;
• applying the transition layer slurry to the component;
• drying the transition layer slurry on the component to form a dried transition layer;
• infiltrating a sol-gel solution into the dried transition layer to form an infiltrated transition layer, the sol-gel solution comprising a sintering aid chosen from the group consisting of aqueous solutions of a water-soluble salt sintering aid and organic solvent solutions of a solvent-soluble salt sintering aid;
• applying the outer layer slurry and any more of the compliant layer slurry or an additional transition layer slurry over the infiltrated transition layer;
• drying the outer layer slurry and the any one or more of the compliant and additional transition layer slurries on the component to form a dried outer layer and any one or more of a dried compliant layer and a dried additional transition layer, respectively;
• and
• sintering the infiltrated transition layer, the dried outer layer, and any one or more of the dried compliant layer and the dried additional transition layer to produce the environmental barrier coating having at least one transition layer formed by the infiltrated transition layer, an outer layer formed by the dried outer layer, and any one or more of a compliant layer or an additional transition layer formed by the dried compliant layer and the dried additional transition layer, respectively;
• wherein the sintering aid dissolves into the primary transition material and the primary outer material during sintering to form a doped rare earth disilicate in the transition layer and form a doped rare earth monosilicate in the outer layer.