US Patent 9212100 Environmental barrier coatings for high temperature ceramic components

Environmental barrier coatings for high temperature ceramic components. The barrier coatings include a bond coat layer containing silicon, an optional silica layer, at least one transition layer containing about 85% to about 100% by volume of a primary transition material comprising mullite, BSAS, or a mullite/BSAS mixture; an outer layer containing about 85% to about 100% by volume of a primary outer material comprising BSAS; and at least one of a sintering aid and a secondary material in the transition layer and/or outer layer. The secondary material is a reaction product of the sintering aid and at least one of the primary transition material and the primary outer material.