Patent ID: 9056802
Filing Date: 2015-06-16
Classification: C04B

Abstract:
1. A method for making an environmental barrier coating on a SiC-based ceramic component of a gas turbine engine to protect the SiC-based ceramic component from a high temperature steam environment in the gas turbine engine, the method comprising: combining at least water, particles of a primary transition material comprising mullite, BSAS, or a mullite/BSAS mixture, and a slurry sintering aid selected from the group consisting of rare earth nitrate, rare earth acetate, rare earth chloride, rare earth oxide, and combinations thereof to produce a transition layer slurry, the slurry sintering aid in the transition layer slurry exceeding an amount of the slurry sintering aid that is soluble in the primary transition material; applying the transition layer slurry to the SiC-based ceramic component; combining at least water and particles of a primary outer material comprising BSAS to produce an outer layer slurry; applying the outer layer slurry to the SiC-based ceramic component having the applied transition layer slurry; and sintering the applied transition layer slurry and the applied outer layer slurry to produce the environmental barrier coating having at least a transition layer and an outer layer formed from the applied transition layer slurry and the applied outer layer slurry, respectively, wherein the sintering step consolidates the particles of the primary transition material within the transition layer in the presence of the slurry sintering aid and forms a secondary material in at least the transition layer as a reaction product of the slurry sintering aid with the mullite, the BSAS, or the mullite/BSAS mixture of the primary transition material, and the secondary material is chosen from the group consisting of rare earth oxides, rare earth disilicates, rare earth monosilicates, rare earth elements, rare earth containing aluminosilicate glasses, rare earth and alkaline earth containing aluminosilicate glasses, rare earth aluminates, and combinations thereof.