Methods for making environmental barrier coatings and ceramic components having CMAS mitigation capability
Methods of making components having calcium magnesium aluminosilicate (CMAS) mitigation capability involving providing a component; applying an environmental barrier coating to the component, the environmental barrier coating having a separate CMAS mitigation layer including a CMAS mitigation composition selected from rare earth elements, rare earth oxides, zirconia, hafnia partially or fully stabilized with alkaline earth or rare earth elements, zirconia partially or fully stabilized with alkaline earth or rare earth elements, magnesium oxide, cordierite, aluminum phosphate, magnesium silicate, and combinations thereof.
1. A method of making a component having CMAS mitigation capability comprising:
providing a component, wherein the component comprises a ceramic matrix composite or a monolithic ceramic;
applying an environmental barrier coating to the component, the environmental barrier coating comprising:
a bond coat layer comprising silicon overlying the component;
an optional silica layer overlying the bond coat layer;
at least one transition layer overlying the bond coat layer or the optional silica layer comprising a composition selected from the group consisting of mullite, BSAS, and combinations thereof;
an optional outer layer comprising BSAS overlying the at least one transitional layer;
an integrated CMAS mitigation layer overlying the at least one transition layer or the optional outer layer, the integrated CMAS mitigation layer consisting of:
BSAS; and
a CMAS mitigation composition selected from the group consisting of magnesium oxide, cordierite, and combinations thereof;
wherein at least a portion of the environmental barrier coating is susceptible to infiltration by CMAS, the BSAS in at least one of the transition layer, outer layer and integrated CMAS mitigation layer is susceptible to reacting with CMAS that has infiltrated thereto, and the integrated CMAS mitigation layer comprises the CMAS mitigation compositions as a grain boundary phase in the BSAS or as dispersed refractory particles in the BSAS.
2. The method of claim 1 wherein the component is a turbine engine component selected from the group consisting of combustor components, turbine blades, shrouds, nozzles, heat shields, and vanes.
3. The method of claim 2 further comprising applying an abradable layer to the integrated CMAS mitigation layer.
4. The method of claim 3 comprising applying the environmental barrier coating using a method selected from the group consisting of plasma spraying, high velocity plasma spraying, low pressure plasma spraying, solution plasma spraying, suspension plasma spraying, chemical vapor deposition, electron beam physical vapor deposition, sol-gel, sputtering, slurry dipping, slurry spraying, slurry painting, slurry rolling, tape-casting, and combinations thereof.