Slurry-Based Environmental Barrier Coatings for Silicon Carbide and its Composites – a Straightforward Approach
When silicon carbide is exposed to combustion gas, rapid material recession occurs. Therefore, an Environmental Barrier Coating (EBC) needs to be deposited on silicon carbide and its composites in order to insert these high-performance lightweight materials in gas turbines replacing the currently used heavy superalloys. State-of-the-art coating techniques for EBCs like plasma spraying or chemical and physical vapour deposition result in an unfavourable microstructures or high costs. Therefore, a simple doublelayer EBC system based on mullite and rare earth silicates has been developed, which can be applied via simple and cost-efficient wet-chemical coating techniques. The top coat based on rare earth silicates is densified via a novel approach using a crystallizing glass system. Some promising results of this slurry-based approach are presented.