Oxidation and thermal shock resistant properties of Al-modified environmental barrier coating on SiCf/SiC composites

SiCf/SiC ceramic matrix composites (CMCs) are being widely used in the hot-sections of gas-turbines, especially for aerospace applications. These CMCs are subjected to surface recession if exposed to heat-corrosion. In this research, an alternative environmental barrier coating (EBC) is introduced to protect the SiCf/SiC CMC from high temperature degradation that is, Al film was deposited on the surface of SiCf/SiC CMC followed by heat-treatment in a vacuum. After that, a dense Al2O3 overlay was in-situ synthesized on the surface of CMC, and in this process the microstructure evolution of SiCf/SiC CMC was analyzed. The oxidation and thermal shock resistance were characterized, showing that the Al-modified SiCf/SiC CMC has a better oxidation resistance, because the dense Al2O3 overlay can hinder oxygen diffusion from environment. What is more, the water-quenching testes show that the Al-modified SiCf/SiC CMC has a good spallation resistance.