1. National Engineering Laboratory for Modern Materials Surface Engineering Technology & The Key Lab of Guangdong for Modern Surface Engineering Technology，Guangdong Institute of New Materials, Guangzhou 510650, China; 2. Hunan Laboratory of Advanced Fibers and Composites, Central South University, Changsha 410083, China
The ceramic matrix composite (CMC) material with low density (1/3～1/4 of superalloy) and high operation temperature (200～240℃>superalloy), it has been became a preferred material in future for high thrust-weight ratio aero-engine. In service operation, hot components are completely exposed to atmospheric environment. Representative CMC component of SiC/SiC faces serious operation conditions such as corrosion, ablation, erosion, etc. Therefore, it is urgent to develop a high performance protective coating for CMC component (i.e. environment barrier coatings, EBCs). In this investigation, three-layer-structured EBCs (Si/mullite/Yb2SiO5) were prepared by atmospheric plasma spray. For improving the performances of EBCs, the EBCs samples were deposited with Al film and carried out with vacuum heat treatment. Through in-situ synthesis between Al and Yb2SiO5 at high temperature in vacuum, a dense α-Al2O3 overlay can be formed. The results show that the Al-modified EBCs samples have better oxygen-water, CMAS corrosion resistance than the as-sprayed EBCs. Besides, Al-modification for EBCs have no apparent negative affection on thermal cycle performance compared with the as-sprayed EBCs.