Thermal cycling behavior of Si/Yb2SiO5/LaMgAl11O19 TEBCs coated SiCf/SiC composites under burner rig tests.

In order to promote the thermal cycling behavior of SiC f /SiC composites at high-speed gas scour and high-temperature environment, we have prepared three-layer Si/Yb 2 SiO 5 /LaMgAl 11 O 19 TEBCs onto the surface of SiC f /SiC composites using atmospheric plasma spraying (APS) method. Burner rig tests were performed to evaluate the thermal cycling behavior of TEBCs. Results show that after being tested in high-temperature and high-speed burner flame, only a small number of TEBCs cracked and peeled in the external area of TEBCs caused by the thermal stress and the corrosion of water vapor, but TEBCs did not crack and spall in the center area. The failure mechanism of TEBCs was investigated. Microstructure characterization indicated that the penetrating cracks in TEBCs provided the channel for oxygen and water vapor diffusion to SiC f /SiC composites leading to the severe corrosion of substrate. [ABSTRACT FROM AUTHOR]