Effect of the surface microstructure ablated by femtosecond laser on the bonding strength of EBCs for SiC/SiC composites

The bonding strength between environmental barrier coatings (EBCs) and silicon carbide fiber reinforced silicon carbide (SiC/SiC) was improved by preparing microstructure on SiC/SiC surface with femtosecond laser. The processing morphologies with different parameters were compared. There was oxidation phenomenon at the edge of laser processing, and the degree of graphitization was increased. Without damage the internal fiber structure of SiC/SiC, reasonable processing parameters were selected, and microgroove structure was processed on the SiC/SiC surface using the femtosecond laser. The tension test results showed that, after the femtosecond laser machining, the bonding strength between EBCs and SiC/SiC could be improved by about 5.5%, and the time spent to reach the critical load was extended by 11.2%. The EBCs regularly adheres to the microgrooves formed by the femtosecond laser processing, while EBCs in the area without the laser processing was completely detached.