Oxidation behavior of TiAl/TiAl–SiC gradient coatings on gamma titanium aluminides

Gradient TiAl/TiAl+SiC coatings on the gamma titanium aluminide were fabricated by using electron beam physical vapor deposition (EB-PVD) technique, and the oxidation resistance behavior was investigated. The coating surface was in the structure containing mainly TiAl and SiC identified by the X-ray diffractometer. The oxidation resistance depends on the ratio of the surfacial content of SiC to TiAl. Only 1.03 mg/cm2 weight gain was recorded after isothermal oxidation at 1173 K in air for 200 h, and no spallation was recognized after cyclic oxidation at 1173 K in air for 100 h for the coating with the ratio of approximately 8:3 TiAl/SiC. The contribution of SiC to the improvement of the oxidation resistance can be considered as the formation of amorphous SiO2.