Research on the Si-Ti high temperature oxidation-resistant coatings for tantalum alloys

Si-Ti coatings were prepared on the surface of T-222 alloy by fused slurry methodat different temperatures(1425-1500 degrees C).Microstructure and composition of the coatings were characterized and analysed through scanning electron microscopy (SEM),X-ray diffraction analysis(XRD),energy dispersive X-ray spectrometry(EDS) respectively. The coating fabricated at 1450 degrees Cexhibited excellent structure compatible with high temperature oxidation resistance. Its surface is relatively smooth with few holes and cracks and the main phase on the surface is (Ti,Ta)Si that possesses outstandingcorrosion resistance.Moreover, the cross-sectional structure of the coating is smooth and compact which can effectively prevent O-2 from permeation. The isothermal oxidation behaviors in pure O-2 atmosphere at 1500 degrees C for 2h finally demonstrate that the optimum coating temperature is 1450 degrees C.