Long-term oxidation of MoSi2-modified HfB2–SiC–Si/SiC–Si coating at 1700°C

ABSTRACT Slurry impregnation and gaseous Si infiltration were effectively used to produce compact MoSi2-doped Si–HfB2–SiC/Si–SiC (HMSS/SS) coatings with a thickness of 250 μm to protect carbon fibre reinforced carbon (Cf/C) composites from oxygen corrosion at 1700°C. The HMSS/SS coating obtained with a mosaic structure makes it possible to protect Cf/C composites at 1700°C for 276 h and the mass reduction is only 0.99%. The pinning effect of the embedded hafnia, the generated MoB together with the Hf, Mo co-doped Si-based glass layer, which successfully prevented the migration of oxygen, was attributed to the superior oxidation protection ability of the HMSS/SS coatings. This work provides a practical method for successfully extending the service life of Cf/C composites in the aerospace industry.