Abstract:To improve the oxidation resistance of boron-modified carbon foams, the B₂O₃ coating was prepared on boron-modified carbon foams by low-cost slurry method. The microstructures and phase compositions of the coated carbon foams were characterized by scanning electron microscopy and X-ray diffraction, respectively. Oxidation resistances of uncoated and coated boron-modified carbon foams were investigated at 873 K in air. The results showed that as-received B₂O₃ coating could protect boron-modified carbon foams from oxidation at 873 K. B₂O₃-coated carbon foam doped with 7% B₂O₃ (mass fraction) (BO-7) had better oxidation resistance, exhibiting mass loss of 17.40% after oxidation at 873 K for 120 min. The melting glass layer formed on the surface of BO-7 could prevent oxygen from diffusing into boron-modified carbon foams substrate during oxidation to some extent.

Key words: carbon foam; B₂O₃; coating; oxidation resistance