Relationship between oxidation resistance and structure of B_4C-SIC/C composites with self-healing properties

摘要

The oxidation behavior of B_4C-SiC/C composites of various compositions at temperatures up to 1500#deg#C was analyzed by the thermal gravimetric/differential thermal analysis (TG/DTA) technique and the surface morphology of the composites after isothermal oxidation at 800,1000 and 1200#deg#C was examined by scanning electron microscopy. The results indicated that the composites exhibited variable oxidation resistance at high temperatures depending on composition and oxidation temperature. The variance of self-healing properties was attributed to the difference of the compositions and the properties of the dedarbonized larers including wetting ability, viscosity, volatlity adn oxygen permeability. The rate-limiting steps of oxidation and the concentration distribution of oxygen acorss the decarbonized layers of the composities after oxidation are discussed.