Investigation of thermal oxidation of Al2O3-coated SiC powder

SiC powder (beta-form) of sub-micrometre size (d(50) of 0.65 mu m) was coated with a thin layer (similar to 12 nm) of boehmite by sal-gel technique. The final powder having similar to 24 wt% boehmite was characterized by particle size and surface area determination, chemical analysis, surface potential measurement and Fourier transform infrared (FTIR) spectroscopic analysis. The thermal oxidation behaviour of the coated powder was examined using the simultaneous TG/DTA technique in dry air. The results indicated crystallization of mullite phase and the activation energy of crystallization was determined to be 368.9 +/- 15.1 kJ mol(-1). Synthesis of porous SiC ceramics of fine pore structure (with average porosity and pore size ranging from 47% to 54% and 170-260 nm, respectively) using thermal oxidation of coated powder was also demonstrated. (C) 2014 Elsevier B.V. All rights reserved.