Role of SiC nanowire coating on oxidation behavior of carbon fibers: Kinetic and thermodynamic study

The oxidation kinetics of SiC nanowire coated carbon fibers in oxygen atmosphere were studied through isothermal thermo-gravimetric analysis and dynamic thermo-gravimetric analysis. The isothermal weight loss curve showed two activation energies for the oxidation of SiC nanowire coated carbon fibers. The oxidation process was reaction controlled below 923 K with an activation energy of 125 kJ mol(-1) and mixed controlled (gas diffusion and reaction) above 923 K with an activation energy of 28 kJ mol(-1). Under nonisothermal condition the oxidation mechanism followed three-dimensional diffusion obeying the Zhuravlev-Lesokhin-Temperman mechanism with differential form F(alpha) = 1.5(1-a)(4/3) [(1-a)(-1/3)-1](-1) and integral form G(alpha) = [(1-a)(-1/3)-1](2). The kinetic and thermodynamic parameters were evaluated and correlated with surface induced oxidation mechanism. (C) 2014 Elsevier B.V. All rights reserved.