Effect of Mechanical Activation on the Kinetics of Silica Carbothermal Reduction in non-Isothermal Conditions.

The effect of mechanical activation on the synthesis temperature decreasing of silicon carbide was investigated and a kinetic model of a carbothermic reduction of silicon carbide was obtained. Silicon carbide was synthesized using silica activated in a planetary mill at different times up to 40 h under an argon atmosphere. Structural changes due to the milling and the reduction of the activated silica were studied by the X-Ray diffraction (XRD) method and non-isothermal TGA with a heating rate of 10 °C min^-1 respectively. The kinetic model obtained by the fitting technique for an unmilled sample was found to be chemically controlled of the second order with E = 138.92 Kcal.mol^-1 and A = 3.92×10¹⁵ s^-1. For the sample milled up to 20 h, according to the Avrami-Erofeev3 equation; A = 1465633 s^-1 and E = 66.71 Kcal.mol^-1. [ABSTRACT FROM AUTHOR]