Oxidation Behavior of β-Sialon Ultrafine Powders Prepared by the Combined Sol-Gel and Microwave Carbothermal Reduction Nitridation Method

摘要

Ultrafine powders of β-Sialon were prepared by the combined sol-gel and microwave carbothermal reduction nitridation method, and their oxidation process was studied by a non-isothermal thermogravimetry method. The results indicated that two different mechanism functions respectively corresponded to the initial and final oxidation stages. The reverse Jander equation F(α) = [(1+α)~(1/3)-1]~2 with activation energy of 240.5 kJ/mol and the Avrami-Erofeev equation F(α) = [-ln(1-α)]~3 with activation energy of 410.7 kJ/mol were respectively identified as the most probable mechanism function for the initial and final oxidation stages in the temperature range of 1423-1623 K.