Résumé:
In this work we have improved, and adapted a domestic microwave oven working under 2.45 GHz, to lead us to reach high temperatures. The heat system is constituted essentially with susceptor (heating element) and heat insulating system. We have made the heating element (susceptor) in a cylinder shape from industrial silicone carbide material (SiC) essentially, with improving his characteristics ( for better interaction with microwave ) by adding different rates of manganese oxide (MnO2) ( 2 % , 5 % , 10 % ), and study the influence of this adds on susceptor heating and on his dielectric proprieties which are relative dielectric constant and dielectric loss angle . The results obtained show that the temperature of heating reaches nearly 1500°C in 10 minutes in the case of heating element prepared from industrial SiC doped with 5 % of manganese oxide and that the same heating element is able to reach more than 1500°C in less than 6 minutes by changing the heat insulating system by another, where we find the relative dielectric constant reaches 1823 and the dielectric loss angle reaches 2.05, under room temperature ( 30 °C ). in the case of the heat element is prepared from industrial SiC only ,we reach just 1268 °C in 10 minutes with the existence of heat spots where reaching this temperature , the relative dielectric constant where 135 And the dielectric loss angle where 0.158 Under room temperature. We have also studied many dimensions which can control and influence on microwave heating by a way or another like heating element density, influence of the wide and thickness of heating insulation system, using supply with different power out and ranging temperature into heating element. In the end the heating system where used to sinter simples from Barium titanate (BaTiO3) adding to it 3 different rates (7 % , 15 % , 20 % ) of iron oxide ( Fe2O3) at 1200 °C along 10 minutes, to study the characteristics ( density , phases , dielectric proprieties ) of the resulting compound and compare it with the traditional processing at 1300 °C along 2 hours.
