微波烧结的“热点”形成机制

Mechanism of “Hot Spot” Generation in Microwave Sintering Process

电磁场理论计算及粉煤灰空气体系实验证明,微波电场会聚作用是微波烧结过程"热点"的产生原因,微波电场会聚受颗粒接触面法向与电场方向的夹角、电介质材料的介电常数影响显著。颗粒接触面法向与电场夹角增加至90°,电场会聚作用消失。材料介电常数增大,电场会聚作用增强。

Theoretical calculation along with sintering experiment of coal fly ash-air system showed that electric field intensification is the reason of the generation of ＂hot spot＂,which would promote the reaction of solid phases under microwave irradiation dramatically. It is found that the electric field intensification is strongly influenced by the dielectric constant of compound and the angle between the direction of E-field and the normal to the surface at the adjacent point of two spheres. With an increase of dielectric constant,the strength of electric field intensification increased. But when the angle changed from 0° to 90°,the intensification disappeared.