铁及其氧化物在微波场中的升温特性

Temperature rising characteristics of iron and iron oxides in microwave field

微波加热具有快速性、整体性、即时性和选择性等优点,且设备紧凑,易于控制,对环境无污染。然而微波加热技术工业化应用发展较缓慢,尤其在高温领域,尚无成熟的工业化生产案例。其中一重要原因是微波与(颗粒)物质相互作用机理的研究滞后。所以对铁及其氧化物在微波场中的升温特性进行研究,不仅可以了解它们与微波的耦合作用能力,便于合理的施加微波能于不同的铁物相,而且通过对几种主要影响因素的探讨,加深了对铁及其氧化物在微波场中升温机理的认识。室温下电磁性能由大到小顺序为:Fe,Fe3O4,FeO,Fe2O3,微波场中升温到1 050℃的过程中,随着性状的改变,升温速度快慢顺序依次为:Fe3O4,FeO,Fe2O3,Fe。成型方式的改变对物料在微波场中的升温速度有很大影响,但其不会改变热失控现象的发生。扫描电镜研究结果表明:结构疏松、孔洞发达、处于无序状态的颗粒物料有利于微波的穿透以及吸收。

The major advantages of microwave heating are rapid heat transfer, volumetric property, immediacy and selectivity, in addition, compactness of equipment, high-controlling accuracy and pollution-free. However, its development for the industrial application is very slow, especially in high temperature areas where there is no mature case of industrial production. One important reason is lag of studying mechanism of microwave interaction with materials （particulates）. Therefore, it was of great significance in studying temperature rising characteristics of iron and iron oxides in microwave field, not only their coupling ability with microwave for applying microwave energy to facilitate intelligently in different iron phases can be understood, but also temperature rise mechanism of iron and iron oxides in microwave field by explored several major factors of heating. The electromagnetic properties in room temperature results show that, Fe〉Fe304〉FeO〉Fe203. Because of the physical properties changed in the process of microwave heating to 1050 ~C, the speed of heating is： Fe304〉FeO^Fe203〉Fe. Briquette has a faster heating rate compares with powder in microwave field, but it does not change the thermal runaway phenomenon. SEM results show that the material is conducive to microwave penetration and absorption when it has loose structure, developed holes and irregular granules.