Article Details
When it comes to the microwave heating function, it is necessary to mention the heated materials. Generally speaking, microwaves can only act on materials that can absorb microwaves, generating heat energy through the vibration of material molecules. So let's talk about four types of materials in the industrial microwave high-temperature field.
Microwave selective heating refers to the fact that microwaves can only heat certain materials but not some others. Therefore, they are introduced in four major categories according to the properties of the materials:
The first type of material is absorbing materials, such as copper oxide. These materials have a good absorption capacity for microwaves. Due to their high dielectric loss, they can convert the electromagnetic energy in microwaves into thermal energy.
The second category is transmissive materials, such as quartz and polytetrafluoroethylene. On the surface of these materials, microwaves are partially reflected and partially penetrated, and are rarely absorbed. Therefore, they cannot or are difficult to be heated by microwaves.
The third category is reflective materials, typically conductive materials such as metal iron blocks and graphite pressed products. They have a reflective effect on microwaves and cannot be heated by microwaves. However, when iron blocks, copper blocks, and graphite blocks are processed into powder form, they have an excellent absorption capacity for microwaves and can rapidly heat up to hundreds of degrees Celsius or even 1000 degrees Celsius within a relatively short period of time. Therefore, whether the material can be heated by microwave is related to the material's own properties as well as its physical state.
The fourth type of material is heterogeneous material, which has been one of the research hotspots in recent years. In the fields of microwave metallurgy and material synthesis, the objects of microwave heating are mostly two-phase or multi-phase heterogeneous materials, and the mechanism of action is very complex. The characteristic of this type of material is that it has a local field enhancement effect under microwave irradiation, which can cause discharge and generate ultraviolet light to promote photocatalysis. This is a new mechanism of microwave-assisted catalysis.
Microwave equipment is a new type of industrial equipment. Its energy conservation and environmental protection have been recognized by many enterprises. Enterprises with relatively serious environmental pollution have begun to choose to use environmentally friendly microwave equipment to replace traditional drying, sintering and other equipment in enterprises.