mechanism of microwave sintering
Author: langfeng Time: 2020-08-21
Microwave sintering is a new technology that uses the dielectric loss of the material in the microwave electromagnetic field to heat the ceramic and its composite materials to the sintering temperature, and finally achieves densification. It is a new technology developed internationally in the mid to late 1980s. A new type of ceramic sintering technology. It is a new subject produced by the intersection of microwave technology and materials science and engineering. Compared with conventional sintering, microwave sintering has a series of advantages such as rapid heating, rapid sintering, high efficiency and energy saving, improvement of material structure, and improvement of material properties, so it is known as "a new generation of sintering technology". Many countries in the world have invested a lot of financial and manpower in research and development of this new technology. In the past 10 years, dozens of units in the United States, Canada, Japan, Europe and other countries have carried out research on this technology, and have made great progress. Research progress in the mechanism of microwave sintering technology
The principle of microwave sintering of ceramic materials is the same as the current one. The conventional sintering process is fundamentally different. Traditional heating relies on a heating element to transfer heat to the heated object through convection, conduction or radiation to reach a certain temperature, and the heat is transferred from the outside to the inside. In the microwave heating process, the heat generation directly originates from the material itself (due to the rotation of the dipole and conduction loss, etc.) rather than from other heating elements. It is precisely because the inside of the material absorbs microwave energy as a whole and is heated, the thermal gradient and heat flow direction inside the sample in the microwave field are opposite to those under conventional sintering. Therefore, the microwave can heat the material quickly and uniformly without causing cracks or forming thermal stress in the sample. More importantly, rapid sintering makes the material form a uniform fine crystal structure and high density, which improves the material's performance. At the same time, due to the different degrees of microwave absorption and coupling of different components in the material, selective sintering can be achieved, so as to obtain materials with new microstructures and excellent properties.