Microwave frequency is 300MHz-300GHz (corresponding to wavelengths in the 1000-1mm) range of electromagnetic waves. Microwave sintering is the use of microwave radiation plus heat source instead of the traditional material through their own absorption of electromagnetic energy to reach the sintering temperature to achieve densification. Compared with the traditional understanding - will block microwave radiation reflected from the metal, the metal in the powder state was able to achieve the effective absorption of microwave heating, and thus able to use the microwave sintering of metal components.
The principle of microwave sintered metal powder are: 1, microwave thermal effects in the microwave electromagnetic field, manganese powder free charge in its internal electromagnetic field, the wizard will quickly gather the surface, the surface free charge gathered in the conductor, the internal free charge density is zero. In the electromagnetic field, the surface of the metal conductor will have current, there is ohmic losses, when reducing the size of the metal conductors of the macro, so that the fully coupled with the microwave electromagnetic field, can effectively achieve the heating and sintering.
2, non-thermal effects of microwave microwave sintering, in addition to microwave thermal effects, there are also some non-thermal microwave effects, including activation rate increased, sintering properties and changes. The mechanism may exist under the conditions in the electromagnetic field, causing the electric field along the direction of the electric potential gradient, resulting in space charge generated additional driving force to enhance the diffusion of charged particles, reducing the activation energy of powder sintering, making the migration of particles becomes more prone, and the migration rate increased a lot, boron powder it can significantly promote the densification process.
Conventional sintering process, the material surface, internal and central regions there is a big temperature gradient, easily lead to non-uniform grain size, there are more internal defects. The microwave sintering depend on penetration of electromagnetic radiation within the material, the material dielectric loss and heating up the whole place, a small temperature difference between the various parts, materials, micro-structure has been improved, nickel powder the performance is excellent. Sintering cycle - Green can be any metal powder within the 10-30min to complete sintering, microwave sintering can also be uniformly fine grain microstructure, porosity and fewer rules, the material has better ductility and toughness, excellent macro performance, while Microwave sintering low energy consumption, high efficiency, energy saving 80% than the traditional role of sintering, and the clean, safe, pollution-free. The unique advantages of microwave sintering with modern materials in preparation indicates that the industry has a broad space for development, sintering technology is widely becoming a revolution. Source:http://www.mhcmp.com