Wed, 06 Jun 2018 03:19:45 +0000
Sintering mechanism and advantages of discharge plasma sintering
Discharge plasma sintering equipment similar to the hot pressing sintering furnace, the difference is there is a pressure on the conductive mould with controllable pulse current, direct current size by adjusting the pulse control of heating rate and sintering temperature. SPS as an effective and novel fast sintering technology, has been applied in the research and development of a variety of materials, but about the SPS sintering mechanism, unified agreement has yet been reached, the sintering in the middle of the process has yet to be further studied.
The first view of the discharge plasma powder particles of the existence of induced electric field is negative, under the effect of pulse current discharge between particles, stimulate the plasma, it is currently used by most journals. It is generally believed that except having the joule heat and pressure of hot press sintering SPS process caused by plastic deformation, promote the sintering process but also dc pulse voltage between powder particles, and effective use of the powder particles between the effects of the spontaneous heat discharge, and therefore have some peculiar to the SPS process is helpful to sintering. The current SPS process can be regarded as the result of a combination of particle discharge, conductive heating and pressurization. The intermediate process and phenomenon of discharge plasma sintering are very complex. Many scientists have built models of SPS sintering process. The establishment of these models has certain guiding significance for the experimental research and production of SPS.
The main characteristic of SPS is to realize super-fast compaction sintering of materials by using body heating and surface activation. Its fast heating, short sintering time, sintering temperature is low, heat evenly, and the advantages of high efficiency, energy saving, in addition as a result of the plasma activated sintering and rapid warming combination, inhibits grain grew up, to keep the original particle microstructure, thus improve the performance of the sintered body in essence, and make the final product has fine uniform, can maintain the natural state of raw materials, high density, etc. Compared with HP and HIP, SPS is simple to operate and does not require specialized expertise.