Spark Plasma Sintering System

Spark Plasma Sintering (SPS) is a facile and affordable method for sintering and manufacturing of various parts of metals, ceramics, polymers and composites. In this process, sintering performs through a chain of events including: melting of contact area among neighboring particles, electric discharge in contact area, and then spark plasma with high temperature- momentarily and locally.

In this process, densification mechanism is based on an electric discharge among neighboring particles gaps and formation of neck-like junction among them due to the local increase in temperature. This process acts like microwave sintering process, both of which use a kind of so called self-heating action from the powder's interior. In SPS process by occurring electric discharge among neighboring particles, the temperature momentarily goes beyond ten thousand degrees Celsius, which causes evaporation and welding of adjacent particles surfaces. In this method, compressed particles surfaces are plastically deformed to shape into the form of contact area. Thereafter, by emerging and growing the neck-like junction during sintering process the compacted powders become even denser. After passing sufficient time, the density of sintered powders can reach to higher than 99%. Since the local increase in temperature only occurs in contact areas of particles—and not inside particles—no noticeable grain growth would be anticipated. Besides, this process enables the possibility of mass production of articles having amorphous or nanocrystalline structure, without any change in properties of primary powder. 

In this process, a mixture of powders is poured into a graphite mold and then powders undergo a high compressive stress through a sintering process. Since all processes are carried out under vacuum, the risk of contamination with active gases in air is no longer existed; therefore, the purity of the resulting product will be improved. SPS system have many advantages over other conventional heating systems such as hot press, hot isostatic press (HIP) or vacuum furnaces, some of which are: the facility in use, the precise control of sintering energy, the high reproducibility of material, the high speed of sintering, safety and reliability. The abrupt increase in temperature through self-heating is an important advantage which enables all compressing and article production processes to be carried out without adverse effect of losing primary features of material.