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PLASMA SYNTHESIS OF NANOPOWDERS

System description

Our nanopowder synthesis system is flexible and provides industries and laboratories with a reliable method to synthesize a wide range of nanopowders. The system uses state-of-the-art control technology to monitor operating conditions and ensure safe operation.

60kW Induction Plasma System for Nanopowder Synthesis

Process description

Tekna’s induction plasma system has been successfully used in the synthesis and preparation of advanced materials such as new ceramics, nanometric metallic powders, biomaterials and superconductors. The typical size of the nanoparticles produced ranges from 20 to 100 nm, depending on the quench conditions employed. Such small-scale materials display unusual properties (chemical, physical, electrical, optical, mechanical, magnetic, etc.) as compared to their bulk states. The industry is extremely interested in nanopowders because of their multiple applications.

The production of nanopowders is one the most noticeable applications of induction plasma. The induction plasma torch possesses a high flexibility and tolerance to the processing chemistry because there are no metallic electrodes to react with the reactants, and therefore oxydizing or reducing atmospheres can be used. Since the residence time in these systems is higher than the ones observed in DC plasmas, the powders are better treated and there is less variation in the quality of the final product.

We have developed processes designed to prevent many of the problems related to conveying nanopowders. Our systems produce nanoparticles with a high and stable quality and require little maintenance or monitoring. On-line surface treatment can be achieved with this technology.

Nanopowders have multiple uses, and Tekna is renowned for its expertise in this area – backed by years of research and development of equipment using different materials.

Batteries and fuel cells
The idea of using a more environmentally friendly means of energy is behind the use of fuel cells, which are expected to be used in electric cars and other applications in the coming years. These cells require metal and metal oxide nanopowders and present an attractive market opportunity.

Powder Metallurgy
Powder metallurgy is the production of sophisticated metal parts by sintering powders. The process compresses the powder to produce a part that has sufficient cohesion to enable it to be handled safely. It is then heated-sintered, usually in a protective atmosphere, to a temperature below the melting point of the main constituent. In this stage the particles weld together and confer sufficient strength on the material for the intended use.
One of the advantages of using powder metallurgy is economical – lower heating needs. Also, the parts produced by this method have a much better uniformity in their chemical composition (lack of segregation). They’re free of ingot defects and secondary phases have a uniform distribution over the piece (carbides and other precipitates).

Nanopowders tremendously improve the results obtained by powder metallurgy because their density and surface area are higher. The parts produced with nanopowders will have higher density, hardness and fracture toughness than others produced using conventional powders.

Refractory, composite and porous materials are used in powder metallurgy. Here are some examples:

Tungsten, Mo, Ta, Copper/Tungsten, Silver/Cd Oxide, cement carbides
Ni, Ni-Co, Ni-Cr, Nickel superalloys, complex steel

Plastic, coating and pigment additives
Using nanopowders as additives in plastics and coatings instead of the standard macroscopic additives helps the manufacturing processes by reducing some of the effects related to mixing materials in different phases (i.e. liquid and solids). In plastics, the use of nanopowders allows an increase in the amount of glass or other stiffeners without clogging problems or particle orientation while molding. As for the coatings, the amount of additives used could sometimes be reduced since they offer a higher surface area than the macroscopic equivalents.

Materials used:
Zirconia, Ceria, Zinc Oxide, Silicon, Stiffeners

Explosives
Metals are used as catalysts in fuels and explosives to make them burn faster. Nanopowders offer more surface area on which a reaction can take place, enhancing the catalytic effects. Aluminum and magnesium are the main materials used to enhance explosive properties.

Microelectronics
Nanopowders offer a unique opportunity for semiconductor packaging. Alumina and silica powders can be used for lapping electronic chips, which dissipate heat faster – a growing concern in small components. Nanoparticles can be added to polymers and adhesives and make them electrically conductive, and the melting point of metals can be significantly reduced if the particles are small enough, giving more freedom to microelectronic manufacturing processes. In addition, the residual magnetism of a magnet and the band gap of a semiconductor strongly depend on the size of the component crystals.

Materials used:
Al, Cu, Ni, Au, Zn, Al2O3

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