Capacitor discharge sintering (CDS) is an electric current assisted

sintering Clinker nodules produced by sintering Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction. Sintering happens as part of a manufacturing ...

(ECAS) technique. The technique is based on storage of electromagnetic energy in a high voltage

capacitor A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals. The effect of ...

bank, and discharge into the sintering apparatus at low voltage (<30 V) and high current through step-down

transformer A transformer is a passive component that transfers electrical energy from one electrical circuit to another circuit, or multiple circuits. A varying current in any coil of the transformer produces a varying magnetic flux in the transformer' ...

s on a pre-compacted powder compact which is kept under pressure. The sintering mould and

Electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials de ...

s are similar to those employed in field assisted sintering techniques (FAST) such as

spark plasma sintering Spark plasma sintering (SPS), also known as field assisted sintering technique (FAST) or pulsed electric current sintering (PECS), or plasma pressure compaction (P2C) is a sintering technique. The main characteristic of SPS is that the pulsed or u ...

and single electromagnetic pulse sintering technologies. The method, analogous to resistive sintering, is a direct evolution of a welding technology named Capacitor Discharge Welding ( Kondensator-Impulsschweißen). CDS seems like an improvement of the less powerful capacitor discharge compaction patented by W.Knoess and M.Schlemmer (EP 0671232, US Patent 5529746). Advantages of the technique are: * short sintering time (less than one second) * no need for a controlled atmosphere even during sintering of highly reactive materials such as

titanium Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in ...

* the ability to obtain metastable and

nanocrystalline A nanocrystalline (NC) material is a polycrystalline material with a crystallite size of only a few nanometers. These materials fill the gap between amorphous materials without any long range order and conventional coarse-grained materials. De ...

materials

Disambiguation

The technique has been studied by Element Six under the name of electro-discharge sintering. This name has been adopted by many authors in the past to describe a range of different technologies which typically adopt very high voltages and completely different machines. For this reason the technique which employs low voltages and high currents adapted from capacitor discharge welding has been named capacitor discharge sintering. Other authors also refer to this technology as spark plasma compaction (in reference to the well known

with whom it has in common only the use of electric currents).

Developments

Capacitor discharge sintering is at an experimental/research stage of development in Germany at the Ruhr-Universität Bochum where a prototype machine is installed. File:CDS_pressure_and_current.jpg, Schematics of pressure and electric current during a typical cycle of capacitor discharge sintering. The characteristic time of the discharge is from 20 to 40 ms.

References

Industrial processes Metalworking {{Metalworking-stub