Capacitor discharge sintering
Encyclopedia
Capacitor discharge sintering (CDS) is an electric current assisted sintering
(ECAS) technique. The technique is based on storage of electromagnetic energy in a high voltage capacitor bank, and discharge into the sintering apparatus at low voltage (<30 V) and high current through step-down transformer
s on a pre-compacted powder
compact which is kept under pressure. The sintering mould and Electrode
s are similar to those employed in field assisted sintering techniques (FAST) such as spark plasma sintering
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).
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.
.
Advantages of the technique are:
Sintering
Sintering is a method used to create objects from powders. It is based on atomic diffusion. Diffusion occurs in any material above absolute zero, but it occurs much faster at higher temperatures. In most sintering processes, the powdered material is held in a mold and then heated to a temperature...
(ECAS) technique. The technique is based on storage of electromagnetic energy in a high voltage capacitor bank, and discharge into the sintering apparatus at low voltage (<30 V) and high current through step-down transformer
Transformer
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors—the transformer's coils. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic field...
s on a pre-compacted powder
Powder
Powder may refer to:*Powder , material composed of very fine particles that are not cemented together* Powder , a 1995 film* Powder , a mid-1990s Britpop band* Powder blue, a color...
compact which is kept under pressure. The sintering mould and Electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s are similar to those employed in field assisted sintering techniques (FAST) such as spark plasma sintering
Spark plasma sintering
Spark plasma sintering , also known as field assisted sintering technique or pulsed electric current sintering , is a sintering technique....
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).
Electro-Discharge Sintering Disambiguation
The technique has been studied by Element SixElement Six
Element Six is a company specialised in providing synthetic diamond, cubic boron nitride and other superhard materials for industrial use. It was created in 1946 and is owned by Umicore and De Beers...
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.
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 and is undergoing developments and industrialization in Italy at the company EPoS srl, start up from Polytechnic University of TurinPolytechnic University of Turin
The Polytechnic University of Turin is an engineering university based in Turin, northern Italy. Established in 1859, Politecnico di Torino is Italy’s oldest Technical University. In 2011 it was ranked as the best engineering university in Italy in the Academic Ranking of World Universities.It is...
.
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 titaniumTitaniumTitanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
- the ability to obtain metastable and nanocrystallineNanocrystallineA nanocrystalline material is a polycrystalline material with a crystallite size of only a few nanometers. These materials fill the gap between amorphous materials without any longe range order and crystalline materials with a clear three dimensional long range order.X-ray diffraction is commonly...
materials (see Capacitor discharge sintering of nanocrystalline copper)