Pulsed Arc Nanoparticle Synthesis
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Pulsed Arc Nanoparticle Synthesis (PANS) is a pulsed power process for manufacturing nanoparticles via an electric arc formed by the discharge of a capacitor bank between two metal rods. The arc ablates the ends of the rods to form a plasma. The plasma then expands into a background quench gas to rapidly cool it thereby forming nanoparticles.[1]
If the background gas is inert, such as helium or argon, then the nanoparticles produced are composed of the electrode material. If the gas contains a reactive species, such as oxygen or ammonia, then the nanoparticles become the most kinetically favorable compound of the electrode material and the gas, such as an oxide or nitride.
PANS has similarities to plasma torch[2], exploding wire, Inductively coupled plasma, and evaporation methods of making nanoparticles all of which heat a solid source material to form a metal vapor that condenses out, and possibly reacts with a quench gas to produce nanoparticles in dry-powder form.
History[edit]
The process is based on electrothermal/electrothermal chemical (ET/ETC)technology. Early versions had the topology of an electrothermal gun -without the projectile.[3] In that case, an intense, wall-stabilized, capillary discharge was established between a breech electrode (cathode) and an annular muzzle electrode (anode).[4] A fuse wire was used to electrically connect the breech and muzzle electrodes, and an ignitron was used to switch a capacitor bank discharge through the fuse wire to establish an electrical connection between the electrodes. When initiated, the ~100MW pulsed electrical discharge would explode the wire, creating a plasma in the bore, which continued to conduct current and be resistively heated by the arc discharge. The high-density, high-velocity plasma would exit the bore, and in the process ablate the muzzle electrode. This material would then expand, mix, and react (if applicable) with the gas to form nanoparticles. This technique was commercially developed by NovaCentrix (then Nanotechnologies, Inc.) in the early 2000s.[5]
In 2002, the company transitioned from the electrothermal gun topology to firing a similar arc discharge between two opposing metal rods. This transition had several advantages over the electrothermal gun technique.[6]
•It eliminated the need for high-pressure plasma seals and increased the purity of the resulting nanoparticles by eliminating the insulating (and ablating) gun bore.
•It allowed electronic switching of the arc, which increased both the reliability and decreased the cost of the process.
•It eliminated the costly machining of the electrodes by using a long spool of wire that could be indexed between pulses.
Unlike ET/ETCS, PANS is an automated process.
Legacy[edit]
Currently, only metal nanopowders are produced with the PANS process.
In the early 2000s, it was discovered that by varying the pulse length of the arc discharge, among other variables, the average nanoparticle size produced could be controlled by an order of magnitude, nominally from about 10nm to about 100nm. When the photonic curing process was discovered using the flash unit from a disposable camera in 2004, the pulse-forming network of the 100 MW PANS reactor was applied to the flashlamp to scale it up. Like the PANS process, pulse-length control was added to the photonic curing equipment in order to tune the power delivery to the thin films being thermally processed.
A technique similar to PANS has been used to synthesize graphene.[7]In that case, solid carbon is packed between the metal electrodes instead of a gas.
References[edit]
- ↑ "Pulsed Arc Nanoparticle Synthesis".
- ↑ US5460701A, Parker, John C.; Mohammed N. Ali & Byron B. Lympany, "Method of making nanostructured materials", issued 1995-10-24
- ↑ D.R. Peterson, “Electrothermal-chemical synthesis of nanocrystalline ceramics,” Ph.D. Thesis, The University of Texas at Austin, 1994.
- ↑ Peterson, D.R. (1997). "Design and operation of the electrogun, an electrothermal gun for producing metal and carbon plasma jets". IEEE Transactions on Magnetics. 33 (1): 373–378. Bibcode:1997ITM....33..373P. doi:10.1109/20.560040. ISSN 0018-9464.
- ↑ Schroder, Kurt A.; Wilson, Dennis E.; Kim, Kyoungjin; Elliott, Henry E. (2002). "Characterization of Metallic and Metal Oxide Nanoparticles Produced by Electrothermal-Chemical Synthesis". MRS Proceedings. 744. doi:10.1557/proc-744-m6.8. ISSN 0272-9172.
- ↑ K.A. Schroder, D.K. Jackson, Radial pulsed arc discharge gun for synthesizing nanopowders. US patent 7,126,081, 2006.
- ↑ Luong, Duy X.; Bets, Ksenia V.; Algozeeb, Wala Ali; Stanford, Michael G.; Kittrell, Carter; Chen, Weiyin; Salvatierra, Rodrigo V.; Ren, Muqing; McHugh, Emily A.; Advincula, Paul A.; Wang, Zhe; Bhatt, Mahesh; Guo, Hua; Mancevski, Vladimir; Shahsavari, Rouzbeh (2020-01-30). "Gram-scale bottom-up flash graphene synthesis". Nature. 577 (7792): 647–651. Bibcode:2020Natur.577..647L. doi:10.1038/s41586-020-1938-0. ISSN 0028-0836. PMID 31988511. Unknown parameter
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