Electrostatic spray-assisted vapour deposition (ESAVD) is a technique (developed by a company called IMPT) to deposit both thin and thick layers of a coating onto various
substrates. In simple terms chemical precursors are sprayed across an
electrostatic
Electrostatics is a branch of physics that studies electric charges at rest (static electricity).
Since classical times, it has been known that some materials, such as amber, attract lightweight particles after rubbing. The Greek word for amber ...
field towards a heated substrate, the chemicals undergo a controlled chemical reaction and are deposited on the substrate as the required coating. Electrostatic spraying techniques were developed in the 1950s for the spraying of ionised particles on to charged or heated substrates.
[Rupp, Joel; Guffy, Eri; Jacobsen, Gar]
"Electrostatic spray processes"
TW Ransburg Electrostatic Systems, in ''Metal Finishing 2012 Organic Finishing Guidebook''. Elsevier. p. 126-127. 2012
ESAVD (branded by IMPT as Layatec) is used for many applications in many markets including:
* Thermal barrier coatings for jet engine
turbine
A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating e ...
blades
* Various thin layers in the manufacture of flat panel displays and
photovoltaic
Photovoltaics (PV) is the conversion of light into electricity using semiconducting materials that exhibit the photovoltaic effect, a phenomenon studied in physics, photochemistry, and electrochemistry. The photovoltaic effect is commercially us ...
panels, CIGS and CZTS-based thin-film solar cells.
* Electronic components
* Biomedical coatings
* Glass coatings (such as self-cleaning)
* Corrosion protection coatings
The process has advantages over other techniques for
layer deposition (plasma, electron-beam) in that it does not require the use of any
vacuum
A vacuum is a space devoid of matter. The word is derived from the Latin adjective ''vacuus'' for "vacant" or "void". An approximation to such vacuum is a region with a gaseous pressure much less than atmospheric pressure. Physicists often dis ...
,
electron beam
Cathode rays or electron beam (e-beam) are streams of electrons observed in discharge tubes. If an evacuated glass tube is equipped with two electrodes and a voltage is applied, glass behind the positive electrode is observed to glow, due to ele ...
or plasma so reduces the manufacturing costs. It also uses less power and raw materials making it more environmentally friendly. Also the use of the electrostatic field means that the process can coat complex 3D parts easily.
References
Further reading
* "Kwang-Leong Choy – Laying It on Thick And Thin". ''Materials World''. June 2003. Electrostatic spray-assisted vapour deposition (ESAVD), first reported in ''Materials World'' in March 1998, is a method for fabricating films and nanocrystalline powders. The inventor describes ongoing progress.
* Choy, K. L., "Process principles and applications of novel and cost-effective ESAVD based methods", in ''Innovative Processing of Films and Nanocrystalline Powders'', K. L. Choy. ed. (World Scientific Publishing Company). 2002. pp. 15–69. .
* Choy, K. L., "Review of advances in processing methods: films and nanocrystalline powders", in ''Innovative Processing of Films and Nanocrystalline Powders'', Choy, K. L. ed. (Imperial College Press), 2002, 1–14.
* Choy, K. L., ''Progress in Materials Science'', 48, 57(2003).
* Choy, K. L., "Vapor Processing of nanostructured materials", in ''Handbook of nanostructured materials and nanotechnology'', Nalwa, H. S. ed. (Academic Press) 2000, 533. . Choy, K. L., Feist, J. P., Heyes, A. L. and Su, B., J. Mater. Res. 14 (1999) 3111.
* Choy, K. L., "Innovative and cost-effective deposition of coatings using ESAVD method", ''Surface Engineering'', 16 (2000) 465.
* R. Chandrasekhar and K. L. Choy, "Electrostatic spray assisted vapour deposition of fluorine doped tin oxide", ''Journal of Crystal Growth'', 231 (1–2) (2001) 215.
Thin film deposition
Semiconductor device fabrication
Metalworking
Coatings
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