Electron beam physical vapour deposition

Electron beam physical vapour deposition (EBPVD) uses a target anode that is bombarded with an electron beam generated by a charged tungsten filament under high vacuum (Figure 5.16). 

Thin layers of catalyst can be deposited onto the surface of silicon microchannels by physical vapour deposition. Silicon is the preferred material, because the equipment for physical vapour deposition is available at microelectronics fabrication sites, which can also produce silicon microreactors. Physical vapour deposition such as cathodic sputtering, electron beam evaporation and pulsed laser deposition but also chemical vapour deposition create uniform metal surfaces with thicknesses in the nm range. Such coatings are rarely suitable as catalysts. However, a few exceptions such as hydrogen oxidation [145] and reactions in the very high temperature range do exist. 

Another problem limiting the application of nanociystalline materials is prep>aration of nanocrystalline alloys. Currently, the bulk metallic nanomaterials can only be prepared at the laboratory scale, usually by compacting prepared nanocrystalline powders. However, consolidation of the nanopowders into bulk materials needs high temperature and pressure which may considerably coarsen the structure. Because of this difficulty, surface nanocoating has been considered a potential industry application. Nanocrystalline costing are often prepared by chemical vapour deposition (CVD), physical vapour deposition (PVD), electrochemical deposition, electro-spark deposition, and laser and electron beam surface treatment. 

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