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Nanostructured coatings can be obtained using a variety of techniques. The simplest way is to use nanopowdersinstead of micron-sized conventional powders as feedstock for thermal spray coating processes like detonationspray, cold spray and suspension plasma spray coating techniques and thereby obtain nanostructured coating up toa thickness of about 250 μm. Similarly, nanoparticles can be added to the solution to obtain sol-gel nanocompositecoatings with unique functional properties. Another way is to use the pulsed electro deposition technique to obtainnanocrystalline coatings and also nanocomposite coatings by dispersing hard reinforcements like SiC, Al2O3 etc.,in the electrolyte prior to pulsed deposition. Superhard nanocomposite and nano multi-layered coatings can beobtained using specialized Physical Vapour Deposition (PVD) techniques as well. Solution precursor can be used asthe feedstock for plasma spray coating and thereby the nanosized particles can be precipitated out of the precursorsolution during the coating process resulting in nanostructured coatings. Finally, it is possible to transform the surfacesof components from having a conventional grain size structure to that with a nano grain size by repeated impact of thecomponent surface by hard balls.
In this presentation, some of the above techniques for obtaining nanostructured coatings will be discussed in detailwith particular reference to the work being done at ARCI and more importantly, the superior tribological, mechanicaland functional properties of these coatings will be highlighted.
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