Indranil Manna

Abstract:

Surface microstructure and composition play an important role in determining resistance of metallic systems and components to corrosion and oxidation in aggressive environment. Hence tailoring and protecting the surface in lieu modifying the entire bulk, commonly referred to as surface engineering is a convenient, logical, economical and effective way of enhancing the performance and service life of various engineering components employed in static or dynamic conditions for applications ranging from micro/miniature devices to mega/large machines exposed to aggressive environment for corrosion/erosion at ambient or elevated temperature. Light amplification by stimulated emission of radiation (laser) offers a non-contact, coherent, monochromatic and directed energy beam of sufficient power density to heat, melt or vaporize almost all solids with unparalleled precision/accuracy that enables tailoring the surface microstructure and/or composition with rare precision, flexibility and novelty. In the present talk, the principle, mechanism and utility of laser assisted surface engineering will be highlighted as examples of tailoring the microstructure (identity, size, shape and distribution of phases) of selected metallic alloys for enhanced wear, corrosion/oxidation resistance, refurbishment by cladding and development of compositionally/microstructurally graded components. It will be evident that the final microstructure and composition of the laser irradiated zone primarily depends on the thermal history (temperature, thermal gradient, heating/cooling rate, etc) and specific material properties (composition, specific heat, thermal conductivity, etc) of the fusion/heat-affected zone. Most of the examples will be derived from the published results of this researcher and his colleagues. Finally, some allied studies on-plasma assisted surface engineering will be discussed to highlight the scope of developing nanostructured surface for improved wear/corrosion resistance of steel and non-ferrous alloys.