it is now generally accepted practice to apply coatings to components in fossil fuel energy processes to protect against surface degradation processes such as wear, oxidation, corrosion and erosion.The nanostructured thin TiAlN and AlCrN coatings deposited by PVD technique and the conventional thick TiAl and AlCr coatings deposited by Plasma Spraying and further gas nitrided; were selected for the present work. After conducting the various experiments on uncoated and coated alloys (total 16 substrate-coating combinations along with the bare alloys) in lab and in actual industrial environment which includes the characterization of the nanostructured and conventional TiAlN and AlCrN coatings on selected Fe-based alloys and their behavior when exposed to high temperature oxidation studies in air, molten salt environment and in a coal fired boiler of a thermal power plant, erosion studies in simulated coal-fired boiler environment; the coating-substrate combinations which are found successful in protecting the substrates from oxidation, hot corrosion, erosion and wear are proposed to provide thermal insulation, corrosion and wear resistance to the components in chemical process plants