NANO STRUCTURED THIN FILMS FOR CORROSION PROTECTION

Abstract

Hot corrosion is a serious problem in Power Generation equipment, Gas Turbines, Internal Combustion engines, Fluidized Bed combustion, Industrial waste Incinerators and Paper and Pulp industries. No alloy is immune to hot corrosion attack indefinitely Superalloys have been developed for high-temperature applications. However, these alloys are not always able to meet both the high temperature strength and high-temperature corrosion resistance simultaneously. In fact, coatings are playing a significant role in today's aero and industrial turbine engines to extend the life or enhance the performance of components. About 75% of all the components in jet engines are coated [9]. The most common metallic coatings used in the hot section of turbine engines are MCrAI type overlay coatings, which can be specifically designed and produced to meet the particular environmental operating conditions independent of substrates. Many studies have been conducted in which the composition and microstructure of MCrAI coatings are modified in order to form a dense, continuous a-alumina, which protects the MCrAI coatings from rapid oxidation [6] . The Nano-coating is a new technology rapidly developing in combating high-temperature corrosion. Here in this work we choose Sputtering technique which is now challenging the remaining coating techniques like High Velocity Oxy-Fuel (HVOF)vacuum plasma spraying technique (VPS), which is very expensive (capital costs approximately 2 million US$). Magnetron sputtering (MS) produces very good thickness uniformity and high density of the films, and the process has good controllability and long term stability.