Nickel base superalloys (containing Cr) are popularly used in the aerospace industry due to their excellent corrosion resistance. Precipitation hardenable nickel-iron base superalloy Inconel (contain significant amounts of Cr, Fe, Nb and Mo) are commonly used in fabricating turbine blades, discs and other critical parts of jet engines, cryogenic storage tanks, pump bodies and parts, rocket motors and thrust reversers, nuclear fuel element spacers, hot extrusion tooling, high strength bolting, and down hole shafting. The alloy is age-hardenable via the precipitation of the meta-stable form of the delta (δ) phase (Ni3Nb), known as δ′. Certain Inconel alloys combine good corrosion and high mechanical properties and have excellent weldabilitty. In spite of their otherwise excellent properties, these superalloys have unsatisfactory wear characteristics. Thus, surface treatments that can improve the tribological behavior without adversely effecting corrosion resistance have high potential to improve performance and expand the field of applications of superalloys.
Plasma Aluminizing Process offers certain advantages over conventional techniques. Disadvantage of conventional diffusion treatment (performed at a temperature of 1000-1050C), is that substrates could distort because of exposure at high temperature. Plasma Aluminizing Process basically involves deploying of aluminium coating by sputtering and simultaneous diffusion at high temperature under plasma to prepare aluminide coatings in-situ. Plasma aluminizing process eliminates the limitations of conventional treatments.