Investigation on in Situ High Temperature Oxidation Behavior of Ni Base and Co Base Super Alloys and Refractory Alloys for Strategic Applications

Abstract

The role of superalloy is significant in aircraft engineering across multiple components. The nickel-based superalloy accounts for over 50% of the weight of a gas turbine engine, encompassing various elements such as the engine walls, turbine blades, and combustion chamber. The components of a gas turbine engine and their materials, predominantly including superalloys such as nickel-based and cobalt-based superalloys, endure high-temperature conditions. Refractory alloys are also employed in aerospace engineering in various components. In aircraft engine components, Inconel 718 is employed in turbine blades as well as in the exhaust nozzle. The turbine disc is made up of In738C, the Combustion chamber liner is made up of Haynes-25, In the hot section combustor is designed in KC20WN and MP35N is used in heat seals and fasteners. newlineHigh-temperature oxidation is a significant challenge in aircraft engine components in the high hot and hard section. At high temperatures, metals and alloys interact with atmospheric oxygen, resulting in the formation of oxide layers on their surfaces. The oxidation process may result in material deterioration, reduction of mechanical characteristics, and eventually, failure of the component. To mitigate the effect of high temperature, aerospace engineers and researcher exploit multiple techniques such as the formulation of oxidation-resistant alloys, the implementation of protective coatings, and sophisticated cooling procedures. newlineThe present work is to study high-temperature oxidation behavior of superalloy and refractory alloys in in-situ environment by novel frequency response analyzer (FRA) using electrochemical impedance spectroscopy (EIS) technique to mimic near real time aerospace environment. EIS is used to explore the oxidation kinetics of the materials which measures the oxidation resistance (Rct) in in-situ and hot air environments. In addition, the oxidation behavior is observed as capacitance by applied frequency for various materials with different conditions.