Production and characterization of Al-Si based coatings on superalloy substrates via mechanical alloying method

Superalloys are alloys primarily used in energy and aerospace fields and preferred in the most critical parts of systems, thanks to their superior mechanical properties at high temperatures. In order to improve the performance of these special alloys used, it is of great importance to improve the corrosion properties of these special alloys at high temperatures. For this reason, in this present thesis, it was aimed to make Al-Si alloy and Al-Si alloy matrix composite coatings on the nickel-based superalloy substrate by applying the mechanical alloying method. Primarily, suitable coating parameters were determined by controlling the different ball sizes, alloying time, and process control agent (PCA) addition in order to optimize the coating production conditions of the mechanical alloying process. Cross-section studies were carried out to determine the relationship of the applied coatings with the interface, and surface examinations were carried out to determine the coating surface properties, XRD method was applied to determine the phase structures, and short-term heat treatments were applied in a controlled atmosphere after the coating in order to improve the surface roughness parameters and interface compatibility. Finally, weight gain, high-temperature oxidation resistance, and wear properties were investigated with 200-hour oxidation studies. Al-Si alloy matrix metal-oxide composite coating studies have been carried out to improve both wear and high-temperature oxidation resistance of the coating studies, and coating mixtures suitable for working in high-temperature environments have been determined by making comparisons with standard Al-Si alloy coatings. As a result, Al-Si based alloy and composite coatings were successfully produced on superalloy substrates by applying the mechanical alloying method, and the surface properties of the coatings were evaluated in terms of high-temperature corrosion, wear, and hardness.