Modified aluminide coatings with reactive element for turbine blade protection

Increasing the maximum temperature of the gases introduced into the turbine increases both the efficiency and performance of a turbo-gas system; Switching from an input temperature of 900 ° C to 1250 ° C can result in a 30% increase in output power, leaving unchanged consumption. In order to ensure the structural integrity of components working in the hottest areas of the engine, research over the last decades has focused on the development of increasingly innovative technologies that aim to increase the efficiency of the system while at the same time increasing its operating life. In this thesis, it was studied a multiple modification approach of a standard aluminide coating in order to increase the oxidation and hot corrosion resistance. The first part of the study has involved the manufacturing, characterization and high temperature tests of a standard aluminide coating obtained by pack cementation. The optimized parameters were selected as deposition parameters for the modified coating: diffusion aluminide were doped with Zr and the characterization test were carried out in order to compare the standard with the modified samples. The second part of the study has involved the introduction of a modified process in order to optimize the manufacturing process of the coating. Electroless pure nickel plating were selected as pre-aluminization process in order to introduce a Ni reservoir onto the substrate surface. Otherwise, n-Al2O3 was used as nano-reinforcement in the Ni layer to improve the oxidation resistance by modifying the kinetic of oxidation. The final part of the work has involved the test of a different aluminization process. In collaboration with the University of La Rochelle, France, slurry-aluminization (low temperature) was carried out onto the standard and the electroless pure nickel samples. Oxidation results were compared with the first part of the work and an innovative production way of diffusion aluminide coating modified with Zr and electroless Ni was proposed and studied.