Abstract
This study investigates the durability and corrosion resistance of Ni-Cr-Al detonation-sprayed coatings when exposed to high-temperature environments containing molten Na₂SO₄ and NaCl. Such conditions are highly corrosive and frequently encountered in aerospace, energy, and chemical industries. Gradient and homogeneous Ni-Cr-Al coatings were compared to understand their behavior under aggressive exposure. The reveal of results those gradient coatings exhibit superior corrosion resistance due to their ability to retain protective oxides, such as Cr₂O₃, and mitigate stress-induced damage through compositional grading. In contrast, homogeneous coatings displayed significant degradation, including widespread corrosion, delamination, and the formation of sodium-based phases like NaNiO₂. XRD analysis confirmed the presence of oxidation and sulfidation products, with gradient coatings showing enhanced stability against phase transitions. These findings highlight the potential of gradient Ni-Cr-Al coatings to improve component performance in extreme conditions and provide valuable insights for optimizing coating compositions and processes to enhance operational reliability in harsh environments.