Sulfate corrosion behavior and structural stability of LaMgAl ₁₁ O ₁₉ coating with different Al plating layer thickness

Abstract This study investigates the sulfate mixture corrosion behavior and structural stability of CoCrNiAlY—YSZ—LMA coatings with varying Al plating layer thicknesses, focusing on the impact of thermal expansion and corrosion degradation. Results revealed that both the corrosion degradation reaction and thermal stress played crucial roles in determining the anticorrosion performance and structural damage of the coating. During the corrosion measurement, this coating with a thin Al plating layer thickness of 5 µm suffered from severe structural damage because the sulfate mixture greatly consumed the thin Al 2 O 3 layer and deteriorated its barrier ability. Although a thick Al 2 O 3 layer provided a strong ability to resist the sulfate mixture corrosion, high thermal stress eventually resulted in severe structural damage of the coating with an Al plating layer thickness of 15 µm. In comparison, the coating with an Al plating layer thickness of 10 µm showed better corrosion resistance and structural stability due to low thermal stress and considerable resistance to sulfate mixture corrosion. These current findings provided a theoretical basis for optimizing Al plating layer thickness but also offered important guidance for achieving long‐term service in more demanding environments.