Steam oxidation of aluminide coatings under high pressure and for long exposures

International audienceB2-FeAl-based aluminide coatings were elaborated on P92 ferritic-martensitic steels by slurry. Under atmospheric pressure of steal and 650°C, a thin protective α-Al 2 O 3 oxide layer formed and was maintained until 5000 h. With increasing pressure to 300 bar, the morphology of α-Al 2 O 3 changed markedly. Iron oxide clusters started to appear at the surface of the scale after 5000 h of exposure and kept on growing till 10000 h. It appears that pressure increased the outward diffusion of Fe through the coating and through the oxide scale and fostered the propagation of the tensile cracks of the coating