Development of a metal dusting resistant functional coating by Sn and Al pack cementation

• New coating against metal dusting as well as oxidation at high temperatures is presented.
• The coating concept combines oxide barrier formation and catalytic inhibition approach.
• Oxide scale formation during exposure in carbon containing, reducing as well as oxidizing atmosphere at 620 °C.

A new coating against metal dusting is developed by the combination of a catalytic inhibition approach with a classical oxide barrier. Coatings were manufactured by co-deposition of tin and aluminum on nickel plated alloy 800H via powder pack cementation with different dwell times. The resulting coatings consist of two phases, a nickel-aluminide phase as oxide forming reservoir and an underlying nickel-tin phase which catalytically inhibits carbon deposition. Coated samples were exposed to H2-22%CO-10%H2O as a laboratory metal dusting environment as well as air at 620 °C. Cross sectional analysis revealed no sign for metal dusting and the formation of a thin alumina layer at the surface.