Development of Chromium and Aluminum Coatings on Superalloys by Pack-Cementation Technique
Austenitic nickel-iron-chromium based superalloys are materials of choice for high temperature applications as they provide high temperature creep resistance associated with a suitable oxidation behavior in the temperature range of 600-1100°C. However, these properties are not sufficient for applications as Steam Methane Reformer (SMR). As a consequence, aluminum and chromium coatings are developed by the pack-cementation technique to improve their corrosion resistance. The oxidation behavior of the coated samples has been carried out in air at 1050°C. Chromium deposition leads to a layer of bcc chromium-iron solid solution. Oxidation tests indicated that a too high chromium concentration induces a too rapid growth of the chromia layer. In the case of aluminum coatings, a layer of -NiAl is formed at the surface of the alloy. It permits a significant decrease of the oxidation rate.
X. Ledoux et al., "Development of Chromium and Aluminum Coatings on Superalloys by Pack-Cementation Technique", Advanced Materials Research, Vol. 278, pp. 491-496, 2011