Oxidation of Iron-Aluminide Coatings Produced on NF616 Ferritic and NF709 Austenitic Stainless Steels

摘要

Aluminide coating of steels enables more efficient power generation through higher operating temperatures that are inaccessible to uncoated low chromium stainless steels due to the inability to form protective chromia scale. Previous research has shown that low-temperature (T<660°C) aluminide coatings form an iron-aluminum intermetallic phase which can provide effective corrosion protection. In current work the coating structures and resultant oxides were examined in both austenitic and ferritic steels at 1000°C and 800°C to evaluate the high temperature oxidation behavior in air. Different asdeposited coating phases are determined by the austenitic or ferritic substrate and result in enhanced corrosion resistance for ferritic steels and limited improvement for austenitic steels. In addition, the oxide and intermetallic phases of coated and uncoated specimens were examined in terms of structure and composition.