EVALUATION OF IRON ALUMINIDE COATINGS FOR OXIDATION PROTECTION IN WATER VAPOR ENVIRONMENT

摘要

Long-term (> 10,000h) oxidation behavior of aluminide coatings made by chemical vapor deposition (CVD) or pack cementation on representative ferritic (Fe-9Cr-1Mo) and austenitic (type 304L stainless steel) are being studied in air + 10 percent water vapor in the temperature range of 650-800 deg C. Unlike the uncoated alloys, which are severely attacked in this environment, the CVD aluminide coatings have not failed after 16,000h at 700 deg C or 10,000h at 800 deg C. The pack aluminide coatings also show good oxidation protection after testing for approx 5,000h at 700 deg C. In addition, initial efforts have been made to fabricate coatings at lower aluminizing temperatures and the current results suggest that FeAl coatings can be synthesized at temperatures as low as 700 deg C.