Effect of fluidized bed CVD aluminide coatings on the cyclic oxidation of austenitic AISI 304 stainless steel

Austenitic AISI 304 stainless steel finds a vast variety of applications du e to its good performance in different environments and its relatively low price. However, its high temperature operation limit is restricted to appro ximately 950 degreesC due to the formation of volatile CrO3 under oxygen en vironments. Thus, the application of aluminide coatings may increase the up per temperature LIMIT of this steel. Chemical vapour deposition in fluidise d bed reactors (CVD-FBR) has been used to coat AISI 304 steel at temperatur es of 525 degreesC for 1.5 h followed by a heat treatment up to 900 degrees C. Cyclic oxidation experiments of both coated and uncoated specimens have been conducted under atmospheric pressure air at 950 degreesC. The results are very promising for the application of the CVD-FBR process as a surface modification technology since the behaviour of the coated specimens is much better than that of the uncoated ones. (C) 2001 Elsevier Science B.V. All rights reserved.