Improvement in Resistance to Steam Oxidation of Aluminide-Coated AISI 304 and AISI 316 Steel Produced by Chemical Vapor Deposition in a Fluidized Bed Reactor

摘要

Various techniques have been used to deposit aluminium on ferritic and austenitic steels to increase their oxidation resistance. An aluminide coating was deposited on AISI 304 and AISI 316 stainless steels by chemical vapor deposition at 580 A degrees C for 1.5 h in a fluidized bed reactor. The as-deposited samples were treated at 750 A degrees C in Ar atmosphere for 2 h. Scanning electron microscopy/energy-dispersive X-ray spectroscopy and X-ray diffractometry were used to study morphology and composition. Deposition results indicated that FeAl, Fe2Al5, Al0.99Fe0.99Ni0.02, AlNi, and Fe2AlCr had formed. Specimens were oxidized in a steam loop at 750 A degrees C for 1000 h to evaluate the steam oxidation resistance of the coating. The thermodynamic software package Thermo-Calc was used for simulations under similar experimental oxidation conditions. Gravimetric measurements verified that the mass change of the coated samples decreased up to 100 times with respect to uncoated steels.