Low cost rare earth elements deposition method for enhancing the oxidation resistance at high temperature of Cr2O3 and Al2O3 forming alloys

Zn this work a deposition method for coating Cr2O3 and Al2O3 forming alloys with rare earth elements is described. This is a modified CVD deposition method based on the pyrolysis of an aerosol produced by ultrasonic waves focused on the surface of a solution containing a soluble salt of the desired element that will later transform to oxide. To test the efficiency of the deposition method, commercial AISI-303 stainless steel samples were coated with lanthanum and cerium nitrates. Oxidation experiments have been performed in a thermobalance at 1173 K in synthetic air atmosphere for 25 h. Oxidation kinetics of coated samples was compared with that of an untreated one. Results show that samples coated with La and Ce improve their high temperature oxidation resistance by decreasing their parabolic rate constant of one order of magnitude. During the oxidation treatment LaCrO3 perovskite forms in the scale of La-coated specimens while CeO2 is the crystalline phase detected in the Ce-coated ones. (C) 2001 Elsevier Science B.V. All rights reserved.