Effect of various lanthanum sol–gel coatings on the 330Cb (Fe–35Ni–18Cr–1Nb–2Si) oxidation at 900 °C

The influence of a lanthanum sol–gel coating on the oxide scale adherence has been studied during the 330Cb (Fe–35Ni–18Cr–1Nb–2Si) oxidation at 900 °C, in air. The alloy oxidation is performed in order to generate a protective chromia scale acting as a good barrier against carburization. Argon annealing of lanthanum sol–gel coatings have been performed at various temperatures in order to find the best conditions to insure the scale adherence. Kinetic results show that lanthanum sol–gel coatings lead to a lower oxidation rate compared to blank specimens. Thermal cycling tests on lanthanum the sol–gel coated specimen show that the oxide scale formed at 900 °C, in air, is adherent.