The aim of the present work is to investigate the effect of Lanthanum surface addition on
the oxidation behaviour of the AISI 304 stainless steel, in air, at 1000°C. The in situ X-ray
diffraction (XRD) analyses on the blank steel reveal that after the first 10h oxidation, a change in
the structural composition of the oxide scale occurs. During the first ten hours oxidation an initial
growth of chromia and Mn1,5Cr1,5O4 is observed. After 10 h oxidation, chromia is not detected
anymore and iron-containing oxides such as hematite (Fe2O3) and iron chromite (FeCr2O4) are
observed in the outer part of the scale. With blank AISI 304 specimens, the iron-containing oxides
are generally not very protective and show severe spallation during cooling to room temperature
due to thermal stresses. They do not allow a good adherence of the corrosion layer under thermal
cycling. On the Lanthanum coated AISI 304 Stainless Steel the oxidation rate is 10 times lower. In
situ XRD analyses show the absence of iron containing oxides. It reveals the formation of a fine
convoluted Cr2O3 layer associated with the formation of the mixed oxides Mn1,5Cr1,5O4 and LaCrO3.
LaCrO3 is found to be located at the oxide/steel interface. Our results show that, even though the
scale formed under isothermal conditions is not composed of iron containing oxides, Lanthanum
sol-gel coating does not prevent spallation during thermal cycling at 1000°C.
Enhancement of corrosion protection of AISI 304 stainless steel by nanostructured sol–gel TiO2 films