Study on Surface Modification of Fe–Si–Cr Alloy by Selective Oxidation Heat Treatment and its Corrosion Properties

Corrosion properties of the insulating oxide layer formed on the Fe–Si–Cr alloy through the selective oxidation heat treatment are evaluated to find out that the oxide layer can play a role as a barrier layer against corrosion. Preferential oxidation of Si and Cr during the selective oxidation heat treatment results in a two‐layered oxide layer. From the X‐ray photoelectron spectroscopy and transmission electron microscope results, it is revealed that the inner layer is SiO 2 and the outer layer is Cr 2 O 3 , and they keep growing with the heat treatment time. The oxide layer formed by the selective oxidation heat treatment causes the ennoblement of the corrosion potential, but additional ennoblement does not occur with the growth of the oxide layer. However, the thickness of the oxide layer influences anti‐corrosion performance in terms of corrosion resistance and deterioration. The thicker the oxide layer is, the higher the corrosion resistance and the slower the deterioration become so that the protection property withstands for 3 h in the 3.5 wt% NaCl solution when the oxide layer has 44.3 nm thickness.