Effects of Fe₃O₄ Addition on the Oxide Scale of a Steam Generator Tube in High-Temperature Water

The current work investigated effects of Fe3O4 addition on the oxide scale of the stream generator (SG) tube in high-temperature water by using different surface analysis methods. It is found that the oxide scale of the SG tube presents a three-layer structure no matter the addition of Fe3O4 or not, namely: the outmost dispersedly deposited particle, the outer layer which is rich in Ni and Fe, and the inner layer which is rich in Cr. The addition of Fe3O4 does not affect the growth dynamics of the Cr enriched inner layer, but can enhance the deposition of NiFe2O4 on the tube surface. Moreover, the deposition of NiFe2O4 on the surface of Fe3O4 is much faster than the one on SG tube surface. The related mechanisms and the implications on the SG tube service performance are also discussed.