Influence of Oxidation Pretreatment at Low Oxygen Partial Pressure on Corrosion Resistance of Nickel Base Alloy 028

The pretreatment of nickel base alloy 028 at low oxygen partial pressure was carried out at 900℃ for 10h. After the pretreatment, the microstructure of the nickel alloy 028 sample was refined, precipitation along with its boundaries decreased and its hardness increased. The Cr2O3 and NiCr2O4 oxide films with continuously compact structural feature were formed primarily on the sample surface. They were examined by SEM, EDS and XRD. The polarization curve of the sample after the pretreatment indicated that its corrosion potential moved from -0.25V to -0.37 V(SCE), and corrosion current density obviously reduced compared with those of the control sample. The measurements of EIS showed that the charge transfer resistance after pretreatment rose by an order of magnitude and the film resistance reached 2 times or more compared with those of the control sample.