First-principles study on corrosion resistance of copper-bearing hypereutectic high chromium cast iron

Abstract

Based on the Tafel formula, Butler-Volmer equation, and first-principles calculations, the bulk model, surface model, and polarization prediction curve of the Hypereutectic High Chromium Cast Iron (HHCCI) matrix were constructed. The results show that the predicted corrosion current density (2.19×10 -5 A·cm 2 ) of the copper-bearing HHCCI matrix is lower than the measured corrosion current density of the copper-bearing HHCCI (4.41×10 -5 A·cm 2 ) under the acidic condition of pH=1. In the neutral environment of pH=7, the corrosion resistance of HHCCI is better than that of HHCCI under acidic conditions. The predicted corrosion current density of the copper-bearing HHCCI matrix (4.39×10 -10 A·cm 2 ) is also smaller than that of copper-free HHCCI (7.98×10 -10 A·cm 2 ), which shows that the corrosion resistance of copper-containing HHCCI matrix is better than that without copper from the perspective of first-principles calculation. Combined with the electrochemical experimental results, it can be seen that the corrosion potential (-409.76 mV) of 1.5 wt.% Cu HHCCI is significantly higher than that of 0 wt.% Cu HHCCI (-450.34 mV). The trend of the electrochemical test results is consistent with the predicted trend of the calculated polarization curve, which indicates that copper alloying can improve the corrosion resistance of HHCCI. Predicted polarization curves on γ-Fe (100) surfaces (PH=1): (a) γ-Fe (Cu-Free); (b) γ-Fe (Cu-Bearing) • Predicting corrosion resistance using equations and first-principles. • Copper improves the predicted current density of HHCCI matrix at pH=1. • Copper improves the current density of HHCCI at electrochemical experiments. • Copper alloying improves HHCCI corrosion resistance.