静水压力对X100钢在NaHCO3+NaCl溶液中电化学行为的影响

Effect of hydrostatic pressure on the electrochemical corrosion of X100 pipeline steel in 0.5 mol/L NaHCO3+0.03 mol/L NaCl solution was investigated by means of methodspotentindynamic polarization, electrochemical impedance spectroscopy and Mott-Schottky. The results show that with the increasing hydrostatic pressure the number and the size of corrosion pits increase, while the activity of ions in the solution also increases, which in turn promotes the adsorpting of Cl- in the passive film. As a result, the corrosion rate and the corrosion current density are increased. The component of the passive film transforms from oxide or hydroxide formed by low pressures to carbonate by high pressures, which may result in the decrease of corrosion-resistance and increase of probability of pitting corrosion nucleation. The passivation film formed on the X100 steel exhibits characteristics of n-type semiconductor. The increase amount of Cl- in the passivation film promotes the increase of lattice imperfections and facilitates the cracking of the oxide film.