Corrosion Behavior of Electroless Ni-P coating in the NaCI solution containing CO_2 and H_2S

摘要

The corrosion behavior of Ni-P coating in 3.5 wt% NaCI solution containing CO_2 and H_2S was investigated using electrochemical methods and surface characterization techniques. The results show that CO_2 can promote the corrosion of Ni-P coating, and the corrosion resistance of the coating significantly decreases with the co-existence of the two gases, implying the accelerating effect of H_2S on corrosion. Moreover, H_2S also promotes the electrolyte penetration through the coating, resulting in the severe localized corrosion and coating disbonding after the long-term immersion. Nickel hydroxide and nickel sulfide are the main corrosion products in CO2/H2S environment.