Unraveling the effects of CO_2 and H_2S on the corrosion behavior of electroless Ni-P coating in CO_2/H_2S/Cl~- environments at high temperature and high pressure

摘要

The effects of CO2 and/or H2S on the corrosion behavior of electroless Ni-P coating were investigated using weight loss method, surface characterization and water chemistry analysis. The results show that Ni-P coating demonstrates good resistance to corrosion in CO2 environment. While in H2S and CO2-H2S environments, corrosion of the coating is aggravated and controlled by H2S. The coexistence of CO2 and H2S causes a CO2-enhanced H2S corrosion effect, synergistically accelerating the coating degradation through increasing the electrolyte aggressiveness and changing the surface film characteristics. Concurrently, H2S facilitates the electrolyte penetration at the coating microdefects, causing the localized corrosion of substrate.