Unraveling the effects of CO2 and H2S on the corrosion behavior of electroless Ni-P coating in CO2/H2S/Cl– environments at high temperature and high pressure

• Published in: Corrosion science Vol. 148; pp. 317 - 330
• Main Authors: Sun, Chong, Zeng, Hongbo, Luo, Jing-Li
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.03.2019; Elsevier BV
• Subjects: A. Metal coatings; B. SEM; B. Weight loss; B. XPS; C. Acid corrosion; C. Pitting corrosion; Carbon dioxide; Coating effects; Corrosion; Corrosion effects; Corrosion environments; Corrosion resistance; Electrolytes; High temperature; Hydrogen sulfide; Localized corrosion; Nickel coatings; Organic chemistry; Pressure effects; Substrates; Surface properties; Water chemistry; Weight loss; B. SEM; B. XPS; A. Metal coatings; C. Pitting corrosion; C. Acid corrosion; B. Weight loss
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2018.12.022

[Display omitted] •Electroless Ni-P coating has a good resistance to CO2 corrosion in CO2 environment.•Coating corrosion is aggravated and dominated by H2S in H2S and CO2-H2S environments.•The localized corrosion of the substrate occurs in both H2S and CO2-H2S environments.•The coexistence of CO2 and H2S synergistically accelerates the coating degradation.•The degradation and film formation model of Ni-P coating with micropores is proposed. 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.