Study on corrosion mechanism of laser-clad Ni-WxC coating by in-situ electrochemical method under high temperature and pressure environment

Corrosion protection of oil and gas equipment by laser cladding technology has emerged as a crucial method to reduce costs and increase efficiency. The in-situ electrochemical method was employed to investigate the microstructure evolution and corrosion mechanisms of laser-clad Ni1725-WxC coatings u...

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Bibliographic Details
Published in:Materials today communications 2024-12, Vol.41, p.110699, Article 110699
Main Authors: Wang, Qin-ying, Ma, Wen-qi, Ji, Yun-han, Chai, Hui, Zhang, Xing-shou, Xi, Yu-chen, Dong, Li-jin, Bai, Shu-lin
Format: Article
Language:English
Subjects:
Corrosion mechanism
High temperature and pressure corrosion
In-situ electrochemical method
Laser cladding technology
Ni-WC coating
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Summary:Corrosion protection of oil and gas equipment by laser cladding technology has emerged as a crucial method to reduce costs and increase efficiency. The in-situ electrochemical method was employed to investigate the microstructure evolution and corrosion mechanisms of laser-clad Ni1725-WxC coatings under high temperature and pressure environment. The coating is composed of cellular γ-Ni (W, Cr, Fe), block W2C, WC/W2C eutectic structure with a shell of WC, and small amount of CrxCy (Cr7C3/Cr23C6) in Ni1725 matrix. The corrosion resistance of the coating is worsened with increasing temperature under in-situ electrochemical method owing to reduced reaction activation energy and increased transfer rate. Furthermore, the surface potentials of the coating follow the order: E1 (WC shell) > E2 (Ni1725 matrix (oxide)) > E3 (WC/W2C eutectic phase) > E4 (block W2C). Therefore, galvanic corrosion occurs between WC shell and Ni1725 matrix. W2C with lower potential corrodes preferentially as well at WC/W2C eutectic structure in WxC particle, which expands with increasing temperature to form a loose internal structure. [Display omitted] •WxC particles have WC shell on the surface and WC/W2C eutectic structure inside.•In-situ electrochemical test evaluated the behavior of Ni1725-WxC laser-clad coating.•Surface potential of WC shell > Ni1725 matrix (oxide) > WC/W2C eutectic > block W2C.•Galvanic corrosion occurs at WC/W2C eutectic and between WC shell and Ni1725 matrix.
ISSN:2352-4928
2352-4928
DOI:10.1016/j.mtcomm.2024.110699