Evaluation of corrosion resistance of Cu, Cu-10 wt% Ni, Cu-20 wt% Ni, and electroless Ni-B and Ni-P coatings in Simulated Seawater

Given the widespread use of cupronickel alloys in the marine industry, despite their higher cost than pure copper, this work explores the application of Ni-B and Ni-P coatings on pure copper as a potential alternative. Ni-6 wt% B (Ni-B) and Ni- 11 wt% P (Ni-P) coatings were applied using an electroless process. The microstructure and morphology of the coatings were analyzed using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). The corrosion behavior of the Ni-B and Ni-P coatings, along with Cu-10 wt% Ni (Cu-10Ni), Cu-20 wt% Ni (Cu-20Ni), and pure copper, was investigated in simulated seawater (SSW) using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization methods. The results showed that the Ni-P coating exhibited the highest corrosion resistance (4.5 ×10 ^− 7 A.cm ^− 2 ), followed by the Ni-B coating (5.5 ×10 ^− 7 A.cm ^− 2 ). The corrosion resistance of Cu-10 wt% Ni (1.2 ×10 ^− 6 A.cm ^− 2 ) and Cu-20 wt% Ni (1.1 ×10 ^− 6 A.cm ^− 2 ) was superior to that of pure copper (2.5 ×10 ^− 6 A.cm ^− 2 ). The corrosion mechanism of the alloys is influenced by both the charge transfer process and diffusion. Additionally, the significantly higher hardness of the Ni-B (930 ± 10 HV) and Ni-P (605 ± 5 HV) coatings compared to the bare alloys suggests improved tribological performance.