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Engineering of zinc-bismuth binary microspheres and evaluation of ZnBi-rich primer for corrosion protection of steel in marine environment

Year: 2025
Type: article
Abstract: • Zn-Bi microspheres with a bilobed morphology and Janus-like configuration synthesized. • Self-corrosion and galvanic corrosion of Zn-Bi microspheres investigated. • ZnBi-rich primer fabricated for steel corrosion protection. • Zn-Bi microspheres exhibited enhanced galvanic activity compared to pure zinc. Zinc-rich primers (ZRPs) are highly effective for steel corrosion protection. In this study, two types of zinc-bismuth binary microspheres (ZnBi1 and ZnBi2) were produced via co-evaporation of zinc and bismuth under gas flow rates of 4 Nl/min and 0.3 Nl/min. Scanning electron microscopy and energy-dispersive spectrometer, X-ray diffraction and differential scanning calorimetry analyses showed that both ZnBi1 and ZnBi2 particles were heterogeneous solidified mixtures, with Zn and Bi non-uniformly distributed in individual particles. ZnBi1, with finer particle size, exhibited higher self-corrosion and galvanic corrosion rates in 3.5 wt.% NaCl solution in its pulverized state. The particles were incorporated into ZRPs, and their sacrificial effects were evaluated using a salt spray exposure test, open circuit potential (OCP) and electrochemical impedance spectroscopy measurements. Compared to conventional ZRP containing 78 wt.% commercial zinc dust, the coating with 78 wt.% ZnBi1 particles exhibited enhanced cathodic protection at an early stage of exposure due to promoted sacrificial oxidation of zinc at damaged areas. However, the accelerated zinc oxidation led to a shortened cathodic protection duration as observed in the OCP result. A combination of ZnBi particles and commercial zinc dust mitigated the intense galvanic function, resulting in a more stable galvanic activity and improved anticorrosion performance.
DOI: 10.1016/j.jmst.2025.04.012
Language: English
Open Access status: hybrid
Estimated APC paid: $3,000
OpenAlex ID: W4410221035
FWCI: 1.044
Cites: 57
Cited by: 5
Related to: 10