Texture evolution and corrosion behaviour of Sn–1.5 wt% Cr coatings containing Graphene oxide

ABSTRACT

Sn–1.5 wt% Cr coating incorporated with varying quantity of Graphene oxide (GO) were deposited using electrodeposition technique on mild steel strip using aqueous electrolyte bath. The aqueous bath was dispersed with GO with increasing concentrations in mg/L (31.2, 62.5, 93.7, 125 and 156.2). All the coatings exhibited compact morphology and contained Sn and Cr-oxide phases (CrO₂ and Cr₂O₃). Potentiodynamic polarisation and impedance spectroscopy techniques showed that the coating corrosion resistance increased for the initial addition of GO till Sn–Cr–GO₂ coating (from 62.5 mg/L of GO) and it decreased thereafter for higher GO additions. The corrosion current density value exhibited by pristine Sn–Cr, Sn–Cr–GO₂ and Sn–Cr–GO₅ (from 156.2 mg/L of GO) was 1.38, 0.5 and 4.09 µA/cm², respectively. Characterisation of the coating texture showed that between all the coatings, low angle grain boundary fraction was highest for Sn–Cr–GO₂ coatings. The highest corrosion resistance was on account of special impermeable and inert properties of GO which was uniformly distributed in the coating matrix and the presence of a large fraction of low energy low angle grain boundaries. High corrosion rate in the case of Sn–Cr–GO₅ coatings was attributed to the agglomeration of GO in the coating matrix which resulted in non-uniform coating morphology with high surface defects.

KEYWORDS:

• Sn–Cr electrodeposition
• microstructure
• corrosion
• electron backscattered diffraction
• texture
• Graphene oxide

Acknowledgements

Research funding received from CSIR, SERB, PMRF, Government of India is highly acknowledged. The Authors also acknowledge Electron Microscopy facility in AFMM, IISc.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by Science and Engineering Research board (SERB), CSIR, Government of India.