Structural, microstructural and corrosion properties of brush plated copper–tin alloy coatings

Cu–Sn alloy coatings on mild steel substrates produced by the brush plating process have been investigated using XRD, SEM and AFM. X-ray diffraction analysis revealed that the brush plated Cu–Sn alloy was heterogeneous and composed of hexagonal η-Cu6Sn5, orthorhombic ε-Cu3Sn, tetragonal β-Sn and cubic Cu phases. Uniform surface coverage of the substrate by granular morphology was observed from SEM and AFM. The alloy composition was determined from atomic absorption spectroscopy (AAS). The corrosion protection performance of brush plated Cu–Sn alloy on mild steel has been assessed using salt water immersion and electrochemical corrosion tests. The results indicated a high charge transfer resistance and very low ICorr for the alloy system comparing with that of individual elements on the substrate and the mild steel substrate.