Electrodeposition of δ-phase based Cu-Sn mirror alloy from sulfate-aqueous electrolyte for solar reflector application

Copper-tin (Cu-Sn) intermetallic alloy coating was developed on mild steel substrate by galvanostatic electrodeposition technique from sulfate-based acidic electrolyte containing Laprol as additive. The homogenous coating containing cubic δ phase with composition of 32.6% Sn was obtained, when a current of −8.5 mA was made to flow through the electrochemical bath. The optimized coating with thickness of ∼0.4-3 μm exhibits ∼80% specular reflectance. The coating has a hardness of 2.6 GPa, suggesting a good scratch resistance property. The experimental results also suggest that the hydrophobic surface of Cu-32.6% Sn thin film can be potentially used as an attractive coating for solar reflector application under dusty and humid conditions.