Electrodeposition of tin coatings having enhanced corrosion resistance and anti-discoloration performance from tin (IV) sols

Due to the extensive application of tin coatings, the electrodeposition mechanism, corrosion resistance and anti-discoloration performance have attracted attention in the past decades. In this paper, tin coatings containing sol particles were successfully prepared using the stable tin (IV) sols as the plating bath, based on the water-ethanol electrolytes. The particle size of the tin sols was largely in the range between 4 and 10 nm. When the sol contained 0.475 mol L− 1 SnCl4·5H2O (Sol 2), the sol particles were uniformly deposited on tin coatings. The concentration of tin sol had a significant effect on the surface microstructure and preferred orientation of the electrodeposited tin coatings. The differences in nucleation process of the electrodeposition between tin sols and the aqueous acidic sulfate plating bath (sulfate bath) were revealed by electrochemical analysis. Compared with tin coatings deposited from sulfate bath, tin coatings deposited from Sol 2 had enhanced corrosion resistance and anti-discoloration performance.