Properties of Bright Tin-Iron Alloy Plating Films from Gluconic Acid Baths Containing Urea and Nitrilotriacetic Acid

Abstract

Results show that bright tin-iron alloy deposits were obtained by polyoxyethyleneglycol （average molecular weight 4000） to gluconic acid baths containing 0.05 mol/dm³ SnSO₄, 0.1 mol/dm³ FeSO₄･7H₂O, 0.15 mol/dm³ potassium gluconate, 0.05 mol/dm³ NTA, 0.5 mol/dm³ urea, and 0.45 mol/dm³ NH₄Cl. The optimum operating conditions were pH 3, bath temperature 45°C, and current density 7-12 A/dm². Tin-iron alloy films were superior in corrosion resistance to bright nickel plating films because of the formation of tin-iron intermetallic compounds.