Abstract
The electrodeposition of tin-nickel alloys from acidic baths containing stannous and nickel chlorides, was investigated in relation to the effects of several addition agents on the appearance and composition of the deposits as well as on the cathode current efficiency. Synergistic use of a combinations of thiourea and either cresol sulfonic acid or 1, 5-sodium naphthalenedisulfonate as addition agents above 65°C produced the best alloy deposit with respect to brightness. The cathode current efficiency and the tin content of the deposit, however, decreased with decreasing the current density below 1A/dm2. A bright and adherent Sn-Ni alloy coating was obtained at 65°C and above 1A/dm2 with a high current efficiency, from the bath containing 30g/l SnCl2⋅2H2O, 300g/l NiCl2⋅6H2O, 132g/l NaCl, 10 vol% HCl and the addition agents as mentioned above; the atomic ratio of Sn to Ni of the alloy was kept to be 1 to 1.
