GB694811A - Electrodeposition of tin-cobalt alloys - Google Patents

Abstract

694,811. Electro-deposition of tin-cobalt alloys. IRELAND, J. Dec. 7, 1951 [Jan. 1, 1951], No. 36/51. Class 41. Tin-cobalt coatings containing 50-90 per cent of tin are deposited from an aqueous solution of salts of the metals in the necessary proportions, the solution comprising fluoride anions. The solution may comprise in addition chloride and/or sulphate ions and cations of an alkali metal or ammonium. The anode may be of a tin-cobalt alloy of the same composition as the required depositor; separate anodes of tin and cobalt may be used in succession or simultaneously with appropriate regulation of the current through each; or an anode of one of the metals may be used, the other metal being replenished periodically by addition of a suitable salt to the bath. Examples of bath compositions &c. are (i) SnCl 2 .2H 2 O 100, Co Cl 2 .6H 2 O 450, NaF 55 gms./lit., temperature 65‹ C., current density 18 amps./sq. ft., coating 80‹ Sn, 20 per cent 60; (ii) SnF 2 20, Co 150, NaF 75 gms./lit., temperature 65‹ C., current density 18 amps. sq. ft., coating 90 per cent Sn, 10 per cent Co; (iii) SnCl 2 .2H 2 O 40, Co Cl 2 .6H 2 O 300, NaF 30, NH 4 HF 2 35 gms./lit., temperature 65‹ C., current density 24 amps./ sq. ft., coating 70 per cent Sn, 30 per cent Co. A prior proposal for a tin bath containing stannous chloride and an alkali metal fluoride, together with 2-10 gms./lit of a cobalt salt and one or more organic addition agents is referred to.