抄録
Gold-tin alloys were electrodeposited in aqueous solution of K4P2O7 containing KAu(CN)2 and Sn2P2O7. Cathode potential on metal electrodeposition in the mixed solution of Au+ and Sn2+ ions was intermediate between the equilibrium potentials of Au+ and Sn2+ in the bath. Gold content in gold-tin electrodeposited alloys was always higher than Au+ concentration in an electrolyte, and that in the coats was within the range of 78-86%, at pH9-11. Gold-tin alloys electrodeposited, whose Au/Sn mol ratio in bath was 0.03/0.25, has a dull gold-gray adhesive and smooth surface. Current efficiency of the alloy electrodeposition was close to 100% at pH9-11, and alloy coats with 20% tin content were obtained at pH8-11. Tin content of electrodeposited alloys increased with increasing current density, tending to decrease with an increase in electrolytic temperature. Cathode current efficiency was over 95% in the range between 0.22 and 0.61 of Sn/Au mol ratio of alloy composition. As a result of X-ray diffraction of gold-tin electrodeposited alloys, the crystal structure was supposed to be similar to that of metallurgical gold-tin alloys. A dully gold-gray adhesive and smooth surface was obtained under the electrolytic conditions of the Au/Sn mol ratio being 0.03/0.25, and at pH9, 25°C, and a current density of 10mA·cm-2.
