抄録
The composition of cathode films formed on tin in CrO3 solutions with and without the addition of H2SO4 was examined by ESCA as a function of cathode potential. In general, films consist of an outer chromic chromate layer and an inner stannous-stannic oxide layer, and changes in the composition with potential are reflected by complex current-voltage curves consisting of several current waves. A metallic tin (Sn0) spectrum appeared at potentials below the natural potential, and the spectrum intensity ratio Sn0/(Sn2++Sn4+), showed minima at the peak current potentials and maxima at the minimum current potentials. Chromic chromate films consisted mainly of trivalent chromium compounds. In the range more negative than about -0.6V, a hexavalent chromium compound was found in cathode films, and the oxide layer of tin consisted mainly of stannic oxide. Thus it is considered that changes in the chemical state of the tin electrode play an important role in chromium deposition.
