非シアン化浴からのAg-La₂O₃分散めっき

抄録

In Ag-La₂O₃ dispersion plating, where lanthanum oxide is regarded as a dispersed phase, silver ion in liquid medium is adsorbed on the colloidal oxide particles, which have negative charge. As the amount of lanthanum oxide in the medium increases, the co-deposition of the oxide in the deposition layer increases linearly. Oxide co-deposition also increases with increasing current density. It was found that the properties of the plated film depended on the amount of lanthanum oxide in the bath as well as the current density, lanthanum oxide was distributed uniformly on the deposition layer and smaller silver crystals were formed. The hardness and antiwear properties of the plated film were markedly improved over those of pure silver. The addition of triethylenetetramine and polyethyleneimine also improved the surface properties.
With the co-deposition of lanthanum oxide particles, the oxide reacts with silver in the deposited layer and a reaction layer is formed, so that the binding energy on the 3d orbit of lanthanum is decreased.