DETERMINATION OF THE EXCHANGE CURRENTS AT THE SILVER MICROCRYSTAL-NITRATE MELT INTERFACE

The exchange currents for the silver deposition-dissolution reaction a re determined in an individual AgNO3 melt and dilute AgNO3-NaNO3-KNO3 solutions at 250-300 degrees C. The exchange current was calculated us ing the experimental time dependences of overvoltage and the data on t he number of crystals formed at the cathode. At a given current densit y of the polarizing current, the exchange current is found to depend o n the cathode material (platinum or iridium) and the state of the cath ode surface, which is governed by the conditions of a preliminary anod ic treatment. The exchange current is observed to increase considerabl y with the increasing current density, which may be attributed to the dependence of the structure and size of growing crystals on the curren t density.