The Thermokinetic Instability of the Surface-covering
Layers during High-Rate Anodic Dissolution Controlled
by Mass Transfer

A. I. Dikusar, A. N. Mustyatse, and S. P. Yushchenko

Institute of Applied Physics, Academy of Sciences of Moldova, Chisinau, Moldova

Received July 31, 1995

Abstract—Anodic dissolution of copper is experimentally studied in nitrate solutions (0.2–20 A cm^–2) in a cell
with chaotic electrolyte agitation. The study is conducted at different electrode configurations, specifically: (a)
a stationary disk electrode and (b) a model of large artificial pitting. The experimental results are utilized to
show that the activation of anodic dissolution and the loss of stability of the surface-covering layers in one case
and the absence of the latter in the other can be attributed to different heat exchange conditions. It is confirmed
experimentally that activation in the (a) case is observed under the condition T_s > , where represents a
critical surface temperature corresponding to transition to thermokinetic instability. The (b) case, on the other
hand, is characterized by passivation, which occurs at the same current densities, because T_s < . It is dem-
onstrated that the loss of stability of surface layers comprising dissolution products, which is observed at T_s
, is associated with the kinetic (thermofluctuation) nature intrinsic to the strength of the solids.

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