_{1}

In this work, the mechanism of interaction of pittings, occurring on the heterogeneous surface of the passivated metal at presence in an aqueous electrolyte solution the activating (halide) anions is developed. A mathematical scheme describing this mechanism is presented. The equations for the currents density of the anodic dissolution of pitting as a function of concentration of activating anions and free water are obtained. The closed system of the equations representing a basis theory of an interaction of pittings is obtained.

Pittings are called, as is known, local, i.e., small on the area (with a radius of r ~ 10^{-}^{2} to 0.5 cm), but deeply penetrating, often through the destruction of the metal lattice in the electrolytes, occurring on the mechanism of its anodic dissolution.

Pittings spontaneously appear as a result of the interaction of the metal surface with an electrolyte with the values of the anode potential, which corresponds to the region of the passiveness of metal and the presence in electrolyte a sufficiently high concentration of activating anions. The most dangerous of them are

The internal surface of a pitting is dissolved at a rate by (10^{2} to 10^{4}) times greater than the rate of dissolution of the surrounding metal surface.

Therefore at the small on mass loss of metal, pittings render inoperable large metal structures, limiting the periods of their exploitation service in different production technologies and other regions.

Consequently, there are many experimental studies concerning pittings but the pitting process theory is underdeveloped. It is necessary to highlight the problem of the localization mechanism of pitting, the mechanism of their interaction and the mechanism of their growth. These tasks can be considered independently.

In [

Relative to this interaction in [

According to [

ions

ample in [

Under these conditions, it is known [

where

The above assessment of the concentration

Therefore, the volume of electrolyte solution is divided into areas

In [

At first let us consider the mechanism of this process by the example of a model of two coupled pittings,

In this model, two interacting pittings are modelled by the anodic dissolving surfaces

As outlined above, by dissolving the water flows arise

ions

On it are continuous the values of free water concentrations in volumes

where

Similar conditions for convection flows

According to the mathematical physics [^{2}・sec). For each mole of metal ions on the cathode utilised is

where x_{k}―cathode plane coordinate,

If

where the upper signs (+) and (−) mean the opposite sides of the interface

They are considered in the coordinate system, connected with metal electrodes. The initial conditions for them determine the composition of the electrolyte, that allows to study its influence on the pitting formation. In (1)-(6) current density

where the stoichiometric number

where the index

In conclusion, we should note that apparently only with the model on