1). This will require applying an external anode current, part of which will go to suppress the cathodic reaction to a value of i , while the other part - to accelerate the reaction of metal ionization in. The rate of metal dissolution at this potential is. From Fig. Table 1 shows that although corrosion rate and decreased, but the overall rate of dissolution of the metal increased the amount.
For these reasons, you can not use the imposition of the anode current for corrosion protection of actively dissolving metals. But Many metals, especially with incomplete d-electron layers, the displacement capacity of up to magnitude Ekor E 'pass into a passive state, which corresponds to a sharp deceleration of the ionization, to protect them used epoxy enamel EP. Current of metal dissolution is reduced to the value of icor ipas (Fig. 3). In this case the current solution of the metal decreases tenfold. External anodic current density, which is required for the transfer of the metal in passive state, is usually quite high. When the metal is turned into a passive state, its maintenance requires further applying an external current, small in size, which makes the anode protection highly effective method of preventing corrosion of metals.
For example, to start the passivation of stainless steel in 66% solution of H2SO4 at room temperature ( 24?) Is required anode current density 6 A/m2, and to further promote passive state - only 10 - 3 A/m2. The currents of the anodic protection is usually much smaller than the corresponding current cathodic protection. It must be emphasized that anodic protection is suitable for corrosion control only easily passivated metals during anodic polarization (Fe, Ni, Cr, Mo, Ti, Zr) and does not apply to metals such as Zn, Cu, Cd, Ag.
For these reasons, you can not use the imposition of the anode current for corrosion protection of actively dissolving metals. But Many metals, especially with incomplete d-electron layers, the displacement capacity of up to magnitude Ekor E 'pass into a passive state, which corresponds to a sharp deceleration of the ionization, to protect them used epoxy enamel EP. Current of metal dissolution is reduced to the value of icor ipas (Fig. 3). In this case the current solution of the metal decreases tenfold. External anodic current density, which is required for the transfer of the metal in passive state, is usually quite high. When the metal is turned into a passive state, its maintenance requires further applying an external current, small in size, which makes the anode protection highly effective method of preventing corrosion of metals.
For example, to start the passivation of stainless steel in 66% solution of H2SO4 at room temperature ( 24?) Is required anode current density 6 A/m2, and to further promote passive state - only 10 - 3 A/m2. The currents of the anodic protection is usually much smaller than the corresponding current cathodic protection. It must be emphasized that anodic protection is suitable for corrosion control only easily passivated metals during anodic polarization (Fe, Ni, Cr, Mo, Ti, Zr) and does not apply to metals such as Zn, Cu, Cd, Ag.
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