Korozní rychlost katodicky "chráněné" oceli v prost edí uhli itan

Cathodic passivation is one of the possible explanations of the protective mechanism of cathodic protection. Cathodic reaction taking place in the vicinity of buried equipment results in alkalinisation of soil, which facilitates transmission of iron in a passive state. However, the passivation of steel occurs only if the impressed protection potential is more positive than the passivation potential. The goal of this paper was to identify the passivation potential and corrosion rate dependence on the corrosion potential in carbonates with variable pH using electrochemical methods and a resistometric technique. We were measuring the corrosion rate of iron during a long-term exposure by a resistometric probe. The passivation potential drops with growing pH. Steel gets passivated in carbonates at a usual protection potential of -850 mV/CSE by reaching pH 11. Below this point, steel corrodes in an active state at a corrosion rate of (> 0.01 mm/year), which is unacceptable for buried equipment.