**3.3 Potentiodynamic polarization tests**

Investigation of the electrochemical corrosion behaviour was done in a PGP 201 potentiostat using a conventional three-electrode cell consisting of a saturated calomel reference electrode (SCE), a platinum counter electrode and the studied specimen as the working electrode. To simulate the corrosion media, 0.5N H2SO4 and 0.5N NaCl solutions were used. The solution temperature was 23°C±1°C. The corrosion behaviour was studied first by measuring the open circuit potential (OCP) for 30 min. Subsequently, anodic polarization curves were registered. The curve started at a potential of ~100 mV below the corrosion potential. The potential has been changed in the anodic direction at the rate of 1 mV/s. After the anodic current density being equal 1mA/cm2 was achieved, the direction of polarization has been changed. Thus, the return curve was registered. The corrosion current densities and the polarization resistance were obtained on the basis of the Tafel analysis.
