2.7. Potentiostatic Corrosion Test

The crevice corrosion resistance test was performed using the potentiostatic method, recording the curves of the current density as a function of time. The same measuring stand was used for the test as in the potentiodynamic tests. The measurements were started with the determination of the value of the open circuit potential E_ocp. Then, a potentiostatic curve was recorded, based on which the surface charge density, Q, was determined and, based on its course, the crevice corrosion resistance was assessed. The change of current density in time t = 15 min was recorded for potential E = 800 mV in accordance with the recommendations of ASTM F745-04:2009 [43]. The crevice corrosion resistance tests were conducted on samples in the form of a 50 mm long bar in the initial state and with coatings of biodegradable polymers. The tests were performed for 3 samples from each variant. The tests were conducted in the artificial urine for the initial state samples and after 30, 60, and 90 days of exposure to the artificial urine.