## 3 Results and Discussion
### In Vitro Electrochemical Tests Using the Potentiodynamic Method  
The next stage in electrochemical research involves conducting the potentiodynamic method in order to determine the susceptibility of the CoCrMo electrode to pitting corrosion in the tested environments. The obtained anodic polarization curves, showing the relationship \(\log\mathrm{|\,j|}=\mathrm{f(E)}\) for the tested material in body fluid solutions, are presented in Figure 8. These tests were carried out at a polarization rate v = 1 mV s\({}^{-1}\). The current density values were logarithmized in order to determine the parameters characterizing the corrosion resistance of the tested electrode in particular environments. The CoCrMo electrode showed passive behavior in each tested environment, thanks to its optimal chemical composition, where the Cr and Mo contents were within the limits, ensuring the highest corrosion resistance [29]. The corrosion potential values determined for the tested material in individual environments vary depending on the pH of the solutions used and the presence of addi  
Figure 8: Anodic polarization curves for the CoCrMo electrode in the applied corrosion environments at 37 \({}^{\circ}\)C.  
tives in the form of mouthwashes and NaF introduced into the solutions as modifiers. The corrosion potential (E\({}_{\text{cor}}\)) of the tested electrode and the corresponding corrosion current density (j\({}_{\text{cor}}\)) vary depending on the environment used. The most negative (cathodic) value was shown by CoCrMo in the (1) artificial saliva solution with pH = 7.4 (E\({}_{\text{cor}}\) = \(-365\) mV, j\({}_{\text{cor}}\) = \(1.25\)\(\times\)\(10^{-8}\) A cm\({}^{-2}\)) [30]. A strongly cathodic value of the corrosion potential was also observed in (7) saline at pH = 7.4 (E\({}_{\text{cor}}\) = \(-237\) mV, j\({}_{\text{cor}}\) = \(2.27\)\(\times\)\(10^{-9}\) A cm\({}^{-2}\)). The CoCrMo alloy tested in the environment of artificial saliva with the addition of Listerine(r) (5) and Meridol(r) (6) mouthwashes had similar corrosion potential values of E\({}_{\text{cor}}\) = \(-295\) (j\({}_{\text{cor}}\) = \(1.65\)\(\times\)\(10^{-9}\) A cm\({}^{-2}\)) and \(-203\) mV (j\({}_{\text{cor}}\) = \(4.53\)\(\times\)\(10^{-9}\) A cm\({}^{-2}\)), respectively. In the artificial saliva solution with pH = 7.4 (3) and pH = 5.5 (4) enriched with NaF, we observed the most positive corrosion potential values of E\({}_{\text{cor}}\) = \(-174\) (j\({}_{\text{cor}}\) = \(6.85\)\(\times\)\(10^{-9}\) A cm\({}^{-2}\)) and \(-128\) mV (j\({}_{\text{cor}}\) = \(5.47\)\(\times\)\(10^{-9}\) A cm\({}^{-2}\)), respectively. This is related to the presence of fluoride anions in the solution which facilitate the formation of a chromium(III) oxide layer on the electrode surface, in accordance with [PERSON]'s theory [32]. Corrosion damage is caused by the adsorption of aggressive chloride ions on the metal surface which penetrate through the passive layer. Chloride anions hinder the incorporation of metal ions into the metal layer and facilitate their penetration into the solution. The highest j\({}_{\text{cor}}\) value of 2.21(24) \(\times\)\(10^{-8}\) A cm\({}^{-2}\) was observed in (2) artificial saliva with pH = 5.5, which indicates the highest rate of electrochemical corrosion in an inflammation-simulating environment with a E\({}_{\text{cor}}\) value of \(-160\) mV. Based on the obtained electrochemical results, a three-layer model centered around the formation of a passive layer on the CoCrMo alloy in the tested corrosion environments can be proposed. It describes the process and chemical description of the reaction of creating a passive layer on the tested material. When the CoCrMo alloy (electrode) is immersed in the corrosive medium and the external voltage is applied to the system, chromium dissolution is initiated according to the Pourbaix diagram [33].