Investigation of microstructural and electrochemical corrosion behaviors of Thermal Barrier Coatings (TBC)

The aim of this study is to observe the effects of electrochemical corrosion working environment on the TBC applied to Inconel 718. The effect of electrochemical corrosion was investigated microstructural on coating surfaces of parts such as propellers used in the high temperature working environments and especially in the subject of the study such as acidic-basic environments and seawater environments. Coating processes was applied byusing HVOF method on the base material Inconel 718. Then the coating was completed by using APS method produced from YSZ (ZrO2 + Y2O3) powders. After that; the effects of electrochemical corrosion were investigated microstructural and elemental on the thermal barrier coating material. 0.1 molar NaCl (Sodium Chloride) solutions were prepared to immerse the samples to be corroded. Experiments were carried out at room temperature and at 3-electrode classical system. Three different corrosion tests were applied to the samples including open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test (PDP). Electrical values of the experiment were realized in the frequency range of 20 kHz-10 mHz and 10 mV AC depending on the OCP test. Gamry Echem Analyst program was used in the analysis of the tests. The starting potential of the curves obtained from the potentiodynamic (PDP) tests is stated as ± 250 mV and the ending potential is +1500 mV.