Surface treatment and its effect on the electrochemical behavior of Ti–15Mo–3Nb–3Al alloy
Abstract
The Ti–15Mo–3Nb–3Al alloy was subjected to four different surface treatments involving alkaline and acidic solutions. HNO3, HF–HNO3, NaOH etching and cathodic cleaning using NaOH were performed. The effect of these etchants on the surface morphology and the surface chemical composition was studied. Energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) studies revealed the loss of oxygen content on the surface which indicated the partial breakdown of the surface oxide layer. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) curves showed the poor protection of the treated alloys against corrosion in 3.5% NaCl. Furthermore, these surfaces were coated with a silica–titania hybrid sol–gel film and the corrosion protection of the coated surfaces was assessed and compared. The results showed that sol–gel coating restored the corrosion resistance of all the treated surfaces.