Corrosion behaviour of Ti6Al4V alloy in artificial saliva solution with fluoride content and low pH value

Abstract

The corrosion resistance of the Ti6Al4V alloy in Carter–Brugirard artificial saliva (pH = 5.2), in saliva with sodium fluoride (NaF) addition (pH = 5.2) and in saliva with NaF and lactic acid (pH = 2.0) was evaluated. The open circuit potential of the alloy in all electrolytes was stable after approximately 2 h of immersion. Higher corrosion rate and lower polarization resistance were measured for the alloy immersed in fluoridated saliva, compared to genuine saliva, indicating that the addition of NaF lead to a worse corrosion resistance. In fluoridated and acidified saliva (pH = 2), the Ti6Al4V alloy exhibited the lowest corrosion resistance. The corroded surfaces are much rougher than those non-corroded. A higher roughness was obtained for the alloy immersed in saliva with NaF and low pH, indicating that the corrosion process was more active in this electrolyte. Large precipitates of corrosion products and corrosive sites were found on the samples immersed in all electrolytes.