Water Wettability of Commercially Pure Titanium and an Alloy Altered by Immersion in Aqueous NaF Solution

Titanium is used as an implant material for dentures. However, the corrosion caused by fluoride and the low wettability of titanium by saliva are still problems. In this study, the corrosion behavior of pure titanium and its alloy was investigated in aqueous NaF solutions, and the macro-wettability change of pure water on these specimen surface after corrosion is discussed. The passive current density of pure titanium and its alloy tended to increase with increasing NaF concentration. The potential distribution nearby pure titanium surface slightly changed after immediate immersion in the solution, then the value soon became relatively stable. The contact angle ratio ψ, which is the ratio of the contact angle before immersion θ0 to that after immersion θi, decreased with increasing immersion time. Higher surface wettability was observed after more active corrosion, indicating that the progression of corrosion significantly influenced the wettability of these surfaces by pure water. The surface roughness Ra was larger after immersion in 2.0% NaF solution than in 0.1% solution, which might also have influenced its wettability by pure water.