Nanotube Formation And Surface Evolution On Hydrothermally Treated Ti In Alkali Solution

Abstract

The present study intends to check which nanotube formation mechanism match the surface evolution on bulk Ti surface after soaked in hydrothermal treatment. Polished cp-Ti disks were hydrothermally immersed in various concentration NaOH for 1h, 2h, and 4h at 220°C. The SEM observations and XRD studies showed a sequence transformation from polished Ti surface into titanium oxide with plate shape and leave-like structure in the beginning. Bigger plates or leaves oxide then evolved into sodium titanate nanorods that finally became nanotubes as the immersing time lengthened. Apparently self-assembly and partial dissolution were the most applied mechanism to explained the sodium titanate formation. Plate and leaves-like oxide mainly formed by dissolution of Ti metal followed by precipitation of TiO6 in self-assemble manner as the resultant of reaction between Ti(OH)3+ and OH−. While, nanorod and nanotube structure were produced by partial dissolution of leaves structure followed precipitation of sodium titanate by reaction of Na+ with HTiO3− generated from OH-reaction with Ti metal and TiO6.