In-situ construction of the hydrophobic structure to improve the corrosion resistance on TA1 pure titanium by vacuum heat treatment

Abstract

The inherent hydrophilicity of titanium causes biological contamination and corrosion, limiting their widespread applications. In this work, the limitations of conventional coating processes were overcome by modifying the microstructure of TA1 pure titanium via vacuum heat treatment. A hydrophilic-to-hydrophobic transition (Contact angle increased tenfold) was achieved, along with improved corrosion resistance. Above phase transition temperature (882 °C), a stepped microstructure and a preferential orientation of low-energy $\left(10\overline{1}0\right)$ and $\left(11\overline{2}0\right)$ grain surfaces were formed on the TA1 pure titanium. A reduction in surface energy was induced through the synergistic effects of grain coarsening, grain orientation, and surface roughening, resulting in a contact angle exceeding 90°. Compared with untreated samples, electrochemical testing showed that the corrosion current density (i_corr) of samples treated at 950 °C decreased by 81 %, and the charge transfer resistance (R_p and R_b) increased by about 10 times, confirming a correlation between hydrophobicity and corrosion resistance. However, treatment above 1050 °C led to performance decline due to grain refinement and increased high-energy surface fractions. This work demonstrates that vacuum heat treatment can simultaneously enhance hydrophobicity and corrosion resistance in TA1 pure titanium, providing a promising strategy for surface modification of uncoated metals in marine engineering and biomedical applications.