Organosilane-functionalized hydrothermal-derived coatings on titanium alloys for hydrophobization and corrosion protection

TL;DR

This study demonstrates that combining alkaline treatment with HDTMS coating significantly enhances the hydrophobicity and corrosion resistance of Ti-6Al-4V alloys, suitable for moisture-exposed environments.

Contribution

It introduces a method to improve hydrophobicity and corrosion protection of titanium alloys through sequential alkaline treatment and HDTMS functionalization.

Findings

HDTMS coating increased water contact angle to about 147 degrees.

Alkaline treatment alone reduced corrosion resistance.

HDTMS coating significantly improved corrosion resistance after alkaline treatment.

Abstract

This work focuses on the structure, wettability and corrosion behaviors of Ti-6Al-4V alloy after roughening treatments in different concentrations of NaOH aqueous solutions followed by low surface energy hexadecyltrimethoxysilane (HDTMS) coating. In this regard, scanning electron microscopy, contact angle measurements, potentiodynamic polarization and electrochemical impedance spectroscopy were used to characterize the samples. In contrast to hydrophilicity caused by the hydrothermal alkaline treatments, the subsequent HDTMS coating donated considerable hydrophobicity. Typically, the highest sessile water contact angle (about 147 deg) was obtained for the sample treated in 3 molar NaOH solution followed by the HDTMS coating. In addition, the alkaline treatment reduced the corrosion resistance of the surface in a NaCl aqueous solution; however, the HDTMS hydrophobization process improved it significantly. It is eventually concluded that the coupled use of alkaline treatment and HDTMS functionalization can be further considered for moisture-exposed applications of Ti-based alloys.