Super-Hydrophobic Multi-Walled Carbon Nanotube Coatings for Stainless Steel

TL;DR

This paper reports a simple method to create super-hydrophobic, biomimetic MWCNT coatings on stainless steel using CVD, resulting in surfaces that resist corrosion and fouling with potential low-friction benefits.

Contribution

It introduces a catalyst-free, low-temperature CVD process leveraging stainless steel's native properties to produce hierarchical super-hydrophobic MWCNT coatings.

Findings

Achieved high contact angle (154°) with MWCNT coatings.

Demonstrated hierarchical morphology with hydrophilic tips on hydrophobic MWCNTs.

Potential for corrosion resistance and low-friction applications.

Abstract

We have taken advantage of the native surface roughness and the iron content of AISI 316 stainless steel to direct grow multi-walled carbon nanotube (MWCNT) random networks by chemical vapor deposition (CVD) at low-temperature ($< 1000^{\circ}$C), without the addition of any external catalysts or time-consuming pre-treatments. In this way, super-hydrophobic MWCNT films on stainless steel sheets were obtained, exhibiting high contact angle values ($154^{\circ}$) and high adhesion force (high contact angle hysteresis). Furthermore, the investigation of MWCNT films at scanning electron microscopy (SEM) reveals a two-fold hierarchical morphology of the MWCNT random networks made of hydrophilic carbonaceous nanostructures on the tip of hydrophobic MWCNTs. Owing to the Salvinia effect, the hydrophobic and hydrophilic composite surface of the MWCNT films supplies a stationary super-hydrophobic coating for conductive stainless steel. This biomimetical inspired surface not only may prevent corrosion and fouling but also could provide low-friction and drag-reduction.