Hydrophobicity and Improved Localized Corrosion Resistance of Grain Boundary Etched Stainless Steel in Chloride-Containing Environment

Abstract

Localized corrosion of stainless steels by chloride ions in seawater leads to metal degradation while fouling of marine organisms increases the occurrence of localized corrosion. We describe a simple method to increase hydrophobicity of austenitic stainless steel using grain boundary etching that can also inhibit adhesion of bio-organisms present in seawater as well as increase the localized corrosion resistance of stainless steel in chloride-containing aqueous environments. This paper describes the corrosion behavior of stainless steel as a result of grain boundary etching to achieve hydrophobicity. Potentiostatic polarization on stainless steel 316L in a nitric acid solution at an anodic potential of 1.3 V vs. saturated calomel electrode (SCE) results in a grain boundary etched structure and a Cr-and Mo-rich passive film as confirmed by scanning electron microscopy and X-ray photoelectron spectroscopy. This modified stainless steel 316L surface exhibits enhanced corrosion resistance to a 0.6 M sodium chloride solution. Specifically, potentiodynamic polarization studies indicate that the breakdown potential increases and the sample-to-sample variability decreases. Due to the ubiquitous use of metals in infrastructure, production and manufacturing, transportation, and utilities, corrosion results in compromised safety and recurring repair costs.1 One of the most commonly employed approaches to control corrosion is the use of corrosion resistant alloys.1 Stainless steels (SSs), which are defined as steel alloys containing at least 10.5% chromium content by mass, are the most frequently used materials in aqueous environments because of their enhanced corrosion resistance relative to carbon steels. 2Chromium participates in the formation of a stable passive film on SSs that protects the bulk metal against corrosion.3 However, SSs still suffer from localized corrosion when exposed to chloride-containing aqueous environments, including seawater 4,5 and bleach plants associated with pulp and paper industries. Strategies to improve the localized corrosion resistance of SSs include enrichment of Cr and Mo at the SS surfaces and removal of surface inhomogeneities.7 These SS surface treatments include mechanical polishing, 8,9 passivation, 7,9-11 and electro-polishing. 8,[12][13][14] Mechanical polishing results in Cr-rich SS surfaces. 9 Surface passivation of SS using a nitric acid solution removes surface inhomogeneities and enhances the formation of a Cr-rich passive film. Electro-polishing is a technique to control the surface finish of a metal by anodic electrochemical dissolution to yield a smooth metal surface. Electro-polishing removes surface inhomogeneities from the SS surface and simultaneously forms Cr-and Mo-rich passive films. Electropolished SS surfaces show higher localized corrosion resistance than mechanically polished and passivated SS surfaces.14 Chromium oxide/hydroxide (Cr 2 O 3 /Cr(OH) 3 ) in the passive film hinders movement of cations into the electrolyte and thereby delays local breakdown of the ...

Effects of Surface Modification by Means of Low-Temperature Plasma Nitriding on Wetting and Corrosion Behavior of Austenitic Stainless Steel

“…Pickling of the surface allows to obtain a fairly high roughness, which promotes lubricant retention [20]. Change from a hydrophilic behavior, typical of a stainless steel surface with a smooth finishing, to a hydrophobic behavior, resulting from a rough surface at the micro/nano scale, has been obtained by chemical treatments [21][22][23], electrochemical treatments [24,25], femtosecond laser treatments [26,27], and low-energy laser shock peening [28]. The increase of surface roughness has drawbacks: in chloride-ion containing solutions the corrosion resistance tends to decrease as the surface roughness increases [29,30], so that for applications which require very high corrosion resistance, as for stents and implants, a smooth surface, obtained with electrochemical polishing, is preferred [31,32].…”

Inhibition of Bacterial Adhesion on Nanotextured Stainless Steel 316L by Electrochemical Etching

“… 26 Compared to other surface finishing techniques, the electrochemical etching process is affordable, fairly scalable, and has fine control of surface structures by electrochemical parameters such as potential and current density. 26 Furthermore, electrochemically etched SS316L surfaces form a superior passive layer for corrosion resistance, 27 which would be another advantage to use this method for biomedical applications.…”

Exploring the corrosion inhibition capability of FAP-based ionic liquids on stainless steel

“…The composition, particularly S20200, is quite far from the expected amounts of chromium in the substrate. The presence of high levels of carbon and low levels of chromium may have contributed to its fast corrosion rate [ 39 ]. It is possible that the passive layer of chromium carbide did not form, given that the composition of chromium is below 10.5%, and the carbon levels are relatively high.…”