Hexacyanoferrate‐Intercalated Layered Double Hydroxides as Nanoadditives for the Detection of Early‐Stage Corrosion of Steel: The Revival of Prussian blue

Abstract

This work describes the synthesis and characterization of Zn‐Al and Mg‐Al layered double hydroxides (LDHs) intercalated with hexacyanoferrate. X‐ray diffraction, infrared spectroscopy and scanning electron microscopy indicated a successful intercalation of hexacyanoferrate in the sub‐micrometer sized platelet‐like particles. Release studies of hexacyanoferrate from LDHs found that the anion is released depending on the concentration of NaCl and under alkaline conditions. When placed in contact with carbon steel under corrosive conditions, the formation of Prussian blue was detected. Furthermore, the application of potentiodynamic polarization and electrochemical impedance spectroscopy revealed that hexacyanoferrate has a detrimental effect on the corrosion of carbon steel, while when intercalated in LDHs this effect is minimized. Overall, these findings open perspectives for the application of these materials as smart nanoadditives in coatings for corrosion detection.

A novel smart coating with hexacyanoferrate intercalated layered double hydroxides nanoadditive for early detection of carbon steel corrosion

“…The released hexacyanoferrate ions can react with iron cations formed during corrosion of steel, providing a strong colorimetric signal-the formation of blue precipitates (Prussian Blue and Turnbull's Blue). The detection ability was confirmed on uncoated carbon steel plates immersed in a chloride-containing solution with the sensing nanoadditive (Wilhelm et al, 2020). Furthermore, the toxicity of the developed nanoadditive was assessed in terms of environmental fate and behavior using the marine microalgae Tetraselmis chuii and the crustacean Artemia salina (Martins et al, 2022).…”

“…In our recent work (Wilhelm et al, 2020), we proposed a novel active nanoadditive for early detection of steel corrosion-hexacyanoferrate intercalated LDH (Mg-Al/[Fe(CN) 6 ] LDH). LDH were used as hosting material for hexacyanoferrate (III) ions, able to provide controlled release of the active agent through the ion exchange mechanism under the conditions associated with the onset of corrosion.…”

Layered double hydroxides for corrosion-related applications—Main developments from 20 years of research at CICECO

“…In a recent work by Wilhelm and co-workers (Wilhelm et al, 2020), hexacyanoferrate salts were investigated as indicators for early detection of corrosion in carbon steel. Both syntheses of MgAl and ZnAl LDH intercalated with hexacyanoferrate salts were attempted, but only MgAl LDH was found suitable for intercalation of this anion, as Zn in ZnAl LDH tends to react with hexacyanoferrate and form a brownish insoluble precipitate.…”

Smart protective coatings with self‐sensing and active corrosion protection dual functionality from pH-sensitive calcium carbonate microcontainers

“…However, these methods are typically non-continuous, measurement techniques, costly and time-consuming and are often limited in the capability and resolution of detecting corrosion especially at very early stage. In recent years, self-sensing coatings capable of showing visible coloration triggered by mechanical or corrosion attacks have attracted increasing interest [5,[12][13][14][15][16]. For example, Robb et al reported a sensitive fluorescence-based method to automatically warn damage position in polymer materials through aggregation-induced emission (AIE) [17].…”

“…The immersion test indicates that the occurrence of early corrosion (~5 mins) can be visualized by the formation of APhen-Fe 2+ ligands with a red color and the presence of hydrogen bonds also endowed the coating matrix with a certain self-healing effect (60% of the tensile strength recovery) in a salt water environment. In another study, Wilhelm et al prepared corrosion-sensing nanoadditives based on layered double hydroxides (LDHs) intercalated with hexacyanoferrate [16]. The aqueous dispersion of hexacyanoferrate-intercalated LDHs turned blue in the presence of Fe 2+ .…”