Raman and IR spectroscopy study of corrosion products on the surface of the hot‐dip galvanized steel with alkaline mud adhesion

Abstract

The corrosion products formed on hot-dip galvanized steel sheets for the automobile application with adhesion of alkaline mud containing different Cl − ion contents are investigated by means of Raman and infrared (IR) spectroscopy. Results show that the Cl − ion content in alkaline mud has great influence on the corrosion behavior of the galvanized steel. The Cl − ions are responsible for the formation of the Zn 5 Cl 2 (OH) 8 · H 2 O layer on the surface of the steel at the early stage of corrosion. The rest of the Cl − ions then penetrate and interrupt corrosion product layer resulting in pitting corrosion. Subsequently, the red corrosion product of α-FeOOH (shaped as needle-like structure) is formed, which then transforms into black rust of Fe 3 O 4 (having a shape of slim needle). It is interesting to find out that pitting depth is inversely proportional to the Cl − ion content. However, corrosion rate decreases with the increase of the Cl − ions in mud.

A Micro-Raman Spectroscopic Study of Marine Atmospheric Corrosion of Carbon Steel: The Effect of Akaganeite

“…[17][18][19][20] Raman spectroscopy, as a powerful non-destructive spectroscopic technique, has been successfully used for the identification of pure iron oxides [21][22][23][24] and steel corrosion products. [8][9][10]12,[14][15][16][17][18][19][20][24][25][26][27][28][29][30] Its ability to distinguish between the various phases of iron oxides and oxyhydroxides, which are normally found in atmospheric corrosion products, is extremely helpful in the identification of corrosion products.…”

Effect of Hot Deformation Process Parameters on Microstructure and Corrosion Behavior of 35CrMoV Steel

“…In the early stages of corrosion, Cl − adsorbed on the metal surface play an erosion role and Fe is dissolved from the anode to form Fe 2+ , combined with Cl − to form FeCl 2 ·4H 2 O [51], and further decomposed to form Fe(OH) 2 . However, Fe(OH) 2 is unstable and decomposed into FeO or oxidized to FeOOH by the O 2 dissolved in the water film (see Equations (1) and (2)) [1,52,53,54].…”

Exploring the Influence of Biologically Relevant Ions on the Corrosion Behavior of Biodegradable Zinc in Physiological Fluids

“…Corrosion product cleaning was performed via brushing followed by a chemical treatment using a solution of chromic acid (200 g L –1 ) at 40 °C for 3 min per cleaning cycle, following ASTM G1-03 . The CR was then calculated using the equation CR = 87.4 × W o − W f A × D × t where W o (mg) is the initial weight of the specimen, W f (mg) is the final weight of the specimen after corrosion cleaning, A (cm 2 ) is the exposed surface area, D (g/cm 3 ) is the alloy density, and t (h) is the exposure time. For each test set, three replicates were performed.…”

“…Though simonkolleite is fairly passive, the presence of Cl − weakens this surface film leading to the separation of ZnCl 2 . 43 The creation of the soluble ZnCl 2 is pernicious since this leads to damage to the protective layer, thereby promoting corrosion, particularly within the covered regions that caused the observed pitting. 41 The dissolution of ZnCl 2 from simonkolleite will also leave behind Zn(OH) 2 , increasing the hydroxide concentration in the corrosion product.…”