Sulfuric Acid‐Induced Corrosion of Aluminum Surfaces

Dai, Qing; Freedman, Andrew; Robinson, G. Y.

doi:10.1149/1.2048463

Cited by 12 publications

(11 citation statements)

References 4 publications

(5 reference statements)

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“…Sulfuric acid, and particularly its aqueous solutions are of considerable industrial, environmental and technological importance. − The thermodynamic properties of this system have also been the subject of a wide range of experimental studies including measurements of the osmotic coefficients, vapor pressures, , heat capacities, free energies, and solid phase equilibrium data. , More recent Fourier transform-infrared spectroscopy studies reveal that the uptake of water in thin H 2 SO 4 films, carried out at a constant water partial pressure, produces a smooth variation in the weight percentage of acid as a function of decreasing temperature.…”

Section: Introductionmentioning

confidence: 99%

Electron Spectroscopy Studies of the Surface Composition in the H₂SO₄/H₂O Binary System

1996

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The surface composition of the H2SO4/H2O binary system in the temperature range (298−170 K) has been studied using differentially pumped Auger electron and X-ray photoelectron spectrometers designed to perform under equilibrium conditions (P H 2 O ≈ 10-6−10-4 Torr). Both spectroscopies have been calibrated on pure sulfuric acid solutions to illustrate their ability to provide accurate atomic stoichiometries within the near-surface region. In the case of AES this ability has also been extended as a tool for the study of the surface composition in the H2SO4/H2O binary system under equilibrium conditions. Compositional analysis of this acidified surface indicates that under these experimental conditions the chemical compositions of the bulk and near-surface region are equal within experimental error. Mass spectrometric analysis of the vapor composition indicates equilibration between the acid solution and D2O.

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Section: Introductionmentioning

confidence: 99%

Electron Spectroscopy Studies of the Surface Composition in the H₂SO₄/H₂O Binary System

1996

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“…In-situ IRAS studies revealed that hydrated aluminum sulfate is the principal product of the corrosion reaction …”

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confidence: 99%

“…The initial concentration of sulfuric acid used in these experiments ranges from 20 to 98 wt %. However, the acid droplets equilibrate rapidly with the ambient water vapor. , For example, at a temperature of 298 K and a RH of 30%, the concentration of sulfuric acid is 55 wt % and at 90% RH, it is 20 wt %…”

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confidence: 99%

Nanoscale Imaging of a Corrosion Reaction: Sulfuric Acid Droplets on Aluminum Surfaces

Dai

Freedman

et al. 1996

J. Phys. Chem.

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The morphological changes of the liquid and solid phases occurring during the corrosion of aluminum by sulfuric acid were imaged in situ with nanometer resolution using scanning polarization force microscopy and conventional atomic force microscopy. The rate of reaction between the acid and the metal is highly dependent on the relative humidity. At high relative humidities, a dramatic spreading of the liquid droplets is observed that is indicative of sulfuric acid-induced aluminum corrosion. The liquid layer consists of a mixture of aluminum sulfate product and sulfuric acid. At low relative humidity, an aluminum sulfate precipitate is formed which segregates from the unreacted liquid acid. This phase separation inhibits further corrosion, in agreement with the results of previous experiments using infrared reflection absorption spectroscopy. The results of these experiments offer new insights into the mechanisms of chemical corrosion at gas-liquid-solid interfaces.Atmospheric chemical corrosion constitutes a severe threat to the structural integrity of many metals and, as such, is responsible for considerable economical loss. 1-4 For example, sulfuric acid droplets from acid rain or dew deposition is the principal cause of corrosion of aluminum. Since atmospheric corrosion reactions occur at the solid-liquid interface and involve submicrometer thick liquid films and droplets, their study constitutes a difficult challenge. Optical imaging and spectroscopy techniques are excellent and nonintrusive but lack the necessary resolution. Atomic force microscopy (AFM) has very high resolution, but it is unable to image liquids, since the contact of the tip causes capillary wetting and strong perturbation of the liquid surface. In this work, we use a new technique, scanning polarization force microscopy (SPFM), 5,6 to image liquids with nanometer resolution. In combination with infrared reflection absorption spectroscopy (IRAS), we were able to follow in unprecedented detail the physical and chemical changes occurring during the corrosion of aluminum by sulfuric acid droplets in humid environments.In the SPFM technique, the electrically charged tip of an AFM scans the surface at a distance of a few hundred angstroms. Maintaining this tip-surface distance is critical in order not to perturb the liquid surface. The SPFM can be operated also as a standard contact mode AFM, and in this case, only the solid substrate is imaged while any liquid deposit is locally displaced by the tip.The aluminum samples were prepared by vapor depositing 2000 Å thick Al films on polished Si wafers. X-ray photoelectron spectroscopy indicated that the native oxide layer of the film was 20-30 Å thick, in agreement with published results. 7 Prior to use, the samples were rinsed with acetone and deionized water. The experiments were always carried out in humidity-controlled chambers.In-situ IRAS studies revealed that hydrated aluminum sulfate is the principal product of the corrosion reaction. 8 The rate of corrosion, measured by the appearance of h...

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“…The corrosion of aluminum surfaces covered with a sulfuric acid film formed from SO 3 (g) and H 2 O(g) at a pressure of 200 Torr was studied by Dai et al, [ 64 ]. The corrosion rate was observed to increase at higher relative humidities and higher deposition of sulfuric acid.…”

Section: Resultsmentioning

confidence: 99%

Vibrational Spectroscopy in Studies of Atmospheric Corrosion

Hosseinpour

Johnson

2017

Materials

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Vibrational spectroscopy has been successfully used for decades in studies of the atmospheric corrosion processes, mainly to identify the nature of corrosion products but also to quantify their amounts. In this review article, a summary of the main achievements is presented with focus on how the techniques infrared spectroscopy, Raman spectroscopy, and vibrational sum frequency spectroscopy can be used in the field. Several different studies have been discussed where these instruments have been used to assess both the nature of corrosion products as well as the properties of corrosion inhibitors. Some of these techniques offer the valuable possibility to perform in-situ measurements in real time on ongoing corrosion processes, which allows the kinetics of formation of corrosion products to be studied, and also minimizes the risk of changing the surface properties which may occur during ex-situ experiments. Since corrosion processes often occur heterogeneously over a surface, it is of great importance to obtain a deeper knowledge about atmospheric corrosion phenomena on the nano scale, and this review also discusses novel vibrational microscopy techniques allowing spectra to be acquired with a spatial resolution of 20 nm.

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Sulfuric Acid‐Induced Corrosion of Aluminum Surfaces

Cited by 12 publications

References 4 publications

Electron Spectroscopy Studies of the Surface Composition in the H₂SO₄/H₂O Binary System

Electron Spectroscopy Studies of the Surface Composition in the H₂SO₄/H₂O Binary System

Nanoscale Imaging of a Corrosion Reaction: Sulfuric Acid Droplets on Aluminum Surfaces

Vibrational Spectroscopy in Studies of Atmospheric Corrosion

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Sulfuric Acid‐Induced Corrosion of Aluminum Surfaces

Cited by 12 publications

References 4 publications

Electron Spectroscopy Studies of the Surface Composition in the H2SO4/H2O Binary System

Electron Spectroscopy Studies of the Surface Composition in the H2SO4/H2O Binary System

Nanoscale Imaging of a Corrosion Reaction: Sulfuric Acid Droplets on Aluminum Surfaces

Vibrational Spectroscopy in Studies of Atmospheric Corrosion

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Electron Spectroscopy Studies of the Surface Composition in the H₂SO₄/H₂O Binary System

Electron Spectroscopy Studies of the Surface Composition in the H₂SO₄/H₂O Binary System