Investigation of the chromate conversion coating on Alclad 2024 aluminium alloy: effect of the pH of the chromate bath

Campestrini, P.; Westing, E.P.M. van; Hovestad, A.; Wit, J.H.W. de

doi:10.1016/s0013-4686(01)00818-0

Cited by 59 publications

(46 citation statements)

References 17 publications

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“…The spectra revealed the presence of asymmetric (2950 cm -1 ) and symmetric (2900 cm -1 ) C-H stretching vibrations. Methylsilil groups were also identified by the bands lying at 1408 cm -1 (asymmetric deformation of CH 3 in (Si(CH 3 ) x ), around 1200 cm -1 (symmetric deformation of CH 3 in Si(CH 3 ) x ) and 800-850 cm -1 (stretching and rotation of CH 3 Table 1. Absorption bands detected in the infrared spectra of plasma-polymerized films from pure HMDSO or using equal proportions of HMDSO and O 2 in the gas mixture.…”

Section: Thicknessmentioning

confidence: 99%

“…The contribution at 1265 cm -1 refers to the D structure; formed by two methyl functional bonded to the silicon network R 2 Si(-O-) 2 . Finally, the absorption at 1275 cm -1 is related to the T group consisting of a methyl and three oxygen atoms, RSi(-O-) 3 . The spectra of Figure 5 shows a clear increment in the contribution of the D and T functional with increasing P. The rise in the proportion of D functional, a propagation unit in the chain, indicates the formation of longer and branched chains, very similar to those found in the conventional polydimethylsiloxane ( Figure 6) structure.…”

Section: Wavenumber (Cm -1 ) Modementioning

confidence: 99%

“…The strength of this material is a consequence of precipitates formed by addition of copper but this incorporation also turns the alloy susceptive to galvanic corrosion 1 , particularly when in contact with chloride-containing 2 and oxygen rich environments. Therefore, improvements on the corrosion resistance of this material are mandatory to enhance its performance in practical applications 3 . Barrier layers grown on metallic surface are recognized as a way to avoid interactions of the corrosive medium and surface species and then the oxidative process.…”

Section: Introductionmentioning

confidence: 99%

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Corrosion resistance of 2024 aluminum alloy coated with plasma deposited a-C:H:Si:O films

et al. 2014

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AA 2024 aluminum alloy is widely employed in aeronautic and automobilist industries. Its hardness and low density are attractive properties for such industrial areas. However, since it contains copper, it undergoes severe corrosion in aggressive media as saline or low Earth orbit environments. In this work, it was investigated the properties of films deposited by PECVD on AA 2024 aluminum alloy as well as the corrosion resistance of the film/substrate systems under different corrosive atmospheres. Films were prepared in a plasma atmosphere composed of 50% of oxygen and 50% of hexamethyldisiloxane resulting in a total gas pressure of 4.0 Pa. Plasma ignition was promoted by the application of radiofrequency signal (13.56 MHz) to the sample holder while grounding the topmost electrode. The plasma excitation power, P, was changed from 10 to 80 W in the six different set of experiments. Film thickness, measured by profilometer, increases by 5 times as P was elevated from 10 to 80 W. As demonstrated by the infrared spectra of the samples, films are essentially organosilicons with preservation of functional groups of the precursor molecule and with creation of different ones. The oxide proportion and the structure crosslinking degree are affected by the plasma excitation power. According to the results obtained by sessile drop technique, hydrophilic to moderately hydrophobic films are produced with changing P from 10 to 80 W. The corrosion resistance, evaluated by salt spray and electrochemical impedance spectroscopy, EIS, experiments, in general increases after film deposition. It is demonstrated that film deposition improves, in up to 36 times, the resistance of the alloy to salt spray attack. It is also shown an improvement of about 240 times in the alloy resistance under NaCl solution by the EIS data. Micrographs acquired by Scanning Electron Microscopy after the corrosion tests furnish further information on the importance of the layer physical stability on its barrier properties. Furthermore, films highly protect the alloy against the oxygen attack. Interpretations are proposed based on the modification of the plasma kinetics with P, altering film structure, composition and properties.

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Section: Thicknessmentioning

confidence: 99%

Section: Wavenumber (Cm -1 ) Modementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Corrosion resistance of 2024 aluminum alloy coated with plasma deposited a-C:H:Si:O films

et al. 2014

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“…25 The driving force for Cr(III) deposition comes from the rise in pH near the metal surface [26][27][28][29] caused by redox reactions on the heterogeneous, heat-treated alloy. 30 The oxidation reaction occurs on Al-rich matrix (similar to our alloy substrates) accompanied by proton reduction on Cu-rich inclusions, which are absent in our films.…”

Section: Film Structure Of Tcp Immersion Filmsmentioning

confidence: 99%

Morphology and Mechanism of Benign Inhibitors

Schaefer¹,

Wang²,

Xin³

2012

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“…This galvanic cell causes a decrease in aluminum's corrosion resistance, particularly against halide ions [5][6][7]. In the past, chromate conversion coatings have usually been employed to protect aluminum alloys against corrosion [8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Corrosion behavior of Ce-oxide/hydroxide coated AA7075-T6 prepared by dip immersion method

Danaee

Kanaani²,

Maddahy³

et al. 2014

Turkish J Eng Env Sci

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Abstract:In this study, cerium-based conversion coating was deposited on aluminum 7075-T6 by dip immersion method.Cerium oxide/hydroxide is an environmentally friendly conversion coating. Its corrosion resistance in 3.5 wt.% NaCl solution was investigated by means of electrochemical impedance spectroscopy, potentiodynamic polarization, and surface techniques. The coated samples showed a significant decrease in corrosion rate and the coating resistance increased with increasing immersion time up to 1200 s. In addition, electrochemical impedance data showed that in the presence of cerium oxide/hydroxide conversion coatings, the charge transfer resistance of aluminum increased. Surface morphology and its chemical composition were analyzed by means of scanning electron microscopy and energy dispersive spectroscopy.

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Investigation of the chromate conversion coating on Alclad 2024 aluminium alloy: effect of the pH of the chromate bath

Cited by 59 publications

References 17 publications

Corrosion resistance of 2024 aluminum alloy coated with plasma deposited a-C:H:Si:O films

Corrosion resistance of 2024 aluminum alloy coated with plasma deposited a-C:H:Si:O films

Morphology and Mechanism of Benign Inhibitors

Corrosion behavior of Ce-oxide/hydroxide coated AA7075-T6 prepared by dip immersion method

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