XPS studies of a ferricyanide accelerated chromate paint pretreatment film on an aluminium surface

Treverton, J. A.; Davies, N. C.

doi:10.1002/sia.740030503

Cited by 57 publications

(26 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The absence of any satellite shake-up lines suggested that both Fe2`and Fe3`occupy low-spin sites. 2 The most likely source of Fe was ferricyanide or ferrocyanide for the high or low binding energy peaks (no Fe was detected in the alloy by XPS). The ferrocyanide could be the chemical reaction product of ferricyanide during coating or its reduction product under the x-ray beam.2,7 The Cr spectra were Ðtted with three 2p 3@2 components at 577.3^0.2, 578.9^0.2 and 580.3^0.3 eV [ Fig.…”

Section: Characterization Of the As-prepared Coatingmentioning

confidence: 99%

“…2 Hence, a well-accepted model of the structure of chromate conversion coatings on pure aluminium includes an outer surface, which is a mixture of Cr3h ydrated oxides and and the bulk of the CrFe(CN) 6 , Ðlm, which consists of largely Cr3`hydrated oxides. 2 The conversion coating also contains a variable amount of Cr6`, which may depend on the structure of the Ðlm. 9 The interface between the coating and the aluminium metal contains a thin aluminium oxyÑuoride layer.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Chromate Conversion Coatings on 2024 Al Alloy

Hughés

Taylor

Hinton

1997

Surf. Interface Anal.

151

100

View full text Add to dashboard Cite

Section: Characterization Of the As-prepared Coatingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chromate Conversion Coatings on 2024 Al Alloy

Hughés

Taylor

Hinton

1997

Surf. Interface Anal.

151

100

View full text Add to dashboard Cite

“…In subsequent studies aimed at clarifying their earlier work, these workers prepared accelerated CCCs on 99.8% Al from a bath formulation based on commercial chemistries. 5 XPS results indicated that Fe(CN) 6 3Ϫ/4Ϫ was present throughout the coating but was concentrated in the near-surface region. Mixed metal cyanides identified in the earlier study were now not present.…”

Section: ϫmentioning

confidence: 99%

Formation of Chromate Conversion Coatings on Al-Cu-Mg Intermetallic Compounds and Alloys

McGovern¹,

Schmutz

Buchheit

et al. 2000

J. Electrochem. Soc.

View full text Add to dashboard Cite

"Accelerated" chromate conversion coating (CCC) formulations are distinguished among all CCC types by the fact that they utilize a special chemical additive to increase coating weight, 1 or increase the rate of the film forming Cr VI to Cr III reduction reaction. 2 Ostensibly, accelerated CCCs are used on corrosion-prone Al-Cu-Mg and AlZn-Mg-Cu alloys to ensure maximum protection. 3 Ferricyanide [Fe(CN) 6 3Ϫ ] has been used as an accelerant in commercial CCC formulations since the 1960s. 1 Despite the long history, its role in coating formation has not been precisely established. Both Fe(CN) 6 3Ϫ and Fe(CN) 6 4Ϫ are readily detected in CCCs by various surface-sensitive techniques, supporting the notion that it contributes to coating weight by becoming part of the CCC film. 1 For example, Treverton and Davies used X-ray photoelectron spectroscopy (XPS) and ion-beam etching to study accelerated CCCs formed on 99.8% pure Al substrates. 4 Results indicated the presence of Fe(CN) 6 4Ϫ/3Ϫ concentrated in the near-surface regions. It was suggested that the compound was probably present as a CrFe(CN) 6 salt. However, the findings were insufficient to establish a clear role for Fe(CN) 6 3Ϫ in coating formation. In subsequent studies aimed at clarifying their earlier work, these workers prepared accelerated CCCs on 99.8% Al from a bath formulation based on commercial chemistries. 5 XPS results indicated that Fe(CN) 6 3Ϫ/4Ϫ was present throughout the coating but was concentrated in the near-surface region. Mixed metal cyanides identified in the earlier study were now not present. Additionally, evidence of ferrocyanide [Fe(CN) 6 4Ϫ ] was found. The authors equivocated on the significance of ferrocyanide determination since ferri-to ferrocyanide reduction in X-ray beams was known to occur. Despite these complications, it was proposed that the primary film growth reaction, chromate reduction, was stifled by adsorption of ferricyanide on the nascent CCC, thereby increasing the availability of free chromate for reaction with uncoated metal.Hagans and Haas specifically considered film formation on Cu and Fe intermetallic compounds (IMCs) in studies of accelerated CCC formation on 2024-T3. 6 Auger electron spectroscopy (AES), XPS, and ion-beam depth profiling were used to show that for coating formation times up to 3 min, the film formation rate on various phases in 2024-T3 decreased in the order: matrix phase > Cu IMC > Fe IMC. After 5 min of immersion time, coating thickness appeared to be similar on the different phases. These workers proposed that ferrocyanide interacted with Cu-rich IMCs to form Cu 4 Fe(CN) 6 or Cu 2 Fe(CN) 6 and that these compounds promoted corrosion resistance by eliminating the galvanic couples that would otherwise form between the noble particles and the matrix phase.Lytle et al. used a variety of surface analytical techniques, including X-ray absorption spectroscopy (XAS), X-ray absorption near edge spectroscopy (XANES), extended X-ray absorption fine structure (EXAFS), and Fourier transform infrared s...

show abstract

“…Various analytical techniques have been used to study the chemical and structured nature of the CCC formed on Al-Cu alloy, including x-ray photoelectron spectroscopy (XPS), 5,7,25,26 x-ray absorption near-edge structure (XANES) spectroscopy, 10,18 -20,27 secondary ion mass spectrometry (SIMS) 28 and Fourier transform infrared (FTIR) and Raman spectroscopy. 1,24,29 -31 Several studies have shown that the CCC is inhomogenously distributed on the AA2024-T3 surface and that the underlying microstructure induces spatial and depth composition heterogeneity in the CCC.…”

Section: Introductionmentioning

confidence: 99%

On the nature of the chromate conversion coating formed on intermetallic constituents of AA2024‐T3

Vasquez

Halada

Clayton

et al. 2002

Surface & Interface Analysis

View full text Add to dashboard Cite

The objective of the research reported in this paper was to refine an existing model for chromate conversion coatings (CCC) formed on the surface of AA2024-T3, an Al-Cu aircraft alloy, by considering the composition and structure of the CCC formed on constituent intermetallic compounds (IMCs). To achieve this aim it was necessary to develop large-area samples composed of compositionally homogeneous thin films of the various IMCs found on the AA2024-T3 surface, which were galvanically attached to thin films of Al-4.2wt.%Cu (representative of the AA2024-T3 matrix). This was performed in a two-step process: disks of IMC compositions were formed by reactive arc melting (RAM), followed by femtosecond laser ablation of the RAM IMCs, resulting in the formation of homogeneous thin films. These thin films were used to analyze the formation of CCC on IMCs, the AA2024-T3 matrix analog and matrix-IMC galvanic couples. Secondary ion mass spectrometry depth profiling revealed significant variations in CCC film thickness and composition related to the underlying IMCs. The SIMS results indicated that the CCC formed on the matrix analog had the same average thickness as the average CCC formed on AA2024-T3, whereas those formed on individual q and S phases were only 9% and 12% as thick, respectively, when uncoupled to the matrix and 11% and 14% as thick when coupled to the matrix. The CCC thickness on the Al 20 Cu 2 (MnFe) 3 was found to be variable, having an islanded structure. Topographical maps indicate that the IMC/matrix boundaries are covered with CCC of a thickness approaching that of the matrix. Inhibition of CCC growth is related to the high copper content (and therefore insufficient aluminum) present in the IMCs compared to the matrix, which provides a more accurate model of CCC formation on AA2024-T3.

show abstract

XPS studies of a ferricyanide accelerated chromate paint pretreatment film on an aluminium surface

Cited by 57 publications

References 17 publications

Chromate Conversion Coatings on 2024 Al Alloy

Chromate Conversion Coatings on 2024 Al Alloy

Formation of Chromate Conversion Coatings on Al-Cu-Mg Intermetallic Compounds and Alloys

On the nature of the chromate conversion coating formed on intermetallic constituents of AA2024‐T3

Contact Info

Product

Resources

About