Chromate Conversion Coating on Aluminum Alloys

Campestrini, P.; Terryn, Herman; Vereecken, Jean; Wit, J.H.W. de

doi:10.1149/1.1736682

Cited by 37 publications

(28 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…18,21,22 McGovern et al 21 concluded that the deposition rate on Mg-containing intermetallics slowed with increased Cu content due to adsorption of cyanide on the Cu-rich sites. The cyanide is derived from potassium ferricyanide that is added to commercial CCC bath formulations to accelerate the coating deposition process on aluminum.…”

Section: Resultsmentioning

confidence: 99%

Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

Isaacs

Sasaki

Jeffcoate

et al. 2005

J. Electrochem. Soc.

View full text Add to dashboard Cite

In situ X-ray adsorption near-edge structure ͑XANES͒ has been used to investigate the formation of chromate conversion coatings on pure Al, commercial Al alloys ͑AA 1100, AA2024, and AA7075͒, and a series of binary Al-Cu alloys. The method employed cells designed to determine the growth of the total chromium ͓Cr͑total͔͒ and hexavalent chromate ͓Cr͑VI͔͒ in the chromate conversion coating ͑CCC͒ as a function of exposure time to a chromate solution. Three sets of data were obtained, where ͑i͒ the Al was exposed to only a limited amount of solution; ͑ii͒ the chromate solution was excluded after short periods of repeated exposures to the solution; and ͑iii͒ the Al was exposed continuously to the chromate solution. All the results showed a very rapid initial growth within the first seconds, followed by a continued increase in thickness for exposures up to 1 h. Measurements with Al-Cu binary alloys demonstrated that the difference observed in AA2024 and AA1100 may not be due to Cu alloying. used electrochemical reduction of chromate on graphite electrodes to monitor chromate that did not react at the Al surface. The former investigators used a rotating ring-disk method with an Al alloy as the disk and graphite ring.2 The latter investigators employed a flow system with a graphite electrode downstream to an Al alloy to study CCC growth following laser removal of a thin mask that initially protected the Al. They also employed a quartz crystal microbalance on which the alloy film was sputtered, and coupled the mass variations with chromate consumption. 3 X-ray adsorption offers a powerful method for the in situ study of the kinetics of chemical changes taking place at surfaces, by monitoring the growth and dissolution of the films.3-12 X-ray adsorption near-edge structure ͑XANES͒ has been used to study the products of reactions of chromate conversion coatings ͑CCC͒ adhering to Al surfaces, and the behavior of these products with time and exposure to solutions. [4][5][6][7][8][9][10][11][12][13] CCCs are made up of Cr͑III͒ and Cr͑VI͒ species such as in CrO 4 2− ; the latter is believed to be responsible for CCC's ability to protect scratches on a metal surface from undergoing further electrochemical degradation. A factor that assists in the determination of Cr speciation is a distinct pre-edge peak at 5993 eV in the XANES spectrum when hexavalent chromium Cr͑VI͒ is present. In addition, the ratio of height above the edge arising from all chromium species present ͓Cr͑total͔͒ to the pre-edge height ͓only Cr͑VI͔͒ provides a quantitative measure of Cr͑VI͒ content in the CCC. However, XANES measurements of CCC have generally been made ex situ.In this study, we introduce designs of cells that allow monitoring of a specimen surface exposed to a chromate solution without being removed from the aqueous environment. We present data on aluminum and its alloys ͑i͒ when exposed to a limited volume of solution; ͑ii͒ when subjected to repeated exposure to the chromate solution; and ͑iii͒ when continuously exposed to the CCC solution. Fro...

show abstract

Section: Resultsmentioning

confidence: 99%

Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

Isaacs

Sasaki

Jeffcoate

et al. 2005

J. Electrochem. Soc.

View full text Add to dashboard Cite

show abstract

“…It has been shown that the formation of a Cr 3+ monolayer inhibits oxygen and further Cr 6+ reduction [18,[27][28][29][30][31][32]. Debate still exists regarding the control over the anodic dissolution of active phases [33].…”

Section: Introductionmentioning

confidence: 99%

A study of the mechanisms of corrosion inhibition of AA2024-T3 by vanadates using the split cell technique

Iannuzzi

Kovač

Frankel

2007

Electrochimica Acta

View full text Add to dashboard Cite

The mechanisms of corrosion inhibition of AA2024-T3 by vanadates were studied in this work using the split cell technique and polarization curves. The electrochemical behavior of clear solutions containing metavanadates and orange solutions containing decavanadates was clearly distinctive. Injection of metavanadates to the cathode side of the different split cell setups greatly reduced the galvanic current, indicating a potent inhibition of the oxygen reduction kinetics. The galvanic current never exhibited a transient current peak, suggesting that metavanadates inhibit AA2024-T3 corrosion by a mechanism that does not involve electrochemical reduction. Injection of metavanadate to the anode side of the different split cells had no effect on the galvanic current. Injection of orange decavanadate to the cathode side of the AA2024-T3 split cell resulted in a large current peak, associated with the electrochemical reduction of decavanadate. However, decavanadates did not impart significant corrosion protection.

show abstract

“…This result indicated that a chemical reaction occurs on the aluminum alloy, leading to the formation of a surface newly created by the chromate solution. This film formation may be adjusted depending on temperature, pH condition, coating time, and chromate solution concentration, [24][25][26][27] which the effects will be contributed in further research. Fig.…”

Section: Surface Characterization Of Conversion Coatingsmentioning

confidence: 99%

“…During the oxidation process, pH of the solution could be increased as forming the chromate film. 17,18) Hence, the coating solution must contain an oxidizing agent; oxidizing agents constitute various forms of acid, where it simultaneously functions as a pH control agent. Accordingly, for effective film formation, the processing time of the chromate solution, as well as pH and temperature, should be appropriately set to form a waterinsoluble salt.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of Cr(III)-based Conversion Coating Solution to Apply Aluminum Alloys for Improving Anti-corrosion Properties

Shim¹,

Kim²,

Han³

et al. 2016

Journal of the Microelectronics and Packaging Society

View full text Add to dashboard Cite

It is imperative to find environment-friendly coatings as an alternative to the currently used hexavalent chromate conversion coatings for the purpose of improving the anti-corrosion properties of aluminum alloys. Hence, in this study, the corrosion properties of a trivalent chromate conversion coating solution are analyzed and measured. Because of the presence of multiple components in trivalent chromate conversion coating solutions, it is difficult to control plating, attributed to their mutual organic relationship. It is of significance to determine the concentrations of the components present in these coatings; hence, qualitative and quantitative analysis is required. The coating solution contained not only an environment-friendly component chromium(III), but also zirconium, fluorine, sulfur, and potassium, in the coating film. These metals are confirmed to produce a film with improved corrosion resistance to form a thin layer. The excellent corrosion resistance for the trivalent chromate solution is attributed to various inorganic and organic additives.

show abstract

Chromate Conversion Coating on Aluminum Alloys

Cited by 37 publications

References 42 publications

Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

Formation of Chromate Conversion Coatings on Aluminum and Its Alloys

A study of the mechanisms of corrosion inhibition of AA2024-T3 by vanadates using the split cell technique

Characteristics of Cr(III)-based Conversion Coating Solution to Apply Aluminum Alloys for Improving Anti-corrosion Properties

Contact Info

Product

Resources

About