Formation of black chromate conversion coatings on pure and zinc alloy electrolytic deposits: role of the main constituents

Gigandet, M.P.; Faucheu, Jenny; Tachez, M.

doi:10.1016/s0257-8972(96)03013-7

Cited by 55 publications

(32 citation statements)

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“…However, according to Beverskog and Puigdomenech [8], for chromium at temperatures of between Thus, the coating is probably hydrated chromium III oxide for the chromate coating-this is also supported by the findings of Asami et al [9] during XPS analysis of similar coatings. However, other authors [10,11] have indicated that chromium hydroxide is a probable product as well.…”

Section: Auger Electron Spectroscopy (Aes)mentioning

confidence: 97%

Chromate and Chromate–Phosphate Conversion Coatings on Aluminium

Oki

Charles

2011

Arab J Sci Eng

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Investigations of chromate and chromate-phosphate conversion coatings on aluminium using SIMS and AES techniques revealed that they are composed of hydrated chromium oxide/hydroxide and chromium phosphate respectively. These compositions are consistent with the electrochemical mechanism for conversion coating formation on aluminium. Enrichment of the outermost regions of the coatings with coating solution species suggests the gradual migration of these species under a concentration gradient towards the metal/coating interface where coating formation and growth consume such species.

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Section: Auger Electron Spectroscopy (Aes)mentioning

confidence: 97%

Chromate and Chromate–Phosphate Conversion Coatings on Aluminium

Oki

Charles

2011

Arab J Sci Eng

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“…This result is different from other Cr 6+ -involved treatments on aluminum alloy and zinc alloy, generally containing hexavalent chromium compounds in the passive films. [22,23] On the basis of classical model for the formation mechanism of passive film, when metal or alloy sample is immersed in a chemical conversion bath, metallic element(s) will react with oxidizer in bath and consume H + simultaneously. Thus, pH value, namely the concentration of OH À in the solution layer very close to the surface of sample, will increase because of consumption of H + .…”

Section: Xps Analysis For the Passivated Ni-p Coatingsmentioning

confidence: 99%

The effect of nonmetallic element P in electroless Ni-P coating on the passivation process during chemical conversion treatment

2014

Surf. Interface Anal.

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Pure Ni and electroless Ni-P coating (ENPC) were passivated by a chemical conversion treatment. The passive films formed on pure Ni and ENPCs (with content of P 2.9, 7.2 and 11.7 at.% respectively) were analyzed by X-ray photoelectron spectroscopy (XPS). High-resolution XPS was also used to analyze the chemical states of the elements detected in the passive films. The results indicated that the detected Ni and P were in elemental states, and no compound with Ni and P element was detected in passive film, meaning that Ni and P did not participate in the formation of the passive film. The content of film-forming reaction product in passive film increases with the content of element P in Ni-P coating, suggesting that the nonmetallic P in Ni-P coating played an important role in the formation of the passive film. The XPS results were used to analyze the formation mechanism of the passive film.

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“…The reduction of Cr(VI) to Cr(III) can contribute to the formation of a passive layer at defects. The cathodic reactions (19) will consume hydrogen ions and locally increase the pH value, which enables a better passivation process. Fig.…”

Section: Corrosion Behaviormentioning

confidence: 99%

Drying Effects on Corrosion Properties of Cr(VI)- and Cr(III)- Treated Electrogalvanized Steel

Zhang¹,

Bos

Sloof

et al. 2006

ECS Trans.

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Drying effects on corrosion performance of Cr(VI)-and Cr(III)-treated electro-galvanized steel have been studied in NaCl solution using potentiodynamic measurements and electrochemical impedance spectroscopy (EIS). The Cr(VI) and the Cr(III) treated specimens were dried at three different temperatures: 60, 110 and 210°C. The surface layers were investigated using SEM, AES and XPS. The results show that the drying temperature not only affects the morphology of the surface layer, but also changes the chromium oxidation states in the layer. The corrosion protection given to the EG steel by Cr(VI) and Cr(III) pretreatments can be severely reduced if the pretreated surfaces are heated above 110°C. Both types of coating undergo some dehydration during heat treatments, which is undesirable for good corrosion protection. For Cr(VI) coatings, additional degradation mechanisms include widening of the cracks in the coating, and reduction of Cr(VI) to the Cr(III) oxidation state.

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Formation of black chromate conversion coatings on pure and zinc alloy electrolytic deposits: role of the main constituents

Cited by 55 publications

References 1 publication

Chromate and Chromate–Phosphate Conversion Coatings on Aluminium

Chromate and Chromate–Phosphate Conversion Coatings on Aluminium

The effect of nonmetallic element P in electroless Ni-P coating on the passivation process during chemical conversion treatment

Drying Effects on Corrosion Properties of Cr(VI)- and Cr(III)- Treated Electrogalvanized Steel

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