Cerium-based conversion layers on aluminum alloys

Dabalà, Manuele; Armelao, Lidia; Buchberger, Alberto; Calliari, Irene

doi:10.1016/s0169-4332(00)00873-4

Cited by 211 publications

(151 citation statements)

References 17 publications

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“…This property is important for a number of applications of cerium salts, including the production of luminescent materials [1][2][3][4]. In addition, cerium salts have been used as corrosion inhibitors [5,6], chemical precursors of organic [7,8] and inorganic [9] reactions, catalysts [10], and can also be used to induce hydrolysis of DNA [11]. Many of the Ce(III) applications occur in surfactant-containing media, such as the formation of cerium-containing nanoparticles [12] and nanowires in reverse micellar environment.…”

Section: Introductionmentioning

confidence: 99%

Aggregation and micellization of sodium dodecyl sulfate in the presence of Ce(III) at different temperatures: A conductometric study

Valente

Burrows

Cruz

et al. 2008

Journal of Colloid and Interface Science

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Aggregation properties of sodium dodecyl sulfate (SDS) in the presence of cerium(III) chloride, at various temperatures (298.15-323.15 K) have been measured by the electrical conductance technique. The experimental data on aqueous solutions as a function of SDS concentration show the presence of two inflexion points indicating the presence of two distinct interaction mechanisms: the first, occurring at SDS concentrations below the critical micelle concentration of the pure surfactant, which can be explained by the formation of aggregates between dodecyl sulfate (DS − ) and Ce(III), while the second one, at SDS concentrations around the critical micelle concentration (cmc) of the pure surfactant which is due to the SDS micellization. The aggregation between DS − and Ce(III) was confirmed by static light scattering. The binding ratio of DS − /Ce(III) changes from 6 to 4, shows a slight dependence on the Ce(III) concentration and is independent of the temperature. The thermodynamic micellization parameters, Gibbs energy, enthalpy and entropy of micellization were calculated on the basis of the experimental data for the aggregation concentration, and the degree of counterion dissociation of the micelles. The SDS micellization is energetically favoured by increasing either the concentration of CeCl 3 or the temperature. Such behaviour is clearly dominated by a decrease of the micellization (exothermic) enthalpy. The entropy of micellization approaches zero as the cerium(III) chloride concentration and temperature increase.

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Section: Introductionmentioning

confidence: 99%

Aggregation and micellization of sodium dodecyl sulfate in the presence of Ce(III) at different temperatures: A conductometric study

Valente

Burrows

Cruz

et al. 2008

Journal of Colloid and Interface Science

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“…This is consistent with the observation that H 2 O 2 in a solution containing Ce 3þ causes oxidation of Ce 3þ to Ce 4þ . 14,15,23) Although the mechanism by which cerium (IV) hydroxide/oxide forms is not clear, it exhibits a quite different morphology than cerium (III) hydroxide/oxide. The surface of cerium (IV) hydroxide/oxide is flat and smooth, while cerium (III) hydroxide/oxide consists of interlaced fibers.…”

Section: Discussionmentioning

confidence: 99%

“…12,13) Furthermore, cerium conversion coatings on aluminum alloys have studied extensively. [14][15][16][17][18][19][20][21][22] In contrast, cerium conversion coating treatments for magnesium alloys are less well studied.…”

Section: Introductionmentioning

confidence: 99%

“…9,10,15,21,23) Because H 2 O 2 is a strong oxidant, its presence in the solution can, on one hand, promote oxidation and dissolution of the substrate, which in turn, accelerate the precipitation of the conversion coating layer. On the other hand, H 2 O 2 in the solution can cause oxidation of Ce 3þ to Ce 4þ .…”

Section: Introductionmentioning

confidence: 99%

“…14,23) During conversion coating treatment, Ce 3þ and Ce 4þ can be precipitated as a conversion coating that contains Ce (III) and Ce (IV) species, respectively. 15) Consequently, in addition to the accelerated coating reaction, the presence of H 2 O 2 in a solution containing Ce 3þ can modify the structure and properties of cerium conversion coating on magnesium. This study details how H 2 O 2 in cerium nitrate solutions influences the microstructure and corrosion resistance of the cerium conversion coating on an AZ31 magnesium alloy.…”

Section: Introductionmentioning

confidence: 99%

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Corrosion Resistance of Cerium-Conversion Coated AZ31 Magnesium Alloys in Cerium Nitrate Solutions

Lin

2006

Mater. Trans.

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Cerium conversion coatings are a potential alternative to chromium conversion coatings for improving the corrosion resistance of magnesium alloys. This study detailed the microstructure and corrosion resistance of cerium conversion coatings on AZ31 magnesium plates treated in 0.05 kmol m À3 cerium nitrate solution, with and without 0.25 kmol m À3 hydrogen peroxide. The results indicate that the corrosion resistance of the coating was related to the microstructure of the major overlay, and to the defects of the coating. The major overlay changed from a fibrous structure to a compact layer, as hydrogen peroxide was added to a cerium nitrate solution. Meanwhile, severely-damaged areas were observed on the coating formed in the presence of hydrogen peroxide. Although the compact coating displayed better corrosion resistance than its fibrous counterpart, both coatings were locally corroded during the polarization test.

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