Corrosion protection of aluminum borate whisker reinforced AA6061 composite by cerium oxide-based conversion coating

Hu, Jin; Zhao, Xintao; Tang, Shawei; Sun, Min

doi:10.1016/j.surfcoat.2006.09.006

Cited by 24 publications

(25 citation statements)

References 22 publications

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“…The surface appears covered by a layer with a lack of the typical "dry mud" morphology that is commonly observed. 85 According to Dabalá et al, the thickest areas can be correlated with the intermetallic particles containing elements such as Ni, Fe, Cr, Mn, and surrounded by an aluminum-based solid solution; as for the AA6061 aluminum alloy, the intermetallic particles can be identified as (Fe, Cr, Mn) 3 -SiAl 12 . 86 The morphology of the coatings also consisted of nodules which were identified by EDS and resulted to be cerium rich phases (Figure 9e).…”

Section: Resultsmentioning

confidence: 99%

Bath Conditions Role in Promoting Corrosion Protection on Aluminum Alloy using Rare Earth Conversion Coatings

Brachetti-Sibaja

Domínguez‐Crespo

Torres‐Huerta

et al. 2011

J. Electrochem. Soc.

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Rare earth conversion films were obtained on the AA6061 aluminum alloy by the immersion method varying several experimental conditions such as rare earth (RE) concentration, bath temperature and immersion time. Formation dynamics of RE coatings and the effect of bath conditions on their structure, morphology, topography and corrosion resistance properties were investigated for the protection of this substrate immersed in an aqueous solution of NaCl. X-ray diffraction and scanning electron microscopy results revealed that the increment of the RE concentration caused some small cracks around the aluminum alloy intermetallic phase, whereas bath temperature and immersion time stimulated the conversion of the rare earths to more stable compounds, La 2 O 3 and CeO 2 . During electrochemical evaluation, the CeCCs displayed a steady state potential at times longer than 250 min; as for LaCCs, longer time intervals were required to reach a stable potential. After covering with rare earth conversion films, the anticorrosive properties of the aluminum alloy were evidently improved. This enhancement is presumably due to the improved barrier properties of the anticorrosion product layer. Additional active corrosion protection was originated from the inhibiting action of the lanthanide ions trapped either as oxides or hydroxides in this surface layer.Chemical conversion treatments (CCTs) are one of the most promising environmentally friendly surface treatments for several metallic substrate alloys. 1-3 CCT is an easy method to grow a good corrosion resistant film on the metallic surface. 4, 5 Such a film can also hinder scale growth and increase scale adhesion in the coatingsubstrate interphase. 5-8 The most widely used is a chromate solution, DOW7, which has been produced by Dow Chemical Company in Japan. With this kind of solution, the film displays excellent corrosion resistance and adhesion ability. Unfortunately, the disadvantages of this treatment process are the environment pollution caused by the wastewater containing hexavalent chromium and the concomitant affection of people's health. 6-8 Currently, aluminum alloy components on military and commercial aircraft are still protected from corrosion by a three-layer coating system consisting of a chrome-based conversion coating, a chrome-containing primer, and a top or color coat. 9-20 This system offers both active (electrochemical) and passive (barrier) protection to the underlying alloys. However, impending regulation will severely limit the use of hexavalent chromium by driving up the costs of worker protection, airborne particles monitoring and waste stream disposal. 6 Despite the imminent regulation of chromium, a suitable replacement has not been identified. In recent years, there has been a considerable development in surface treatments with lanthanide salts since Hinton et al. 21-25 used them for the first time during the 80's in order to replace highly toxic and carcinogenic chromate conversion coatings. Rare earth elements have shown three principal advantages: ...

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Section: Resultsmentioning

confidence: 99%

Bath Conditions Role in Promoting Corrosion Protection on Aluminum Alloy using Rare Earth Conversion Coatings

Brachetti-Sibaja

Domínguez‐Crespo

Torres‐Huerta

et al. 2011

J. Electrochem. Soc.

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“…Because of their low toxicity, rare-earth salts are not considered as health hazard materials. Consequently, coatings containing rare-earth elements have been recommended as potential replacements for chromate-based formulations in metal finishing 29,30 . Cerium conversion coatings are one of the most promising environmentally friendly surface treatments for a range of metals [31][32][33] .…”

Section: Introductionmentioning

confidence: 99%

Preparation and Anti-Corrosive Properties of Cerium Oxide Conversion Coatings on Steel X52

2017

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In this study, cerium-based conversion coating was deposited on steel X52 by dip immersion method. Cerium oxide/hydroxide is an environmentally friendly conversion coating. The effects of immersion times and immersion temperatures on corrosion properties of cerium conversion coating on steel X52 were studied. 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 corrosion current decreased with increasing immersion time up to 60 s. In addition, electrochemical impedance data showed that in the presence of cerium oxide conversion coatings, the charge transfer resistance of aluminum increased. The experimental results indicated that the corrosion resistance decreased with increasing the operating temperature. Surface morphology and its chemical composition were analyzed by means of scanning electron microscopy and energy dispersive spectroscopy.

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“…7) Conversion coatings prepared using non-Cr(VI) solutions, such as those containing titanium, zirconium, molybdenum, cerium, and trivalent chromium, exhibit low pollution and toxicity; in addition, these coatings are harmless to humans; hence, they have been widely developed. [8][9][10][11][12][13] Trivalent chromate coatings are attracting attention as an advantageous alternative for commercial applications because their treatment solutions are significantly less toxic than those containing hexavalent chromium compounds. Typically, as compared to hexavalent chromium coatings, the trivalent chromium coatings exhibit low corrosion resistance, 14) albeit the addition of other substances into the coating solution results in improved corrosion resistance.…”

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

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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.

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Corrosion protection of aluminum borate whisker reinforced AA6061 composite by cerium oxide-based conversion coating

Cited by 24 publications

References 22 publications

Bath Conditions Role in Promoting Corrosion Protection on Aluminum Alloy using Rare Earth Conversion Coatings

Bath Conditions Role in Promoting Corrosion Protection on Aluminum Alloy using Rare Earth Conversion Coatings

Preparation and Anti-Corrosive Properties of Cerium Oxide Conversion Coatings on Steel X52

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

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