The corrosion rate of aluminium in the orthophosphoric acid solutions in the presence of sodium molybdate

Kwolek, Przemysław; Kamiński, Artur; Dychtoń, Kamil; Drajewicz, Marcin; Sieniawski, Jan

doi:10.1016/j.corsci.2016.02.005

Cited by 39 publications

(38 citation statements)

References 23 publications

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“…Its lower oxidizing power increases the chances of its compatibility with post-sealing applied organic coatings. Furthermore, on the basis of reports of the respective inhibitive effects of cerium [251][252][253][254][255][256][257], and molybdates [152,217,220,[258][259][260][261][262][263][264] on corrosion of aluminum alloys, and active corrosion of aluminum by cerium molybdate [265][266][267], we postulate that simultaneous inclusion of both cerium and molybdate species in the sealing bath preferably as their respective sulphates or acetates or as cerium molybdate might be beneficial to the sealing of aluminum and impart some active corrosion protection to sealed materials. The preference for inclusion of these into the sealing baths as sulphates and/or acetate is premised on the known non-deleterious effects of these anions on the sealing process [37].…”

Section: Candidate Chromate Alternativesmentioning

confidence: 99%

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

2020

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Increasing demands for environmental accountability and energy efficiency in industrial practice necessitates significant modification(s) of existing technologies and development of new ones to meet the stringent sustainability demands of the future. Generally, development of required new technologies and appropriate modifications of existing ones need to be premised on in-depth appreciation of existing technologies, their limitations, and desired ideal products or processes. In the light of these, published literature mostly in the past 30 years on the sealing process; the second highest energy consuming step in aluminum anodization and a step with significant environmental impacts has been critical reviewed in this systematic review. Emphasis have been placed on the need to reduce both the energy input in the anodization process and environmental implications. The implications of the nano-porous structure of the anodic oxide on mass transport and chemical reactivity of relevant species during the sealing process is highlighted with a focus on exploiting these peculiarities, in improving the quality of sealed products. In addition, perspective is provided on plausible approaches and important factors to be considered in developing sealing procedures that can minimize the energy input and environmental impact of the sealing step, and ensure a more sustainable aluminum anodization process/industry.Coatings 2020, 10, 226 2 of 55 sealing methods. Furthermore, the applicability of another hitherto popular sealing process; chromate sealing, is currently limited to essential parts in the aerospace industry due to toxicological, health, and environmental implications traced to Cr(VI) employed in the process [7][8][9][10][11][12][13][14][15][16]. On the other hand, the advantages of another industrially utilized sealing process; the nickel fluoride (cold) sealing process is limited by the toxicity of nickel salts which narrows its range of application, and introduces added costs due to post-sealing wastewater treatments and management [17][18][19][20]. Further efforts at sealing anodized aluminum at temperatures lower than that used in hydrothermal (high temperature) sealing, have led to much variety in the chemical constitution and operating temperatures of sealing baths [21]. On the basis of temperature at which the sealing step is carried out, sealing can be classified into three major categories; high temperature, mid-temperature, and room-temperature or cold sealing. In this work sealing at temperatures from 0 to 40 • C is classified as low temperature sealing, from ≥ 40 • C to 70 • C as intermediate or mid temperature sealing, and sealing at temperatures > 70 • C as high temperature sealing.

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Section: Candidate Chromate Alternativesmentioning

confidence: 99%

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

2020

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“…polyoxyethylene (80) monostearate and polyoxyethylene (20,40,80) . polyoxyethylene (80) monostearate and polyoxyethylene (20,40,80) .…”

Section: Organic Corrosion Inhibitors In Hcl Solutionmentioning

confidence: 99%

“…[OL(EO)20 ], [OL(EO)40 ], and [OL(EO) 80 ], in the corrosion of 99.89% aluminium in 1 M H 2 SO 4 solution at 25 °C, using the WL and PDP techniques. [OL(EO)20 ], [OL(EO)40 ], and [OL(EO) 80 ], in the corrosion of 99.89% aluminium in 1 M H 2 SO 4 solution at 25 °C, using the WL and PDP techniques.…”

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confidence: 99%

Organic corrosion inhibitors for aluminium and its alloys in acid solutions: a review

2016

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The aim of this review is to summarise the research work published in the last two decades on the use of organic compounds as corrosion inhibitors for aluminium and its alloys in acidic solutions. The focus is on HCl and H 2 SO 4 solutions due to their extensive use in different applications, such as chemical and electrochemical etching, acid cleaning, anodising, and acid pickling of aluminium. Other acids are also reviewed. The inhibition effectiveness of numerous organic compounds and their possible inhibition type and mechanism are also discussed. Electrochemistry is mainly used to investigate inhibitor performance. permanent contact of aluminium (or an alloy of aluminium) with a certain solution. This type of corrosion is especially frequent in chloride solutions. Corrosion protectionThere are several methods to protect aluminium and its alloys, among which the anodising process, conversion coatings, paints, organic coatings, and corrosion inhibitors are found to be the most effective.Anodising is an electrochemical process to increase the thickness of aluminium oxide, where aluminium metallic material is connected as an anode in the electrolytic cell. The anodised oxide layer is thus thicker (5-30 μm) than the natural oxide layer 2, 3, 10, 13, 14 .Conversion coating consist of poorly soluble phosphate or chromium oxides, which are tightly bound to the surface of aluminium or its alloys 15-17 . These coatings affect the appearance, corrosion potential, electrical resistance, and other surface properties. Conversion coatings are formed via a chemical oxidation-reduction process on the metal surface. However, the drawback of these coatings and the accompanying procedures is their negative environmental impact 2 . Therefore, in recent years increasing interest has been shown in conversion coatings containing cerium 18-23 and metallic ions 24-28 or their combination 29, 30 .As mentioned above, another method of corrosion protection is to employ organic coatings. Before applying the organic coating, the aluminium surface should be cleaned and prepared. The process consists of degreasing the surface, followed by removal of the existing oxide layer and the application of the base layer and the primer. The surface cleaning and treatment influences the adhesion and anticorrosion properties of these coatings 31, 32 . The final layer is selected depending on the environmental conditions in which the product will be used [33][34][35][36] . The use of organic-inorganic coatings in the protection of aluminium and its alloys has been also studied 37-39 . Corrosion inhibitorsCorrosion inhibitors modify the metal surface either by forming insoluble compounds with aluminium or by forming a protective surface layer. Based on the electrochemical mechanism of action, the inhibitors can be classified as mixed-type inhibitors (inhibiting both cathodic and anodic reactions of the corrosion couple), anodic-type inhibitors (inhibiting the anodic reaction), or cathodic-type inhibitors (inhibiting the cathodic reaction). Inhibitors may ...

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“…Heteropolyoxoanions can be formed by about 60 elements on the periodic [24,[27][28][29]. Interestingly, iso-and heteropolyoxomolybdates also decrease the dissolution rate of anodic coatings in solutions of orthophosphoric acid [30].…”

Section: Introductionmentioning

confidence: 99%

Orthophosphoric acid solutions of sodium orthovanadate, sodium tungstate, and sodium molybdate as potential corrosion inhibitors of the Al2Cu intermetallic phase

Kwolek

Dychtoń

Pytel

2019

J Solid State Electrochem

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Orthophosphoric acid solutions of sodium orthovanadate, sodium tungstate, and sodium molybdate are tested as potential corrosion inhibitors of the Al 2 Cu intermetallic phase. Corrosion inhibition is observed for 0.2 M solutions of Na 3 VO 4 and Na 2 WO 4 by increasing the pH to > 2. When the pH is < 2, the aforementioned salts increase the corrosion rate of the intermetallic phase. A 0.2 M solution of Na 3 VO 4 causes the precipitation of vanadium phosphate on the surface of the Al 2 Cu phase at pH = 1.

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The corrosion rate of aluminium in the orthophosphoric acid solutions in the presence of sodium molybdate

Cited by 39 publications

References 23 publications

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

The Sealing Step in Aluminum Anodizing: A Focus on Sustainable Strategies for Enhancing Both Energy Efficiency and Corrosion Resistance

Organic corrosion inhibitors for aluminium and its alloys in acid solutions: a review

Orthophosphoric acid solutions of sodium orthovanadate, sodium tungstate, and sodium molybdate as potential corrosion inhibitors of the Al2Cu intermetallic phase

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