Non-nickel-based sealing of anodic porous aluminum oxide in NaAlO2

Kim, Moonsu; Yoo, Hyeong Seon; Choi, Jinsub

doi:10.1016/j.surfcoat.2016.11.100

Cited by 14 publications

(9 citation statements)

References 36 publications

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“…Since the temperature of NaAlO 2 sealing reached about 85 °C, it can be seen from Table that the value of AlOOH(or Al(OH) 3 )/Al 2 O 3 in the NaAlO 2 sealed sample is similar to that of hydrothermally sealed sample, we speculated that the reaction of Equation can also occur with NaAlO 2 sealing. As mentioned in the previous report, AlOOH can also be generated on the surface of anodized film through the reaction of Equation . Therefore, from the above discussion, we think that Equations and may both occur and more AlOOH was formed with NaAlO 2 sealing.…”

Section: Resultsmentioning

confidence: 78%

“…Based on the above discussion, the following mechanism for NaAlO 2 sealing was proposed:

{A l}_{2} {normalO}_{3} + {normalH}_{2} O \to 2 A l O O H

{N a A l O}_{2} true(normals true) + 2 {normalH}_{2} O true(normall true) \leftrightarrow {N a}^{+} + {O H}^{-} + A l {(O H)}_{3} true(normala normalq true) \to A l O O H true(normals true) + {normalH}_{2} O true(normall true)

…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, NaAlO 2 is also used in the anodizing solution of aluminum alloy and the results show that lower corrosion current densities (5.64 × 10 −6 mA/cm 2 ) and higher corrosion voltages (−1.10 V) can be obtained in electrolytes containing high concentrations of NaAlO 2 compared to those without NaAlO 2 (1.10 × 10 −5 mA/cm 2 and −0.97 V) . More meaningfully, it is also applied to sealing of pure aluminum anodized film, the corrosion resistance obtained from which is almost the same as that of nickel salt and has low energy consumption process . As mentioned above, NaAlO 2 plays an important role in enhancing the corrosion resistance of Mg alloy, pure aluminum, and aluminum alloy.…”

Section: Introductionmentioning

confidence: 98%

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Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Yang

Cheng

Liu

et al. 2018

Materials & Corrosion

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In order to effectively improve the corrosion resistance of aluminum alloys, anodic oxidation technique was used to generate the oxide film. Sealing after anodization is an important step to improve the corrosion resistance of aluminum alloys. In this paper, sealing effect of NaAlO2 solution on the oxalic acid anodized aluminum alloy was studied by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and X‐ray photoelectron spectroscopy (XPS). Experimental results show that unsealed anodized aluminum alloys display a porous structure and have poor corrosion resistance but the pores are filled and the corrosion resistance of the sample is significantly improved when anodized aluminum alloy was immersed in 0.2 m/L NaAlO2 solution with pH of 7 for 5 min at 85 °C. Moreover, the anodized aluminum alloy with NaAlO2 sealing exhibited better corrosion resistance compared to the hydrothermally sealed sample, because of the formation of more AlOOH in NaAlO2 sealing treatment.

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Section: Resultsmentioning

confidence: 78%

“…Based on the above discussion, the following mechanism for NaAlO 2 sealing was proposed:

{A l}_{2} {normalO}_{3} + {normalH}_{2} O \to 2 A l O O H

{N a A l O}_{2} true(normals true) + 2 {normalH}_{2} O true(normall true) \leftrightarrow {N a}^{+} + {O H}^{-} + A l {(O H)}_{3} true(normala normalq true) \to A l O O H true(normals true) + {normalH}_{2} O true(normall true)

…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

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Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Yang

Cheng

Liu

et al. 2018

Materials & Corrosion

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“…This indicates that the dominant O species in the corrosion products changes from O 2-to OHas the corrosion time increases. The Al2p band consists of one peak at 74.2 ± 0.2 eV, which corresponds to Al(OH)3 [22], as shown in Figure 4c. Combining the XRD and EDS results, the corrosion products of 12Cr1MoV steel corroded for 1 d were mainly To further understand the corrosion products, XPS characterizations were used to survey the elemental states of the Fe, O, and Al species.…”

Section: Analysis Of the Phase And Chemical Composition Of The Corrosmentioning

confidence: 96%

Initial Corrosion Behavior of 12Cr1MoV Steel in Thiosulfate-Containing Sodium Aluminate Solution

Yuan

Chen

et al. 2020

Metals

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When alumina is produced by the Bayer process with high-sulfur bauxite, the sulfur would strongly corrode the 12Cr1MoV steel made heat exchanger. This study investigated the initial corrosion behavior of the 12Cr1MoV steel exposed to a thiosulfate-containing sodium aluminate (TCSA) solution under the evaporation conditions of alumina production. The obtained corrosion rate equation is V = 6.306·t·exp(−0.71). As corrosion progressed, with the corrosion product film growing, the corrosion current density declines slowly, and the corrosion resistance of the steel is increased. At 1–3 days, the corrosion product film consisted of FeO, Fe2O3, and FeOOH. S2O32− lead to corrosion in local areas of the steel and pits appeared. AlO2− is transformed into Al(OH)3 and filled in the corrosion pits. At 4 and 5 days, Fe3O4 is generated in the outermost layer, and Al(OH)3 is shed from the corrosion pits. The corrosion mechanism of 12Cr1MoV steel in a TCSA solution is proposed based on the experimental results.

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“…Therefore, this hydrothermal sealing method possesses the advantages of [17]. Sealing by using nickel salt solutions can effectively improve the sealing quality, lower the sealing temperature, reduce the sealing time, and stabilize the organic dye molecules in the micropores of the anodic oxidation film, but the insurmountable problem lies in the environmental pollution as caused by nickel ions [18]. Additionally, sealing with a bichromate solution has the merits of easy operation and satisfactory corrosion resistance, which can thus be applied for protection applications through sealing the holes of the anodic aluminum oxide (AAO) film on aluminum alloys, but the high toxicity of hexavalent chromium, even with a carcinogenic effect, largely limits the practical applications [13].…”

Section: Introductionmentioning

confidence: 99%

Sealing Holes of an Anodic Aluminum Oxide Alloy by Nanotitania for Enhanced Corrosion Resistance

Chang¹,

Wei²,

Chen³

et al. 2017

Nano Res Appl

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This study aims to explore an effective, novel, and environmentally friendly method that overcomes the limitations and shortcomings existing in the traditional approaches for sealing holes on aluminum alloy. Herein, the holesealing treatment of an Anodic Aluminum Oxide (AAO) alloy film using two types of titanium sources with a high stability in aqueous electrolytes, that is, ammonium fluorotitanate and titanium potassium oxalate, to electrically deposit nanotitania on the film surface was investigated. The nanotitania deposited electrochemically for hole sealing has the advantages of the high physiochemical stability, low cost, and non-toxicity, which can thus readily improve the corrosion resistance of the sealed AAO in an environmentally friendly manner. Such sealed AAO can also result in a UV-shielding performance due to the commonly-known UV absorption properties of nanotitania. The hole sealing effect is also compared between the two systems involving the two types of titanium sources at different concentrations, voltages and time. The optimization of the preparation conditions is achieved by means of weight loss measurements. Potentiodynamic scan and electrochemical impedance spectroscopy results reveal that the hole-sealed sample-based on ammonium fluorotitanate shows a higher corrosion resistance as compared to the one based on titanium potassium oxalate. Significantly, the optimal conditions for the hole sealing of the aluminum alloy are evidenced to be the concentration of ammonium fluorotitanate of 0.1 mol/L, AC voltage of 3 V, and time of 900 s.

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Non-nickel-based sealing of anodic porous aluminum oxide in NaAlO2

Cited by 14 publications

References 36 publications

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Initial Corrosion Behavior of 12Cr1MoV Steel in Thiosulfate-Containing Sodium Aluminate Solution

Sealing Holes of an Anodic Aluminum Oxide Alloy by Nanotitania for Enhanced Corrosion Resistance

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Non-nickel-based sealing of anodic porous aluminum oxide in NaAlO2

Cited by 14 publications

References 36 publications

Effect of NaAlO2 sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of NaAlO2 sealing on corrosion resistance of 2024 aluminum alloy anodized film

Initial Corrosion Behavior of 12Cr1MoV Steel in Thiosulfate-Containing Sodium Aluminate Solution

Sealing Holes of an Anodic Aluminum Oxide Alloy by Nanotitania for Enhanced Corrosion Resistance

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Product

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Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film

Effect of NaAlO₂ sealing on corrosion resistance of 2024 aluminum alloy anodized film