Citric Acid as an Alternative to Sulfuric Acid for the Hard-Anodizing of AA6061

Miramontes, José Ángel Cabral; Almeraya-Calderón, Facundo; López, Francisco Estupiñán; Lara-Banda, María; Olguín-Coca, F. J.; López-Léon, Luis Daimir; Castañeda-Robles, Iván Erick; Alcála, Miguel Ángel Esneider; Zambrano‐Robledo, Patricia del Carmen; Gaona-Tiburcio, C.

doi:10.3390/met11111838

Cited by 13 publications

(3 citation statements)

References 71 publications

(79 reference statements)

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“…DC power supply as high-power current generator model XLN30052-GL with a capacity of 300 Volts (V) and 5 Amps (A). The parameters used in the process anodized were the anodizing electrolyte baths and the current densities of 3 and 4.5 A/dm 2 [20]. The anodization was carried out in a cold-water bath for 60 minutes at a temperature 0 °C ± 2 °C with constant stirring of the solution.…”

Section: Anodizing (Electrode Preparation)mentioning

confidence: 99%

Citric Acid as an Alternative to Sulfuric Acid for Hard Anodizing in Aluminum Alloys Used in the Aeronautical Industry

Cabral

Tiburcio

López³

et al. 2023

ECS Trans.

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In the aircraft industry, Al-Cu alloys are widely used as a structural material in the manufacture of commercial aircraft due to their high mechanical properties and low density. Al-Cu alloy have low resistance to corrosion in aggressive substances; as a result, these alloys are surface treated to increase their resistance to corrosion. Anodizing was done hard in aluminum alloy AA 2024 in a solution composed of citric and sulfuric acid for 60 minutes with constant agitation using current densities of 3 and 4.5 A/dm2. Afterwards, a sealing procedure was performed for 60 minutes in water at 95 °C. Scanning electron microscopy (SEM) was used to characterize the microstructure and Vickers microhardness (HV) as a mechanical test of the material. The electrochemical evaluation was carried out using cyclic potentiodynamic polarization curves (CPP). The results indicate that the corrosion resistance in citric acid solutions with a current density of 4.5 A/dm2 was the best, with corrosion current densities of 2 x 10-8 and 2 x 10-9 A/cm2.

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Section: Anodizing (Electrode Preparation)mentioning

confidence: 99%

Citric Acid as an Alternative to Sulfuric Acid for Hard Anodizing in Aluminum Alloys Used in the Aeronautical Industry

Cabral

Tiburcio

López³

et al. 2023

ECS Trans.

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“…The process can be potentiostatic or galvanostatic for constant voltage or constant current application, respectively. In either of the anodic process routes, the thickness, and characteristics of resulting anodic oxide lm, are dependent on the anodizing time, voltage, current density, temperature, electrolyte, and its concentration [9][10][11][12]. Usually, the longer the anodizing time, the thicker the resulting anodic oxide lm formation.…”

mentioning

confidence: 99%

Effects of Speeds, Voltages, and Electrolytes on Localized Surfaces of Al 6061 Alloys Anodized Using a Direct Writing Pen

Obielodan,

III,

Delwiche

2023

Preprint

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For many applications, aluminum alloys require anodization to produce alumina film that protects the surfaces against corrosion and abrasive wear. This process is often carried out traditionally, by dipping the substrate into a suitable bath of electrolyte. A study on the effectiveness of a direct writing pen for localized anodization of aluminum 6061 surface is presented. The writing pen is designed for applications in which complete submersion of the substrate in an electrolyte is inconvenient or unnecessary. Three aqueous electrolyte solutions were used: 15% (v/v) sulfuric acid; 10% (v/v) sulfuric acid plus 5% (v/v) citric acid; and 5% (v/v) sulfuric acid plus 10% (v/v) citric acid. Voltage levels of 30, 40, and 50 volts were applied, while the writing traverse speeds were 0.1, 1, and 3 mm/s on different experimental samples. The anodic oxide films were characterized for surface morphology, thickness, micro-hardness, and ability to hold dyes through the nanopores. The results show that the lower the pen traverse speeds, the higher the thickness of the alumina films produced. The thicknesses obtained were highest at 21.5 μm for oxide films generated at 0.1 mm/s traverse speed at 50V using sulfuric acid. However, the hardest surfaces were obtained for samples processed at 50V with two-pass anodization and 1 mm/s, yielding 596 Hv and softest for films with single pass anodization obtained at the 3 mm/s pen traverse speed with 40V. The direct write anodizing pen was found to demonstrate effectiveness for localized surface anodization that would be cost-effective in niche applications.

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“…Cabral-Miramontes et al [5] report on the characterization of mechanical properties and corrosion resistance of hard-anodized aluminum 6061 in a citric acid solution as a replacement for sulfuric acid. Hard anodizing was conducted in a citric and sulfuric acid solution by applying current densities of 3 and 4.5 A/cm 2 and subsequently exposed to 3.5 wt.% NaCl solution.…”

mentioning

confidence: 99%