Influence of addition agents for a.c. anodizing in sulphuric acid electrolytes

Balasubramanian, V.; John, S.; Shenoi, B.A.

doi:10.1016/0376-4583(83)90034-1

Cited by 16 publications

(9 citation statements)

References 9 publications

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“…When sulfuric acid is used for AC anodization, sulfur and sulfur compounds are deposited in the pores of films because of the reduction of sulfuric acid during AC anodization. 14,15 To avoid deposition of such sulfur compounds, it was desired to change the electrolyte. In addition, oxalic acid has the advantage that the range of anodization conditions for AC-bipolar anodization can be extended because the appropriate applied potential difference for anodization in oxalic acid is higher than that of sulfuric acid.…”

Section: Bipolar Anodization Of Aluminum Sheet Under Ac Electric Field-mentioning

confidence: 99%

AC-Bipolar Anodization of Aluminum: Effects of Frequency on Thickness of Porous Alumina Films

Asoh

Ishino

Hashimoto

2018

J. Electrochem. Soc.

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The formation of porous alumina films using bipolar electrochemistry under alternating current (AC) electric fields without a direct electrical connection ("wireless treatment") was investigated. The effect of frequency on the thickness of the films was evaluated using spectrophotometric analysis of dyed specimens and field-emission scanning electron microscopy. A film formation was simultaneously achieved on both sides of a high-purity aluminum electrode in oxalic acid under an AC electric field. A film formed at 150 Hz was thicker than those formed at other frequencies even in the same reaction time. Although the growth of non-uniform films were observed for AC-bipolar anodization, the morphology of the obtained films was roughly the same as those formed using conventional AC anodization with a direct connection, suggesting a similar oxide formation mechanism. Moreover, the dependence of film thickness on frequency was almost in agreement with the tendency observed for conventional AC anodization reported previously. The main disadvantage of AC-bipolar anodization lies in the decrease of the efficiency of film formation. From the application standpoint, however, the wireless treatment can introduce new possibilities for electrochemical surface treatment of small conductive materials that require a specific manipulation for a direct electrical connection.

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Section: Bipolar Anodization Of Aluminum Sheet Under Ac Electric Field-mentioning

confidence: 99%

AC-Bipolar Anodization of Aluminum: Effects of Frequency on Thickness of Porous Alumina Films

Asoh

Ishino

Hashimoto

2018

J. Electrochem. Soc.

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“…The composition of the film prepared in sulfuric acid was estimated and the sulfur content was not related to the anodizing conditions [85, 101]. The effects of current density or potential and electrolyte temperature and concentration on film growth were also investigated [102]. The thickness of the films increased as the reaction time increased [72, 86], but the hardness decreased with the anodization time because the porosity increased [86].…”

Section: Ac Anodizationmentioning

confidence: 99%

Fabrication of alumina films with laminated structures by ac anodization

Segawa

Okano

Wada

et al. 2014

Science and Technology of Advanced Materials

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Anodization techniques by alternating current (ac) are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50–200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.

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“…[18][19][20][21] In addition, presence of solid particles in the electrolyte can also influence coatings properties. [4,9] For instance, it has been reported that anodizing of aluminum in baths containing different types of solid particles such as Al 2 O 3 /PTFE, [22] SiC/PTFE, [23] and also additives like Na 2 SO 4 , [24] Ce 2 (SO 4 ) 3 and Nd (NO 3 ) 3 [25] influences the morphology, anodizing efficiency, crystal structure, chemical composition, corrosion, and wear resistance of the resulting coatings.…”

Section: Introductionmentioning

confidence: 99%