Porosity of Anodic Oxide Coatings on Aluminum. Comparison of n-Butane and Krypton Sorption

Cosgrove, Lee A.

doi:10.1021/j150538a001

Cited by 15 publications

(6 citation statements)

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“…The surface areas we obtain are roughly the same as those obtained by Burwell, Smudski, and May (13); Cosgrove (14); and Paolini, Masoero, Sacchi, and Paganelli (15), although direct comparison is difficult. Burwell et al report 600 cm 2 real surface per cm 2 geometrical surface on coatings formed at about 14 A/ft 2 and 17V in 15% H2SO4 at 21~ If we make a reasonable assumption of coating density, this converts to about 19 m2/g (for an apparent density of 2.5 g/cm :~ and the density may be somewhat higher).…”

Section: Resultssupporting

confidence: 85%

Sealing Studies of Anodic Oxides by Wide-Line NMR Spectroscopy

Baker¹,

Pearson²

1972

J. Electrochem. Soc.

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Wide-line nmr measurements show that anodic coatings formed in 15% H~SO4 at 25~ and 12 A/ft 2 for 1 hr and sealed for 30 min in boiling water at pH 6 contain 11-13% H20 as OH groups plus 1-4% physically adsorbed water. Nitrogen adsorption measurements show a surface area of about 20 m2/g for unsealed coatings and about 5 m2/g for sealed coatings. The unsealed coatings contain about 1.2 • 10~' pores/cm 2 of mean radius of 60A. About 46% of the water contained in a sealed coating is on a surface. From this, and from nmr line widths, a surface area of 260 m2/g is estimated. The difference between the gas adsorption and nmr estimates of surface areas is explained by the model proposed for the coating structure, one consisting of an array of microcrystallites estimated to be about 25A in radius. Gas adsorption analyzes only the major pore surfaces, but nmr analyzes the crystallite surfaces as well. Sealing is regarded to be primarily a surface reaction on the crystallites. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 157.182.150.22 Downloaded on 2015-06-23 to IP Vol. 119, No. 2 SEALING STUDIES 161

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Section: Resultssupporting

confidence: 85%

Sealing Studies of Anodic Oxides by Wide-Line NMR Spectroscopy

Baker¹,

Pearson²

1972

J. Electrochem. Soc.

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“…It seems that the pore structure of anodic oxides is not as simple and uniform as one could expect and depends on the conditions of anodization (e.g., Figure of ref ). It should also be noted that sorption hysteresis loops for anodized alumina have been reported (e.g., Figure of ref ). It is obvious from Figure (1-a) that this type of loop is formed by two more or less vertical branches at relatively high P / P 0 values, i.e., higher than 0.7, and falls in the H 1 -type categoryaccording to the IUPAC classification (part 1 of this work).…”

Section: Introductionmentioning

confidence: 79%

A New Model for Capillary Condensation−Evaporation Hysteresis Based on a Random Corrugated Pore Structure Concept: Prediction of Intrinsic Pore Size Distribution. 2. Model Application

Androutsopoulos

Salmas

2000

Ind. Eng. Chem. Res.

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A performance assessment of the corrugated pore structure model (CPSM), developed in part 1 (Ind. Eng. Chem. Res. 2000, 39, 3747), is carried out through a simulation of experimental gas sorption hysteresis, covering all IUPAC versions and that of the novel MCM-41 materials. The materials studied are an anodic aluminum oxide film, HDS catalysts, montmorillonite, lignite, pillared clays, and MCM-41. CPSM evaluations of pore surface areas are consistent with the pertinent BET estimates while for partly microporous structures approach those obtained by the restricted adsorption BET variant. CPSM predictions of pore size distribution (psd) have been compared with those obtained by the Roberts method. In several examples, the latter method, when applied exclusively to condensation data, yielded psd's approaching the relevant CPSM distributions while, in other examples, by using evaporation data only, deduced psd's comparable to those yielded by the CPSM model. CPSM predictions are in partial agreement with the novel molecular simulation and the NLDFT theories. The CPSM model proved to be a simple, flexible, purely analytical model enabling meaningful predictions of intrinsic psd's and evaluations of a statistical pore shape parameter (N S ) related to pore structure tortuosity.

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“…The thickness obtained by the RBS measurements scale with target angle with respect to the incident beam; hence the layers cannot have large porosity. The films studied here have approximately 15% porosity (8). Thus, it is concluded that the lower densities reported here are not accounted for by the porous nature of the films.…”

Section: Discussionmentioning

confidence: 46%

Density Determination and Analysis of Porous Anodic Aluminum Surfaces Using MeV Ion Beams

Simons

Crowe

Brown

et al. 1980

J. Electrochem. Soc.

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Densities of porous anodic aluminum oxide coatings have been measured to range from 1.1 to 2.2 g/cm3, values approximately 0.3–0.6 times those of bulk Al2O3 . These measurements are obtained by using two independent techniques for determining film parameters, Rutherford backscatter (RBS) of MeV protons and alpha particles and optical or scanning Auger microscopy. The former gives areal densities in units of g/cm2 and the latter two thicknesses in units of cm. Additional information on the composition of the films studied using ion‐induced x‐ray analysis simultaneously with RBS is: (i) the compositions are mainly Al2O3 with small amounts of SO3 or CrO3 for those anodic layers grown in H2SO4 or H2CrO4 electrolytes, respectively; (ii) sulfur is present as a contaminant in layers grown in H2CrO4 electrolytes; (iii) there is a reduction in the concentration of the alloying elements in anodized films grown on 7075 T‐73 Al; (iv) atoms from the cathode are deposited on the film surfaces during anodization; (v) chlorine is present throughout the surface of alumina samples severely corroded in normalNaCl solutions.

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Porosity of Anodic Oxide Coatings on Aluminum. Comparison of n-Butane and Krypton Sorption

Cited by 15 publications

References 0 publications

Sealing Studies of Anodic Oxides by Wide-Line NMR Spectroscopy

Sealing Studies of Anodic Oxides by Wide-Line NMR Spectroscopy

A New Model for Capillary Condensation−Evaporation Hysteresis Based on a Random Corrugated Pore Structure Concept: Prediction of Intrinsic Pore Size Distribution. 2. Model Application

Density Determination and Analysis of Porous Anodic Aluminum Surfaces Using MeV Ion Beams

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