Spectroscopic Investigations of Porous and Sealed Anodic Alumina Films

Abstract

Porous anodic alumina films grown in sulfuric acid and similar specimens sealed in nickel acetate and dichromate sealing baths were subjected to a number of surface and bulk analytical techniques (XPS, RBS, SIMS, and XRD). All the oxide films were found to be amorphous‐like in nature, to contain significant amounts of H, and have a S content of 1.5–3 atomic percent (a/o) uniformly distributed throughout the oxide matrices. For the sealed oxide films, surface enrichment of Ni and Cr species was observed, being particularly significant in the case of Ni. Uniform bulk concentrations for Ni and Cr were found to be of the order of 0.5 and 1 a/o, respectively. The S, Ni, and Cr species present in the oxide films were identified as sulfate‐like, nickel hydroxide and dichromate‐like in nature. Ion beam‐induced reduction of incorporated S, Ni, Cr, and C species was observed.

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

“…From their observations they [172] concluded that the major morphological changes due to sealing occurs in the outer 2-3 µm of the anodic oxide film, pore closure commences at the outer surface and proceeds towards the entire depth, and that an intermediate layer is formed between the outer surface crystals and the filled pores. Murphy et al [58] studied sealing of porous anodic layer on aluminum using different sealing methods and concluded that sealing increases the degree of hydration throughout the oxide layer irrespective of sealing method but the degree of hydration with nickel acetate sealing is much higher than that obtained by dichromate sealing. Patermarakis and Papandreadis [173] carried out prolonged sealing treatment of porous anodic films on aluminum in water at 100 • C for 4.5 h, calculated the quantity of H 2 O retained, correlated it to the pore void volume of dry films, and reported that complete blocking of the pore mouths significantly retard hydration process(es), and suggested that the formation of a gas phase is a likely factor contributing to inhibition of hydration processes.…”

XPS Analysis of the Surface Chemistry and Interfacial Bonding of Barrier-Type Cr(VI)-Free Anodic Oxides

“…So far, changes in the oxide chemistry on aluminum have been explained in terms of changes in the acid–base properties, , the surface charge, − and the hydroxyl fraction. , It is interesting to note that although the incorporation of anions during anodizing in sulfuric and phosphoric acids has been extensively reported (e.g., refs − ), studies including these type of pretreatments did not explicitly account for their presence. ,, Because it is mostly the outer region of the oxide, the part that comes into contact with the organic resin, that is contaminated by these anions, , their consideration seems vital to understand how electrolyte variations will affect interfacial bonding with organic resins on a molecular and atomic level.…”

The Mechanism of Cathodic Disbonding of Hydroxy‐Terminated Polybutadiene on Steel from Acoustic Microscopy and Surface Energy Analysis

“…Alternatively, the sample was polarized galvanostatically with a cathodic current of typically 200 i~A/cm 2 while recording both the wetting force and potential. This method for wetting tension measurement is often referred to as the Wilhelmy plate method and has been reported previously as a viable method for characterizing electrochemically governed wetting (8,9).…”

“…For epitaxial growth, vapor phase epitaxy (VPE), molecular beam epitaxy (MBE), hot wall epitaxy (HWE), and metallorganic chemical vapor deposition (MOCVD) techniques have been used. In addition to these methods, the simplest and the most convenient method is chemical deposition, which has been used to prepare a large number of semiconductor thin films such as PbS (1-5), PbSe (6), CdS (7), CdSe (6,8), ZnSe (9), Cdi =Pb=Se (10), Pb~_fl-IgxS (10,11), CdL_=Zn~S (10), and CdI_=Hg=S (11).…”