Influence of the anodizing process variables on the acidic properties of anodic alumina films

Abstract

In the present work, the effect of the different variables involved in the process of aluminum anodizing on the total surface acidity of the samples obtained was studied. Aluminum foils were treated by the electro-chemical process of anodic anodizing within the following variable ranges: concentration = 1.5-2.5 M; temperature = 303-323 K; voltage = 10-20 V; time = 30-90 min. The total acidity of the samples was characterized by two different methods: acid-base titration using Hammett indicators and potentiometric titration. The results showed that anodizing time, temperature and concentration were the main variables that determined the surface acid properties of the samples, and to a lesser extent voltage. Acidity increased with increasing concentration of the electrolytic bath, whereas the rest of the variables had the opposite effect. The results obtained provide a novel tool for variable selection in order to use synthetized materials as catalytic supports, adding to previous research based on the morphology of alumina layers.

Fast Fabrication of Localized Porous Alumina Patterns with 3D Printed Microdroplet Cell

“…The oxide formation rate increases due to increased reaction speed. 44 The magnified view of cross-sectional SEM images show that porous alumina lines consists of straight cylindrical pores. No layered-type structure was observed due to the back and forth movement of the Sf-MDC, unlike the previous study.…”

Preparation and properties of the anodized film on Fe-Cr-Al alloy surface

“…Thin alumina films grown on metal and metallic alloys substrates are of great interest for applications such as gas sensors, catalysis, corrosion protection, thermal barrier coatings and microelectronics. All surface properties can be affected by the nature and thickness of the passivation oxide layer which was caused by the chemical composition of the electrolyte, the duration of oxidation and the thickness of the film (Parle et al, 2013;Boldrini et al, 2017). When alloys are immersed in suitable electrolytes, dense oxides are usually produced (Keller and Strehblow, 2004;Chung et al, 2017).…”