Salt spray corrosion and electrochemical corrosion property of anodic oxide films on ADC12 aluminum alloy

Anodic oxide films were prepared by anodic oxidation on the surface of ADC12 aluminum alloy and their corrosion properties were explored. The original samples, anodized samples, and sealed samples were placed in the salt spray corrosion chamber and were taken out at different times. Then the corrosion resistance of the ADC12 aluminum alloy was discussed, and the electrochemical corrosion test was researched. The results indicated that the surface of the original samples reveals many large-area pits after salt spray corrosion, while the sealed samples present a smoother surface. The dense oxide films on the surface of the base metals effectively prevent Cl[Formula: see text] entering into aluminum alloys especially after sealing. Electrochemical tests including the potential polarization curve and electrochemical impedance spectroscopy (EIS) as functions of exposure time were employed to reveal the corrosion behavior of surface layers. After the sealing treatment on the oxide films, the corrosion potential moved in the positive direction, the corrosion current density decreased, and the corrosion resistance of the ADC12 aluminum alloy was significantly improved.

Influence of Calcium Acetate Concentration in Electrolyte on Tribocorrosion Behaviour of MAO Treated Titanium

Ti-based materials are widely used for dental and orthopaedic implant applications due to their adequate mechanical properties, corrosion behaviour and biocompatibility. However, these materials are biologically inert and display poor wear resistance. In one of the most studied processes that aims to overcome these drawbacks, Ti surfaces are often covered by anodic oxide films with the incorporation of bioactive agents such as Ca and P. Although there are several works on the tribocorrosion behaviour of MAO-treated Ti surfaces, the influence of electrolyte composition on the corrosion kinetics under sliding is yet to be fully understood. In the present work, anodic oxide films were produced on cp-Ti surfaces with different calcium acetate concentrations in the electrolyte. Tribocorrosion behaviour was investigated by reciprocating sliding tests performed in 8 g/L NaCl solution at body temperature, under potentiostatic conditions. The results showed that higher concentrations of calcium acetate had a detrimental effect on tribocorrosion kinetics, however, they resulted in less mechanical damage due to alterations in the topography and structure of the MAO layer.

Preparation of 1060, 2024 and 7075 Aluminum Alloy Anodic Oxide Films

On aluminum alloys of grades 1060, 2024 and 7075, regular and highly uniform oxide films were formed by anodic oxidation. Anodizing was carried out at a constant pressure in a phosphoric acid solution of various concentrations. Using scanning electron microscopy (SEM) and X-ray diffraction (XRD), the optimal characteristics of the method of anodic oxidation for forming uniform oxide films on aluminum alloys were determined: anodic oxidation time, temperature, voltage and the concentration of H3PO4. It was found that, in the process of anodizing, the films have gone through four stages: a non-porosity stage, a mixed stage, an ordered porosity stage and a disordered porosity stage.

Nanostructured electrodes for supercapacitors

The paper presents the results of studies on the formation of planar capacitive systems based on nanoporous anodic oxide films and a conducting polymer. According to voltammetry data, the capacity of the systems under study was determined. The structure of the porous layers was judged by impedance spectroscopy and electron microscopy.

Nanostructure Analysis of Anodic Films Formed on Aluminum-Focusing on the Effects of Electric Field Strength and Electrolyte Anions

In this review, the research conducted by the authors on anodic oxide films on aluminum is described, paying particular attention to how the electric field strength, as a factor other than voltage, controls the nanostructures and properties of the films. It will also be indicated what factors contribute to the formation of defects, which, in contrast to the ideal or model film structure, contains a significant number of defects in the film. In addition to electrochemical measurements, the films were examined with a variety of advanced instruments, including electron microscopes, to confirm the “reality of film nanostructure” from a slightly different angle than the conventional view. The following topics on anodic films formed in four types of major anodizing electrolytes are discussed: pore initiation process, steady-state porous structure, sealing mechanism, the relationship between cell parameters and voltage/electric field strength, amount and depth of anion incorporation, electrolyte types, radial branching of pores, atypical pore structures, defect formation mechanism, self-ordering, Al coordination number, and the creation of α-alumina membranes.

Morphological and Optical Characterization of Colored Nanotubular Anodic Titanium Oxide Made in an Ethanol-Based Electrolyte

In this paper, the possibility of color controlling anodic titanium oxide by changing anodizing conditions of titanium in an ethanol-based electrolyte is demonstrated. Colored anodic titanium oxide was fabricated in an ethanol-based electrolyte containing 0.3 M ammonium fluoride and various amounts of deionized water (2, 3.5, 5, or 10 vol%), at voltages that varied from 30 to 60 V and at a constant anodization temperature of 20 °C. Morphological characterization of oxide layers was established with the use of a scanning electron microscope. Optical characterization was determined by measuring diffusion reflectance and calculating theoretical colors. The resulting anodic oxides in all tested conditions had nanotubular morphology and a thickness of up to hundreds of nanometers. For electrolytes with 3.5, 5, and 10 vol% water content, the anodic oxide layer thickness increased with the applied potential increase. The anodic titanium oxide nanotube diameters and the oxide thickness of samples produced in an electrolyte with 2 vol% water content were independent of applied voltage and remained constant within the error range of all tested potentials. Moreover, the color of anodic titanium oxide produced in an electrolyte with 2 vol% of water was blue and was independent from applied voltage, while the color of samples from other electrolyte compositions changed with applied voltage. For samples produced in selected conditions, iridescence was observed. It was proposed that the observed structural color of anodic titanium oxide results from the synergy effect of nanotube diameter and oxide thickness.