Search results

The purpose of this paper is to provide acid‐dyes, known for the dyeing of porous aluminum oxide films, as inhibitors of the corrosion of aluminum in neutral chloride solutions.

Potentiodynamic polarization plots are recorded on mechanically pretreated aluminum using a three‐electrode cell containing 0.01 M NaCl solution with or without 0.025 mM of the acid‐dyes monosulfonic methyl orange (MO), disulfonic chromotrop RR (CH), disulfonic alphazurine A (AZ) and trisulfonic light green SF yellowish (LG). The X‐ray fluorescence technique is used in certain cases for the estimation of sulfur net content of the surface of the probes and thus of the concentration of the adsorbed dye.

The inhibition efficiency of acid dyes on corrosion of mechanically pretreated aluminum seems to be related more to the presence of a following quinonoid structure which probably contributes more to the formation of mono‐ or bi‐dentate compounds with the aluminum cations in the substrate than to the number of sulfonic groups in their molecule. Thus, the triphenylmethane dyes LG and, to a greater extent AZ, having this quinonoid structure means they are more efficient as corrosion inhibitors in near‐neutral chloride solution than the azo dyes MO and CH, that do not have it.

Selected acid‐dyes such as triphenylmethane sulfonic‐dyes, which have found wide application in the dyeing industry, seem to protect aluminum against the corrosive action of chlorides.

This paper is intended to be the nucleus for the electrochemical studies of the effectiveness of acid dyes as corrosion inhibitors for aluminum.

This study aims to investigate the effect of different pore diameter and pore length on corrosion properties of anodic aluminum oxide (AAO) film.

AAO layer was produced by two-step anodization aluminum in oxalic acid. The surface morphology was investigated using field emission scanning electron microscopy. The pore diameters were ranging from 25 ± 5 to 65 ± 5 nm and the pore length ranging from 5 to 17 µm. The corrosion properties of the AAO films was analyzed by potentiodynamic polarization and electrochemical impedance spectroscopy tests. Corrosion properties and morphology of the anodic films depending on anodization times and pore expansion times were evaluated.

All highlights of this work can be summarized with the following specified below: more treatment with the protective barrier layer of the solution as the pore diameter increases depends on the morphology of the nanotube structured AAO layer. The excellent corrosion resistance renders AAO films without pore expansion very promising. The oxide layer thickness does not affect the corrosion resistance. The better corrosion resistance of AAO films at low pore length can be ascribed to the barrier layer thickness and the more homogeneous structure. The presence of defects for the higher pore length decreases its corrosion resistance.

The AAO films were fabricated by a two-step anodization method in oxalic acid. The anodization times and pore expansion times affect the corrosion performance. The AAO film without pore expansion has good corrosion resistance. The corrosion resistance decreases as the pore length increases.

The purpose of this paper is to join an anodized aluminium alloy AA6061 sheet with high-density polyethylene (HDPE) using friction spot process.

The surface of AA6061 sheet was anodized to increase the pores’ size. A lap joint configuration was used to join the AA6061 with HDPE sheets by the friction spot process. The joining process was carried out using a rotating tool of different diameters: 14, 16 and 18 mm. Three tool-plunging depths were used – 0.1, 0.2 and 0.3 mm – with three values of the processing time – 20, 30 and 40 s. The joining process parameters were designed according to the Taguchi approach. Two sets of samples were joined: the as-received AA6061/HDPE and the anodized AA6061/HDPE.

Frictional heat melted the HDPE layers near the lap joint line and penetrated it through the surface pores of the AA6061 sheet via the applied pressure of the tool. The tool diameter exhibited higher effect on the joint strength than processing time and the tool-plunging depth. Specimens of highest and lowest tensile force were failed by necking the polymer side and shearing the polymer layers at the lap joint, respectively. Molten HDPE was mechanically interlocked into the pores of the anodized surface of AA6061 with an interface line of 18-m width.

For the first time, HDPE was joined with the anodized AA6061 by the friction spot process. The joint strength reached an ideal efficiency of 100 per cent.

The purpose of this investigation is to understand the structure of trapped intermetallics particles and localized composition changes in the anodized anodic oxide film on AA1050 aluminium substrates.

The morphology and composition of Fe‐containing intermetallic particles incorporated into the anodic oxide films on industrially pure aluminium (AA1050, 99.5 per cent) has been investigated. AA1050 aluminium was anodized in a 100 ml/l sulphuric acid bath with an applied voltage of 14 V at 20°C ±2°C for 10 or 120 min. The anodic film subsequently was analyzed using focused ion beam‐scanning electron microscopy (FIB‐SEM), SEM, and EDX.

The intermetallic particles in the substrate material consisted of Fe or both Fe and Si with two different structures: irregular and round shaped. FIB‐SEM cross‐sectioned images revealed that the irregular‐shaped particles were embedded in the anodic oxide film as a thin strip structure and located near the top surface of the film, whereas the round‐shaped particles were trapped in the film with a spherical structure, but partially dissolved and were located throughout the thickness of the anodic film. The Fe/Si ratio of the intermetallic particles decreased after anodizing.

This paper shows that dual beam FIB‐SEM seems to be an easy, less time consuming and useful method to characterize the cross‐sectioned intermetallic particles incorporated in anodic film on aluminium.