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Velocity Velocity affects the kinetics of the dissolution of the protective film mainly. After the velocity has reached a critical level it may cause dissolution by erosion. Jet impingement tests have been devised to check the susceptibility of various materials to velocity. The corrosion of aluminium depends to a large degree on the sea water velocity. The corrosion rates of various materials in synthetic sea water having velocities from 2 to 16 m/sec at 20°C‐have been measured and with increased velocity the rate of corrosion was found to have increased and aluminium is not too much of an exception. About 2.3 m/s is the conventional agreed figure for aluminium and most users agree with it.

The relatively complex corrosion mechanism of aluminium has been studied by several authors. Corrosion of aluminium occurs only when the metal protective oxide layer is damaged and when the repair mechanism is prevented by chemical dissolution. Polarization methods have been extensively used to investigate the mechanism of localised corrosion and processes that lead to localised corrosion. The potential‐pH diagrams are shown in Fig. 1A. In using potentiostatic techniques, the potential is controlled and current is determined as the independent variable. Potentiostatic and potentiody‐namic techniques have been applied by several authors to study the corrosion of aluminium in different environment. Both anodic and cathodic polarization curves have been used to interpret the kinetics of pitting corrosion of aluminium in chloride containing environments. Both the anodic and cathodic process are complex and the interpretation of the anodic and cathodic polarization curves of aluminium is often tedious. The situation arises partly from the fact that the role of film formation on the kinetics of corrosion is not clearly understood. Previously there is not established mechanisms of initiation and propagation of pits in aluminium and its alloys. Several parameters such as pitting potential, breakdown potential, active passive transition potential, related to the pitting process of aluminium, are full of controversy. Numerous references on the above can be found in literature).

The purpose of this paper is to study the influence of rhamnolipid biosurfactant complex on the corrosion and the repassivation of a freshly cut Al-Cu-Mg aluminium alloy surface.

The electrochemical methods, supported by quantum-chemical calculations and scanning electron microscopy data, were used.

It was established that the rhamnolipid biosurfactant effectively inhibits corrosion of the alloy in synthetic acid rainwater. The efficiency of inhibition becomes stronger with the increase of biosurfactant concentration; however, above the critical micelle concentration, the further improvement in inhibition is minor. It is believed that the mechanism of corrosion inhibition is related to the adsorption of the biosurfactant molecule on the aluminium alloy surface and the formation of a barrier film; however, the formation of a complex compound (salt film) between aluminium ions and rhamnolipid on anodic sites of the alloy is not ruled out. In case of surface mechanical activation of the alloy, the biosurfactant molecule effectively prevents corrosion. Furthermore, addition of the biosurfactant to the corrosion environment increases the repassivation kinetics of the alloy by two to four times as compared with an uninhibited environment.

The commercial impact of the study consists in the possibility of obtaining of environmentally safe corrosion inhibitors of aluminium alloys by biosynthesis from renewable agricultural raw materials.

The originality of this paper is to study the effectiveness of “green” corrosion inhibitor based on biogenic product on freshly generated surface of aluminium alloy.

This concluding part reviews the actions of inhibitors to acidic, ammonical, organic, atmospheric and miscellaneous product corrosion on aluminium. The comprehensive reference list is also concluded.

The purpose of this paper is to investigate and find out the surface and electrochemical behaviours of twin roll cast (TRC) 8006 aluminium alloy with different thicknesses due to the cold rolling rates after the TRC process.

The 8006 aluminium alloys are mostly used for the food packaging industry, as they are corrosion resistant, lightweight and shapable materials. The present work investigates the surface and corrosion behaviours of 8006 aluminium alloys at different thicknesses. TRC aluminium alloys were cold-rolled at two different reduction rates before investigation. X-ray diffraction (XRD) and energy dispersive spectroscopy (EDX) tests were used to examine the phase and elemental analyses. FE-SEM and 3D profilometry also used to observe surface morphology. Open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy tests (EIS) were carried out to find out corrosion behaviours. The results show that the more cold rolling reduction (CRR), the more corrosion rate and surface affection of the TRC 8006 aluminium alloys.

According to the electrochemical tests (OCP, potentiodynamic polarization test and EIS) and surface morphology results (such as SEM, 3D profilometry and XRD) the more the rolling rate the less the corrosion resistance.

First corrosion behaviour investigation of twin-rolled 8006 Al alloys using electrochemical techniques. First investigation of CRR effects on electrochemical corrosion behaviour of 8006 Al alloys with 3.5 wt.% NaCl solution using EIS. First investigation of 8006 Al alloys as a food packaging material with electrochemical ways.

Geigy Co. Ltd. Stand 75. Diversified application of benzotriazole as a corrosion inhibitor specifically for copper and its alloys is the main theme of Geigy's stand.

ALUMINIUM alloys have been important structural materials in aircraft from very early days, and there is no doubt that the course of aeronautical development would have been very different without them. It would be pointless to review the classification of these alloys and their respective fields of application in quite the same way as was done in the two previous articles of this series, those on titanium and magnesium. The aircraft industry has used many of the traditional alloys for years, and is highly familiar with their possibilities and limitations. In this article we shall outline, in the first place, the extent of present alloy development, giving some special attention to matters of particular aeronautical significance, and then limit further consideration to certain specific types of alloy which, for one reason or another, are the most promising as well as being the most difficult to use successfully in aircraft structures. These alloys are all of the high‐strength precipitation‐hardening type.

Two types of aluminium alloys, 2024‐T3 and 7075‐T6, having been selected, this study aims to investigate the effect of metallurgical aspects on intergranular corrosion.

To determine and evaluate the metallurgical effects of heat treatments on corrosion behaviour of these alloys, G67 ASTM test was selected.

The results showed that with increasing the aging time in aluminium alloy type 2024‐T3 the susceptibility to intergranular corrosion increases, while in type 7075‐T6 with increasing aging time the intergranular corrosion rate remains nearly unchanged.

As these results refer to precipitate the intermetallic compound phases, the amount of these phases increases with the increase of the aging time in both alloys.

The investigations showed that the phases that initiate in 2024‐T3 act as anode sites, while in 7075‐T6 they act as cathode sites.

The industrial expansion of the post‐war period has resulted in the development of new products and processes, specialised equipment and new materials of construction. Materials science, technology and engineering, has emerged as an independent discipline during the last decade. These changes have brought up the importance of corrosion problems and the urgency to apply preventive methods. It is probably true to say at the present time that the losses due to metallic corrosion give a fair index of the industrial prosperity of a nation. A developing country like India had to face the challenge posed by corrosion, and there is now an increasing awareness of the imperative need for corrosion research and the application of the findings to meet specific situations.

ZIRCONIUM Corrosion in hot water and steam. Metallic zirconium and its alloys have assumed much importance as construction and protection material in nuclear reactors cooled with water or heavy water. Among the properties favouring this application are low neutron absorption, favourable mechanical characteristics, and a high corrosion resistance to water and steam. This corrosion resistance can be further improved by using suitable zirconium alloys. Even so, there are still certain undesirable corrosion phenomena which cause trouble. These have been made the subject of further research, e.g. in the metal laboratory of the Metallgesellschaft A.G., Frankfurt‐am‐Main. In this connection, a distinction must be made between two phenomena which occur simultaneously but are, as far as it's known at present, basically independent of each other, viz. oxidation and hydrogen absorption. But the extent to which the hydrogen freed in the course of the oxidation process can be absorbed by the zirconium and thereby cause brittleness depends not only on the external conditions but also on the type and quantity of the alloying components. During oxidation, the slow formation of a thin, bluish oxide film is liable to be followed by a more rapid ‘breakaway’ corrosion process in which a white oxide is formed that will soon peel off. There is, as yet, no satisfactory theory which would appear to provide a full explanation of all the phenomena encountered. The author discusses the research methods, the corrosion phenomena as such, the influence of certain alloying constituents on these phenomena and the various attempts at interpreting them.—(H. W. Schleicher, Metalloberfläche, 1961, 15 (8), 234–240.)