Aluminum Alloys In Seawater Research Articles

Effect of Copper(II) Ions on Corrosion Resistance of Al-Zn Coated 5052 Aluminum Alloy in Seawater

Effect of Copper(II) Ions on Corrosion Resistance of Al-Zn Coated 5052 Aluminum Alloy in Seawater

Corrosion Mechanism of 5083 Aluminum Alloy in Seawater Containing Phosphate

As a material with good corrosion resistance, 5083 aluminum alloy has a great application prospect in marine environment. In this work, the corrosion characteristics of 5083 aluminum alloy in seawater containing phosphate were investigated with Potentiodynamic Polarization, Electrochemical Impedance Spectroscopy (EIS), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy Analysis (EDSA), X-ray Photoelectron Spectroscopy (XPS) and Laser Confocal Microscope. The results indicated that the effects of phosphate in seawater were two-fold. Firstly, phosphate slightly accelerated the corrosion of 5083 in seawater in the early stage of corrosion. HPO42− competed with OH− in the adsorption process on the alloy surface, which weakened the contact between OH− and Al3+ near the interface of the alloy, and inhibited the formation as well as the self-repair of the passive film, thus accelerating the activation dissolution process. Compared with the natural seawater, the charge transfer resistance of 5083 in the seawater containing phosphate decreased faster during the early stage of corrosion, and the corrosion current density icorr was higher in seawater containing phosphate. On the other hand, the addition of phosphate would not affect the cluster distribution of the second phase of 5083 in seawater, but it changed the composition of the corrosion product layer and had an obvious inhibitory effect on the local corrosion of 5083 in seawater. After 16-day exposure, shallower and more sparsely distributed pits could be observed on the derusted surface of 5083 in the seawater containing phosphate, and the pitting coefficient in the seawater containing phosphate was significantly lower than that in natural seawater. The reduction of pitting tendency could be realized mainly through two ways. First, the HPO42− adsorbed on the surface of the passive film in the early stage of corrosion and repeled the corrosive anions such as Cl−. Second, phosphate participated in the construction of the CaHPO4 precipitation film, which acted as a barrier and protection.

К ВОПРОСУ О ПОДТВЕРЖДЕНИИ ИДЕНТИЧНОСТИ МЕХАНИЗМА КОРРОЗИОННОГО РАЗРУШЕНИЯ АЛЮМИНИЕВЫХ СПЛАВОВ (обзор) Часть 2. Коррозия в морской воде

The paper presents an overview of studies of the corrosion destruction mechanisms of aluminum alloys in seawater. The main factors that have the greatest impact on corrosion are considered: physical and chemical parameters, the depth of the test objects, as well as the role of biofouling. It has been determined that the parameter of the species composition of the fouling organisms is an important factor in the corrosion of metals in seawater and should be taken into account when identifying the mechanism of corrosion destruction during tests under various conditions.

Study of pitting corrosion inhibition effect on aluminum alloy in seawater by biomineralized film

Metallic materials can be easily corroded in marine environments, in which pitting corrosion is very common. In this study, we investigated the effect of Bacillus subtilis, isolated from the South China Sea on the corrosion behavior of 2A14 aluminum alloy in seawater. Surface analysis of the alloy in the presence of the bacteria was used to observe corrosion morphology and the corrosion products studied. Electrochemical method was used to analyze the corrosion susceptibility of the alloy in seawater in the presence of the bacteria. Surface analysis suggested that a protective film with CaMg(CO3)2 was gradually formed on the surface of the alloy in the presence of the bacteria. The electrochemical results showed that the radius of the impedance arc of the alloy immersed in seawater with bacteria increased gradually with time. The bacteria promoted the formation of the CaMg(CO3)2 film, which blocked seawater from the alloy and consequently, inhibited pitting corrosion.

Electrochemical Characteristics of Aluminum Alloys in Sea Water for Marine Environment

Electrochemical Characteristics of Aluminum Alloys in Sea Water for Marine Environment

The Effect of Concentration of Lawsonia inermis as a Corrosion Inhibitor for Aluminum Alloy in Seawater

Lawsonia inermis also known as henna was studied as a corrosion inhibitor for aluminum alloy in seawater. The inhibitor has been characterized by optical study via Fourier transform infrared spectroscopy (FTIR). The FTIR proves the existence of hydroxyl and carbonyl functional groups in Lawsonia inermis. Aluminum alloy 5083 immersed in seawater in the absence and presence of Lawsonia inermis was tested using electrochemistry method, namely, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PP). EIS and PP measurements suggest that the addition of Lawsonia inermis has caused the adsorption of inhibitor on the aluminum surface. The adsorption behavior of the inhibitor follow Langmuir adsorption model where the value of free energy of adsorption, -ΔG, is less than 40 kJ/mol indicates that it is a physical adsorption. Finally, it was inferred that Lawsonia inermis has a real potential to act as a corrosion inhibitor for aluminum alloy in seawater.

Potentiostatic corrosion protection technology under cavitation condition for 5083-H116 Al alloy

This study aims to characterize the cavitation damage behavior of aluminum alloys in seawater and thus to enhance its cavitation resistance. Potentiostatic experiments were performed under various potential conditions to determine the optimum protection potentials, at which cavitation damage was suppressed. A potential range was selected for the experiment from −2.2 to −1.4 V, which corresponded to the concentration and activation polarization regions on the cathodic polarization curve of the 5083-H116 alloy. After the experiments, the current density–time behavior was investigated, and the degree of surface damage was observed using three-dimensional microscopy and scanning electron microscopy (SEM). The optimum protection potential was determined to be in the range of −1.9 to −1.5 V under which the cavitation damage was reduced significantly.

Al-4.5%Mg-0.6%Mn 알루미늄 합금의 정전위 시간 변수에 따른 손상거동 평가

In general, aluminum alloys forms the passive film(, ) in neutral solution. However, the passive film created on the surface will be destroyed by chloride ions contained in sea water so the corrosion will occur. In this study, in order to solve the problem of corrosion under a seawater environment, potentiostatic protection techniques were applied to Al-4.5%Mg-0.6%Mn aluminum alloy in seawater. At polarization experiments, active state were observed at anodic polarization and concentration polarization by reduction of dissolves oxygen and activation polarization were found at anodic polarization. As a results of potentiostatic experiment, calcareous deposit were created much more as applying time increase from the turning point of the concentration polarization and activation polarization and crevice corrosion was partially observed between calcareous deposit and surface of base metal. Overall potentiostatic anodic polarization experiment was difficult to apply potentiostatic corrosion protection technology by occurrence of active state, whereas potentiostatic cathodic polarization experiment examined optimum corrosion protection condition of -1.1 V~-0.75 V within the range of concentration polarization considered various applying time.

Study of Henna (Lawsonia inermis) as Natural Corrosion Inhibitor for Aluminum Alloy in Seawater

Commercial henna (Lawsonia inermis) was investigated to inhibit the corrosion of aluminum alloy through immersion in seawater. The aluminum alloy (5083) was prepared in size of 25mm × 25mm × 3mm. The immersion test was conducted in seawater with different concentration of henna, 100ppm, 300ppm, 500ppm for duration of 60 days. Four characterizations were performed in this study which was weight loss study, Fourier Transform Infrared (FTIR), Electrochemical Impedance Spectroscopy (EIS) and adsorption isotherm. The results indicated that henna has major constituents of lawsone which contributed to the chemisorptions or adsorption process by forming an isolation layers on the aluminum alloy surface which follows the Langmuir adsorption isotherm. It was found that the protection layer attached on metal was not permanent and precipitation occurred as the time increases. The highest inhibition efficiency was found at 88% (500ppm). This research found that henna is an excellent natural inhibitor for aluminum alloy in seawater.

Electrochemical properties and corrosion inhibition of AA6061 in tropical seawater

The corrosion inhibition of aluminum and its alloys is the subject of tremendous technological importance due to the increased industrial applications of these materials. This study reports the results of potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM) on the corrosion inhibition of AA6061 aluminum alloys in seawater using sodium benzoate as an inhibitor. The electrochemical measurements for aluminum alloys in seawater after varied immersion period showed that the presence of sodium benzoate significantly decreases the corrosion currents densities ( i corr), corrosion rates and double layer capacitance ( C dl), as simultaneously increase the values of polarization resistance ( R p). Charge transfer process and development of thin film on the specimen have been proven by morphology study using SEM.

A study on the corrosion behavior of aluminum alloys in seawater

In this study, the aluminum alloys AA5083 and AA1100 were tested in seawater at 23 and 60 °C. Polarization plots showed that the alloys suffered from pitting attack. The breakdown potential of the two alloys decreased with an increase in test temperature with better corrosion resistance for alloy 1100. The weight loss tests revealed low corrosion rate values for both alloys, indicating a beneficial use for these alloys in marine environments. The pit morphology on the polarized aluminum alloys showed hemispherical isolated deeper pits on the 5083 alloy. Samples of the 1100 alloy revealed a higher number of shallow pits (more close to patches of general dissolution). The results showed that the type of intermetallic particles in the aluminum alloy played a major role in passivity breakdown and pit morphology in seawater.

Marine Corrosion and Protection of Aluminum Alloys According to Their Composition and Structure

Based on long-term tests of aluminum alloys in seawater of various climatic zones from the Arctic to the tropics, the peculiarities of their corrosion behavior are revealed. In contrast to other alloys, hydrogen sulfide has a beneficial effect on their corrosion resistance due to the passivation. However, deep in the Black Sea, the alloys, which are susceptible to structural types of corrosion, were subjected to strong exfoliation corrosion, because hydrogen sulfide excluded fouling with microorganisms that inhibits exfoliation corrosion. Alloys of the Al-Mg system exhibit the highest corrosion resistance in seawater. Alloy of an AMr61 type (σul = 340 MPa, σ0.2 = 180–210 MPa, δ = 11–15%) has shown a good performance. Alloying with scandium and thermomechanical treatment make possible further simultaneous improvement of mechanical properties and corrosion resistance. It is shown that crevice corrosion is more typical of corrosion-resistant low aluminum alloys possessing lower free-corrosion and pitting potentials compared to high alloys, which are susceptible to structural types of corrosion, in particular, exfoliation corrosion. The methods of the aluminum alloys protection against marine corrosion are considered. It is shown that, in contrast to carbon steels, the anodic-cathodic protection is used for aluminum alloys.

The Influence of Incubation Time on the Passive Film Breakdown of Aluminum Alloys in Sea Water

Potential‐controlled electrochemical methods were used to characterize the pitting behavior of 6061 alloy aluminum in synthetic ocean water. Irreproducible breakdown potentials (Ebd) and reproducible repassivation potentials (Erp) were determined from cyclic anodic polarization (CAP). Reproducible breakdown and repassivation potentials were found from the quasi‐stationary anodic polarization method; however, the breakdown potential values were shifted in the electronegative direction relative to the CAP method, due to the allowance of a longer incubation time. These results support the theory that with sufficient incubation time, pit initiation and propagation will occur at potentials at or slightly above the repassivation potential, and that the repassivation potential value is the only characteristic potential for aluminum. The quasi‐stationary anodic polarization method used for Erp determination provides a reproducible electrochemical method for obtaining Erp after minimal pit growth or surface damage. Cyclic anodic polarization can also be used for determining a representative repassivation potential if surface damage subsequent to pit initiation is minimized.

Corrosion fatigue resistance of 1561 aluminum alloy in sea water

Corrosion fatigue resistance of 1561 aluminum alloy in sea water

Morphological Studies of Occluded Cells in the Pitting of Dilute Aluminum Alloys in Seawater

not Available.

Stress Corrosion Testing of 7079-T6 Aluminum Alloy in Seawater Using Smooth and Precracked Specimens

Stress corrosion cracking of a 7079-T6 aluminum alloy in seawater was investigated by bend tests of smooth and precracked specimens. It was found that there was a general agreement between results of the two methods. The susceptibility of this alloy to inter-granular cracking was shown to depend on its directional characteristics. The use of precracked specimens for stress corrosion testing is discussed.

Studies on corrosion of surface-treated aluminum alloys in sea water

Several kinds of surface-treated aluminum alloys were dipped in sea water for one year and their corrosion effects were observed.The results obtained were as follows.(1) Among surface treatments such as as pre-treated MBV process, anodizing in sulfuric acid, painting of organic poisons, specimens by the latter two treatments were never corroded because of short dipping times.2) All the specimens treated by MBV process were corroded after dipping for one year and their anticorrosion effect was not very hopeful.(3) The maximum depth of pits formed on the specimens of non-surface treated or MBV treated increased with the increase of dipping time. The depth was large for pure aluminum (such as 1050 and 1100) and 6063 alloy, but it was relatively small for 3003 and 5052 alloys. In alclad 3003 alloy, the core part of 3003 alloy was protected, though the clad part of 7072 alloy was corroded.(4) The relationship between corroded parts and location of barnacles was observed and it was known that many deep pits were formed close to their shells and that several parts just underneath the shells seemed to be dissolved. It was supposed that these results were due to crevice corrosion attack or corrosion effects of secretions of barnacles. Accordingly, the sticking of barnacles was not desirable for aluminum.