Corrosion Of Pure Aluminium Research Articles

MgO/KH2PO4 and Curing Moisture Content in MKPC Matrices to Optimize the Immobilization of Pure Al and Al-Mg Alloys.

Magnesium Potassium Phosphate Cements (MKPCs) are considered a good alternative for the immobilization of aluminium radioactive waste. MKPC composition and moisture curing conditions are relevant issues to be evaluated. The corrosion of pure aluminium (A1050) and AlMg alloys (AA5754) with 3.5% of Mg is studied in MKPC systems prepared with different MgO/KH2PO4 (M/P) molar ratios (1, 2, and 3M) and moisture curing conditions (100% Relative Humidity (RH) and isolated in plastic containers (endogenous curing)). The Al corrosion potential (Ecorr) and corrosion kinetic (icorr and Vcorr) are evaluated over 90 days. Additionally, the pore ion evolution, the matrix electrical resistance, the pore structure, and compressive strength are analysed. The corrosion process of Al alloy is affected by the pH and ion content in the pore solution. The pore pH increases from near neutral for the 1M M/P ratio to 9 and 10 for the 2 and 3M M/P ratio, increasing in the same way the corrosion of pure Al (AA1050) and AlMg alloys (AA5754). The effect of Mg content in the alloy (AA5754) becomes more relevant with the increase in the M/P ratio. The presence of phosphate ions in the pore solution inhibits the corrosion process in both Al alloys. The MKPC physicochemical stability improved with the increase in the M/P ratio, higher mechanical strength, and more refined pore structure.

The effect of adding different percentages of Copper on corrosion of pure Aluminum

Aluminum and its alloys normally solidify in a columnar structure according to directionally slow cooling rate which results in decreasing the mechanical strength. Aluminum has a huge tendency to unite with oxygen to form oxide film on its surface, offers of it excellent resistance to corrosion and provides years of maintenance-free service and offered it excellent corrosion resistance and spare a lot of years without maintenance. Because of the aluminum and its alloys in fact work applications. Study was carried out on the coppers impact in addition to pure aluminum were six different Al-Cu alloys of (1, 2, 3, 4, 5 and 6) wt% Cu content were prepared and experimentally tested in acidic and alkaline medium. As in general the increase in the percentages of copper led to increased total corrosion rates of the samples submerged in corrosive medium. From obtained results has been reached that the corrosion rate of the alloy which 6%Cu content was (0.02585MPY) higher than the corrosion rate of the alloy of the 1%Cu content where it was (0.00081MPY) were the two alloys submerged in acidic medium, while the corrosion of the alloy 6%Cu was (0.505414MPY) higher than the from the corrosion rate of 1%Cu which it was (0.433369MPY) were the two alloys submerged in alkali medium. As was attained that the corrosion rates in the alkaline medium were higher in acidic medium corrosion rates.

Study of some basic operation conditions of an Al-air battery using technical grade commercial aluminum

Commercial Al-6061 has been used as anode electrode to construct alkaline Al-air batteries. Functional batteries with satisfactory operation record have been constructed by using air-breathing Pt-free cathode electrodes simply made by depositing carbon black on carbon cloth. The devices were functional also in the absence of oxygen either by water reduction or by using hydrogen peroxide as oxidant, thus providing a variety of operation conditions. Al-6061 corroded fast in the alkaline electrolyte producing hydrogen at rates that approached the theoretical maximum. Fast corrosion was associated with the presence of grain impurities in the alloy and the existence of extensive grain boundaries. In this respect, corrosion of pure aluminum was much slower under the same conditions and resulted into a slower rate of hydrogen production.

The effect of adding different percentages of Copper on corrosion of pure Aluminum

Aluminum and its alloys normally solidify in a columnar structure according to directionally slow cooling rate which results in decreasing the mechanical strength. Aluminum has a huge tendency to unite with oxygen to form oxide film on its surface, offers of it excellent resistance to corrosion and provides years of maintenance-free service and offered it excellent corrosion resistance and spare a lot of years without maintenance. Because of the aluminum and its alloys in fact work applications. Study was carried out on the coppers impact in addition to pure aluminum were six different Al-Cu alloys of (1, 2, 3, 4, 5 and 6) wt% Cu content were prepared and experimentally tested in acidic and alkaline medium. As in general the increase in the percentages of copper led to increased total corrosion rates of the samples submerged in corrosive medium. From obtained results has been reached that the corrosion rate of the alloy which 6%Cu content was (0.02585MPY) higher than the corrosion rate of the alloy of the 1%Cu content where it was (0.00081MPY) were the two alloys submerged in acidic medium, while the corrosion of the alloy 6%Cu was (0.505414MPY) higher than the from the corrosion rate of 1%Cu which it was (0.433369MPY) were the two alloys submerged in alkali medium. As was attained that the corrosion rates in the alkaline medium were higher in acidic medium corrosion rates. http://dx.doi.org/10.25130/tjps.23.2018.037

Corrosion and Corrosion Inhibition of Aluminum Alloys A5052 and A5754 in Sulfuric Acid Solutions by Some Inorganic Inhibitors

AbstractThe corrosion of aluminum alloys (A5052 and 5754) in sulfuric acid solutions was investigated using potentiodynamic polarization curves, electrochemical impedance spectroscopy (EIS), scanning electron microscope (SEM), and energy-dispersive X-ray (EDX) methods. For comparison, the corrosion of pure aluminum in sulfuric acid was examined potentiodynamically. The data reveal that increasing sulfuric acid concentrations and solution temperature enhance the corrosion rate of aluminum alloys. The two aluminum alloys exhibit higher corrosion resistance than pure aluminum. Moreover, A5052 involves more corrosion resistance than A5754. The effect of WO2−4and MoO2−4anions as inorganic inhibitors on the corrosion of aluminum alloys in 0.3 M H2SO4solution has also been studied. Results show that the presence of either WO2−4or MoO2−4anions in the acid solution decreases the corrosion of aluminum alloys. The Langmuir isotherm is found to be an accurate isotherm describing the adsorption of these oxyanions on the alloys surface.

Corrosion behavior of aluminum in 1 M HCl solution

The corrosion behavior of pure (99.999) aluminum in 1 M HCl solution is studied. The regularities of local gas evolution on the surface of test specimen at the open-circuit potential are determined. A number of sites, where hydrogen gas evolves, varies with the time passing through a maximum. The sizes of bubbles prior to their detachment from the specimen surface are determined. The time dependences of gas bubble radius in the course of the bubble growth are obtained. From the experimental results, it is concluded that, at the sites of hydrogen gas evolution, the cathodic reaction prevails, whereas the anodic reaction (aluminum etching) proceeds at the rest specimen surface area. No pits form at the sites of hydrogen evolution during the experiments (up to 5 h). The quantitative analysis of the cathodic polarization curve enabled us to estimate the rate (the corrosion current density) of almost general corrosion after the decay of local gas evolution. The long-term experiments (for 2 months) showed that the pitting corrosion of pure aluminum takes place in 1 M HCl.

Simulated and measured response of oxygen SECM-measurements in presence of a corrosion process

Scanning electrochemical microscopy (SECM) with its high spatial resolution and chemical selectivity is a powerful technique for studying a wide range of corrosion processes. A common procedure to detect qualitatively a corrosion activity on a metal substrate consists of measuring the local oxygen concentration.The aim of this work is to clarify the local impact of the O2 measurement and the undesired effect on the corrosion process. By means of numerical simulation the variations of the anodic and cathodic currents on the aluminum substrate, as well as concentration profiles, are obtained. The multi-ion transport and reaction model (MITReM) is used considering the homogeneous reactions taking place in the solution, transport of species dominating the corrosion process and the electrochemical reactions. The model case study in this work is corrosion of pure aluminum in chloride solution. We concluded that amperometric O2 SECM measurements lead to a local increase of the solution pH and decrease of partial current densities for O2 reduction on the metal. This influence becomes significant when the distance to the substrate and when the size of the active surface is comparable with the size of the SECM probe.

Synergistic Inhibition Effect of Sodium Oleate and Sodium Vanadate on the Corrosion of Pure Aluminum in NaCl Solution

Synergistic inhibition effect of sodium oleate and sodium vanadate on the corrosion of pure aluminum in NaCl solution has been investigated by open circuit potential, potentiodynamic polarization curve, and electrochemical impedance spectroscopy(EIS). Experiment results show that the pure aluminum has the lowest corrosion current density under the optimum technological conditions at room temperature, which can be expressed as follows: the 3.5wt.% NaCl solution contains two inhibitors of sodium oleate and sodium vanadium, and their mole concentration ratio is 1:2, solution pH value is 8.0~8.5. In addition, these two inhibitors have played the major role of corrosion inhibition at different stage respectively, which can be attributed to the formation of continuous phase on the surface of pure aluminum.

ChemInform Abstract: The Effect of Propargyl Alcohol on the Corrosion of Pure Aluminum and Aluminum Alloys in Aqueous Solutions.

ChemInform Abstract: The Effect of Propargyl Alcohol on the Corrosion of Pure Aluminum and Aluminum Alloys in Aqueous Solutions.

Effect of Deaeration on the Corrosion of Pure Aluminum and Its Three alloys in NaOH solution at pH=11

Effect of Deaeration on the Corrosion of Pure Aluminum and Its Three alloys in NaOH solution at pH=11

The Cooperative Inhibition Effects of Alkaline Earth Metal Ions and EDTA on the Corrosion of Pure Aluminum in an Alkaline Solution

The cooperative effects of alkaline earth metal ions and EDTA (ethylenediamine tetraacetic acid) on the corrosion inhibition of pure aluminum in 4 mol center dot L-1 KOH solution were investigated by hydrogen collection, polarization curve and electrochemical impedance spectroscopy (EIS). It was found that aluminum exhibits minimum corrosion rate in 4 mol center dot L-1 KOH solution containing 0.02 mol center dot L-1 EDTA, saturated Ca(OH)(2) and saturated Sr(OH)(2). EDAX analysis showed that alkaline earth metal ions and EDTA have no contribution to the formation of the surface film on aluminum. Therefore the inhibition effect may be caused by the adsorption of the inhibitor on aluminum surface. This fact indicates that these two ions act as interface inhibitors rather than inter-phase ones.

Effects of SO42−, S2O32− and HSO4− ion additives on the pitting corrosion of pure aluminium in 1 M NaCl solution at 40–70 °C

Effects of sulphate (SO 4 2− ), thiosulphate (S2O 3 2− ) and hydrogensulphate (HSO 4 − ) ion additives on the pitting corrosion of pure aluminium in 1 M NaCl solution have been investigated at various solution temperatures Ts, 40–70 °C using potentiodynamic polarisation experiment, double current step experiment and scanning electron microscopy (SEM). From the analysis of the galvanostatic potential transients obtained from the double current step experiment, it was suggested that both SO 4 2− and S2O 3 2− ions retard the initiation of the etch pits, and that they also inhibit the passivation of the etch pits during the current interruption to promote the subsequent re-activation of the etch pits over the whole range of Ts. In contrast, it was found that HSO 4 − ions promote the initiation of the etch pits and at the same time, they enhance the passivation of the etch pits during the current interruption with rising Ts. From the SEM micrographs, it was revealed that as Ts increased the pit morphology changed from circular shape to irregular shape with rough surface in the presence of SO 4 2− or S2O 3 2− ions, but it changed to strip-like shape in the presence of HSO 4 − ions. The beneficial effects of anion additives on the increase in surface area were discussed on the basis of the morphological change of the etch pits in the presence of anion additives.

Influences of zinc oxide and an organic additive on the electrochemical behavior of pure aluminum in an alkaline solution

The corrosion behavior of pure aluminum in inhibited and uninhibited 4 MKOH was investigated by means of hydrogen collection, polarization curve measurement and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion of pure aluminum was greatly inhibited by the addition of ZnO and dimethyl amine epoxy propane (designated as DE). EIS and EDAX analyses revealed that ZnO produces its effect by depositing on the aluminum surface, which increases the overpotential of hydrogen evolution. It was also found that the addition of DE could greatly improve the deposition of zinc layers.

Electrochemical thermodynamic and kinetic studies of the behaviour of aluminium in hydrochloric acid containing various benzotriazole derivatives

In this study the inhibitive behaviour of benzotriazole, 5-methyl benzotriazole, 5-chloro benzotriazole and 5-nitro benzotriazole on the corrosion of pure aluminium in 0.1M HCl has been investigated by the potentiostatic polarisation technique. For this purpose, corrosion potentials Ecorr, corrosion rates icorr, anodic and cathodic Tafel slopes βa, βc, inhibition efficiencies IE, and surface coverages θ, were determined in 0.1M HCl solutions containing various concentrations (i.e. 1×10-5 M, 5×10-5 M, 1×10-4 M, 5×10-4 M, 1×10-3 M) of benzotriazole derivatives. The efficiency of the studied benzotriazole derivatives at a concentration of 1×10-4 M was found be in the following order: 5-nitrobenzotriazole > 5-methyl benzotriazole > 5-chloro benzotriazole > benzotriazole. It was observed that the benzotriazole derivatives were behaving as cathodic inhibitors and the inhibiting action of these heterocyclic compounds was mainly due to adsorption on the metal surface, which parallels the total negative charge of each molecule. From the adsorption isotherms, values of the free energy of adsorption ΔGads and the equilibrium constant Kads for the adsorption processes were calculated. Corrosion rates were determined electrochemically at 20°C, 30°C, 40°C, 50°C and 60°C with 1×10-4 M or 1×10-3 M of these compounds in 0.1M HCl. From the corrosion rates obtained at different temperatures, activation parameters for the corrosion processes such as activation energies Ea, activation enthalpies ΔH* and activation entropies ΔS* were determined and possible mechanisms for the corrosion and inhibition processes have been proposed.

Laser optical interferometry as NDT methods for cleaner and sustainable desalination plants: pitting and crevice corrosion

In the present investigation, an optical corrosion-meter has been developed for materials testing and evaluation of different corrosion phenomena. The idea of the optical corrosion-meter was established based on principles of 3D-holographic interferometry for measuring microsurface dissolution, i.e. mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e. corrosion current of metallic samples in aqueous solutions. In the present work, an early stage of pitting corrosion of pure aluminium, UNS No.304 stainless steel alloy and copper in seawater were monitored in situ by the optical corrosion-meter during the cyclic polarization test. Also, an early stage of pitting corrosion of pure copper and an aluminium-brass alloy in tap water were monitored in situ by the optical corrosion-meter during the cyclic polarization test. The observations of pitting were basically interferometric perturbations detected only on the surface of the aluminium in seawater, UNS No.304 stainless steel in seawater, pure copper in tap water. In addition, an early stage of crevice corrosion of a carbon steel alloy, a titanium alloy, UNS No.316 stainless steel, UNS No.304 stainless steel, pure aluminium, and an aluminium-brass alloy in seawater as well as pure copper in tap water were monitored in situ by the optical corrosion-meter during the cyclic polarization test. The observations of crevice corrosion were basically interferometric perturbations detected on the surface of most of the tested samples in solutions, except UNS No.304 stainless steel and the pure aluminium in seawater. The crevice corrosion was detected underneath a crevice assembly on the surface of the samples. The crevice assembly made of Teflon bolt, Teflon nut, and Teflon washer. The crevice assembly was used on all tested samples to create a differential aeration cell between the surface of the sample and areas underneath the crevice assembly in solutions. Each Teflon washer contained radial grooves and had 20 plateaus which formed crevices (shield areas) when pressed against the surface of the sample. The interferometic perturbations interpreted as a localized corrosion in a form of an early pitting corrosion or crevice corrosion of a depth ranged between 0.3 μm to several micrometers. Consequently, results of the present work indicate that holographic interferometry is very useful technique as a 3D-interferometric microscope for monitoring pitting corrosion and crevice corrosion at the initiation stage of the phenomena for different metallic samples commonly used in desalination plants.

Inhibition Effect of Calcium Tartrate on the Corrosion of Pure Aluminum in an Alkaline Solution

Abstract The corrosion behavior of aluminum in 1 M potassium hydroxide (KOH) solution with and without calcium tartrate was investigated by means of weight loss measurement, open-circuit potential ...

Effects of applied potential and solution temperature on the pitting corrosion of pure aluminium in sulphate ion-containing chloride solution

Effects of applied potential and solution temperatureT s on the pitting corrosion of pure aluminium (Al) were investigated in 0.01 M NaCl solutions containing various sulphate (SO4 2-) ion concentrations using a potentiodynamic polarisation experiment, the potentiostatic current transient technique, ac impedance spectroscopy and atomic force microscopy (AFM). The potentiodynamic polarisation curves showed a rise in the pitting potentialE pir values and a simultaneous increase in anodic current density at potentials much higher than theE pit value as the SO42~ ion concentration increases. This implies that (SO4 2-) ions impede pit initiation at potentials belowE pit but enhance pit growth aboveE pit. This was confirmed from the larger pit growth rate parameterb values of pure Al exposed to (SO4 2-) ion-containing chloride solutions during the abrading action than those exposed to (SO4 2-) ion-free chloride solution. Furthermore, at 7s=25°C, the charge densityQ values for the Al metal dissolution in the presence of (SO4 2-) ions were smaller than the value in its absence. By contrast, as validated by the capacitance values and the AFM images of the re-anodized specimens, an enhanced metal dissolution was observed in (SO4 2-) ion-containing chloride solutions at 7s=60° and 80°C. From the experimental findings, it is suggested that (SO4 2-) ions act as inhibitors of pitting corrosion on pure Al belowE pit and at 7s=25°C, whereas they act as promoters at 7s=60 ° and 80°C. This originates from the accelerated dissolution of the bare metal extensively exposed to the temperature-sensitive Cl ion attack, which occurs at potentials aboveE pit

Corrosion of Pure Aluminium in Organic Acid Media in the Presence and in the Absence of Chloride Ions: Mass Transport Effects

The influence of mass transport on the corrosion behaviour of pure aluminium in 0.75% citric acid solution in the presence and in the absence of 104 ppm of chloride ions under anodic and cathodic polarisation was investigated with a rotating disk electrode and using electrochemical impedance spectroscopy. For anodically polarised electrodes, the impedance diagrams are composed of a high frequency (HF) capacitive loop followed by a low frequency (LF) inductive loop, whose shape and size are modified neither with immersion time nor with rotation speed. Addition of chloride ions causes a diminution of the diameter of the HF capacitive loop while the influence on the inductive loop cannot be clearly detected due to data scattering. Under conditions of cathodic polarisation, the diagrams present the shape described above, however, the diameter of both loops decreases with immersion time and electrode rotation speed.

The effect of propargyl alcohol on the corrosion of pure aluminium and aluminium alloys in aqueous solutions

The corrosion characteristics of pure aluminium and aluminium alloys containing different alloying elements prepared as a rotating disc electrode were investigated in aqueous solutions of HCl, NaCl, NaCl + NaOH and H 2SO 4. The corrosion characteristics such as corrosion potential, corrosion rate, polarization resistance, pitting potential and inhibition effect of propargyl alcohol on the pure aluminium and aluminium alloys were determined. The working temperature was chosen as 25°C and the rotating speed of the electrode was chosen to be 2200 rpm.

Effect of fluoride ions on the corrosion of aluminium in sulphuric acid and zinc electrolyte

The effect of fluoride ions on the corrosion of aluminium in sulphuric acid and zinc electrolyte has been investigated through thermodynamic analysis and corrosion experiments. The solution chemistry of aluminium, zinc, and iron in aqueous solution in the absence and in the presence of fluoride ions was studied with the construction of the Eh-pH diagrams for the Al−F−H2O, Zn−F−H2O and Fe−F−H2O systems at 25°C. In the presence of fluoride ions, aluminium can form a series of aluminium-fluoride complexes depending on the fluoride concentration and pH whereas zinc and iron can form soluble or insoluble metal-fluoride complex species only at relatively high fluoride concentration and at higher pH values. Experimental results show that in the presence of fluoride ions, the corrosion of pure aluminium in sulphuric acid is due to uniform dissolution and the reaction rate depends on the fluoride concentration. In zinc electrolyte containing fluoride ions, zinc deposits onto the pure aluminium substrate spontaneously and the amount of deposited zinc also depends on the fluoride concentration. On the other hand, the presence of iron in the Al−Fe alloy accelerates the corrosion of aluminium in H2SO4 and zinc electrolyte significantly and prevents the deposition of zinc on the aluminium surface. The effect of fluoride ions on zinc adherence to the aluminium is also discussed.