Corrosion Rate Of Aluminum Research Articles

Effect of Sodium Chloride on Corrosion of Aluminum Alloys Burried in Mortar and Concrete

The effects of sodium, calcium and chloride ions in mortar and concrete on corrosion of aluminum alloys were studied. Chloride and especially sodium ions were concentrated in the inner layer of corrosion product. The corrosion rate increased with increasing sodium content in the inner layer and was almost independent of the chloride content. Calcium ions existed only in the outer layer. It is concluded that the corrosion rate of aluminum increases with increasing hydrated sodium aluminate content. Such a compound is likely to accelate the crystallzation to trihydrated aluminum oxide and then to keep the strong alkaline environment at the metal surface.

A Study of the influence of pH on the corrosion rate of aluminium

Extensive investigations of the aluminium electrolyte interface were undertaken in order to check the pH dependence of the corrosion rate aluminium, i.e. the pH value at which the rate of aluminium corrosion is lowest. Part of this research which deals with measurements of the loss of mass and polarization resistance as functions of pH is presented in this paper. The measurements were performed over a broad range of pH in the presence and absence of ethylenediamine inhibitor. The results are shown as plots of log(1/ R p) and log Δ m against the pH. Two straight lines of opposite slope were obtained for each method of investigation and each system investigated. The intercepts obtained by extrapolating the straight lines, which represent minima of 1/ R p and mass loss, indicate the corresponding pH values. The results obtained are discussed in terms of the interaction of water dipoles with the oxide film during the corrosion process. The change in the surface charge of the corroding aluminium as the pH is altered plays an important role in the corrosion process.

アルミニウムの腐食電位変動と腐食速度の関係

アルミニウムの腐食電位変動と腐食速度の関係

Corrosion Characteristics of Some Aluminum Alloys in Nitric Acid

Corrosion characteristics of some commercially pure aluminum alloys (1060, 1100, 3003, and 5052) in different concentrations of nitric acid have been studied at different temperatures. Alloy 3003 exhibits maximum corrosion in all the acid concentrations followed by 5052, 1100, and 1060 alloys. The corrosion rate of aluminum is found to increase and decrease with time in 20 and 70% acid solutions, respectively. In the concentration range of 20–50% of the acid, all the alloys exhibited slightly passivating tendency during the potentiostatic anodic polarization. The breakdown potential of the alloys varies inversely with temperature, whereas an invariable enobling in steady‐state corrosion potential with rise in temperature is noted. The current density required for initiation of passivation, i.e. is related to temperature bywhere and are constants. The alloys exhibited negative steady‐state corrosion potentials in a concentration range of 1–58% of the acid, but above this concentration positive values of the potentials have been noted. Variation of corrosion rates of the different alloys in different concentrations of the acid has been discussed in the light of the presence of different alloying elements. The influence of the addition of 0.025M, 0.05M, 0.1M, 0.25M, and 0.5M chloride, bromide, iodide, acetate, citrate, sulfate, and nitrate as their sodium salts has also been investigated on the anodic dissolution of 1060 alloy in 20% nitric acid. At concentrations of 0.025M, 0.05M, and 0.1M, Cl−, Br−, and I− have little noticeable effect, but at concentrations of 0.25M and 0.5M of the former two compounds very fast corrosion was recorded and the last compound appeared to be a corrosion inhibitor. The tolerable concentration of chloride ion increases with increase in the concentration of nitric acid in conformity withAcetate, citrate, sulfate, and nitrate ions inhibit the dissolution of the alloy at all the concentrations used. It has been concluded that the sodium ion does not affect the dissolution tendency of the alloy and the anions are solely responsible for inhibiting the dissolution of the metal.

Non-corrosive action of the tertiary phosphate ion on aluminium

The corrosion rate and potential of aluminium were measured in 0.05–0.5 M NaOH solutions containing 0.001–1 M Na 3PO 4 at 30°C. Anodic polarisation was also carried out in the different solutions within the current density range 10 −6–10 −1 A cm −2. The results indicated that the tertiary phosphate ion has no corrosive properties. The increase of corrosion rate at high Na 3PO 4 concentrations (above ca. 0.05 M) is attributed to the adsorption of Na + ions on the metal surface and hence the cathodic reaction is accelerated. The passivation current determined from polarisation curves decreases with the increase of phosphate concentration. This is due to a larger contribution of the phosphate ion in the transfer of current and the consequent lack of OH − at the anode surface. In the very dilute sodium hydroxide solutions (below 0.1 M), addition of very small amounts of Na 3PO 4 decreases the corrosion rate and corrosion potential to a minimum. This might be due to the replacement of water molecules (from which hydrogen is evolved), originally present near the electrode surface, by Na + ions.

Corrosion of aluminium in aliphatic amines and its inhibition by some dyes

AbstractCorrosion rates of aluminium alloys 2S, 3S, M57S and B26S in aqueous solutions of aliphatic amines and the inhibition efficiency of some dyes on the corrosion of 3S aluminium in these amines has been studied. The corrosion rate increases with the amine concentration up to 0.1 M and then decreases. The general order of corrosivity of amines is: tertiary < primary < secondary while for ethanolamines, the order is: tri‐ < di‐ < monoethanolamine. The order of corrosion susceptibility of different alloys in uninhibited amines M 57S < 2S < B26S < 3S. A rise in temperature increases the corrosion rate of 3S aluminium in 0.1 M amine with the energy of activation having an almost constant value of 48.9 kJ/mol in the temperature range 20–50° C.In 0.1 M methylamine, the inhibiting efficiency of different compounds (concentration 0.1%) increases in the order: alizarin red‐S (5.8%) < fluorescein sodium < eosin < congo red < phenol red < thymol blue < safranine‐T < methylene blue < rhodamine‐B (94.2%). The efficiency of rhodamine‐B for 3S aluminium in 0.1 M solutions of various amines in creases in the order: monoethanolamine (75.4%) < cyclohexylamine < n‐butylamine < triethylamine < n‐propylamine < diethylamine < trimethylamine < diethanolamine < ethylenediamine < triethanolamine < dimethylamine < ethylamine < methylamine (94.2%).The increase in corrosion potential of 3S aluminium in 0.1 M amine containing 0.1% rhodamine‐B and the galvanostatic polarization data indicate that the inhibitor has preponderant action on local anodes.

Corrosion behaviour of aluminium in NaOH solutions

The electrode potential and the corrosion rate of aluminium were measured in 0.001–2 M NaOH solutions at 30°C. Up to 0.005 M (pH 11.7) the potential was found to be independent of concentration, whereas the corrosion rate is proportional to the alkali concentration. Hence, the corrosion process is diffusion-controlled. Within the concentration range 0.01–0.5 M (pH 12–13.5), the potential decreases at a gradient of 51 mV pH−1 and the corrosion rate is almost proportional to the square root of concentration. These results were discussed in the light of the kinetics of the anodic and cathodic reactions. Above 0.5 M, both the potential and corrosion rate increase rapidly with concentration. This was attributed to adsorption of Na+ ions, which leads to the formation of active cathodic areas at the expense of the anodic ones.

Corrosion behaviour of aluminium in NaOH solutions

The electrode potential and the corrosion rate of aluminium were measured in 0.001–2 M NaOH solutions at 30°C. Up to 0.005 M (pH 11.7) the potential was found to be independent of concentration, whereas the corrosion rate is proportional to the alkali concentration. Hence, the corrosion process is diffusion-controlled. Within the concentration range 0.01–0.5 M (pH 12–13.5), the potential decreases at a gradient of 51 mV pH −1 and the corrosion rate is almost proportional to the square root of concentration. These results were discussed in the light of the kinetics of the anodic and cathodic reactions. Above 0.5 M, both the potential and corrosion rate increase rapidly with concentration. This was attributed to adsorption of Na + ions, which leads to the formation of active cathodic areas at the expense of the anodic ones.

Aluminium corrosion studies. II. Corrosion rates in water

The corrosion rate of aluminium in flowing neutral waters at 50�C has been determined as a function of pH, oxygen concentration and chloride concentration. The corrosion rate, At, as total aluminium lost between the 4th and 80th day was observed to be logarithmic according to At = B log t+C with a minimum rate in the pH range 5-6, and with B c. 3 x 10-5g cm2, C c. 20 x 10-5 g cm-2 and t in days for oxygen-saturated water. Saturating the water with nitrogen or adding up to 15 mg Cl- l-1 increased the corrosion rate. It was concluded that this was due to competitive action on the oxide surface, between dissolved oxygen and chloride ions.

Factors contributing to the corrosion of the aluminum metal on semiconductor devices packaged in plastics

Using a test structure with an evaporated aluminum metallization pattern on the surface of a phosphorus “doped” oxide layer of a silicon semiconductor chip, the rate of corrosion of the aluminum metallization in a d.c. electric field at 85°C and 85% relative humidity was studied. The test structure was attached to a metal frame and molded in a variety of epoxy and silicone plastics. The relative contribution of the nature of the plastic encapsulant used, the presence of phosphorus in the silicon oxide layer and the strength of the electric field on the corrosion of the aluminum metallization was investigated. Under the above conditions it was established that in the presence of phosphoric acid extracted from the phosphorus-doped oxide layer corrosion occurs exclusively at the cathode. The rate is dependent upon the applied d.c. voltage. In the absence of phosphorus in the oxide layer and other ionic contaminants in the moisture on the surface of the device (pH 6–8) the rate of aluminum corrosion is low and occurs principally at the anode. The type of plastic encapsulant used influences the rate of moisture penetration to the device surface but once there the rate of corrosion under high temperature and bias is similar for all plastics if the acidity of the surface layer is high. It is shown that moisture penetration is diffusion-controlled and does not correlate with adhesion of the plastic to the external leads. On the basis of observations of the conditions favoring cathodic or anodic corrosion of the aluminum on semiconductor devices together with aluminum electrodes in various electrolytes, the electrochemical and chemical reactions occurring at the electrodes between the aluminum and the electrolytes are postulated.

Study of Aluminum Corrosion in Chloride and Nitrate Media and its Inhibition by Nitrite

Aluminum corrosion has been studied in aqueous chloride and nitrate media. Potentiodynamic method is applied to carry out the individual effect of chloride and nitrate ions on the commercial grade aluminum corrosion. In both chloride and nitrate media the corrosion behavior is affected at pH 4 and 10. The corrosion rate of aluminum increases with the increase of concentrations of chloride and nitrate ions. In both media corrosion behavior is significant at higher pH value due to the instant dissolution of metal ions as complex. The nitrite plays an important role as a corrosion inhibitor in both chloride and nitrate media.DOI: 10.3126/jncs.v22i0.519Journal of Nepal Chemical SocietyVol. 22, 2007 pp.26-33

Galvanic corrosion of aluminum alloy castings

Galvanic corrosion of aluminum alloy castings, composed of 99.8% Al, Al-5% Cu, Al-4% Si-4% Cu, Al-11% Si, Al-7% Si-6% Cu, and Al-5% Mg, was investigated in contact with 18-8 stainless steel, mild steel, and copper in 5% NaCl aqueous solution at 35°C and at boiling point under ordinary atmospheric pressure. corrosion behaviors of these alloys at boiling point were quite different from those at 35°C. The increasing order of corrosion rate of the aluminum alloys at 35°C was arranged as follows.Al-5% Mg=99.8Al<-11% Si<Al-7% Si-6% CuHowever, the above order was observed inversely at boiling point. Al-5% Mg was most strongly attacked among these alloys when it was coupled with the stainless steel at boiling point. High corrosion rate of this alloy was attributed to Mg(OH)2 formed in the solution, because of its basicity. The corrosion rate of aluminum would be high under this condition. Al-7% Si-6% Cu was least corroded; in particular, very little galvanic effect was observed when it was coupled with mild steel.The gravimetric loss of weight on galvanic corrosion of pure aluminum was about three times as large as that calculated from the current flowing through the galvanic couple.Maximum galvanic current was observed at about 75°C in the couple of pure Al-mild steel or pure Al-copper. However, extraordinary large galvanic current was observed in the couple of pure Al-stainless steel.

Effect of barrier layer thickness on aqueous corrosion of aluminum

Barrier layer thickness of aluminum, which had been subjected to corrosion tests in water containing a few ppm of various reagents, was determined by the polarization method proposed by M. S. Hunter and P. Fowle.The thickness of barrier layer formed in the air decreased with increasing time of immersion in pure water up to 100hrs. The same behavior was also observed on aluminum tested in water containing any one of NaNO3, NaCl, NaOH, and HCl. While, in water containing any one of NaF, Na2SO4, Na2SiO3, H2SO4, and H3PO4, the thickness of the layer formed in the air once decreased at the initial stage of immersion, and then, began to increase.These results were compared with the corrosion rate of aluminum tested in the solutions mentioned above.It was concluded that there was inverse correlation between the corrosion rate of aluminum and the barrier layer thickness after the tests in the various testing solutions for 100hrs. Further studies shall be made in future to reveal the reason of specific effects of anion in testing solutions on the barrier layer thickness of aluminum which was immersed in the solutions.

Comportement de l'aluminium dans l'eau oxygénée concentrée

AbstractThe electrochemical behaviour of aluminium in concentrated hydrogen peroxide has been studied by measuring the electrode potentials and the “corrodance”, i.e. the inverse of polarization resistance.Electrode potentials are very affected by the presence of chloride and nitrate whereas “corrodance” determination is a convenient method for the rapid measurement of the very low corrosion rate of aluminium in hydrogen peroxide.

Initial Corrosion of Aluminum Alloys In High Temperature Water

Abstract The corrosion rates of commercial 2S aluminum and two iron- and nickel-containing alloys have been obtained by measuring the thickness of the oxide film on specimens after exposure to high...

Effect of Nitrogen Tetroxide On Metals and Plastics

Abstract The corrosion rates of carbon steel, stain-less steel (304-L and PH 15-7 Mo), aluminum (5086), and titanium (75A and 6Al 4V) in dry and wet nitrogen tetroxide were determined under static conditions of exposure at —9 G to 74 C. Carbon steel and aluminum were attacked in proportion to water concentration and temperature. Stainless steel 304-L and titanium were un-attacked, and PH 15–7 Mo only slightly attacked. Significant corrosion of stainless steel (304-L) occurred in the presence of Teflon. Corrosion by dry nitrogen tetroxide under flow conditions was negligible. Teflon was the most resistant of the plastics exposed to nitrogen tetroxide. 4.3.3

Corrosion of Metals in Tropical Environments (Part 1—Five Non-Ferrous Metals and a Structural Steel)★

Abstract An extensive investigation has been in progress since 1940 in the Panama Canal Zone to study the corrosion rates and characteristics of fifty different metals and alloys exposed to five natural tropical environments for periods of one, two, four, eight, and sixteen years. Up to the present, specimens through the eight year period have been removed and examined. The report describes the corrosion rate of aluminum, lead, nickel, zinc, and copper along with structural steel. Corrosion data for these metals as observed in the five environments have been obtained from weight loss and pitting measurements, visual inspection and physical property studies. Corrosion rates for these metals in the tropics are related to corrosion rates previously reported for these metals in temperate latitudes. 2.2.2

Influence of crystallographic orientation on the corrosion rate of aluminum in acids and alkalies

Influence of crystallographic orientation on the corrosion rate of aluminum in acids and alkalies

Corrosion Rate and ETCH Structures of Aluminum; Effect of Heat Treatment and Impurities

The effect of heat treatment of aluminum alloys ranging in purity from 99.2 to 99:998 per cent Al on the rates of dissolution and resulting etch structures in hydrochloric acid and sodium hydroxide solutions has been studied. The results are listed at the end of the paper under SUMMARY.

Effect of Addition Agents upon the Corrosion Rate of Aluminum by Alkalies

Effect of Addition Agents upon the Corrosion Rate of Aluminum by Alkalies