Pitting corrosion of Al and Al–Cu alloys by ClO4− ions in neutral sulphate solutions

Amin, Mohammed A.; Rehim, Sayed S. Abd El; Moussa, Sherif; El-Lithy, Abdallah S.

doi:10.1016/j.electacta.2008.03.010

Cited by 43 publications

(18 citation statements)

References 56 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Interestingly, the categorization of anions is compatible with the observed inhibiting effects of divalent anions, such as SO 2À 4 , HPO 2À 4 and CrO 2À 4 , on the breakdown of passivity of certain valve metals in the presence of halide anions such as Cl À , Br À , I À [47,63] but also with other chaotrope anions like NO À 3 [63] or ClO À 4 [64]. It is generally accepted that the origin of this behavior results from a competition between the anions for adsorption sites at the passive film-solution interface [64,65]. The double negatively charged anions are more attracted and are thus preferentially adsorbed [15,65].…”

supporting

confidence: 57%

Influence of the anion specificity on the anodic polarization of titanium

et al. 2011

View full text Add to dashboard Cite

The anodic polarization of titanium in the presence of selected electrolytes at 0.1 mol/L concentration has been investigated. The results were interpreted according to the categorization of anions based on their cosmotrope/chaotrope character. The aggressiveness of the anions is found to be related for a part to their proneness to loose their hydration shell during the penetration of the passive film, provided they can access sufficiently to the passive surface.

show abstract

supporting

confidence: 57%

Influence of the anion specificity on the anodic polarization of titanium

et al. 2011

View full text Add to dashboard Cite

show abstract

“…Despite the weak adsorption of ClO 4 -ions, there is some evidence from literature [19][20][21] and various studies in our lab [22][23][24][25][26][27][28] proving the occurrence of the pitting corrosion on the surface of some metals and alloys as a result of passivity breakdown by ClO 4 -ions. This means that the adsorption ClO 4 -ions, despite its weakness, has a significant role in passivity breakdown and initiation of pitting corrosion.…”

Section: Effect Of Perchlorate Concentrationmentioning

confidence: 98%

“…5). The samples were first passivated at -600 mV (SCE) in 1.0 M Na 2 SO 4 solution for 15 min, in order to get a stable Al 2 O 3 film on the electrode surface [28], and then NaClO 4 was added to the sulphate solution to establish a 0.005 M perchlorate concentration. Exactly the same procedure was followed for Al in 1.0 M Na 2 SO 4 solution containing 0.005 M NaClO 4 + 0.001 M of the inhibitor.…”

Section: Effect Of Inorganic Inhibitorsmentioning

confidence: 99%

Role of alloyed silicon and some inorganic inhibitors in the inhibition of meta-stable and stable pitting of Al in perchlorate solutions

et al. 2008

Self Cite

View full text Add to dashboard Cite

The study of both meta-stable and stable pitting events on the surface of pure Al and three Al-Si alloys, namely (Al + 6%Si), (Al + 12%Si) and (Al + 18%Si) alloys, was carried out in deaerated neutral NaClO 4 solutions of various concentrations (10 -4 -10 -2 M). Measurements were carried out under the effect of various experimental conditions using potentiodynamic anodic polarization and potentiostatic techniques. The results presented below showed that meta-stable pits (appeared as oscillations in current) form at potentials close to the pitting potential (E pit ) and during the induction time for stable pit formation. Various factors affecting the rate of meta-stable and stable pits were studied. The presence of Si as an alloying element in Al reduces the rate of formation of meta-stable pits, corresponding to a reduction in the probability of developing stable pits, and an increase in the pitting potential results. The inhibitive effects of chromate, silicate, molybdate and tungstate on pitting corrosion in Al were also studied. Results obtained showed that these known inhibitors retard both meta-stable and stable pitting events. This makes attainment of stable pit growth more difficult in presence of these inhibitors.

show abstract

“…Pure aluminum's thermal conductive qualities make it a common metal in a variety of heat exchanger constructions as well as cooling systems . Ensuring a strong adhesion bonding for subsequent paints, conversion coatings as adherent surface layers of low‐solubility oxide are able to make Al more resistant to corrosion.…”

Section: Introductionmentioning

confidence: 99%

Optimization of silane sol–gel coatings for the protection of aluminium components of heat exchangers

Naderi

Fedel

Urios

et al. 2013

Surface & Interface Analysis

View full text Add to dashboard Cite

Despite the relatively low mechanical properties respect to the aluminium alloys but due to high thermal exchange capacity, pure aluminium (AA1XXX series) is widespread for industrial applications for heat exchanger components or cooling systems (like refrigerator systems). The corrosion protection properties of aluminium components are commonly enhanced by applying organic coatings or by performing chemical conversion treatments on aluminium surface. One of the routes for the protection of aluminium components for heat exchangers is the application of silane sol-gel coatings. In this work, a thin silane sol-gel coating improving the corrosion protection of aluminum for heat exchanger and avoiding the loss of thermal exchange due to the presence of the protective layer was developed. Prior to deposit, the silane layer as a mixture of three different silicon alkoxides precursors (such as tetraethoxysilane, glycidoxypropyltrimethoxysilane and methyltrithoxysilane), the optimum surface chemical treatment of the 1050 aluminum alloy, widely employed in the heat exchanger and cooling system industry, was investigated using electrochemical impedance spectroscopy (EIS). In order to enhance protective properties, different amounts of nano-sized sodium montmorillonite were embedded into the silane network. Through taking advantage of some parameters extracted from EIS, the most efficient concentration of nanoclay was determined, confirmed by scanning electron microscopy and Fourier transform infrared analysis as well. The resistance of the different sol-gel layers to thermal cycles (strictly related to the application in the heat exchanger industry) was carried out to stress the sol-gel coating. The behavior of the investigated sol-gel layer after the thermal cycles was evaluated by means of EIS.

show abstract

Pitting corrosion of Al and Al–Cu alloys by ClO4− ions in neutral sulphate solutions

Cited by 43 publications

References 56 publications

Influence of the anion specificity on the anodic polarization of titanium

Influence of the anion specificity on the anodic polarization of titanium

Role of alloyed silicon and some inorganic inhibitors in the inhibition of meta-stable and stable pitting of Al in perchlorate solutions

Optimization of silane sol–gel coatings for the protection of aluminium components of heat exchangers

Contact Info

Product

Resources

About