Corrosion Behavior Of Aluminum Research Articles

Influence of the Chemical Composition of Ceria Conversion Coatings, Sealed in Solution of NaH2PO4 and Ca(NO3)2, on the Corrosion Behavior of Aluminum.

The corrosion-protective influence of eco-friendly ceria conversion coatings deposited on Al-1050 alloy, additionally treated in mixed NaH2PO4 and Ca(NO3)2 solution, was studied. The main aim of this work was to investigate how the obtained mixed systems of coatings eliminates the negative role of cracks and pores on the surface formed after deposition only of ceria coating. For this purpose, the growth structure, main components and corrosion resistance of the so formed protective systems were investigated by SEM, EDS, XRD, XPS and electrochemical (PDP, Rp, etc.) methods. The results obtained show that the basic components of the conversion layers (before and after exposure in model corrosion media) are characterized by Al2O3, Al(OH)3, CePO4 and Ca5(PO4)3(OH). Based on these results, the optimal conditions of immersion treatment(s) of Al substrate are established. At these regimes, the relationship of co-deposited Ce3+, PO43+ and Ca2+-containing components of the conversion layers determine the maximum values of their polarization resistance-a basic criterion for corrosion protection of Al. This effect is related to the formation of fill out of the defects of the conversion coatings and additional Ca5(PO4)3(OH), CePO4 AlPO4 and Al(OH)3 deposits, leading to the decrease of the corrosion rate.

Corrosion behavior of aluminum in a weak acetic acid solution containing halogen ions as simulated cooling water in HVDC transmission

The effects of F−, Cl−, and Br− on aluminum corrosion in weak acetic acid solutions were studied using a combination of electrochemical methods and physical characterizations, and the pitting factors for aluminum were calculated and used as an effective and intuitive parameter for evaluating aluminum corrosion. The results showed that an increase in the NaCl concentration led to more serious aluminum corrosion, and an increase in the Cl− concentration deepened the degree of pitting corrosion. Among the halogen ions, Cl− was more likely to cause aluminum corrosion. The mechanism for pitting corrosion was developed from these conclusions, which provide guidance for addressing aluminum corrosion.

Corrosion behavior of Aluminium in alkaline-water hyacinth plant extract functionalized solution: An electrochemical and weight loss study

Corrosion behavior of Aluminium in alkaline-water hyacinth plant extract functionalized solution: An electrochemical and weight loss study

Corrosion Behavior of Aluminum in some Short-chain Carboxylic Acid solutions as a Simulant for Cooling Water in HVDC Transmission

Corrosion Behavior of Aluminum in some Short-chain Carboxylic Acid solutions as a Simulant for Cooling Water in HVDC Transmission

Enhancement of Physical Properties and Corrosion Resistance of Al-Cu-Al2O3/Graphene Nanocomposites by Powder Metallurgy Technique.

In this study, we enhanced the adhesion of graphene nanosheets to achieve homogeneous dispersion, consequently improving the electrical and thermal conductivity, coefficient of thermal expansion, and corrosion resistance with an aluminum matrix containing up to 1.5 wt. % graphene. First, 2.5 wt. % Al2O3 and varying ratios of graphene up to 1.5 wt. % were coated with 5 wt. % silver nanoparticles to metalize their surfaces. Predetermined portions of coated alumina and graphene were mixed with Al/10 wt. % Cu powder for 45 h. Mixed samples were compacted under 600 MPa and sintered at 565 °C in a vacuum furnace for 60 min with a low heating rate of 2 °C/min. The strengthening effect of the added materials on the density, microstructure, electrical and thermal conductivities, thermal expansion, and corrosion behavior of aluminum were investigated. Excellent adhesion and homogeneous dispersion of the investigated reinforcements were achieved. Three phenomena were observed: (1) an improvement in the densification, electrical and thermal conductivity, thermal expansion, and corrosion rate by adding 10 wt. % Cu to the aluminum matrix; (2) deterioration of the properties of Al/10 wt. % Cu with the addition of 2.5 wt. % alumina nanoparticles; and (3) improved properties with the addition of graphene nanosheets up to 1 wt. % and a decrease in property values beyond 1.5 wt. % graphene content due to the formation of agglomerations and pores in the metal matrix.

Effect of Low Chloride and Sulfate Concentrations on Corrosion Behavior of Aluminum and Zinc Arc Thermal Sprayed Coatings

The aim of this study was to determine the suitability of arc sprayed zinc and aluminum coatings as materials for protective coatings of different heating systems. The most aggressive chemical agents occurring in heating water are chloride and sulfate anions. Both ions are responsible for the corrosion of metals due to their high electronegativity and standard electrochemical potential. Water in heating systems should not contain more than 150 mg/L anions, including no more than 50 mg/L of chlorides and 100 mg/L of sulfates. To determine the corrosion resistance of three types of zinc and aluminum coatings, open circuit potential and linear polarization resistance (LPR) tests were conducted in eight alkaline solutions with different sulfate and chloride contents. The SEM/EDS structural properties of sprayed coatings at specific arc process parameters were investigated. Zinc coatings exhibit the most stable corrosion potentials in varying environments but have higher corrosion current density. Aluminum coatings exhibit much higher potential values in a chloride environment than in any other. A chloride environment also causes the lowest corrosion rates for aluminum-coated samples. A small addition of aluminum to the zinc coating (15 wt.%) does not appear to affect the stability of the corrosion potential but does result in a reduction in corrosion rates in chloride solutions.

Corrosion Behavior of Aluminum in Dilute Acetic Acid Solution Simulating Cooling Water in HVDC Transmission

Corrosion Behavior of Aluminum in Dilute Acetic Acid Solution Simulating Cooling Water in HVDC Transmission

Effect of intermetallic compounds on the mechanical property and corrosion behaviour of aluminium alloy/steel hybrid fusion-brazed welded structure

Al alloy/steel joint was produced by fusion-brazing welding with different heat inputs to obtain intermetallic compounds (IMCs) layer with different thicknesses. Following by enhancing heat input, not only the FeAl binary IMCs (Fe2Al5 and Fe4Al13) became thicker at the interface, the formation of Fe-Al-Si ternary IMCs, such as Fe2Al8Si, also became evident. Nevertheless, the joint strength was maintained at a high level. An increase of corrosion current density with three orders of magnitude was identified when the joint was welded under a high heat input (>632 J/cm) due to the appearance of enhanced tunnelling corrosion caused by ternary IMCs with weld seam. Binary IMCs became less corroded with the increase of heat input arising from the cathodic corrosion protection. Therefore, a low heat input should be utilised to preserve the corrosion resistance of the joint, while keeping its mechanical performance.

AC Corrosion behaviour of aluminium and zinc sacrificial anodes in seawater

ABSTRACT In this work, the corrosion behaviour of aluminium (Al) and zinc (Zn) sacrificial anodes under AC interference were studied in 3.5% NaCl solution by AC corrosion simulation experiments, weight loss tests and surface morphology analyses. It was found that AC accelerated the corrosion of Al and Zn, and their corrosion rates increased with the AC current density, besides the localised corrosion of Al was much more obvious than Zn. When the AC current density was 100 A m−2, the uniform corrosion rates of Al and Zn increased to 14.6 and 0.46 mm/year, respectively, which were 34.8 and 1.48 times of the free-corrosion rates of them. Meanwhile, both the uniform and localised corrosion rates of Al increased much more significant than that of Zn under AC interference.

Mitigating CO2 Corrosion of Natural Gas Steel Pipelines by Thermal Spray Aluminum Coatings

Internal pipeline corrosion due to carbon dioxide (CO2) is a major challenge facing the oil and gas industry. The objective of this study was to investigate the corrosion behavior of aluminum (Al)-based alloys as sacrificial coatings to protect pipelines in a CO2-saturated aqueous electrolyte (3.5 wt% NaCl) at 4 bar CO2 partial pressure (3 bar) and 40°C. The corrosion resistance of Al-based alloys and thermal spray coatings was evaluated in an electrochemical reaction autoclave using electrochemical methods (potentiodynamic polarization, linear polarization resistance, and electrochemical impedance spectroscopy). Post-corrosion surface characterization was performed by scanning electron microscopy equipped with energy-dispersive x-ray spectroscopy. The obtained data show Al-based alloys demonstrated promising protection against CO2 corrosion with no breakaway degradation issues.

Corrosion Behavior of Aluminum in Dilute Fluoride and Sulfate Solutions for Use as Bipolar Plate of PEFC

ABSTRACT In polymer electrolyte membrane fuel cell (PEFC), bipolar plate (BP) is a vital multifunctional component which constitute more than 80% of the total stack weight and about 30% of the materials cost.[1-3] Among many materials act as BP, aluminum (Al) is one of the most alternative for fulfilling the requirements that mentioned above for its special qualities such as mechanical properties, low cost and low density.[4-5] It is also generally required for a BP to be corrosion resistant even in sulfuric acid solution with a pH around 3.0, but it would be difficult for BP like Al to sustain under this condition. To fulfil this condition, a new type of BP is proposed by Yashiro et al. [6] that made of two sections: a flow path that directly contacts with MEA and a gas isolation plate. The gas isolation plate contacts with the generated water which is near to pure water and bare Al can also be used for this section. Therefore, in our previous works, the effects of fluoride and sulfate ions on pure Al in the simulated PEFC environment was studied at 80°C.In this study, the corrosion behavior of Al in dilute sodium fluoride and sodium sulfate solutions with different concentrations at 40°C was evaluated. Open circuit potential (OCP), scanning electron microscopic (SEM) images, energy dispersive x-ray (EDX) spectra and cross-sectional images were also taken to check the corrosion potential, surface morphology, elemental composition and other analyses.Pure Al having a thickness of 1 mm and area of 10 cm2 were used as the test samples for immersion process. 0.1ppm F- (pH 5.70), 0.1ppm SO4 2- (pH 5.64), mixture of 0.1ppm F- and 0.1ppm SO4 2- (pH 5.66), mixture of 0.1 ppm F- and 1ppm SO4 2- (pH 5.57) and distilled water (DSW) were used as the test solutions using NaF and Na2SO4. Firstly, Al was cut into desired sizes and polished by emery paper down to #2000, rinsed and immersed in around 90 cm3 aerated aqueous solutions. The immersion process was carried out at 40°C for a period of 24h, 48h, 72h, 96h and 120h. After the immersion test, weight was increased in all the test samples with increasing time regardless of the solutions. It is considered that the oxide film was formed in Al surfaces because of the oxidized aluminum at the time of immersion process. It is considered that the oxide films formation occurred because of the corrosive properties of the test samples with test solutions.A significant amount of corrosion of pure as-polished Al immersed in different solutions for 24 to 120h at 40°C was found. The results show that corrosion amount is higher in 0.1ppm F- solution and lower in 0.1ppm SO4 2- solution. It is considered that the inhibition of corrosion was occurred by sulfate ions, and the amount of corrosion was decreased. However, the corrosion amount was increased more when a mixture of 0.1ppm F- and 0.1ppm SO4 2- was used, and vice versa in case of DSW. Furthermore, when the concentration of sulfate ions was increased around 10 times using 1ppm SO4 2- with 0.1ppm F-, the lowest amount of corrosion was found among the used solutions.Fig. 1 shows the SEM images of pure as-polished Al of before and after immersion for 24h. Some irregular shaped particles of different sizes are observed in the Al surfaces that indicate the presence of aluminum oxide as corrosion products. In addition, thick oxide layers along with many cracks are found in the case the Al samples immersed in 0.1ppm F- and 0.1ppm F- + 0.1ppm SO4 2- solutions. Besides, very low amount of cracks are found in the case of DSW and 0.1ppm SO4 2- solution. Therefore, it is concluded that the presence of F- ions were confirmed which act as corrosion promoter and SO4 2- ions were act as corrosion inhibitor when Al is used as bipolar plates in the PEFC environment. Acknowledgements This work was supported by JSPS KAKENHI grant number JP19K05091.

Corrosion Behavior of Aluminum in Dilute Fluoride and Sulfate Solutions for Use as Bipolar Plate of PEFC

The corrosion behavior of pure aluminum was evaluated in dilute concentrations of sodium fluoride and sodium sulfate solutions at 40°C. The open circuit potential (OCP), corrosion amount, and surface roughness were measured to check the corrosion potential, amount of corrosion, and surface roughness, respectively. Scanning electron microscopy (SEM) images and energy dispersive X-ray (EDX) spectra were also taken to observe the surface morphology, elemental composition, and other analyses.

Study of The Structure and Corrosion Behavior of Al-15%Mo Alloy

The influence of the addition of molybdenum on the structure and corrosion behaviour of aluminium was studied using optical microscopy, scanning electron microscope (SEM), potentiodynamic polarization and electrochemical impedance spectroscopy. The results show that the addition of 15%wt molybdenum causes the precipitation of the AI12Mo intermetallic phase which appears in plate form on the aAl matrix. The results of the electrochemical tests show that the addition of molybdenum displaces the corrosion potential of aluminium towards positive values from -699 mV/ECS to -633 mV/ECS and increases the charge transfer resistance from to 4752 Ω2.cm2 to 6608 Ω2.cm2.

Effect of ZrB2 on microstructural, mechanical and corrosion behaviour of aluminium (AA7178) alloy matrix composite prepared by the stir casting route

The aim of this work is to develop a new class of aluminium alloy matrix composites (AAMCs) reinforced with different weight percentages of zirconium diboride (ZrB2) particles through the bottom pouring type stir casting process. The mechanical and corrosion behaviours of aluminium can be improved by the addition of ceramic particles. Mechanical behaviours and microstructure of the composites were studied. Homogeneous distribution of ZrB2 particles in the matrix was analysed using scanning electron microscope. The corrosion behaviour of the proposed composites was analysed by electrochemical assessments, such as polarization tests and AC impedance spectra. Prepared specimens are submerged inside aqueous sodium chloride (NaCl: 3.5%) solution. Corrosion potential, current, resistance of linear polarization, capacitance of double layer, resistance of charge transfer and resistance of corrosion in material were determined. From corrosion outcomes, we concluded that AA7178–ZrB2 metal matrix composite revealed higher corrosion resistance than AA7178. The rate of corrosion resistance, hardness, impact strength and tensile strength was augmented gradually by way of increasing weight per cent of ZrB2 particles in the AA7178 matrix. Hardness was improved by 26% and the ultimate tensile strength was improved by 15% for the inclusion of 10 wt% ZrB2 particles in the AA7178 matrix.

Microstructural characterisation and corrosion behaviour of aluminium alloy/steel hybrid structure produced by friction welding

Abstract An aluminium (Al) alloy to stainless steel friction welded joint, being of potential as an alternative for the existing structural component, was obtained under specifically designed heat inputs at three different levels (low, medium and high). Heat input significantly affected the mechanical properties of the joint where the joint welded at the medium level posed the highest tensile strength (325 ± 14 MPa). When the heat input was at a low level, an un-welded zone was observed with no obvious signs of IMCs. Upon increasing heat input to a higher level, weld defects disappeared with sub-micron sized IMCs layer formed. The IMCs layer demonstrated rather distinct thickness characteristics at different interfacial regions, but a higher heat input resulted in a thicker layer at similar regions. Although it was identified that a thicker IMCs layer might pose an adverse effect on the corrosion resistance, the friction welded Al alloy/steel joints had only a marginal change in corrosion potential and corrosion current intensity under various heat inputs, presumably due to fine (sub-micron) sized IMCs formed at various regions along weld interface. Therefore, friction welding could realise the sound joining of Al alloy and steel with both satisfying mechanical properties and corrosion resistance by restricting the IMCs at sub-micron level.

Assessment of AA5005 aluminum alloy corrosion resistance by Direct Blue 15 inhibitor in sodium chloride medium

The effect of Direct Blue 15 dye (DB-15) on the corrosion of aluminum AA5005 in 3% NaCl solution was studied using gravimetric techniques. The results indicate that the DB-15 acts as an inhibitor in the NaCl environment by adsorption on the metal surface. The inhibition efficiency was found to increase with dye concentration and attained 90.8% at 400 ppm. The effect of temperature on the corrosion behavior of aluminum in 3% NaCl was studied in the range 298 K and 328 K. The inhibition performance was also tested by immersing aluminum in 3% NaCl solution using electrochemical methods; potentiodynamic polarization (PP) curves and electrochemical impedance spectroscopy (EIS). PP measurements showed that DB-15 can be considered as mixed-type inhibitor with predominant anodic action and with inhibition efficiencies that improve with concentration. Electrochemical impedance spectroscopy measurements reveal that the corrosion resistance of oxide film increases with dye inhibitor concentrations. The adsorption of the inhibitor on the AA5005 aluminum alloy surface obeyed the Langmuir adsorption isotherm. The values of inhibition efficiency calculated from weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy are in good agreement.

Effects of environmental factors on corrosion behavior of aluminum

AbstractAluminum, used as a material for heat exchangers in air conditioners, often has problems of leakage of refrigerant on the Al surface due to corrosion. The problems originate from pitting corrosion of the Al in an external environment. To understand corrosion problems, it is necessary to study the corrosion behavior of Al in various environments. In this study, the effects of environmental factors on the corrosion behavior of Al were studied by the surface analysis and electrochemical testing in 3.5 wt% NaCl solutions, with changes of dissolved oxygen, temperature, and concentration of Cl− and S ions. Among the external environmental factors, the presence of oxygen and the increase of Cl− ion concentration do not significantly affect the corrosion potential of Al, leading to an increase of only 1.1 and 6 times, respectively. There was a significant decrease in the corrosion resistance of Al, approximately 40 and 800 times, respectively, with the increase of concentration of S and temperature.

Effects of Na2s, NaCl, and CuCl2 Concentrations on the Corrosion of Aluminum

The corrosion behavior of aluminum in the mixed solution of Na2S, NaCl, and CuCl2 was investigated by potentiodynamic polarization tests and statistical analysis based on DOE (Design of Experiment). The effects of ions on the corrosion potential, the corrosion rate, and the pitting potential of aluminum were analyzed to elucidate the main effect and interactions between ions.

Effect of carboxymethyl cellulose on the corrosion behavior of aluminum in H2SO4 solution and synergistic effect of potassium iodide

The corrosion inhibition of aluminum in 2 M H2SO4 solution by carboxymethyl cellulose (CMC) alone and in combination with iodide ions has been investigated using electrochemical measurements and surface analysis techniques. The results showed that CMC moderately inhibited aluminum corrosion in the H2SO4 solution, and the inhibition efficiency of CMC was increased with the addition of inhibitor concentration, indicating the physical adsorption mechanism. The synergistic effect of 5 mM KI at all concentrations of CMC was assessed by calculating the synergism parameters, indicating that the increased inhibition efficiency of the CMC caused by addition of iodide ions is due to synergism. Additionally, the analysis of the morphology and composition of the aluminum surface suggests that with addition of iodide ions, more CMC molecules are adsorbed on the aluminum surface, thereby enhancing the inhibition efficiency of CMC.

Corrosion inhibition of aluminum by oxalate self-assembling monolayer

PurposeThis paper aims to evaluate the inhibition efficiency (IE) of oxalate ions in controlling corrosion of aluminum at pH 10.Design/methodology/approachThe IE has been determined by the classical weight loss method. The corrosion behavior of aluminum was investigated by using potentiodynamic polarization and electrochemical impedance measurements. Ultra violet (UV)-visible and Fluorescence spectra have been used to analyze the film formed on the aluminum surface after immersion.FindingsThe maximum IE was 88 per cent, which was offered by a mixture of 250 ppm oxalate ions and 50 ppm [Zn2+]. Potentiodynamic polarization data revealed that the protective film was formed on the metal surface. UV-visible and Fluorescence spectra indicated the presence of Al3+−oxalate complex in the protective film formed on aluminum substrate after immersion in [OX]/[Zn2+] solution.Originality/valueThe findings of this work shed more light on the corrosion inhibition of aluminum by oxalate self-assembling monolayers.