Alloys In NaCl Solution Research Articles

The Influence of HCO3− Concentration on the Corrosion Resistance of 6061 Aluminum Alloy in NaCl Solution

The Influence of HCO3− Concentration on the Corrosion Resistance of 6061 Aluminum Alloy in NaCl Solution

Study on the synergistic effect of second phases and product films to significantly improve the corrosion resistance of Mg-Gd-Y-Nd alloy

A uniform and compact product film with the same microstructure as Mg substrate is formed on the surface of Mg-RE alloy in NaCl solution, which still keeps in good condition after immersion for 5 months. Formation mechanism of the special film was investigated by electrochemical measurements, transmission electron microscopy (TEM), scanning kelvin probe microscopy (SKPM) and finite element modelling (FEM). The results show that fine and evenly distributed second phases provide reasonable galvanic effects, resulting in uniform self-corrosion of substrate, the stable “skeleton structure” of second phases and product film PBR of 1.33 also play key roles in corrosion resistance.

Corrosion behavior of two Cu‐based shape memory alloys in NaCl solution: An electrochemical study

AbstractThe corrosion behavior of two different Cu–Al–Mn–Ni alloys, pseudoelastic and pseudoplastic, was studied in a 0.6 M sodium chloride aqueous solution by monitoring the open circuit potential for 100 h and characterizing the resulting corrosion products. Electrochemical impedance spectroscopy analysis detected three processes related to the electrochemical double layer, a passive film and a diffusive contribution associated with the dissolution/precipitation of corrosion products. Potentiodynamic scans revealed a cathodically controlled corrosion mechanism and the presence of active–passive behavior at anodic potentials for both alloys studied. Polarization of the samples at selected potentials in the anodic branch allowed the investigation of the reactions involved, highlighting an improved corrosion resistance of the pseudoelastic alloy. The corrosion rates of the pseudoelastic and pseudoplastic alloys, after 100 h of immersion, were determined to be 0.007 and 0.011 mmpy, respectively. The post‐experiment characterization was carried out by means of scanning electron microscopy, micro‐Raman spectroscopy and X‐ray diffraction, supporting the electrochemical results.

Influence of annealing temperature on the mechanical properties and corrosion behavior of Ti-5.5Al-2.0Zr-1.5Sn-0.5Mo-1.5Nb alloy

In this work, the effect of annealing temperature of Ti552 titanium alloy is systematically investigated based on mechanical property tests, electrochemical tests and static immersion tests. The results show that after the annealing treatment, the microstructure morphology of the α-phase transforms from striated to equiaxed, and the intergranular β-phase gradually increases. As the annealing temperature increases, the grain size gradually increases and the volume fraction of α-phase gradually decreases. The tensile strength and Vickers hardness are the maximum and the elongation is the minimum in the hot-rolled condition. With increasing annealing temperature, the strength and Vickers hardness of Ti552 alloy gradually decrease, while the elongation gradually increases. In 3.5 wt% NaCl solution, Ti552 alloy has similar corrosion behavior at different annealing temperatures, although its corrosion resistance varies. In potentiodynamic polarization and EIS testing, the annealed Ti552 alloy shows a low corrosion current density (10-6 A/cm2) and a high polarization impedance (106 Ω·cm2), indicating the formation of a dense and stable oxide film. Under annealing at 800 °C, the corrosion resistance is at its highest and the corrosion rate is the lowest, according to electrochemical and static immersion studies. The comprehensive analysis suggests that the corrosion behavior of Ti552 alloy in NaCl solution may be a result of the combined effect of the volume fraction of the β-phase and the grain size of the α-phase.

Effect of micro-alloying elements on the microstructure and properties of Ti-1300 alloy fabricated by directed energy deposition

In this research, Al0.5CoCrFeNi high-entropy alloy (HEA) multi-element micro-alloyed Ti-1300 alloy is fabricated by directed energy deposition. The microstructure, mechanical and electrochemical properties of Ti-1300 alloys are investigated. The average grain size of the Ti-1300 alloy is considerable reduced by 32.8% to 77.3 μm after micro-alloying. In addition, micro-alloying elements significantly improves the mechanical properties of the Ti-1300 alloy, with an increase in ultimate tensile strength of 13.4%, yield strength of 14.9% and average microhardness of 6.6%, while elongation remains essentially unchanged. Solution strengthening and refined crystalline strengthening are the dominant strengthening mechanisms. Electrochemical tests show that the micro-alloying elements results in a thicker and denser passivation film of Ti-1300 alloy in NaCl solution. This increases the resistance of the passivation film, leading to a reduction in both the corrosion current density and the corrosion rate. Multi-element micro-alloying is an effective strategy to improve the microstructure, mechanical and electrochemical properties of Ti-1300 alloy.

Ocimum Basilicum Seeds as a New Natural Corrosion Inhibitor for AA7075-T6 Aluminum Alloy in Nacl Solution: Electrochemical, Thermodynamic, Surface, and Theoretical Studies

Ocimum Basilicum Seeds as a New Natural Corrosion Inhibitor for AA7075-T6 Aluminum Alloy in Nacl Solution: Electrochemical, Thermodynamic, Surface, and Theoretical Studies

Electrochemical corrosion behaviour and corrosion mechanism of Sn-9Zn-xGe solder alloys in NaCl solution

The electrochemical corrosion behaviour and corrosion mechanism of Sn-9Zn-xGe alloy in 3.5 wt.% NaCl solution was investigated using electrochemical techniques combined with surface characterization techniques. The results showed that the alloy corrosion was mainly affected by the rupture of passivation film and Cl- migration along grain boundaries. Trace Germanium (Ge) addition refined the microstructure and improved the corrosion potential of the alloy. Solder alloys containing 0.6 wt.% Ge formed a uniform and dense passivation film on the corrosion surfaces, which reduced the corrosion rate and increased the corrosion resistance.

Corrosion mechanism and corrosion behavior prediction of Cu-10Ni-X alloys in NaCl solution combining DFT calculation and experiments

The corrosion resistance of Cu-Ni-based alloys depends on their Cu2O passivation film, and the effect of third element X is hardly characterized. The corrosion behavior and mechanisms of Cu-10Ni-X (Al, Fe, Mn, Cr, Sn, Ti, Zn) alloys in a 3.5% NaCl solution were systematically investigated combining DFT calculation and experiments. Both computational and experimental results revealed that except Ti, other elements could enhance the corrosion resistance of Cu2O passivation film, and the effect was ranked as Fe > Cr > Mn > Al > Sn > Zn. Based on DFT and experimental data, a corrosion behavior prediction model was established.

Insight into influence of temperature on electrochemical corrosion behavior of SAC305 tin-based solder alloy in NaCl solution

Insight into influence of temperature on electrochemical corrosion behavior of SAC305 tin-based solder alloy in NaCl solution

Corrosion Behaviour of High-Pressure Die-Cast AZ91 Alloy in NaCl Solution: Effects of Friction Stir Process at High Rotational Speed.

The AZ series of Mg alloys have become promising in several industrial fields thanks to its potential microstructure refinement and the β-Mg17Al12 eutectic that controls the mechanical behaviour. Simultaneously, the rapid degradation characterizing Mg alloys makes the investigation of their corrosion behaviour necessary. The present work considers high-pressure die cast (HPDC) AZ91 alloy to evaluate its corrosion behaviour in 1M NaCl solution and investigates how different friction stir process parameters can affect the corrosion responses. No studies analyse the effects induced by the friction stir processed zone, reached using high rotational speeds (>2000 rpm), on the unprocessed HPDC AZ91 alloy. In addition, the morphological analysis of the corroded surfaces having a friction stir processed zone, in which the grain refinement was not obtained, is not present in the literature yet. Microstructural features were investigated by optical microscope and X-ray diffraction analysis before and after the friction stir process. These were subsequently correlated to the corrosion responses after the immersion tests. The results show that HPDC samples with a very smooth surface have the best corrosion resistance with a corrosion rate lower than 3 mm/year, evaluated through the weight loss, compared to the rougher ones. Both the amount of β-Mg17Al12 eutectic and the wt.% Al in the α-Mg matrix, as well as the surface roughness, influence the corrosion behaviour of friction stir processed samples. The best corrosion resistance was obtained with an HPDC alloy processed at 2500 rpm and 50 mm/min.

Growth characteristics of stress corrosion cracking in high-strength 7075 aluminum alloy in sodium chloride solutions

Stress corrosion cracking occurs in alloys subjected to tension in specific corrosive environments. Corrosion products that affect crack growth can be formed. This study aims to clarify their influence on the crack growth of 7075-T651 aluminum alloy in NaCl solution and proposes a method to obtain the crack growth property. Crack growth tests reveal that corrosion products create crack bridging which hinders crack opening, and as a result, the crack growth is decelerated. Hence, to obtain the crack growth property in 7075-T651 in NaCl solution, it is effective to use additives that prevent the formation of corrosion products.

Study on the Corrosion Behavior and Mechanism of CoCrNi Medium-Entropy Alloy in NaCl Solution with Various NaHSO3 Concentrations

Study on the Corrosion Behavior and Mechanism of CoCrNi Medium-Entropy Alloy in NaCl Solution with Various NaHSO3 Concentrations

Insight into the Corrosion Inhibition Mechanism of Sodium Silicate on the Magnesium Alloy Surface: Experimental and Theoretical Calculations.

The corrosion inhibition mechanism of sodium silicate (SS) for WE43 magnesium alloy in NaCl solution was investigated by in situ observation, electron probe microanalysis (EPMA), electrochemical test, and theoretical calculations. In situ observation showed that local corrosion was markedly inhibited after the addition of the SS inhibitor. Electrochemical data revealed that a protective layer was formed on the metal/solution interface and an optimum inhibition efficiency of 98.3% in the case of 2.5 g/L SS. A uniform magnesium silicate layer with a thickness of ∼2 μm formed on the uncorroded area was confirmed. Quantum chemical calculations revealed that SiO32- could absorb on the MgO (1 0 0) surface in a parallel orientation through the coordinate bonds between the O and Mg atoms. The distances of Mg-O bonds are 2.052 and 2.249 Å, suggesting that they are coordinated. The adsorption/interaction mechanisms of SiO32- were also analyzed through charge density distribution and atomic densities. Molecular dynamics simulations further confirmed that a uniform SiO32- layer was absorbed on the MgO surface. In the local corroded area, free SiO32- would react with Mg2+ and OH- produced by corrosion to form the insoluble magnesium silicate compound, which hindered the spread of corrosion.

Effect of Li Content on the Surface Film Formed on the Binary Mg–Li Alloys in NaCl Solution

Effect of Li Content on the Surface Film Formed on the Binary Mg–Li Alloys in NaCl Solution

Unveiling the effect of Al–Mn intermetallic on the micro-galvanic corrosion of AM50 Mg alloy in NaCl solution

The influence of Al–Mn intermetallic on corrosion resistance of AM50 alloy was investigated. TEM-SAED was utilized to identify microstructure and composition of the corrosion products on Al–Mn intermetallic. The electrochemistry results revealed that the corrosion rate of pure Mg was lower than AM50 due to thermodynamic driving force for micro-galvanic corrosion by Al–Mn with matrix. Although the Volta potential difference reduce because of accumulation of corrosion products, the cathodic activity of AM50 alloy increases with exposure time. The progress of corrosion could not be inhibited since the loose and porous corrosion products provided an area for containing and storing the corrosion medium.

The Corrosion Properties of Bronze Alloys in NaCl Solutions.

Chloride ions play an important role in the corrosion of bronze through their active reactivity to copper alloys. The corrosion behavior of bronze alloys in NaCl solution was investigated by using X-ray diffraction (XRD), a scanning electron microscope (SEM), and electrochemical tests, with a special emphasis on the corrosion resistance of the α and δ phases in Cu-20 wt%Sn bronze alloys. The experimental results show that the corrosion current density of Cu-20 wt%Sn bronze alloys increases from 1.1 × 10-7 A/cm2 to 2.7 × 10-6 A/cm2 with the increase in the chloride ion concentration from 10-3 mol/L to 1 mol/L. After a soaking duration of 30 days, the matrix corrosion depth reaches 50 μm. The α phase of the alloys is easily corroded in NaCl solution, while the δ phase with high Sn content has strong corrosion resistance. This study provides relevant data for the analysis and protection of ancient bronze alloys.

Assessment of corrosion inhibition performance of quaternary ammonium based dicationic ionic liquids for AZ91D magnesium alloy in NaCl solution

Quaternary ammonium based ionic liquids (ILs) are considered as good corrosion inhibitors to protect substrates of metals such as carbon steel, copper and aluminum alloys against corrosion. However, studies applying them to the corrosion protection of magnesium (Mg) alloys still remain scarce. Herein, in this work, three quaternary ammonium based dicationic ILs, namely [DMBAB][MOPS]2, [DMBAB][Phe]2 and [DMBAB][Trp]2 were synthesized and applied as corrosion inhibitors to improve the corrosion protection ability on AZ91D Mg alloy in 0.5 wt% NaCl solution. Their corrosion inhibition performances were evaluated by electrochemical measurements, and the relevant corrosion results were investigated by extensive characterizations including scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). Results show that the [DMBAB][Trp]2 obtains an 88.8 % inhibition efficiency for AZ91D Mg alloy in 0.5 wt% NaCl solution, clearly higher than those of [DMBAB][Phe]2 (80.4 %) and [DMBAB][MOPS]2 (81.7 %). This suggests that [DMBAB][Trp]2 presents the best corrosion protection ability on AZ91D Mg alloy among these ILs considered here, which is associated with the largest steric body and the most active adsorption sites of [DMBAB][Trp]2 in comparison with other two compounds, hence resulting in a highest surface coverage. The present work offers a guidance for understanding the structure–property relationship of quaternary ammonium based dicationic ILs through a convenient, economical and effective way with a promising application in the field of material protection.

Effect of ZnAl‐LDH on corrosion resistance of Zn–55Al alloy in NaCl solution

AbstractZnAl layered double hydroxides (Zn6Al2(OH)16CO3, LDH) are the unique phase in the corrosion products of Zn–Al coating compared with the corrosion products of pure Zn coating. The effect of LDH on the corrosion resistance of Zn–55Al coating is investigated in this work. The LDH preferentially grows on the Zn‐rich region of Zn–55Al alloy, and then gradually grows on the Al‐rich region. The prepared LDH film can effectively inhibit the formation of simonkolleite (Zn5(OH)8Cl2, ZHC), hydrozincite (Zn5(CO3)2(OH)6, HZ), and ZnO in the corrosion product film of Zn–55Al alloy, making the corrosion product film more dense and less prone to cracking, which can effectively prevent the corrosion of Zn–55Al alloy. The LDH film can effectively reduce the corrosion current density and improve the electrochemical impedance of pure Zn. In the end, the corrosion protection mechanism of LDH on the surface of Zn–55Al alloy was discussed.

Corrosion inhibition of aluminium alloy in NaCl solution by glycerol from biodiesel production

It was evaluated the potential of using crude glycerol, a by-product of biodiesel production from vegetable oil, as a «green» corrosion inhibitor for aluminum alloys in the neutral chloride-containing medium. It was found that it has inhibitory properties and efficiently protects aluminum alloys from corrosion in 0.1% NaCl solution; the degree of protection was up to 79%. The protective action of crude glycerol increases with increasing its concentration to 2.5 g/l. Impedance modulus of aluminum alloy increases in inhibited corrosion solution. The mechanism of corrosion inhibition is the physical and partially chemical adsorption of molecules of crude glycerol components, and probably the formation of copper-glycerol complexes on the metal surface. The adsorption of the studied inhibitor is described by the Frumkin isotherm. Energy dispersive x-ray analysis confirmed the formation of an organic protective layer on the metal surface.

Cerium lactate as green corrosion inhibitor of AA2024 alloy

AbstractThis paper evaluated the inhibitory effect of Ce‐chloride and Na‐lactate mixture on the AA2024 aluminum alloy in 0.1 M NaCl solution. Electrochemical impedance spectroscopy (EIS) was applied for testing the general corrosion resistance, while potentiodynamic polarization measurement was applied for determining the alloy pitting corrosion resistance in NaCl and inhibitive solutions. The presence of cerium on the cathodic intermetallic particles was confirmed by scanning electron microscope/energy‐dispersive X‐ray spectroscopy analysis. The mixture of Ce‐chloride and Na‐lactate was a more effective corrosion inhibitor than Ce‐chloride alone. The inhibitors mixture is a mixed‐type corrosion inhibitor with a higher influence on slowing down the cathodic reaction of oxygen reduction. The adsorption of the inhibitor, the presence of cerium in different oxidation states (Ce3+ and Ce4+), and lactate anion (C–C/C–H, C–OH, C═O, and O–C═O group) were confirmed by X‐ray photoelectron spectroscopy analysis. A mechanism of inhibitor adsorption on the surface of AA2024 alloy in NaCl solution was proposed.