Galvanic Corrosion Behavior Research Articles

Experimental study of galvanic corrosion behaviour of carbon fibre composite coupled to aluminium in artificial seawater

The galvanic corrosion behaviours of carbon fibre composite coupled to aluminium are studied when the galvanic couple is just immersed in artificial seawater or connected to a closed electric circuit. The effects of grinding condition, concentration of artificial seawater, applied torque, applied current and experimental time are studied. The roughness average, weight gain of carbon fibre composite and weight loss of aluminium are investigated as a function of the above variables. The results show that the applied current can accelerate the galvanic corrosion greatly. With improving grinding condition and increasing applied torque, the roughness average, weight gain of carbon fibre specimen and weight loss of aluminium specimen increase, reach maximum and then decrease. With increasing concentration of artificial seawater, applied current and experimental time, these measured values increase. Corroded surface morphology is also investigated using scanning electron microscopy.

Effects of Solution Annealing Temperature on the Galvanic Corrosion Behavior of the Super Duplex Stainless Steels

This study investigated the active dissolution of super duplex stainless steel (SDSS) at various solution annealing temperatures. The active dissolutions of the α-phase and γ-phase were compared, and the effects of the surface area ratio on the active dissolutions of both phases were investigated. There were two peaks in the active-passive transition region in the potentiodynamic test in the modified green-death solution. The two peaks changed as the solution annealing temperature was increased from 1050 to 1150 °C. The solution annealing temperature difference affected the critical anodic current densities. This provides useful information for determining the appropriate solution annealing temperature in the modified green-death solution for SDSS.

Micro‐electrochemical characterization of galvanic corrosion of TA2/316L composite plate

AbstractGalvanic corrosion behavior of TA2/316L composite plate was investigated in the solution of 3.5 wt% NaCl by galvanic potential monitoring, scanning localized electrochemical impedance spectroscopy (LEIS) and scanning vibrating micro‐electrode (SVME) techniques. The results demonstrated that the pitting corrosion resistance of 316L for the galvanic combination sample is lower, and the coupled current density is higher than for the single 316L sample. It indicates that the galvanic action works on the corrosion behavior of the TA2 titanium alloy/316L stainless steel galvanic combination in sodium chloride solution. The galvanic effect width was determined as 1500 µm.

Computer Simulations of Galvanic Corrosion Behaviour of Zinc –Aluminium Based Composites Reinforced with Red Mud by Potentiodynamic Polarization Techniques Leading to Corrosion Control

The present investigation aims to evaluate the corrosion control properties of metal matrix composites in comparison with matrix alloy using different concentration of Sodium chloride solutions and potentiodynamic polarization techniques. Matrix alloy used in ZA-27 and the reinforcement used was red mud particulates of size 50-80 microns. Composites are prepared by liquid melt metallurgy technique using vortex method. Red mud particulates reinforced varying from two to six percent by weight in steps of two percent under dry conditions. Specimens are prepared according to ASTM standards. Both composites and corresponding base alloys were subjected to identical test conditions to understand the influence of the reinforcement on alloy corrosion behaviour and effective corrosion control. Composites became less prone to corrosion and pit formation than the matrix alloy, which may be due to chemically inert red mud particles present in the metal matrix composites. On the other hand the test also reveals that corrosion resistance of both alloy and composites in crease with increase in normality of the sodium chloride solution, which may be due to increasing concentration of hydrogen ions in the solution. Corrosion of alloys can be effectively controlled by converting them in to composites by the addition of inert materials like silica particulates. If any automobile parts like bearing are made using these composites corrosion control properties can be tailored so that they can be used effectively in wide area of application.

A study of the galvanic corrosion of titanium/L 316 stainless steel in artificial seawater using electrochemical noise (EN) measurements and electrochemical impedance spectroscopy (EIS)

PurposeThis paper aims to investigate the galvanic corrosion of titanium/L 316 stainless steel, by electrochemical noise (EN), electrochemical impedance spectroscopy (EIS), and anode/cathode area ratio effect on the galvanic behavior of the couple.Design/methodology/approachThe EN measurement was employed to examine effects of anode to cathode area ratio on the galvanic corrosion behavior between stainless steel L 316 and titanium in artificial seawater. Current noise and potential noise were monitored simultaneously using a three‐electrode configuration under open‐circuit condition. The noise resistance was evaluated as the ratio of the standard deviation of the potential to that of the current noise after removing the DC component. The time‐series noise patterns were transformed into frequency domain by fast Fourier transformation and then their power spectrum densities (PSDs) at specified frequency were determined and compared with the EIS and polarization results.FindingsThe EN, EIS and polarization results were in agreement. Galvanic corrosion density increase and galvanic potential moved slowly to negative direction with decrease in anode/cathode area ratio. The results showed that the slope of PSD of the current (i.e the “roll off”) was rising slowly where the anode/cathode area ratio was declined. The relationship between polarization resistance (Rp) and noise resistance (Rn) was investigated. Rt was determined by EIS for samples, and its value compared with Rp and Rn. The result indicates that galvanic corrosion has an inversely relation with anode/cathode area ratio that exposed to aggressive environment.Originality/valueThis paper presents the application of noise analysis to demonstrate galvanic corrosion and the effect of area ratio anode/cathode on current density and galvanic potential.

Galvanic Corrosion Behavior and Three Protection Techniques of Magnesium Alloy Coupled to A6N01S-T5 Aluminum Alloy in NaCl Solution

In this work, the galvanic corrosion behavior of AZ31 magnesium alloy in contact with A6N01S-T5 aluminum alloy in NaCl solution was investigated by electrochemical method, the salt immersion method, SEM. And three protection techniques: (a) rubber gasket technique ,(b)organic coating technique and (c) anodizing technique were used to inhibit the galvanic corrosion. The results of open circuit potential and polarization curve method were explained the corrosion behavior of AZ31 and A6N01S-T5.It was found that AZ31 as anode was accelerated corrosion and A6N01S-T5 as cathode was also corrode in salt immersion experiment. With the increasing of immersion time, the corrosion rate of AZ31 and A6N01S-T5 was gradually decreasing. Then, the efficacy of different anti-corrosive technologies was compared. Fluorine coating technique was an effective way to protect Mg alloy and Al alloy. It was possible to guide the anti-corrosion of magnesium alloy in mobile industry.

The effect of Al content on the galvanic corrosion behaviour of coupled Ni/graphite and Ni–Al coatings

In this study, the corrosion behaviour of 75Ni/25graphite abradable coating and Ni–Al bonding coatings with different Al content were investigated with open circuit potential and polarization tests. The galvanic corrosion of the coupled Ni/graphite and Ni–Al coatings was studied by using a zero-resistance ammeter in 5 wt% NaCl solution. The experimental results showed that the corrosion resistance of the Ni–Al coatings decreased with increasing Al contents. In the galvanic corrosion test, the Ni–Al coatings with high Al contents (80Ni–20Al, 85Ni–15Al, and 90Ni–10Al) were the anodic element of the couples, while, the 95Ni–5Al acted as the cathode element in the couple.

Galvanic Corrosion of a Carbon Steel-Stainless Steel Couple in Sulfide Solutions

The galvanic corrosion behavior of carbon steel-stainless steel couples with various cathode/anode area ratios was investigated in S2−-containing solutions, which were in equilibrium with air, by electrochemical measurements, immersion test, and surface characterization. It is found that the galvanic corrosion effect on carbon steel anode increases with the cathode/anode area ratios, and decreases with the increasing concentration of S2− in the solution. A layer of sulfide film is formed on carbon steel surface, which protects it from corrosion. When the cathode/anode area ratio is 1:1, the potentiodynamic polarization curve measurement and the weight-loss determination give the identical measurement of the galvanic corrosion effect. With the increase of the cathode/anode area ratio, the electrochemical method may not be accurate to determine the galvanic effect. The anodic dissolution current density of carbon steel cannot be approximated simply with the galvanic current density.

Effect of nitric acid on wet etching behavior of Cu/Mo for TFT application

Recently, copper metallization has been widely developed in TFT-LCD industry, because of its lowest electrical resistivity compared to other metal candidates such as aluminum and molybdenum. In addition, the copper metallization becomes more significant issue in a high frequency driving TFT-LCD with large sized panel. Since the copper has a low adhesion force against the glass substrate, the copper is inevitably used with an aid of an adhesive metal layer such as Ti, Ta and Mo. When the dissimilar metals like the copper and molybdenum are exposed together in a wet etchant, a typical galvanic reaction occurs and this results in an undercutting of copper line or partial stains on the metal surface after drying. Especially, it is well-known that the suitable taper angle of Cu/Mo is difficult to obtain. Such failures often lead to a bad performance of thin film transistor and the display quality. Wet galvanic corrosion behavior of DC magnetron sputtered the double layers of Mo alloys and copper on the glass substrate has been examined. Compared with Cu/Mo–Ti system, the pure Mo/Cu system shows recessed galvanic corrosion behavior.

Electrochemical behaviour of aluminium/steel rivet joints

The galvanic corrosion behaviour of a rivet joint of two sheets of the aluminium alloys EN AW-6014-T4 and EN AW-6082-T5 joined by an electrogalvanized steel blind rivet was investigated. The potentiodynamic polarization curves in a 5 wt.% NaCl solution show a potential reversion of the anodic and cathodic regions of the rivet joint. The surface potential was investigated with a capillary electrode before and after corrosion. From the measurements by the capillary electrode and SEM-observations an improved resistance against galvanic corrosion is expected after the dissolution of the zinc layer of the blind rivet.

Galvanic Corrosion Behavior between Duplex and Austenitic Stainless Steels

not Available.

P‐62: Wet Patterning of Copper/Molybdenum Thin Films in Phosphoric Acid Solution

AbstractRecently, copper metallization has been widely developed in TFT‐LCD industry, because of its lowest electrical resistivity compared to other metal candidates such as aluminum and molybdenum. In addition, the copper metallization becomes more significant issue in a high frequency driving TFT‐LCD with large sized panel. Since copper has a low adhesion force against the glass substrate, copper is inevitably used with an aid of an adhesive metal layer such as Ti, Ta and Mo. When dissimilar metals like copper and molybdenum are exposed together in a wet etchant, a typical galvanic reaction occurs and this results in an undercutting of copper line or partial stains on the metal surface after drying. Especially, it is well‐known that the suitable taper angle of Cu/Mo is difficult to obtain. Such failures often lead to a bad performance of thin film transistor and the display quality. Wet galvanic corrosion behavior of DC magnetron sputtered the double layers of Mo alloys and copper on the glass substrate has been examined. Compared with Cu/Mo‐Ti system, the pure Mo/Cu system shows recessed galvanic corrosion behavior.

Potential and current distributions of one-dimensional galvanic corrosion systems

Many practical galvanic corrosion problems can be simplified into a one-dimensional mathematical equation. In this study, theoretical expressions for galvanic potentials and currents of one-dimensional systems are deduced and some critical parameters involved in the potential and current equations are systematically discussed. The developed analytical approach is then applied to some practical galvanic corrosion cases, such as a steel–Al joint exposed to bio-fuel E85, a galvanic couple separated by a passive spacer and a scratched organic coating. It is demonstrated that the analytical approach can examine the reliability of a computer modeled galvanic corrosion process and help understand the mechanism behind the computer modeled galvanic corrosion behavior.

Corrosion protection behavior of AZ31 magnesium alloy with cathodic electrophoretic coating pretreated by silane

As an alternative process to phosphate and chromate conversion coatings, silane pretreatment was used to improve the performance of cathodic electrophoretic coating (E-coat) on AZ31 Mg alloy in this study. The galvanic corrosion behavior of AZ31 Mg alloy with E-coat coupled with Q235 steel was investigated. Compared to bare Mg alloy and Mg alloy with conventional painting, the corrosion properties of the AZ31 Mg alloy pretreated with silane and subsequently E-coated were studied during salt solution immersion and salt spray testing. The surface morphologies of the Mg alloy were examined in detail after immersion in NaCl solution for different times using digital photography and scanning electron microscopy (SEM). The corrosion current density of the specimens was characterized by DC polarization tests. It was found that silane pretreatment of AZ31 Mg alloy followed by subsequent E-coat led to much better corrosion protection than that without silane treatment. The silane pretreatment and E-coat delayed the galvanic corrosion of Mg alloy coupled with 235 steel bolts.

Galvanic Corrosion Behavior of Friction Stir Welded Copper Alloy in 3.5% NaCl

not Available.

Effects of electroplated coatings on corrosion behavior of Ti-1023/30CrMnSiA galvanic couple

Galvanic corrosion behavior of Ti-1023 titanium alloy coupled 30CrMnSiA steel was investigated in 3.5% NaCl solution. Particular attention was given to the effect of three different electroplated coatings on corrosion behavior of the galvanic couple. Galvanic corrosion test was conducted on Ti-1023 titanium alloy which coupled Ni-electroplated 30CrMnSiA, Zn-electroplated 30CrMnSiA, Cd-electroplated 30CrMnSiA and bare 30CrMnSiA, respectively. Corrosion properties including open circuit potential (E oc ), galvanic corrosion potential (E g ), and galvanic corrosion current (I g ) were monitored. Corrosion morphology was observed by optical microscope (OM) and corrosion mechanism was analyzed and discussed. The results show that the three electroplated coatings improve the corrosion resistance of the anode in different magnitudes. Ni-electroplated 30CrMnSiA and Cd-electroplated 30CrMnSiA coatings are found to be least susceptible to galvanic corrosion when coupled Ti-1023 titanium alloy. Zn-electroplated 30CrMnSiA is moderately susceptible to galvanic corrosion. But the bare 30CrMnSiA is highly susceptible to galvanic corrosion in corrosive environment.

Experimental study on seawater-pipeline internal corrosion monitoring system

In this paper, a Cu–Zn galvanic sensor is developed for the internal-pipeline corrosion on-line monitoring system, in which the internal-pipeline corrosion state is grasped based on monitoring the corrosion capability of the internal electrolyte environment. The galvanic corrosion behaviors of the sensor in a simulated seawater environment are investigated using a 50-m-long pipeline in the laboratory. After long-term test and analysis, the effective working period of the sensor is confirmed, and the influence caused by the oxidative film on the electrode working face is eliminated by an amendatory correlation coefficient relating to the electrolyte flow rate and the temperature. A complex and non-linear relationship, among the electric current of the galvanic sensor, flow rate and temperature of the electrolyte, the concentration of dissolved oxygen (DO) in pipeline, is acquired. Finally, back-propagation artificial neural network (BP-ANN) is employed to estimate the concentration of DO of the electrolyte according to the measured factors such as the electric current of the galvanic sensor, flow rate and temperature of the internal electrolyte. Based on the comparison between corrosion coupons test and monitoring system, it is affirmed that a more reasonable evaluation of internal-pipeline corrosion can be proposed in the monitoring system.

Galvanic corrosion associated with SM 80SS steel and Ni-based alloy G3 couples in NaCl solution

Abstract Potentiodynamic polarization and electrochemical impedance measurements were used to examine the effects of area ratio Sc/Sa and temperature on the galvanic corrosion behavior between SM 80SS steel and Ni-based alloy G3 exposed to CO2 and NaCl environment. It mainly comprised of the electrochemical characterization such as the self-corrosion potential, the galvanic current and Nyquist plots and so on. Weight loss method was utilized to investigate the corrosion rate of the galvanic couples in high temperature and high-pressure autoclave. After the tests, the surface morphologies of the samples were detected by SEM. In addition, pitting corrosion behavior of anodic material caused by galvanic corrosion was also investigated. The quadratic polynomials corresponded to similar parabolas were fitted to compare the curves of Ig vs. Sc/Sa and CRa vs. Sc/Sa. The results indicate that temperature and Sc/Sa have important effects on the couples of the galvanic corrosion.

Galvanic Corrosion between Dental Precious Alloys and Magnetic Stainless Steels Used for Dental Magnetic Attachments

In this study, we examined the corrosion behavior of dental precious alloys and magnetic stainless steels, namely SUS 444, SUS XM27, and SUS 447J1, used for dental magnetic attachments. Their galvanic corrosion behavior was evaluated from the viewpoint of corrosion potentials when they were in contact with each other. Rest potentials of the precious alloys were constantly higher than those of magnetic stainless steels. Since most gold alloys raised the corrosion potential more significantly than silver alloys did, silver alloys seemed to be better suited than gold alloys for combination with magnetic stainless steels. However, all corrosion potential values were sufficiently lower than the breakdown potentials of the stainless steels and existed within their passive regions. Based on the findings of this study, SUS XM27 and SUS 447J1--which exhibited higher breakdown potentials than SUS 444--emerged as the preferred choices for combination with gold alloys.

Pitting and galvanic corrosion behavior of stainless steel with weld in wet-dry environment containing CI −

Accelerated corrosion test of stainless steel with weld was carried out to investigate the corrosion behavior under the wetdry cyclic condition in the atmosphere containing Cl −. In the surface morphology, corrosion products were analyzed by metallographic observation, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that the damage to stainless steel with weld in the atmosphere containing Cl − is due to localized corrosion, especially pitting and galvanic corrosion. Weld acts as the anode, whereas matrix acts as the cathode in the corrosion process. The pitting corrosion, including the nucleation and growth of a stable pit, is promoted by the presence of wet-dry cycles, especially during the drying stage. Pits centralizing in weld are found to be grouped together like colonies, with a number of smaller pits surrounding a larger pit. The composition of the corrosion products is Fe 2O 3, Cr 2O 3, Fe 3O 4, NiCrO 4, etc.