Galvanic Corrosion Current Research Articles

Investigation of CuAl IMCs Corrosion in Chloride Environment and its Prevention Strategy

Abstract In most current wire-bonding applications, electrical interconnection is accomplished by fine Cu wires bonded to Al bonding pads microfabricated on an IC chip and external contact pins of the PCB board. Corrosion-related failure defects between the Cu wire and Al bond pad have been an ongoing un-trackable reliability issue plaguing the IC packaging industry for the past ten years, despite approaching ppb levels. Most prior studies hypothesized that intermetallic compounds (IMCs) like Cu9Al4, and CuAl2 were responsible for the observed acute wire-bond lift-off corrosion defects. Further studies sought to quantify the rates of corrosion of these IMCs and explore the effects of mitigation efforts of adding Pd, relevant to Pd-coated Cu wire-bonding. However, utilizing a novel real-time corrosion screening approach, we previously established that peripheral bimetallic contact between Cu ball-bonds and Al bond pads also plays a substantial role in the aggressive Al pad corrosion, induced by chloride ion penetration, which often leads to device failure. In this work, we further explored the role of IMCs corrosion in wire-bond lift-off failure utilizing fundamental electrochemical studies to quantify rates of galvanic-induced corrosion of IMCs within the broader context of an interconnected stack of Al bond pad, Cu-Al IMCs and Cu bonding wire. We also explored the use of a corrosion inhibitor to suppress the galvanic corrosion currents of Al bond pad, and Al-rich IMCs when electrically connected to Cu wire or Cu-rich IMCs.

Monitoring the galvanic corrosion of copper–steel coupling in bentonite slurry during the early oxic phase using coupled multielectrode arrays

AbstractIn the case of a two‐part container for spent nuclear fuel, consisting of an iron‐based inner structure with a copper coating, the potential perforation of copper through minor damage may result in intensive galvanic corrosion between copper and steel. The present work focuses on the corrosion of steel galvanically coupled to copper and exposed to a slightly saline environment under oxic conditions. The electrochemical processes on individual electrodes were monitored by coupled multielectrode arrays (CMEAs). The CMEAs were either in contact with groundwater saturated with bentonite or immersed in groundwater only. Very high galvanic corrosion currents were detected between carbon steel and pure copper in the early oxic phase. Additionally, the use of CMEAs further made it possible to monitor the distribution of cathodic currents around the steel electrode, which behaved anodically. Various microscopy and spectroscopy techniques were applied to identify the modes of corrosion and the type of corrosion products present at the end of the period of exposure.

STRESS CORROSION CRACKING SAMBUNGAN LAS CDW SS 316L DAN ASTM A36 DALAM VARIASI SUHU LINGKUNGAN KOROSIF FeCl2

Stress Corrosion Cracking (SCC) is known as a trigger for material failure, especially in Dissimilar Metal Welding (DMW). Although DMW promises wide application in structural design, it is found that there is high SCC mitigation making it prone to failure. Capacitor Discharge Welding (CDW) is one of the best dissimilar metal welding methods. This article observes the weld joints of CDW ASTM A36 and SS 316L against the phenomenon of SCC in a corrosive environment temperature variation of FeCl2 0.5 Molar (30, 40, and 50 0C). The results of the Constant Load Test (CLT) show that the welding threshold strength has decreased significantly due to the increase in the galvanic corrosion current which increases at high temperatures. The stress threshold of specimen T1 with a temperature variation of 30 0C K1cc 360 MPa, the specimen T2 produces a threshold of 216 MPa and the specimen T3 with 144 MPa. It can be concluded that changes in the temperature of the corrosive environment accelerate the galvanic reaction which accelerates the occurrence of corrosiveness in the weld joint. SEM/EDS photo evaluation provides a perfect picture of the corrosive distribution of the fracture surface. At the highest temperature of 50 0C, the surface corrosive rate causes a lot of bubbles and porous pores in the weld fracture, this causes the connection threshold stress to weaken.

Insulation voltage experimental study of the galvanic couple in flow seawater

The problem of insulation voltage selection in potential-difference detection method of insulation performance of electrical insulating metal pair in flowing seawater is discussed. In flowing seawater, 921A-B10 pair was taken as the research object to design the insulation corrosion test of the pair material. The natural corrosion test, the galvanic corrosion test and the simulated electrical insulation test of the pair material were carried out respectively. The test shows that the larger the analog insulation resistance of the pair material in series is, the smaller the galvanic corrosion current is, and the larger the voltage at both ends of the insulation resistance is. Finally, the range of insulation setting voltage is obtained.

Galvanic Corrosion and Fatigue Behavior of a SM480C Welded Joint Steel in a Sea-Crossing Suspension Bridge

The corrosion tendency and fatigue behavior of a SM480C welded joint in a sea-crossing suspension bridge after twenty-year exposure to a marine environment was investigated in this work. It was found that the corrosion product on the whole surface of the welded joint is loose, with many holes and cracks, which allowing corrosive media enter and reach the surface of the substrate. Localized corrosion occurred in the weld zone (WZ) and the heat-affected zone (HAZ), the maximum depth of localized corrosion in the HAZ reached 1.8 mm, and the maximum local corrosion rate is 0.082 mm/y. By using Bimetallic Conjugation Theory calculations, the galvanic effect of the welded joint was qualified, indicates that HAZ was the most corrosion susceptible area in the welded joint. The galvanic corrosion current on HAZ reached approximately 2 μA, which is much higher than the corrosion of isolated HAZ by about 6.5 times. The corrosion has an obvious influence on the fatigue performance, the elongation of the bridge deck decreases by 40%~70%, and the tensile strength decreases by 4.5%~31.33%. In order to ensure the service safety and avoid premature failure, the average thickness of the corroded bridge deck should not be less than 10 mm under the stress amplitude of 115 MPa.

An Al-Cu Multielectrode Model for Studying Corrosion Inhibition with Praseodymium Mercaptoacetate at Intermetallic Particles in AA2024

Dealloying of S-phase particles on AA2024-T3 leave behind highly cathodic Cu-rich particles, creating a galvanic corrosion environment. Clustering of these particles intensify localised dissolution of adjacent matrix leading to pitting. Evaluation of such galvanic activities is critical to develop effective corrosion inhibitors. Unfortunately conventional electrochemical methods are unable to probe this type of anodic attack because in principle they only evaluate general corrosion and cannot measure galvanic corrosion currents flowing between particles and adjacent matrix. This work uses a multielectrode composed of four copper and forty-four aluminium electrodes to model galvanic activities occurring over a cluster of dealloyed S-phase particles to better understand localised attack and at clustered sites. The model Al-Cu multielectrode was shown to be an effective tool to investigate local interactions between Cu electrodes and Al electrodes which undergo significant anodic current densities, simulating the anodic attack on the aluminium matrix of AA2024-T3. Additionally this tool can more strictly differentiate between inhibitors for localised corrosion control. An environmentally friendly rare earth corrosion inhibitor, praseodymium mercaptoacetate (Pr(MAcet)3), has been evaluated by this technique and has been found to rapidly reduce anodic current densities at a faster rate than PrCl3 when concentrations were sufficiently high (>10−3 M).

Galvanic corrosion study between low alloy steel A508 and 309/308 L stainless steel dissimilar metals: A case study of the effects of oxide film and exposure time

The effects of oxide film and exposure time on the galvanic corrosion between low alloy steel (LAS) A508 and 309/308L stainless steel (SS) dissimilar metals were studied by several electrochemical techniques and surface composition analytical tools. The zero resistance ammeter (ZRA) result shows that the trend of galvanic corrosion current between the coupled LAS A508 and 309/308L SS changes with respect to exposure time. Furthermore, from the ZRA measurement, the quantitative relationship between galvanic current and dissolution rate of the coupled LAS A508 anode metal was established by statistical approach. Electrochemical impedance spectroscopy (EIS) results and analyses demonstrated that the increasing galvanic corrosion rate observed between the coupled dissimilar metals as exposure time prolonged was suppressed by the oxide film effect. The suppression occurred as a result of the transformation of unstable oxides to stable oxide forms, and the oxide film thickening phenomenon experienced on the LAS A508 surface as exposure time prolonged. Generally, a synergy between both effects was observed in this study.

Fastening Strategies to Prevent Galvanic Corrosion

In marine applications aluminum structures are commonly fastened together with stainless steel fasteners. This combination of dissimilar metals causes galvanic corrosion currents which degrade the aluminum structure. The purpose of this research is to develop fastening strategies that will reduce the degradation of the aluminum structure. The impetus for this research is specifically to increase reliability and availability of equipment installed on Navy range craft which operate in the support of training and test and evaluation (T&E) events. Direct fastener substitution would cause the least impact to the overall design of a system reducing alteration costs. Therefore, in this research different types of fasteners were tested to determine their effect on corrosion in the aluminum structure. Fastener types: 316 stainless steel (control), Titanium (Ti-6Al-4V), 316 stainless steel PVD coated with TiN, 316 stainless steel PVD coated with CrN, and 316 stainless steel coated with a Sol Gel. The efficacy of each fastener type was determined by several tests. Samples representing a bolted join in an aluminum structure were assembles using each type of fastener and deployed in a marine environment, after exposure weight loss data was collected. The fasteners were also subjected to cathodic potentiodynamic polarization to determine the kinetics of oxygen reduction and hydrogen evolution on the bare 316 SS, coated 316 SS, and bare Ti-6Al-4V. The cathodic polarization data of the fasteners were compared to that of the anodic polarization data of AA6061-T6. The potentiodynamic polarization data was used to gain an understanding of the galvanic corrosion mechanisms between the fasteners and AA 6061-T6. The results from the polarization experiments were compared to the actual corrosion damage of galvanic couples in the field. Acknowledgements: This material is based on research sponsored by the USAFA and University of Hawaii under agreement number FA7000-18-2-0004. The U.S. Government is authorized to reproduce and distribute reprints for Governmental purposes notwithstanding any copyright notation thereon.

Influence of artificial cracks and interfacial defects on the corrosion behavior of steel in concrete during corrosion initiation under a chloride environment

In this study, the effect of both artificial crack and defects of the steel-concrete interface on the initiation and propagation of steel reinforcement corrosion in concrete under a chloride environment is investigated. This work was based on two groups of reinforced concrete blocks, with or without artificial crack. The microstructures of the steel-concrete interface, the cement hydration products at the steel-concrete interface, the chloride profiles, the galvanic corrosion current, and the distribution of pitting corrosion on steel rebar were studied and compared. Experimental results show that the location of initial corrosion is related to top-casting defects but not to the location of air bubbles. Pitting corrosion mainly initiated at the rib foot of the bottom side of the deformed steel rebar with top-casting defects. Steel in concrete with an artificial crack exhibited a fast initiation period immediately followed by a propagation period. The presence of both artificial crack and top-bar effect thus led to faster deterioration than in un-cracked structures.

Determination of chloride threshold initiating corrosion: A new set-up taking the localized aspect of corrosion into account

In spite of much research invested in the study of concrete reinforcement corrosion induced by chlorides, there is still no agreement on an accurate method for determining the chloride threshold value initiating corrosion. The objective of this work is to present a new test set-up that considers the localized character of corrosion initiated by chlorides. This approach is based on a physical separation between the anode, contaminated with chlorides, and the cathode, which is chloride free. This approach will allow to quantify the galvanic corrosion current, making it possible to determine, in a second step, the chloride threshold values for corrosion initiation. The criteria for corrosion initiation was a threshold corrosion current defined as a current that is independent of the cathode/anode surface ratio. It was then important to test the influence of the geometric surface ratio on the galvanic corrosion current. It was found that it is an important parameter that needs to be taken into account when studying corrosion in the presence of chlorides. Preliminary results of threshold values were determined based on this criterion for CEMI and for several types of steel surface conditions. The preliminary results also give an idea of the influence of chloride contents on the galvanic corrosion currents.

Galvanic Couple Behavior Between AA7050-T7451 and Stainless Steel in a Fastener Arrangement Assessed with Coupled Multi-Electrode Arrays Under Atmospheric Exposure Conditions

Dissimilar metal coupled multi-electrode arrays (CMEAs) of AA7050-T7451 and Type 316 stainless steel were utilized to investigate galvanic coupling behavior under atmospheric conditions, represented by thin electrolyte films and wet/dry cycling. CMEAs were used to analyze location specific galvanic current densities under both a simple flat geometry and in a simplified two dimensional (2D) representation of a fastener geometry. Cyclic wet/dry exposures on the flat CMEAs under 70 μm thin films increased the anodic charge density by over one order of magnitude relative to the 70 μm exposure of a flat CMEA under constant 98% relative humidity. During the wet/dry cycle, sharp current increases were observed upon the onset of wetting and drying attributed to the high Cl− concentration in the droplet and thin electrolyte layer. Using a CMEA arranged to represent a 2D representation of a fastener in a plate, the anodic charge for galvanic corrosion currents increased under a static 70 μm thin film of NaCl soluti...

Potassium Oleate as a Dissolution and Corrosion Inhibitor during Chemical Mechanical Planarization of Chemical Vapor Deposited Co Films for Interconnect Applications

1,2-4 Triazole (TAZ), N-lauroylsarcosine sodium salt (NLS) and potassium oleate (PO) were tested as passivating additives to previously developed H2O2 and citric acid-based silica dispersions for the polishing of chemical vapor deposited Co films for interconnect applications. In comparison to TAZ and NLS, Co corrosion currents are ∼1 to 2 order of magnitude lower (∼1–3 μA cm−2) at pH 7 with PO and post-polish surface quality was much better. The galvanic corrosion currents between Co-Ti and Ti-TiN couples with PO were also very low (∼0.1 μA cm−2), making the previously developed silica and citric acid-based dispersion, now containing PO, suitable for both bulk removal of Co (step I) and for planarizing Co/Ti/TiN structures (step II) with excellent selectivity while stopping on low-k dielectric. Langmuir adsorption isotherm model analysis showed that the standard free energies of adsorption values were ∼−40 kJ/mol for PO suggesting chemisorption. Fourier transform infra-red (FTIR) and attenuated FTIR spectroscopy data show bridging coordination between the carboxylate ligand of PO and the Co surface.

SVET Study of Galvanic Corrosion of Al/Mg2Si Couple in Aqueous Solutions at Different pH

The galvanic corrosion behavior between pure Al and synthesized bulk Mg2Si in 0.01 M NaCl solution at different pH values has been investigated by the scanning vibrating electrode technique (SVET). At pH 2, bulk Mg2Si actively dissolves and it acts as an anode. With the increase of exposure time, the anodic activity of Mg2Si decreases drastically and eventually anodic activity appears on Al surface. In alkaline solution, Mg2Si phase always acts as the cathode. The preferential dissolution of Mg and enrichment of Si found by energy dispersive X-ray spectroscopy are responsible for the observed anodic activity decay of Mg2Si in acidic solution. At pH 6, the galvanic corrosion current of Al/Mg2Si couple is much less than those at pH 2 and pH 13, and Mg2Si mainly undergoes self-dissolution. These results indicate that the dealloying of binary Mg2Si phase depends on the solution pH value and corrosion time, which subsequently have a great influence on the galvanic corrosion current of Al/Mg2Si couple.

Galvanic Corrosion Inhibitors for Cu/Ru Couple during Chemical Mechanical Polishing of Ru

Galvanic corrosion of Cu is a critical issue during the chemical mechanical polishing (CMP) process of barrier layer, especially when KIO4 is used as the oxidant in the polishing slurry. This paper focuses on the investigation of galvanic corrosion inhibitors (BTA and 1, 2, 4-triazole) for Cu/Ru couple in the KIO4-based solutions. The galvanic corrosion current of Cu was directly measured, and the corrosion inhibition efficiencies (CIE) were calculated. Results show that both BTA and 1, 2, 4-triazole are effective galvanic corrosion inhibitors of Cu. The CIE of 5 mM BTA and 2 mM 1, 2, 4-triazole is up to 69.4 and 59.7, respectively. On this basis, the corrosion inhibition mechanism was proposed. BTA forms a complete and tight three-dimensional multilayer structure on Cu when the concentration is over 0.5 mM. With regard to 1, 2, 4-triazole, the protective film on Cu is two-dimensional, and excessive dosage of 1, 2, 4-triazole will reduce the stability of the surface film, as well as the corrosion inhibition efficiency of Cu.

The role of corrosion product deposition in galvanic corrosion of aluminum/carbon systems

This study is concerned with the role of corrosion product deposition in the galvanic corrosion between aluminum and Carbon Fiber Reinforced Polymer matrix composite (CFRP). The galvanic corrosion of a high voltage conductor assembly consisting of a cylindrical CFRP rod surrounded by tightly wound aluminum wires has been investigated through experimental work and modeling. The main corrosion product is Al(OH)3, which presents as a gelatinous substance in the crevices between the Al wires. The formation of Al(OH)3 was observed to coincide with the decay in the galvanic corrosion current. A new analytical model was developed to investigate if the decay could be caused by corrosion products restricting the transport of oxygen to the cathode. Modeling of the oxygen diffusion through the deposited corrosion products generated galvanic corrosion rates that agreed well with the experimental measurements after an early exponential decay period. The findings suggest that the corrosion product deposition may be the most important galvanic corrosion rate controlling mechanism in this geometry and similar geometries.

The Influence of Non-Passivating and Passivating Alloys on the Galvanic and Local Corrosion Rates of 6061-T6 Al

Galvanic corrosion of 6061-T6 aluminum-coupled metals was studied in marine, volcanic, and rainforest environments. In addition to outdoor exposure, the galvanic couples were subjected to the chloride-containing GM 9540 accelerated corrosion test. The galvanic couple types included 6061-T6 Al paired with Ti-6Al-4V, 316 stainless steel, silver, copper, 1018 steel, or Mg AZ31B using fiberglass-epoxy fasteners. In this experiment, galvanic corrosion currents were measured through portable data loggers connected to each metal in the aluminum-coupled specimens. The total corrosion on the 6061-T6 Al in the galvanic couple resulted from the galvanic corrosion between the 6061-T6 Al anode and the cathode plus additional simultaneous local corrosion on the 6061-T6 Al caused by local cathodic reactions occurring on the 6061-T6 Al. The value of the total corrosion rate (i.e., local corrosion plus galvanic corrosion) was determined by mass loss of the galvanically coupled aluminum coupons. The local corrosion rate was determined using the difference between the total corrosion rate and the galvanic corrosion rate, as determined from the galvanic current data and Faraday’s law. The corrosion rates of the coupled 6061-T6 Al coupons were up to approximately 20 times greater than the uncoupled 6061-T6 Al coupons. Interestingly, less than 30% of the mass loss of the coupled 6061-T6 Al was directly due to the galvanic current, and accordingly 70% or more was due to local corrosion on the 6061-T6 Al. This implied that corrosion-product contaminants from the cathodic coupons (i.e., Ti-6Al-4V, 316 stainless steel, silver, copper, and 1018 steel) or byproducts such as excess H+ on the anodic 6061-T6 Al and excess OH- on the adjacent cathode may have had a major influence on the local corrosion of the 6061-T6 Al. In some cases, the type of cathodic coupon (i.e., Ti-6Al-4V, 316 stainless steel, silver, copper, and 1018 steel) made a significant difference on the corrosion rates of the 6061-T6 Al. Potentiodynamic polarization experiments were also conducted to study the mechanisms of galvanic corrosion for the couples described above.

Galvanic Corrosion Studies of Aluminum Coupled to Non-Passivating and Passivating Alloys

Research has been conducted to study the corrosion behavior of galvanic couples in order to develop a thorough understanding of the galvanic corrosion of aluminum (i.e., 6061-T6 Al) in atmospheric environments when it is coupled to more noble non-passivating metals (i.e., silver and copper), passivating metals (i.e., Ti-6Al-4V and 316 stainless steel), and non-passivating active metals (i.e., mild steel and Mg AZ31B). The couples were subjected to atmospheric exposure in marine, volcanic, and rainforest environments, as well as the chloride-containing GM 9540 accelerated corrosion test. The purpose of the research project is to obtain a scientific understanding of the galvanic corrosion mechanisms and quantitative metrics for aluminum so that the data can be used to predict the effects of galvanic corrosion in multiple component systems. The determination of overall corrosion damage during atmospheric exposure is complicated because non-passivating, noble metals (e.g., Cu and Ag) can contaminate the aluminum surface and change the local-action corrosion rates; whereas, passivating metals (e.g., 316 stainless steel and Ti-6Al-4V) are less likely to contaminate the Al surface. In this experiment, corrosion rate was determined by measuring galvanic corrosion currents and total corrosion was measured via mass-loss data. The differing corrosion rates between each atmospheric condition can be attributed to environmental parameters such as specimen temperature, time of wetness, chloride deposition, acid rain, etc. Potentiodynamic polarization experiments were also conducted to study the mechanisms of galvanic corrosion for the couples described above.

Electrochemical Characteristics of TiAl Coating on Aluminum Alloy Surface by Supersonic Particles Deposition

In this study, Ti-45Al-7Nb-4V alloy protective coating which base on γ-TiAl phase was deposited on the surface of 5803 aluminum alloy by supersonic particles deposition technology. Researchers observed the micro-structure of the TiAl alloy casting and coating by SEM, and researched the electrochemical characteristics and the galvanic corrosion between TA2 titanium alloy and 5083 aluminum alloy or TiAl alloy casting and coating by electrochemical work station. The results show that,the galvanic corrosion current between 5083 aluminium alloy and TA2 titanium alloy declines from 16.2μA to 0.27μA after TiAl protecting coatings are prepared on the substrates, besides, the corrosion susceptibility drops from E degree to A degree. It also manifests that the 5083 aluminium alloy with Ti-45Al-7Nb-4V coatings can be contacted and utilized with TA2 titanium alloy directly, which tackles the issues of gavanic corrosion prevention between aluminium alloys and titanium alloys.

Examination of the Electrochemical Compatibility of a Selection of Bimetallic Coins Using 3D-Skp and 3D-Svet

Coins as a means of exchange or barter have existed for over 2000 years. Early examples from the Bronze Age were stamped from crudely shaped discs of metal and this principle of manufacture has continued through to the present day. With the face value of modern coins usually being significantly higher than the material value and production cost, they can be prone to forgery, with a reported 3% of certain denominations in the UK being counterfeit1. In an effort to combat this and to add distinguishing features to the different denominations, an increasing number of coins around the world consist of two or more alloys. These are usually arranged as an inner and outer piece, to form two concentric rings. With two different alloys in electrical contact there exists the possibility for bimetallic corrosion to occur; hence it is important that the two alloys are potentiometrically matched. In this study, a selection of bimetallic coins has been examined via 3D-SKP and 3D-SVET. The SKP technique is used to examine the surface potential differences between the two alloys. The SKP scans have been performed using height scanning mode in order to compensate for the topographical features present and enable a sufficiently close scan distance to elucidate good potential measurements. Subsequently the coins have then been subjected to 3D SVET scans while immersed in an electrolyte, in order to assess if the potential differences identified during the SKP assessment result in measureable galvanic corrosion. The SKP was able to determine a Volta potential difference of between 50 – 100mV for the paired alloys. When investigated via the SVET, this relatively small potential difference was sufficient to generate measureable galvanic corrosion currents when immersed in weak electrolyte and scanned using the 3D-SVET. The anodic and cathodic sites detected via the SVET corresponded to the relative Volta potentials as detected with the SKP. Osbourne, G. (2014), Chancellor George Osborne's Budget 2014 speech , Available: https://www.gov.uk/government/speeches/chancellor-george-osbornes-budget-2014-speech [20 March 2014].

Microcell versus galvanic corrosion currents in carbonated concrete

This paper presents specific experiments developed to assess galvanic corrosion currents in carbonated concrete. The work investigated the influence of both the steel–concrete interface condition and the cathodic to anodic surface ratio. Galvanic corrosion currents were compared with microcell corrosion currents. In the quasi-saturated condition, galvanic corrosion currents were systematically found to be much higher than microcell corrosion currents. Moreover, the presence of defects at the interface between the anodic steel surface and concrete leads to a significant increase in the macrocell driving potential and, therefore, in the galvanic corrosion current. Furthermore, the galvanic current density strongly increased with increasing cathodic to anodic surface ratio. The coupling of a high cathodic to anodic surface ratio and the presence of steel–concrete interface defects at the anodic surface leads to huge galvanic corrosion current densities.