Acceleration Of Corrosion Research Articles

Development of Evaluation Method of Corrosion Resistance and Long-Term Durability of Stainless Steel for PEMFC

In recent years, Proton Exchange Membrane Fuel Cell (PEMFC) have attracted attention as an important technology for achieving carbon neutral society due to high energy efficiency without carbon dioxide emission during power generation. In order to cost reduction of PEMFC, the use of cheaper structural materials, such as stainless steels, that possess excellent processability, has been studied in substitution for titanium for bipolar plate (separator). The practical environment in PEMFC is severely corrosive: high temperature, acidic, and fluoride-containing solution. Many study has been conducted on the development of materials that have sufficient corrosion resistance and low contact resistance enabling long-term durability even in such severe environment. However, present evaluation method is insufficient for diagnosis the lifetime of bipolar plate. The new evaluation technique, that accurately simulates the environment inside PEMFC and appropriately accelerates the corrosion degradation reaction, make it easier to predict the lifetime of products and precisely evaluate the performance of newly developed materials. Therefore, the purpose of this study is development of novel corrosion evaluation method with high reproducibility, high and rapid diagnosis performance via applying various electrochemical measurements simulating PEMFC environment and for elucidation the corrosion behavior in practical environment.Firstly, several common corrosion resistance tests were performed in a specific solution (80 ℃, pH3, 10ppm Cl-, 3ppm F-) that simulated the internal environment of PEMFC. As a result, potentiostatic polarization (0.724 V vs. Ag/AgCl, 24 h) showed poor reproducibility because the corrosion behavior in later stage depends largely on the occurrence of localized corrosion initial stage of the test. In the case of potentiodynamic polarization(+1 mV/s sweep from open-circuit potential), risk of localized corrosion could be investigated, however, it was not suitable to predict long-term corrosion behavior. In the case of potentiodynamic cyclic polarization (cyclic voltammetry), it was found that the cathodic sweep, which never occur at in-sever PEMFC condition, inhibited the stable growth of the passivation film on the steel surface by reduction reaction, resulting in improperly accelerated excessive corrosion.Then, new testing method of the intermittent polarization, which was a combination of potentiostatic polarization and open-circuit condition, was performed. It has the advantage in flexibility of testing conditions such as polarization potential and duty cycle in accordance with to the degree the corrosion acceleration. In fact, it was found that the localized corrosion caused by initial stage of potentiostatic polarization step was repassivated during the following open circuit step. Therefore, the reproducibility was improved and the passive film growth was properly evaluated by intermittent polarization test, therefore. It was expected to be promising technique to diagnose the long-term durability of PEMFC bipolar plate.In order to demonstrate the effectiveness of the intermittent potentiostatic polarization method, a variety of type 304 stainless steel specimens with different corrosion resistance were used. The detailed results will be presented on the relevant session.

Molecular insights into the effect of adsorption and reaction of H2O-O2-Cl- on initial electrochemical corrosion of steel

A deeper understanding of the effect of chloride on the process of iron initial corrosion could reveal the detailed mechanism of the Cl--induced acceleration corrosion of steel. In light of the difficulty to unravel the intricacies of H2O-O2-Cl- interactions in experiments, this study conducted the molecular study on the effect of H2O, O2 and Cl- coadsorption and interactions on the electrochemical corrosion process of Fe (100) surface by DFT method, and the electron-correlation functional is GGA-PW91. It is discovered that the adsorption of H2O, O2 and Cl- all promote the electrochemical corrosion of iron. The electrochemical corrosion rate of iron surface rises as the Cl-/H2O concentration ratio increasing, while decrease with the Cl-/O2 concentration ratio increasing. The transition state search found that the presence of Cl- assists the dissociation of H2O on the iron surface, while the interaction between Cl- and O2 could be ignored. Moreover, the successive reaction of Cl-, H2O and O2 with iron surface were further investigated. When the Cl- reacts with H2O ahead of O2, the Cl- promotes the iron oxidation via promoting the dissociation of H2O. While O2 and Cl- firstly coadsorb on iron surface, Cl- accelerates iron oxidation by exacerbating the iron surface losing electrons. These findings could facilitate the development of anti-corrosion techniques for steel in chloride environment.

Electro-chemo-physical analysis for long-term reinforcement corrosion within the reactive system of concrete

This paper presents an electro-chemo-physical model for analyzing long-term chloride-induced reinforcement corrosion in concrete structures. The integration of electrochemical and thermodynamic analyses enables the proposed model to capture the influence of simultaneous reactions within concrete on the corrosion process. The model is validated against experiments, where the necessity of considering the complicated reactions within concrete in long-term corrosion modeling is underscored. Building upon experimental observations and numerical explorations, a potential corrosion acceleration effect resulting from Friedel's salt dissolution in a longer term of corrosion propagation is discovered. Thereafter, a new qualitative model for describing the reinforcement depassivation process in concrete is proposed, along with discussions on governing mechanisms. From a computational perspective, the study also identifies hematite and magnetite as thermodynamically stable rusts under different concentrations of Fe2+ and O2. The proposed model and discoveries are poised to contribute significantly to scientifically robust predictions of deterioration and remaining service life for aging reinforced concrete structures.

Insight into the acceleration effect of current-carrying condition on copper conductor atmospheric corrosion

Copper is widely used as conductive components in transmission lines, facing severe corrosion risks. The current passing through copper conductors will significantly affect its corrosion process, yet there is a lack of detailed study on the corrosion mechanism under this specific condition. Thus, this study investigated the effect of direct current current-carrying (DC C-C) conditions on the atmospheric corrosion behavior of copper conductors under thin electrolyte layer (TEL) through electrochemical measurements and corrosion exposure experiments. Results revealed that the presence of DC C-C significantly hastened the corrosion process of copper conductors in the TEL, leading to distinct corrosion patterns at the input and output ends. Furthermore, both the extent of corrosion acceleration and the unevenness of corrosion were positively correlation with the DC C-C level. The above phenomenon was attributed to the special motion of charged particles and paramagnetic substances in TEL under the self-generated magnetic field.

Preparation and Properties of Carbon Fiber/Flexible Graphite Composite Grounding Material

In this paper, flexible conductive composite materials were prepared from flexible graphite and carbon fiber by mould pressing, and their micromorphology was studied by SEM. The influence of carbon fiber content on the mechanical properties and electrical conductivity of the flexible conductive composite material was studied, and the corrosion rate of the flexible conductive composite material coupling with galvanized steel in soil with different SO42− concentrations was studied. The results showed that the tensile strength reached 5.82 MPa when the mass ratio of carbon fiber to flexible graphite was 1:20, and the volume resistivity achieved 4.76 × 10−5 Ω·m when the mass ratio of carbon fiber to flexible graphite was 1:30. With the increase in molding pressure, tensile strength and electrical conductivity had a slight increase. When the flexible conductive composite material was coupled with galvanized steel, sulfate could accelerate the galvanic cell corrosion between the flexible graphite grounding material and galvanized steel. The increase in the sulfate concentration led to more corrosion acceleration. With the increase in corrosion time, the corrosion potential of the flexible graphite grounding material and galvanized steel coupling body decreased to its lowest at 30 days, and then increased gradually. The corrosion current was the highest at 30 days, and then decreased gradually.

Experimental investigation of using Ultra-High-Performance Concrete coating for anti-corrosion protection of reinforced concrete induced by chloride ions

The emergence of Ultra High-Performance Concrete (UHPC) is one of the latest developments in concrete technology. Repairing and rehabilitating damaged structures by applying a thin layer of several centimeters on conventional concrete (with or without reinforcement) has been one of the applications of UHPC. Due to its very small porosity and excellent permeability, UHPC has extremely high durability against the penetration of destructive substances such as water, chloride ions, oxygen, etc. In this work, we investigated the durable effect against external aggressive corrosive substances by coating a 2.5 cm thickness layer of UHPC on conventional concrete. The desired composite concrete consists of a conventional concrete core with a compressive strength of 40 MPa and a coating with a thickness of 2.5 cm of UHPC cover. Then, this concrete went through oxygen penetration, Rapid Chloride Permeability Test (RCPT), and electrical resistance tests. Finally, to verify the results of the durability tests, two sets of comparison reinforced concrete specimens with 5 cm as their covers were exposed to an accelerated corrosion test. It is found that the substitution of a 2.5 cm layer of UHPC instead of the conventional concrete resulted in a 30-times increase in resistance against water penetration, 41 times against chloride ion penetration, 307 times against oxygen penetration, and 8 times in its electrical resistance. Based on corrosion acceleration test results, after 30 days of applying a current with a voltage of 31 volts, the control specimens with a 5 cm cover started to corrode after one week. After 30 days, 47 % corrosion was observed. Even though after 365 days, no signs of corrosion were found in the UHPC-coated specimens.

Effect of corrosion on bond between reinforcement and concrete-an experimental study

The presence of cracks in concrete structures can lead to corrosion as it exposes the steel reinforcement to environmental factors. When moisture and oxygen reach the steel, corrosion weakens the bond between the steel and the surrounding concrete. This weakening can reduce the load-carrying capacity and, in severe cases, lead to failure. Understanding the relationship between corrosion and bond strength is vital for reinforced concrete structures. This paper investigates the impact of corrosion on bond strength in reinforced concrete structures by examining the bond performance of concrete with both corroded and uncorroded reinforcement bars. The study considers concrete grades M20, M25, and M30, as well as corrosion levels varying from 0 to 20% in intervals of 5%. To conduct the study, cylindrical samples with different levels of corrosion were created using the corrosion acceleration process with the impressed current technique. Pull-out tests were then carried out to determine the bond-slip relationship and the degradation of bond strength due to corrosion. The test results show that lower-grade concrete (M20) experiences a significant decrease in bond strength compared to higher grades (M25 and M30), with M20 showing a 30.7% reduction and M25 showing a 25.8% reduction in bond strength relative to M30 in controlled specimens. The bond stress-slip relationship reveals a non-linear response, with reduced bond stress and slips for all grades of concrete as corrosion levels increase. Additionally, the reduction in bar diameter due to corrosion ranged from 11.3 to 11.6 mm at 5% corrosion and from 9.4 to 9.7 mm at 20% corrosion, significantly impacting the load-carrying capacity of the reinforced concrete structures. These findings underscore the importance of considering concrete grade and corrosion levels when assessing and maintaining bond performance in reinforced concrete structures.

Impact of anti-corrosion coatings and maintenance on high-strength bolt friction connections in C4 marine environment

High-strength bolt friction connections (HSBFCs) in steel constructions often employ exterior anti-corrosion coatings, and some connections in steel bridges extend these coatings to their friction surfaces. However, previous studies on HSBFCs have overlooked the influence of external anti-corrosion coatings and coatings on friction surfaces. This research investigates the impact of internal and external anti-corrosion coatings on shear performance through experimental testing. Shear tests were conducted on 43 connections under 17 different conditions, varying the presence of anti-corrosion coatings on friction surfaces and external coatings, including conditions of construction and maintenance. Calibration tests revealed varying anti-slip coefficients: sandblasted surfaces measured 0.44, below specification; epoxy zinc-rich primer coatings measured 0.27; and alcohol-soluble inorganic anti-rust primers measured 0.50, both meeting or exceeding specifications. Simulated C4 atmospheric corrosion environments and dry-wet alternating copper accelerated acetic acid salt spray tests were performed. Results indicate predictable indoor corrosion acceleration and significant shear capacity degradation (4.9 % to 19 %) despite external coating use. Coatings on friction surfaces delayed degradation, while external anti-corrosion coating effectiveness declined post-construction and maintenance. Analysis shows shear capacity degradation in unprotected connections was 1.5 to 1.8 times higher than protected counterparts, attributed to reduced anti-slip coefficients and bolt pre-tension loss.

Optimization and Evaluation of Accelerated Corrosion Tests Based on Mechanism Equivalence Principles.

Conventional indoor corrosion test design methods primarily focus on the rapid evaluation of material corrosion resistance, often neglecting the impact of environmental stress levels on the equivalence of corrosion mechanisms. This study introduces a novel indoor corrosion test design method based on the principle of corrosion mechanism equivalence, aimed at improving the accuracy of indoor accelerated corrosion simulations. We define the characteristic of corrosion mechanism equivalence as the Corrosion Mechanism Equivalence Degree (CMed), which quantifies the similarity between corrosion mechanisms in indoor accelerated tests and field tests. Then, modified conventional link function models are defined, integrating the probability distribution of environmental factors to estimate corrosion model parameters more precisely. Finally, an optimization problem is constructed for accelerated corrosion tests based on CMed, incorporating constraints on environmental stress levels and acceleration factors. A case study demonstrates the proposed method's ability to accurately simulate the actual service environment of materials, determining the appropriate stress levels for indoor accelerated corrosion tests while ensuring the desired acceleration factor and corrosion mechanism equivalence.

Corrosion Initiation on Reinforcing Steel with Mill Scale in Mortar

Corrosion of reinforcing steel rebar is the main cause of loss of the long-term reliability of concrete structures. When the rebar is corroded, the rust induces cracks and detachment of the cover concrete. The mill scale, a thick oxide film, is formed on the rebars when the rebar is hot rolled. The role of mill scale on the corrosion resistance of rebars in concrete has not been clarified, yet. This study studied the corrosion behavior of rebars with mill scale in mortar.The samples are commercial rebars with 19 mm diameter, which have a mill scale of several tens of micrometers in thickness. The rebars without mill scale prepared by the electrolytic polishing were used as the comparison samples. A Hyperbaric-oxygen accelerated corrosion test (HOACT) [1] was carried out using the rebars embedded in the mortar with a 5.5 mm cover thickness. To prompt the breakdown of passive film on the rebars, 2.1 M NaCl solution was mixed with the mortar. In the HOACT, pressurized oxygen gas is supplied to the sample, and the oxygen reduction reaction on the steel surface is enhanced, leading to the steel's corrosion acceleration. The oxygen pressure was 0.6 MPa and the test period was 14 days. The corrosion of the rebar with a mill scale was more significant than that without a mill scale. This result shows that the mill scale reduces the corrosion resistance of the steel rebar in concrete [2].To investigate the effect of the mill scale on the corrosion resistance of the rebar, anodic polarization measurements of the rebars with and without the mill scale were carried out in a saturated Ca(OH)2 solution containing Cl-. The pitting potential of the rebar with mill scale was more noble than that of the sample without mill scale. However, when the mill scale was scratched, the pitting potential was significantly shifted to the less noble direction, and it was below that of the rebar without the mill scale. These results show that the mill scale improves the corrosion resistance of the rebar in concrete, in contrast, the corrosion resistance of the rebar with a defective mill scale becomes even worse than that of the rebar without the mill scale [2].[1] K. Doi, S. Hiromoto, H. Katayama, E. Akiyama, J. Electrochem. Soc., 165(9), C582-C589 (2018).[2] K. Doi, S. Hiromoto, T. Shinohara, K. Tsuchiya, H. Katayama, E. Akiyama, Corrosion Science, 177, 108995 (2020).

The mechanism of gold nanoparticle-enhanced corrosion acceleration of polylactide (PLA)-coated biodegradable iron and zinc

The commercial application of biodegradable metals (BMs), such as iron (Fe) and zinc (Zn), is hampered by their slow degradation rate. Polylactide (PLA) coatings on BMs have been proven to accelerate the corrosion of Fe and Zn but with limited success. This is the first study exploring the use of gold nanoparticles (Au NPs) to enhance and control the corrosion of polylactide (PLA)-coated Fe and Zn. The Au NPs enhanced the corrosion rate of Fe and Zn by promoting micro-galvanic corrosion after nanoparticle agglomeration. The optimal corrosion acceleration depended on the polymer's molecular weight, coating thickness, and coating structure. The results suggest that the Au-reinforced PLA-based coatings can be used to control Fe and Zn corrosion rates in the physiological environment.

Hydrocarbon-degrading Shewanella algae shows oxidative deterioration corrosion at the aluminium alloy & coating interface

In this investigation, microbial adhesion expedites formation and alteration of aluminous minerals within aviation fuel tank systems. The corrosion mechanisms of two uncoated aluminium alloys and three types of coating-pretreated aluminium alloys by hydrocarbon-degrading Shewanella algae are examined. NO3- reduction of microorganisms induces corrosion acceleration of LY12 aluminium alloy (1.48 g*m−2*h−1) and corrosion inhibition of 7B04 aluminium alloy. CLSM and SEM observation of coating morphology highlight the microbial deterioration behaviors of coatings (pitting, swelling, and peeling). It inspires material selection and surface coating of microbial corrosion protection of aluminium alloy in marine and aerial environments.

Evaluation of Corroded OPS Fibre-Concrete using NDT Method

Concrete is one part of an infrastructure that is very commonly used, materials widely used in concrete, such as sand and gravel, come from nature that are limited and will run out if used continuously. Oil palm shell (OPS) waste is an alternative that canbe used to solve this problem. In this study, the proportion of OPS used was 0%, 25%, 50%, and 75% as a partial substitute for coarse aggregate. Pre- and post-corrosion specimens use beam sizes with dimensions of 100 mm × 100 mm × 500 mm. The specimen has a corrosion rate of 7%. The specimen is tested for flexural strength, in addition, the specimen is tested using the Non-Destructive Testing (NDT)method at the age of 28 days and after acceleration corrosion. The NDT methods used in this study were resistivity and impact-echo as evaluation tools for the influence of OPS and fiber on corroded concrete. Based on the results, the lowest value of resistivity was 10.87 kohm/cm on 0% OPS post-corrosion specimen, and the highest value of resistivity of 24.12 kohm/cm on 0% OPS pre-corrosion specimen. Meanwhile, the impact-echo test obtained the lowest value of 2625.33 kHz on 75% OPS post-corrosion specimens and the highest impact-echo value of 11725.26 kHz on 0% OPS post-corrosion specimens. With the increase in the percentage of OPS, the resistivity obtained in pre-corrosion concrete will decrease as well as the impact echo value, except for the 75% OPS specimen, while in post-corrosion specimen impact-echo and resistivity are inversely proportional. The greater the percentage of OPS in concrete, the resistivity value tends to increase but the frequency of impact-echo tends to decrease except in specimens with 75% OPS.

Simultaneous removal of Cr, Cu, Zn, and Cd by nano zero-valent iron modified sludge biochar in high salinity wastewater

Cr, Cu, Zn, and Cd commonly coexisted in the electroplating wastewater with high salinity and organics, while their removal was often investigated individually. In this study, the simultaneous removal of Cr, Cu, Zn, and Cd was investigated by nano zero-valent iron modified sludge biochar (nZVI@SBC). The results showed that nZVI@SBC could significantly improve the removal efficiency of the four heavy metals (HMs) in high salinity wastewater. NO3– (N-NO3–) and humic acid (HA) could promote the removal of Cr, Cu, Zn, and Cd, and PO43- (P-PO43-) could enhance the removal of Cd. EPR analysis demonstrated the generation of 1O2 in different water matrices. The 1O2 intensity increased in the presence of NO3– and HA, which indicated the acceleration of the nZVI corrosion and the promoted electron transfer in the system. To further understand the reaction mechanism, the variation of nZVI@SBC structures and compositions during the treatment process were characterized by SEM-EDS, XRD, BET, and XPS. Cr and Cu were removed through adsorption and co-precipitation after reduction by nZVI, while Cd and Zn were removed by alkali precipitation and complexation. This work improves the understanding of simultaneous removal of HMs by nZVI@SBC and provides a cost-effective approach for the electroplating wastewater treatment.

Estimation of Early Corrosion Mechanism on the Upper Surface of Wire Ropes in Suspension Bridges

This study is focused on the heterogeneous corrosion phenomenon of the general segment of suspension bridge main cables in mountainous/plain areas, specifically focusing on the uppermost surface. The primary objective of this research is to elucidate the corrosion mechanism by investigating the corrosion environment and performing corrosion acceleration tests using simulated ropes. Consequently, it has been revealed that during the summer season, the surface temperature of the rope reaches approximately 65°C, corresponding to the zenith of zinc corrosion rates. Moreover, in the upper surface of the rope, which is particularly susceptible to the influence of solar radiation, it has been disclosed that condensation occurs as a non-rainfall-related factor, creating an environment conducive to condensation. These factors suggest that the moisture supplied to the upper surface and the residue of corrosive elements exert an influence on the skewed corrosion mechanism of the rope surface.

Effect of Bacillus Subtilis Bacteria on The Mechanical Properties of Corroded Self-Healing Concrete

Reinforced concrete has a weakness for corrosion which can cause the concrete to crack and the concrete structure to fail. To overcome this problem, a self-healing concrete method is needed that can close cracks and inhibit the rate of natural corrosion. Bacillus subtilis as a self-healing agent in concrete has been proven to be able to increase the compressive strength and flexural strength of concrete. The method used in this research is to add bacterial hydrogel encapsulation to concrete with a variation of 0%; 0.1%; 0.6%; and 1.5% by weight of sand. The test object is a reinforced concrete beams and cylindrical concrete with compressive design strength of 30 MPa. The concrete specimens will go through a series of tests, such as corrosion acceleration tests using DC power supply, self-healing tests by visual observation, flexural strength, ductility, stiffness, and compressive strength tests using Universal Testing Machine (UTM). From the test results, it was found that the addition of 0.1% bacterial encapsulation variation was the optimum value for increasing the mechanical properties of self-healing concrete and reduce the corrosion rate on self-healing concrete.

Monitoring and Accelerating Methods of Corrosion for Reinforced Concrete: A Review

AbstractCorrosion is the irreversible, interfacial reaction of metals in the presence of an electrochemical environment which ultimately results in the deterioration of metals. Corrosion of reinforcement is the major problem in the reinforced concrete (RC) structure. Corrosion of reinforcement is a slow process because of the protective layer of concrete. Even in a severely corrosive environment corrosion process takes time to be initiated and propagated. Since to carry out research work, some techniques are required to accelerate the corrosion process in the shortest period. To overcome this problem, in the past, many researchers use a different method to accelerate the corrosion of steel in concrete. In this paper, a review is presented of various techniques used for accelerated corrosion testing. The suitability of reviewed methods on corrosion acceleration for several research works is presented. After that few case studies review to make use of various predicted empirical models and an experimental technique for predicting corrosion rate and the assessment of the remaining life of the structure. And finally, the paper is concluded by comparing the natural method of corrosion and the accelerated method of corrosion and the future scope of accelerated corrosion.

Oxide characteristics of 90Nb-10Zr alloy corroded under different water chemistry conditions

In water-cooled nuclear power reactors, zirconium alloys as fuel cladding are important structural materials. Many factors will lead to the failure of the zirconium alloy cladding, and the corrosion resistance is the most important factor that affects the service life of the fuel element. E110 (Zr-1Nb, wt.%) and M5 (Zr-1Nb-0.16O) alloys are typical Zr-Nb series zirconium alloys used in commercial reactors. It is well-known that most of second phase particles are β-Nb in Zr-Nb series alloys, and many researchers believe that the corrosion resistance of Zr-Nb alloy is related to the oxidation process of β-Nb precipitates. Due to its size limitations, it is difficult to conduct in-depth and systematic research on the oxidation process of β-Nb precipitates. Therefore, we prepared the 90Nb-10Zr binary alloy with the same microstructure and composition of β-Nb and investigated its oxide characteristics in different water chemical environments. The corrosion products of 90Nb-10Zr alloy vary with the corrosion environments. Based on the transmission electron microscopy observation results of corrosion products formed on the 90Nb-10Zr alloy, a hypothesis of corrosion acceleration of Zr-1Nb alloy in lithiated water is proposed from the perspective of β-Nb SPPs oxidation.

Simulation of Pitting Corrosion Under Stress Based on Cellular Automata and Finite Element Method

Abstract A new cellular automaton (CA) program was written in python language to simulate the random pitting evolution process, which can not only obtain a variety of different corrosion products but also obtain a variety of common corrosion morphologies on the surface of metal pipes, bridge steel members, etc. In addition, commercial finite element (FE) software abaqus was redeveloped using python scripting language, and the FE mesh with the same size as the cellular mesh was established based on the consistent mesh algorithm, which ensured the efficiency and accuracy of the cyclic iterative algorithm. The stress and strain fields were calculated in real-time by applying the force load, the dissolution probability parameter P was updated in python according to the force-chemical coupling model, and a new corrosion morphology was obtained in python. At the same time, the birth and death element method was applied in abaqus to kill the corrosion elements in this iterative step simultaneously, and the new stress-strain field was recalculated in abaqus. The established consistent grid modeling strategy and cyclic iterative algorithm can significantly improve the solving efficiency of pitting evolution under the coupled action of corrosive medium and load. The results show that the stress concentration caused by pit expansion and the corrosion acceleration effect dominated by plastic deformation will promote each other, leading to the continuous growth of pitted pits. The established modeling strategy and cyclic iterative algorithm can significantly improve the solving efficiency of pitting evolution under the coupled action of corrosive medium and load.

Tribocorrosion behavior of TC18 titanium alloy: A discussion about the interaction between galvanic corrosion and wear

Titanium and aluminum couplings are susceptible to both corrosion and wear during their service life. When the passive film on the titanium surface is worn off, the galvanic effect will affect the corrosion-wear interaction, and tribocorrosion mechanism is altered accordingly. A combination of electrochemical techniques (Potentiostatic and Potentiodynamic Polarization), characterization of wear scar morphology (Scanning Electron Microscope, SEM and a 3D profilometer), and analysis of wear debris composition (Surface-Enhanced Raman Spectroscopy, SERS) were employed to clarify the tribocorrosion mechanism. The results show that the wear effect is predominant for the tribocorrosion of TC18 titanium alloy, and the corrosion-induced wear increment mainly comes from the ploughing effect of regenerated passive film. When the titanium alloy is coupled with aluminum, the corrosion acceleration is weak, while the cathodic reaction increases due to the negative shift of the corrosion potential. This results in the regenerated passive film containing a higher proportion of easily sheared low-valent titanium oxides and titanium hydrides, promoting the wear rate.