Electrochemical Corrosion Rate Research Articles

Effect of protective coatings on serviceability of aluminium alloys in environment of oil production

The effect of protective coatings on the wear resistance and corrosion resistance of the 2024 aluminium alloy used for the oil drill pipes producing is studied. The nature of the drill pipes damage made of aluminium alloys during operation is analyzed. The microstructure of the coatings, the electrochemical potential and corrosion rate of the 2024 aluminium alloy with and without coatings of various compositions are studied, and comparative analysis of the adhesion and wear resistance of coatings is performed. It is shown that tube billet made of 2024 alloy with сoating based on tungsten carbide has the highest range of service properties and can be used to effectively protect the surface of aluminium drill pipes during operation.

Comparative study on corrosion behaviour of rusted X100 steel in dry/wet cycle and immersion environments

A dry/wet cycle corrosion test device was constructed to study the corrosion behaviour of X100 steel under rust layer in dry/wet cycling and immersion conditions. Results showed that the exposure of X100 steel in dry/wet cycle condition with high concentration of Cl−, fast diffusion of O2, and wetness of the rust layers led to an accelerated corrosion process. The initial corrosion rate in the dry/wet cycle environment was higher than that in the immersion environment. As the corrosion time increased, the α-FeOOH content in the rust layer increased, resulting in a decrease in the rate of electrochemical corrosion of metals. In the immersion environment, the corrosion mechanism involved was a typical oxygen-absorbing corrosion mechanism. Under dry/wet cycle conditions, the simultaneous effects of Cl−, O2, and rust layer were studied. The three stages of the wet surface in dry/wet cycle environment were described, and the corrosion mechanism was clarified.

Effect of composition on in vitro degradability of Ti-Mg metal-metal composites.

In this work, Ti and Mg alloys were made into composites by using spark plasma sintering, in order to combine the high stiffness of Ti and biodegradability of Mg alloys. The effect of the content of Mg-3Zn alloy on the degradability was studied by using electrochemical corrosion, immersion in simulated body fluid and incubation of Saos-2 cells. The results show that Ti-Mg metal-metal composites (MMCs) exhibit low Young's modulus (31-48 GPa) and good yield strength (616.5-642.8 MPa). The modulus and strength both decrease with the content of Mg-3Zn alloy increasing. The electrochemical corrosion rates of Ti-Mg MMCs were much lower than that of monolithic Mg-3Zn alloys. After an immersion for 21 days, Ti matrix remained integrity and Mg phase dissolved in the solution, inducing the formation of apatite layer on the MMCs. The precipitation of apatite increased with the content of Mg-3Zn alloy increasing. In vitro study indicated that Ti-10Mg and Ti-20 Mg MMCs possessed good biocompatibility to Saos-2 cells, while the biocompatibility of Ti-30 Mg MMCs decreased slightly. In summary, Ti-Mg MMCs are promising implant materials with adjustable degradation rates and improved biocompatibility for orthopedic applications.

Investigation of the stress corrosion cracking behavior in annealed 5083 aluminum alloy sheets with different texture types

Al–Mg alloys are commonly employed for anti-corrosion parts in marine and rail vehicles. However, the corrosion resistance of these alloys is affected by the alloy microstructure. In this study, 5083 aluminum alloy sheets with different recrystallized textures (a low-intensity texture, a cube-based texture, and a brass-based texture) were obtained by cold rolling and annealing. The stress corrosion cracking and short crack propagation behavior were investigated based on the microstructural characterization, intergranular corrosion, electrochemical corrosion, and slow strain rate testing. The results showed that the tested samples exhibited large differences in stress corrosion properties, although they had a similar resistance to intergranular corrosion. The sample dominated by the brass texture exhibited the best resistance to stress corrosion cracking (SCC) with an ISSRT of 11.7%, while the sample with the low-intensity texture exhibited the worst resistance to SCC with an ISSRT of 29.7%. Moreover, the stress corrosion crack in the sample dominated by the brass texture propagated along a more tortuous path. The crack was deflected at brass texture grains, which was attributed to the combined effects of the relatively large twist angle between the grain boundaries of brass grains and neighboring grains and the low grain boundary energy configuration of {011} orientation grains.

Corrosion Behavior of AZ31 Magnesium Alloy Produced by Continuous Variable Cross Section Direct Extrusion

In order to study the corrosion behavior of magnesium alloys of high performance in the simulated seawater by continuous variable cross section direct extrusion (CVCDE), an electrochemical method and weight loss method were used to study the difference between AZ31 magnesium alloys produced by CVCDE with different numbers of interim dies to examine the electrochemical corrosion behavior and corrosion rate at 3.5 wt.% NaCl solution in this paper. Scanning electron microscopy and x-ray diffraction were used to analyze the morphology of corrosion surfaces and the composition of the corrosion products of samples soaked for different times. The results show that after CVCDE with different numbers of interim dies, the size of the microstructure is refined gradually, and the grain orientation is also different; with the increase in the number of interim dies, the thermodynamic corrosion tendencies are different, and the corrosion resistance of samples extruded by conventional extrusion is relatively good; the charge transfer and material transfer process are the two main factors affecting the corrosion rate, which determines the direction of the electrochemical reaction; the corrosion form of the sample extruded by CVCDE is the local corrosion which is the filiform corrosion and pitting corrosion, and the corrosion product is mainly water-insoluble Mg(OH)2.

Effect of Extrusion Temperature and Extrusion Ratio on Microstructure and Biodegradation Behavior of Mg-4.5Zn Binary Alloy

Hot mechanical working is among the remedies to improve the corrosion resistance of magnesium and its alloys as the third generation of biomaterials. In the present study, Mg-4.5Zn alloy was extruded at different temperatures (300°C, 350°C, and 400°C) and ratios (6:1, 12:1, and 18:1). Optical and scanning electron microscopes were used to characterize the microstructure evolutions of the alloy after the extrusion. The degradation behavior of the alloy after extrusion was studied in the simulated body fluid using immersion and electrochemical tests. Results showed that a decreasing extrusion ratio reduces the number of dynamically recrystallized grains as well as the extrusion shearing fringe parallel lines. Besides, the alloy extruded at higher temperature is relatively larger with few dynamic recrystallized grown grains. It was revealed that the corrosion resistance of the extruded alloy is linearly enhanced with decreasing grain size. Moreover, a higher extrusion ratio results in a lower corrosion rate, while a higher extrusion temperature leads to a higher corrosion rate. The results also showed that the alloy extruded at 300°C and 18:1 ratio possesses the finest grain size (18.2 μm) and the most equiaxed grains, which provide the lowest electrochemical corrosion rate (0.89 mm/year).

Study on Electrochemical Corrosion Rate of Braided Wire Rope

Taking 8×19 traction galvanized Braided steel wire rope as the research object, we carried out the electrochemical corrosion test of the steel wire rope matrix and the galvanized layer. And the response surface method was used to examine the influence of the interaction of three factors on the corrosion rate of steel wire rope. The results show that the corrosion rate of the braided steel wire rope matrix and the galvanized layer increases with the increase of temperature and the decrease of pH value, and increases first and then decreases with the increase of Cl− concentration. There is a nonlinear relationship between corrosion rate and temperature, Cl− concentration and pH value. In the same corrosive environment, the corrosion rate of the galvanized layer of the wire rope is greater than the corrosion rate of the matrix. The influence degree of the three factors on the corrosion rate of the steel wire rope matrix and the galvanized layer under the interaction is: pH>temperature>Cl− concentration.

Reliability and long-term evaluation of GO-MnO2 nano material as a newer corrosion monitoring sensor for reinforced concrete structures

Graphene oxide-manganese oxide (GO-MnO2) nanomaterial was tried as electrochemical corrosion potential sensor and corrosion rate monitoring sensor in reinforced concrete structures. Graphene oxide-manganese dioxide nanomaterial was prepared by a simple chemical method. The synthesized material was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Raman spectra and transmission electron microscopy (TEM). An embeddable corrosion potential sensor (ECPS) and embeddable corrosion rate monitoring sensor (ECRMS) was assembled using nanomaterial suitable for measuring rebar potential and corrosion rate of rebar in concrete structures. The reversibility and reliability of the sensors were monitored under simulated concrete environmental conditions. The long-term stability was monitored for a period of 24 months under an active and passive state of reinforcing steel in concrete with respect to ECRMS and the results were compared with the surface mounting techniques. The stability of GO-MnO2 based ECPS and ECRMS was found to be excellent in an active and passive condition and hence can be put forth as a promising new candidate material for corrosion monitoring in concrete structures.

Preparation of calcium manganese phosphate by mechanochemical synthesis of manganese and hydroxyapatite

Biocompatible hydroxyapatite (HA), with chemical formula Ca5(PO4)3(OH), is widely used in dentistry and orthopedics. Inorganic additions of metal ions into HA structure can significantly influence physicochemical properties of HA-based ceramics. Calcium manganese phosphate (Ca19Mn2(PO4)14) was successfully synthesized by mechanochemical method where the manganese was added to HA with 5, 10, 15, and 20 wt%. The mechanochemical process was investigated by using Fourier-transform infrared spectrometer (FT-IR), X-ray diffraction (XRD), and differential thermal analysis (DTA). The compacted circular disc samples heat-treated at 1200 °C were also investigated using field emission scanning electron microscopy (FE-SEM) where fine agglomerates with small grain size were found. Sample densification improved with increasing sintering temperature. Calcium manganese phosphate (Ca19Mn2(PO4)14), beta-tricalcium phosphate (β-Ca3(PO4)2), and manganese oxide (Mn2O3) phases were formed and increases with increasing sintering temperature. The electrochemical behaviors and corrosion rate were investigated by potentiodynamic polarization, which confirms low corrosion rate that calculated by weight loss test of HA/Mn sample in Hank’s solution. With increasing Mn content, Vicker’s hardness and contact angle of the 1200-°C sintered materials decrease.

Calculation of the rate of electrochemical corrosion during the operation of longitudinal macro galvanic pairs in the pipeline section

Calculation of the rate of electrochemical corrosion during the operation of longitudinal macro galvanic pairs in the pipeline section

Influence of carbon ion implantation energy on aluminum carbide precipitation and electrochemical corrosion resistance of aluminum

The effects of varying carbon ions (C+) implantation energies on Aluminum Carbide (Al4C3) precipitation, surface morphology and electrochemical corrosion resistance of aluminum (Al) were evaluated. The Al samples were implanted with C+ of different energies of 0.25, 0.5, 1, 2, and 4 MeV at a constant dose of 1 × 1015 ions/cm2. The X-rays diffraction (XRD) and field emission scanning electron microscope (FESEM) results showed Al4C3 precipitates in the ion-implanted Al which were decreased at higher implantation energies (≥1 MeV). The decrease in Al4C3 precipitation was attributed to the lower chemical reactivity of C+ with Al due to ion-induced lattice defects. The Al surface became rough, and micro-cracks appeared on it as the ion energy increased above 0.25 MeV. The electrochemical corrosion rate of Al decreased from 469.9 mpy to 70.32 mpy after C+ implantation at 0.25 MeV. However, the corrosion rate increased with increasing ion energy above 0.25 MeV. This changes in corrosion rate were elucidated on the basis of Al4C3 precipitation and lattice defects in Al created by C+ implantation. The SEM analysis of electrochemically tested samples indicated lower pitting in the sample implanted with 0.25 MeV ions as compared to those implanted with higher energy.

Investigation of multiple laser shock peening on the mechanical property and corrosion resistance of shipbuilding 5083Al alloy under a simulated seawater environment: publisher's note.

This publisher's note corrects the labeling of Figs.10-13 in Appl. Opt.57, 6300 (2018)APOPAI0003-693510.1364/AO.57.006300.

Investigation of multiple laser shock peening on the mechanical property and corrosion resistance of shipbuilding 5083Al alloy under a simulated seawater environment

To investigate the effect of laser shock peening (LSP) with different LSP impacts on the mechanical properties in artificial seawater and corrosion resistance of shipbuilding 5083Al alloy in 3.5% NaCl solution, wear property and electrochemical corrosion resistance tests were performed by a ball-on-disk sliding wear tester and electrochemical workstation. The wear mass losses of the samples treated by 1 and 3 LSP impacts are much lower, by 55.22% and 65.94%, respectively, than those of untreated specimens in artificial seawater. Compared with the untreated sample, the electrochemical corrosion rate of the treated samples decreased by 74.91% and 95.03% after being treated by 1 and 3 LSP impacts, respectively. The reasons for the enhancement of the wear properties and electrochemical corrosion behavior were caused by the increased residual stress and microhardness after the LSP treatment.

Corrosion Behavior of Highly As-Doped Oriented Si-Wafer Anodes in Alkaline Si–Air Batteries

One line of development to establish resource-efficient metal–air batteries is focusing on silicon materials as anode electrodes. While operation of primary Si–air batteries with ionic liquid electrolytes is one possible approach [1], employing conventional alkaline electrolyte is also considered by the recent investigations [2]. At the current state of development, the alkaline Si–air batteries suffer from high corrosion rates that reduce the theoretical specific capacity of 3820 mAh/g to 120 mAh/g [3]. Thereby, corrosion as being the major challenge has to be overcome in order to establish practical application of primary alkaline Si–air batteries. The objective of the present work is to investigate the corrosion behavior of highly As-doped <100> oriented silicon wafer anodes in alkaline solutions for a scope of conditions that may arise in battery operation. Firstly, the influence of the immersion times on the open-circuit corrosion rates are discussed in combination with the surface morphology development in 72 h. Secondly, the impact of KOH electrolyte concentration on the open-circuit corrosion rates is investigated and three ranges of KOH concentrations are identified with different limiting mechanisms. Moreover, basing on the electrochemical corrosion rates obtained from potentiodynamic polarization method, the comparison between the chemical and electrochemical corrosion mechanisms are pointed out. Further investigations are carried out on the corrosion behavior of Si wafers under anodic voltages as present during the discharge of batteries. The dependency of the discharge characteristics as the discharge voltage, corrosion rates, and mass conversion efficiencies on the KOH concentrations and current densities are analyzed and accordingly, optimum conditions for the battery application are discussed.

Effect of Ag Content and β-PbO2 Plating on the Properties of Al/Pb-Ag Alloy

Due to the excellent electrical conductivity and mechanical properties, Al/Pb-Ag alloy has a great potential to be used as an alternative anode for zinc electrowinning. In this work, the effects of Ag content and surface plating with β-PbO2 on the anodic behavior and reaction kinetics were investigated by cyclic voltammetry (CV), anodic polarization curves, electrochemical impedance spectroscopy (EIS) and corrosion rate test. The phase composition and microscopic morphology of the anode oxide layers after electrolysis were observed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The results indicate that high content of silver and electroplating β-PbO2 layer can increase the oxygen evolution activity, electrocatalytic activity and corrosion resistance of the anodes. Al/Pb-0.75%Ag plating β-PbO2 has the lowest oxygen evolution overpotential followed by Al/Pb-0.3%Ag plating β-PbO2, Al/Pb-0.75%Ag and Al/Pb-0.3%Ag. Besides, high content of silver is more beneficial to improving corrosion resistance compared with electroplating β-PbO2 on anode. In addition, the phase composition of four anodes layer are mainly composed of α-PbO2, β-PbO2, Pb and PbO.

Correlation between electrochemical impedance measurements and corrosion rates of Mg-1Ca alloy in simulated body fluid

The corrosion behaviour of an Mg-1Ca alloy in simulated body fluid (SBF) for 14 days was investigated by electrochemical impedance spectroscopy (EIS), hydrogen evolution measurement, weight loss and observation of the corroded alloy surfaces, with the aim of establishing a clear correlation between the values of the parameter obtained from EIS fitting and corrosion rates. It was found that corrosion proceeds in three stages, characterized by differences in the values of resistances and by the weight of the relative contribution of the inductive behaviour to the overall EIS response. Among all the parameters obtained from EIS fitting, only the charge transfer resistance presented a good correlation with the corrosion rate over the whole duration of the measurement, and an apparent Stearn-Geary coefficient could be calculated. Based on the EIS results, a better understanding of the corrosion behaviour of the Mg-1Ca alloy in SBF solution was attained.

Влияние Co, Ni, Mo и W на коррозионные свойства аморфных электроискровых покрытий

Coatings based on amorphous metals with a different number of elements: nickel, cobalt, molybdenum and tungsten, were obtained by electrospark deposition in a mixture of crystalline granules. The thickness of the deposited coatings was 20 to 33 μm. X-ray diffraction analysis showed a wide halo in the range of angles 2θ ~ 43 °, which indicates the predominance of the amorphous phase in the coating composition. The content of the amorphous phase, depending on the coatings composition, varied from 81 to 99 vol.%. The smallest fraction of the amorphous phase was observed in the coating without molybdenum. According to the EDS analysis, it was shown that the concentration of elements along the cross-section of coatings was constant, which indicates the homogeneity of the composition of the deposited coatings. A study by the SEM showed that the coatings have a homogeneous structure and do not have a precise boundary with the substrate which indicates good adhesion of the coatings to the substrate. Potentiodynamic polarization tests in 3.5% NaCl solution showed that amorphous coatings can improve of the corrosion resistance of the steel 35 surface up to 5 times. Tungsten reduced the rate of electrochemical corrosion of coatings, while cobalt worsen the corrosive properties of FeCrCoNiMoWCB coatings. A high-temperature corrosion test for 100 hours at temperature of 700°C showed that the samples with coatings were oxidized 3.4 to 7.9 times less than steel 1035. Barrier properties, under high-temperature gas corrosion, coatings without tungsten were ~ 2.3 times lower than coatings without cobalt.

Analysis and choice of coatings for increasing the durability of parts of diffusion units of sugar plants

We carried out the study on properties of coatings made of powder materials, which have a high wear and corrosion resistance, to increase durability of parts of diffusion apparatus, which operate in aggressive technological media of sugar beet production. We studied electrochemical properties of the selected coatings and determined the influence of temperature, composition of a technological medium of beet sugar production and electrochemical characteristics of coatings on processes of corrosion and mechanical wear of equipment parts. When the temperature of acidic diffusion juice increases, the electrode potential of friction surfaces moves to the negative side, corrosion currents increase, which indicates an increase in the rate of corrosion. A rate of electrochemical processes on friction surfaces determines the intensity of corrosion and mechanical wear of metals and protective coatings. One of the reasons for slowing down the intensity of wear of materials is the presence of sucrose in the solution. An increase in the concentration of sucrose in diffusion juice leads to the passivation of surfaces of friction of parts, increases the carrying capacity of sliding bearings and reduces the intensity of corrosion and mechanical wear. PN55Т45 coating has the highest corrosion resistance according to the obtained values of electrochemical characteristics and corrosion rates under conditions of corrosion and mechanical wear. We established that the intensity of wear of all coatings reduces with the increase in the load on a friction contact at the selected range, and the intensity of wear of all investigated coatings remains approximately the same at the maximum sliding rate. The highest wear resistance at low loads and sliding rates has PN85U15 covering. We can recommend all investigated protective coatings for the protection of parts in neutral technological media with abrasive wear. In particular, PN55Т45 coating can be used to protect cases and screws, and PN85U15 coating - to strengthen sliding bearings of diffusion apparatus. The study carried out makes possible to substantiate and rationally choose materials for strengthening of surfaces of equipment parts of sugar factories, which operate under conditions of active liquid medium under the action of corrosion and mechanical wear.

An empirical model for the corrosion of stainless steel in BWR primary coolant

ABSTRACTA model to evaluate the electrochemical corrosion potential (ECP) and corrosion rate of stainless steel in neutral water was developed by coupling a static electrochemical analysis and a dynamic oxide layer growth analysis. ECP is much affected not only by water chemistry conditions but also by the oxide layers that develop on the metal surface. As an example application of the model, the effects of oxide layers on ECPs were calculated and a good agreement with the measured results was shown. Major conclusions obtained using the coupled model were as follows:The effects of H2O2 and O2 concentrations on ECP were successfully explained as the effects of oxide layer growth.Decreases in ECP due to neutron exposure were explained well by radiation-induced diffusion in the oxide layers.Hysteresis of ECP was well explained by the coupled model.

Properties of Al/conductive coating/α-PbO2-CeO2-TiO2/β-PbO2-WC-ZrO2 composite anode for zinc electrowinning

The properties of Al/conductive coating/α-PbO2-CeO2-TiO2/β-PbO2-WC-ZrO2 composite anode for zinc electrowinning were investigated. The electrochemical performance was studied by Tafel polarization curves (Tafel), electrochemical impedance spectroscopy (EIS) and corrosion rate obtained in an acidic zinc sulfate electrolyte solution. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDXS) were used to observe the microstructural features of coating. Anodes of Al/conductive coating/α-PbO2-CeO2-TiO2/β-PbO2, Al/conductive coating/α-PbO2-CeO2-TiO2/β-PbO2- WC, Al/conductive coating/α-PbO2-CeO2-TiO2/β-PbO2-ZrO2, and Pb-1%Ag anodes were also researched. The results indicated that the Al/conductive coating/α-PbO2-CeO2-TiO2/β-PbO2-WC-ZrO2 showed the best catalytic activity and corrosion resistant performance; the intensity of diffraction peak exhibited the highest value as well as a new PbWO4 phase; the content of WC and ZrO2 in coating showed the highest value as well as the finest grain size.