Changes In Corrosion Rate Research Articles

Effect of Temperature and Oxygen Concentration on Corrosion of J55 Steel in an O2/CO2 Environment

ABSTRACTThe corrosion product competition and transformation process of J55 under an O2/CO2 environment in the temperature range of 50–350°C and 0–1 MPa oxygen partial pressure range, respectively, were studied using electrochemical and surface analysis techniques as well as thermodynamic calculations to determine its corrosion rate change law and pitting corrosion phenomenon. This study demonstrates that the uniform corrosion rate of J55 with increasing temperature shows a trend of first increasing, then decreasing, and finally increasing. The transformation of its corrosion products, from FeCO3 into Fe3O4, is consistent with the altering corrosion rate law with increasing temperatures. J55 corrodes faster at 350°C as the O2 partial pressure increases. When the O2 partial pressure is low, the predominant kind of corrosion product that is obtained is FeCO3; when the O2 partial pressure exceeds 0.2 MPa, all corrosion products are transformed into iron oxides. As the oxygen partial pressure increases, J55's corrosion product film becomes increasingly less protective of the substrate, making the substance more vulnerable to corrosion reactions.

Effect of 2-amino pyridine inhibitor on the rehabilitation of chloride contaminated reinforced concrete with bidirectional electromigration method

Conventional anti-corrosion techniques provide short-term protection and are only suitable for low contaminate concrete. However, electrochemical techniques benefit highly contaminated concrete, but chlorides may reappear after some time. Developing on these techniques, Bidirectional Electromigration (BIEM) has recently received extensive interest. The present research injected an organic 2- Amino Pyridine Inhibitor into chloride-contaminated concrete under an electric field. The system's effectiveness was tested by measuring the chloride profile, inhibitor profile, change in corrosion rate and steel/concrete potentials. In addition, influence on various parameters such as initial admixed chloride content (1% and 3%), treatment duration (7 and 15 days), applied current density (1 A/m2 and 0.5 A/m2) and inhibitor concentration in the aqueous solution (0.3 M/L and 0.15 M/L) on treatment effectiveness was also investigated. The results indicated that after application of the BIEM, chlorides were extracted and inhibitors were migrated towards the steel bar. Further, chloride extraction and inhibitor migration efficiencies increased by increasing the treatment duration and current density. Additionally, results indicated that BIEM would be more effective for more severely chloride-contaminated structures.

How surface-to-volume ratio affects degradation of magnesium: in vitro and in vivo studies.

Despite the many studies carried out over the past decade to determine the biodegradation performance of magnesium and its alloys, few studies focused on the effect of altered surface area to volume ratio on in vitro and in vivo degradation rate and osteogenesis. Here, high purity magnesium cylindrical rods with gradient of surface area to volume ratio were processed by excavating different numbers of grooves on the side surface. The immersion test in SBF solution and the rat femoral condylar bone defect model were used to evaluate the degradation of magnesium rods in vitro and in vivo, respectively. We demonstrated that, the increased number of grooves on the HP magnesium surface represented a decrease in the percentage of residual volume over time, not necessarily an increase in absolute degradation volume or a regular change in corrosion rate. Furthermore, there were strong linear correlations between the relative degradation volume and the initial surface-to-volume ratio of HP magnesium rods both in vitro and in vivo. The difference in the slope of this relationship in vitro and in vivo might help to determine the possible range of in vivo degradation rates via in vitro data. In addition, the corrosion rate is more suitable for evaluating bone formation surrounding the different HP magnesium rods. Our findings in this work may facilitate adjusting the in vivo degradation and osteogenesis of different kinds of orthopedic implants made of the same magnesium-based material, and thus, accelerate the clinical popularization and application.

Optimizing microstructure for enhanced atmospheric corrosion resistance of a novel Ni–Mo weathering steel: A field exposure study in Thailand's tropical marine environment

This study compares the weathering performance of steel with three microstructures: ferrite, ferrite + bainite, and bainite. The rolling and cooling processes of a novel and cost-effective Ni–Mo weathering steel (WS) were manipulated to achieve these microstructures. Validation of these microstructures was performed through field exposure tests in Trat, Thailand, representing a typical tropical marine atmospheric environment. The bainitic steel exhibited better weathering resistance. After 12-month of exposure, the corrosion rates for ferritic + bainite and bainitic steels were 105.6 % and 97.9 % respectively, compared to ferritic steel. The variation in corrosion rates confirm that modifying the microstructure, with emphases on bainite, improves the WSs' resistance to atmospheric corrosion. Changes in corrosion rate mainly depend on the rust layer's adherence. Interestingly, α-FeOOH predominantly characterizes the rust layer on the skyward side of the samples following 12-month of exposure, while the earthward side is mainly composed of Fe3O4/γ-Fe2O3.

Research on Explosive Hardening of Titanium Grade 2.

In this investigation, three different explosive materials have been used to improve the properties of titanium grade 2: ammonal, emulsion explosives, and plastic-bonded explosives. In order to establish the influence of explosive hardening on the properties of the treated alloys, tests were conducted, including microhardness testing, microstructure analysis, and tensile and corrosion tests. It has been found that it is possible to achieve a 40% increase in tensile strength using a plastic explosive (PBX) as an explosive material. On the other hand, the impact of the shock wave slightly decreased the corrosion resistance of titanium grade 2. The change in corrosion rate is less than 0.1µm/year, which does not significantly affect the overall corrosion resistance of the material. The reduction in corrosion resistance is probably due to the surface geometry changes as a result of explosive treatment.

On the Tribocorrosion Behavior of Fe-Mn-Al-C Alloys in Ringer’s Solution

The long-term performance of steels is affected by the simultaneous actions of wear and corrosion, known as tribocorrosion. The tribocorrosion behavior of fully austenitic steels: Fe-Mn-xAl-C (x = 0, 3.5 and 8.3 wt.%) in Ringer’s solution was investigated by using a pin on disk tribometer adapted with a three-electrode corrosion cell. Open circuit potential and coefficient of friction evolution as well as polarization curves were measured. Corrosion rates were calculated by the Tafel extrapolation method, and wear rates were calculated by using a linear profilometer. Pure and total wear rates were higher for the 3Al alloy due to the greater precipitation and embedded calcium minerals, hydroxides, and oxides on the surface, to the detachment of the deformed layer and its adhesion to the counterbody. Additionally, the 8Al alloy exhibited the lowest tendency to corrosion and corrosion rate and the greatest synergistic effect, indicating that this alloy is more sensitive to this effect than the other alloys. For the three materials, the change in the wear rate due to corrosion had a greater contribution to the synergy than the change in corrosion rate due to wear and the damage in the materials was derived mainly from pure mechanical wear.

Projections of corrosion and deterioration of infrastructure in United States coasts under a changing climate

Climate change can accelerate infrastructure deterioration in coastal areas because increased temperature and humidity can promote steel corrosion. This study (1) projects corrosion rate changes for reinforced concrete and steel structures in 223 coastal counties, (2) assesses the impact of corrosion rate changes on the useful life of structures, and (3) evaluates direct economic losses due to shortened useful life of highway bridges over the period 2000-2100. The results show that the useful life of concrete structures may decrease by 1.7-2.7% under the representative concentration pathway (RCP) 8.5 and decrease by 0.7-1.1% under RCP 4.5 by the end of the 21st century. The useful life of steel structures may decrease by 7.9-15.9% under RCP 8.5 and 3.3-6.7% under RCP 4.5. Concrete bridges may suffer an average loss of $6.5-11.7/m2 under RCP 8.5 and $3.3-16.5/m2 under RCP 4.5 due to shortened useful life. Steel bridges may suffer an average loss of $73.4-111.3/m2 under RCP 8.5 and $46.9-81.2/m2 under RCP 4.5. In both climate scenarios, 10% of counties may have negative losses and 10% of counties may have losses greater than $20 million due to corrosion rate changes for concrete and steel bridges. The results reveal the spatial difference of climate change impacts on infrastructural deterioration and suggest the importance of developing regional specific adaptation strategies.

Effectiveness of a fish scales-derived chitosan coating for corrosion protection of carbon steel

Many naturally-derived organic coating has been proposed for corrosion protection of carbon steel, but its effectiveness is challenged by poor coating adhesion. In this work, chitosan was extracted from Nila tilapia fish scales and coated onto ASTM A36 carbon steel surface by using electrophoretic deposition (EPD) and dip coating (DC) techniques. The work aims at determining the coating technique and process parameters that result in effective corrosion protection of carbon steel in acid solution. The effectiveness of corrosion protection was determined by calculating inhibition efficiency from corrosion parameters obtained by polarization test and electrochemical impedance spectroscopy. Results showed that each coating technique provides different mechanism of corrosion protection. The DC-made coating showed a physisorption mechanism where the steel's corrosion rate increases as the temperature increased. The EPD-coated specimens demonstrated a chemisorption mechanism with its minor change in corrosion rates than those of DC-coated specimens. The DC technique resulted in a higher inhibition (73 %) efficiency and lower corrosion rate than that of EPD (41 %) with some degree of stability over increasing temperature.

Закономерности коррозии стали в нейтральной и щелочной железооксидных пульпах

The study identifies and theoretically substantiates the steel corrosion patterns in aqueous slurry of iron-ore concentrate. The purpose of the study was to examine the effect that the content of dissolved oxygen(PO2), pH, the concentration of chloride ions (CCl-) and the rate of movement of the iron oxide slurry (ω) produce on the corrosion losses of steel 20. Comparative analysis of the corrosion rate values obtained by the gravimetric method and the polarization resistance method showed that the reciprocal of the polarization resistance and the corrosion rate change symbatically with increasing pH, the corrosion rate values are quantitatively well consistent with each other. To identify the corrosion patterns, the method of polarization resistance was used. The dependence of the corrosion rate (ρ) on рН revealed two characteristic areas: in the first one, there is no dependence of the rate on pH (6.5--9.0); in the second one, there is a sharp decrease in corrosion losses when the pH goes from 9.0 to 12.5. For pH = 6.5--9.0, the corrosion rate increases linearly with an increase in the partial pressure of oxygen, and corrosion losses in the slurry are higher than in the background solution. The dependence ρ(√ω) is linear over the entire pH range (6.0--9.0), which indicates the diffusion control of the corrosion process. Findings of research show that in order to protect carbon steel from corrosion in the iron oxide slurry, it is necessary to take into account the pH and О2 concentration. Optimal reduction of corrosion losses can be achieved by alkalizing the slurry and removing dissolved oxygen

Research on the stress corrosion and cathodic protection of API X80 steel under AC stray current interference

Purpose The corrosion of buried steel pipelines is becoming more serious because of stress corrosion, stray current corrosion and other reasons. This paper aims to study the various alternating current (AC) interference densities on the stress corrosion cracking behaviors of X80 steel samples under cathodic protection (CP) in the simulated soil electrolyte environment by using an electrochemical method. Design/methodology/approach The change of corrosion rate and surface morphology of the X80 steel samples at various AC current densities from 0 to 150 A/m2 or CP potential between −750 and −1,200 mV in the soil-simulating environment was revealed by the electrochemical methods and slow strain rate testing methods. Findings The results revealed that with the increase of interference density, the corrosion potential of the X80 steel samples shifted to the negative side, and the corrosion pitting was observed on the surface of the sample, this may cause a danger of energy leak. Moreover, the corrosion rate was found to follow a corresponding change with the stress–strain curve. Besides, with the introduction of the CP system, the corrosion rate of the X80 steel working electrode decreased at a low cathodic potential, while showed an opposite behavior at high cathodic potential. In this study, the correlation between AC stray current, cathodic potential and stress was established, which is beneficial to the protection of oil and gas pipeline. Originality/value Investigation results are of benefit to provide a new CP strategy under the interference of AC stray current corrosion and stress corrosion to reduce the corrosion rate of buried pipelines and improve the safety of pipeline transportation.

FLUID-INDUCED ELECTROCHEMICAL CORROSION OF 13Cr STAINLESS STEEL IN HIGH-SPEED FLOWING LIQUID CONTAINING 1 w/% AND 2 w/% NaCl

In order to study the electrochemical corrosion law for the 13Cr stainless-steel tubing material in a high-speed Cl-containing liquid, a high-speed-flow experiment and a small three-electrode system, embedded in a small pipe, were used. The open circuit potential (OCP), polarization curve (PC) and electrochemical impedance spectroscopy (EIS) of the stainless-steel surface were tested in a medium with a flow velocity ranging from 10 to 22 m/s containing 1 w/% and 2 w/% of NaCl. By comparing it with the changes in the electrochemical-reaction parameters of the material in distilled water, the results of the experiment including the critical flow velocity, the change of corrosion rate and the electrochemical-reaction control steps were obtained. By theoretically solving the frictional force of the liquid against the wall surface and the adsorption capacity of the oxide film, and assuming that the oxide film is a macromolecular combination, the relationship between the adsorption capacity of different surface films and the critical flow velocity in the high-speed pipe flow was established. The results of this experiment and calculation can provide a preliminary prediction of the critical flow velocity corresponding to the inflection point of the wall-surface corrosion rate in an industrial pipe flow, thereby improving the process parameters and reducing the wall damage.

Study of the Effect of Oil Borehole Water-Salt Medium on Pipe Steel X60 Electrochemical Corrosion Resistance

Corrosion-electrochemical processes for pipe steel X60 in model solutions of the Usinsk deposit with different pH values are studied. In an acidic medium with (pH 2.10) the test steel corrosion rate is faster by more than a factor of 2.5 than in a medium with pH of 6.31. In the range of pH values 6.31–4.01 steel X60 corrosion rate changes insignificantly (1.88–1.95 g/(m2 ·h)). With an increase in pH from 2.10 to 6.31 steel X60 free corrosion potential moves into the region of negative values (from –0.307 to –0.416 V /n.h.e/) due to formation of sulfide porous films of complex composition fulfilling the function of cathodes in a corrosion microgalvanic element Fe–FexSy. Corrosion process cathodic and anodic reaction parameters are calculated from polarization curves. In an acid medium (pH < 4) liberation of hydrogen proceeds with a limiting stage, both as a slow discharge, and also as delayed recombination. The anodic process of steel dissolution is accomplished by a Bockris mechanism with formation of a catalytic complex $$ \mathrm{Fe}-{\left(\mathrm{H}-\mathrm{SH}\right)}_{\mathrm{ads}}^{+} $$ or Fe(HS−)ads.

Experimental Apparent Stern–Geary Coefficients for AZ31B Mg Alloy in Physiological Body Fluids for Accurate Corrosion Rate Determination

The corrosion behavior of AZ31B Mg alloy exposed to Ringer’s, phosphate-buffered saline (PBS), Hank’s, and simulated body fluid (SBF) solutions for 4 days was investigated using electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, weight loss, and surface characterization. Changes in corrosion rates with immersion time determined by weight loss measurements were compared with EIS data to determine the possibility of obtaining quantitative electrochemical information. In addition, changes in the protective properties of the corrosion product layer calculated from the EIS parameters were evaluated as a function of their surface chemical composition as determined by X-ray photoelectron spectroscopy (XPS) and visual observations of the corroded specimen’s surface. Apparent Stern–Geary coefficients for the AZ31B Mg alloy in each test solution were calculated using the relationship between icorr from weight loss measurements and the EIS data (both Rp and Rt). This provided experimental reference B′ values that may be used as a useful tool in independent investigations to improve the accuracy of corrosion rates of AZ31B Mg alloy in simulated body solutions.

Pressure-Driven Fiber-Optic Sensor for Online Corrosion Monitoring

For many industrial applications, corrosion is a life-limiting phenomenon and therefore requires careful consideration and rigorous experimental testing before structural materials can be reliably deployed, particularly in harsh chemical environments. The traditional approach to measuring corrosion requires exposing many samples to the intended environment and then extracting them individually at discrete intervals for postexposure characterization. This approach does not provide a high degree of temporal resolution, nor does it provide any real-time information regarding dynamic changes in corrosion rates. Developing an online corrosion monitor capable of surviving harsh chemical environments could provide valuable information regarding the structural health of components and changing process conditions that could accelerate corrosion. To this end, a corrosion sensor was developed based on a pressure-driven Fabry-Pérot cavity (FPC). This sensor uses a pressure control system to internally pressurize the FPC formed between the sensor's housing and a metal-embedded singlemode optical fiber. Simultaneous measurement of the change in FPC length using low-coherence interferometry and the applied pressure enables the calculation of the relative changes in the sensor's diaphragm thickness due to corrosion on its outer surface. Measurements were made in situ while actively corroding the sensor and were validated against surveillance specimens that were corroded simultaneously. The uncertainties in the measured corrosion were analyzed using error propagation of the uncertainties in the measured pressures and displacements and were found to be <; 1% of the initial diaphragm thickness.

Network structure in alteration layer of boroaluminosilicate glass formed by aqueous corrosion

Exogenously-added LiCl has been shown to slightly accelerate the corrosion rate of a boroaluminosilicate glass called International Simple Glass (ISG) in aqueous solutions over forward- and residual-rate regimes, while KCl and CsCl impede. To understand the effect of exogenously added electrolytes on resulting hydrous species and the network structure of alteration layers, infrared spectroscopy was implemented. It was found that the fraction of molecular water relative to the surface-bound hydroxyl species is lower in the KCl and CsCl conditions compared to the LiCl and pure water conditions. An approximation for the spectral features of the thin surface films from an experimentally-obtained specular-reflectance infrared (SR-IR) spectrum was proposed; results indicate no significant difference in the Si-O bonding network of the alteration layers formed in the presence of exogenously added LiCl, KCl and CsCl. The observed change in corrosion rates might be linked to the relative abundance of molecular water species in the porous network, rather than the silicate bonding structure.

The impact of corrosion-stress interactions on the topological features and ultimate strength of large-scale steel structures

Aged marine structural analysis often relies on simplified corrosion modelling. Empirical or statistical methods are used to predict a uniform thickness reduction over time. Although convenient, this approach cannot incorporate the corrosion evolution or the rough surfaces in the damaged area. This is fundamentally due to the lack of representation of the underlying corrosion mechanisms in service environments. To better understand how structural response changes based on corrosion under service loads, this paper presents a series of finite element analyses which consider the coupling relationship between the surface mechanical stresses and the resulting change of corrosion rate. The coupling provide complex corrosion-stress interaction depending on the experimental datasets. The quantification of this interaction is based on in situ experimental measurements of corrosion kinetics at different stress levels. The simulations show the stress effect results in the generation of more realistic corrosion patterns on the structural surface, based on a two-bay/two-span large-scale panel model subject to uniaxial compression. In addition, the incorporation of corrosion experiments allows the modelling of corrosion evolution based on physical observations instead of empirical assumptions. The irregular surface damage leads to a change in structural buckling mode, and up to 8% reduction in ultimate strength compared to models without considering the stress effect.

Allowing for the Stochastic Nature of Corrosion Damage in Marine-Based Objects Including Submerged Radiation-Hazardous Objects

A mathematical model of corrosion damage to the protective barriers of radiation hazardous marine-based objects, taking account of the stochastic nature of this process, is constructed. The rate of pitting corrosion is determined by many mutually independent factors containing random components. This makes it possible to model pitting corrosion as a random walk process in which the corrosion rate changes discreetly and remains constant for one computational time step. The Monte Carlo method is used to calculate the depressurization time of an object with one protective barrier. The obtained estimates agree with expeditionary observations.

Influence of the Conditions for Obtaining Coatings on the Structure and Properties

The paper considers the change in the mechanical and performance properties of galvanic coatings obtained under various electrodeposition and annealing operating conditions. It also shows the influence of the structure on the properties. The graphs of the dependence of the change in corrosion rate on the annealing temperature are given.

Effect of Elevated Temperature on the Corrosion Polarization of NO7718 and NO7208 Nickel Alloys in Hot Acid Chloride Solution

The effects of ambient and elevated temperatures (35 °C, 45 °C, 65 °C, 85 °C and 100 °C) on the corrosion resistances of NO7718 and NO7208 nickel alloys were evaluated in 2 M H2SO4/6% aqueous media using potentiodynamic polarization method and micro-analytical studies. Data obtained showed temperature increase restricted the passive film formation on NO7718. Beyond 45 °C, passivation disappeared leading to significant localized corrosion and comparatively higher corrosion rate values. NO7208 retained its passivation characteristics up to 100 °C with minimal change in corrosion rate. Metastable pitting activity was visible on NO7208 with respect to temperature. Negative entropy values for NO7718 and NO7208 show the activation complex is an association between the alloy cations resulting in slower corrosion from reactants to the activation complex at specific localized corrosion reaction sites. The exothermic nature of the corrosion reactions was shown from the negative enthalpy values. Lower enthalpy of NO7208 compared to NO7718 shows that heat of corrosion reaction is lower due to slower rate of corrosion. The activation energy for NO7208 is lower than the value for NO7718 due to its more resistant passive property. The exothermic nature of the corrosion process is responsible for the positive Gibbs free energy of both steels. Superficial oxide with numerous corrosion pits appeared on the morphology of NO7718 at 35 °C compared to NO7208 morphology of which showed the presence of fewer pits. At 100 °C, NO7718 morphology was severely degraded with respect to its intermetallic phases coupled with visible corrosion pits, and intergranular cracks, while on NO7208, the corrosion pits and intergranular cracks where relatively superficial.

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.