Mathematical models were proposed to clarify the effect of alloying on corrosion of magnesium alloys based on film-free and film-covered status. The models are applicable to explain the “barrier effect” by cathodes ...Mathematical models were proposed to clarify the effect of alloying on corrosion of magnesium alloys based on film-free and film-covered status. The models are applicable to explain the “barrier effect” by cathodes and the “analogous Hall-Petch relationship” between corrosion rates and grain size. The slope of corrosion rates versus alloying content is determined by the dissolution ability of film-free substrate and the hindering effects by corrosion product film. Designing strategy for corrosion-resistant Mg alloys is established.展开更多
Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosi...Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosion treated samples were then subjected to high-temperature experiments at 25,300,600,and 900℃,and triaxial compression experiments were conducted in the laboratory.The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality,wave velocity,porosity and compression failure characteristics of the rock.Based on the Lemaitre strain equivalent hypothesis theory,the damage degree of rock material was described by introducing damage variables,and the spatial mobilized plane(SMP)criterion was adopted.The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process,which verified the rationality and reliability of the model parameters.The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage,which had certain practical significance for rock engineering construction.展开更多
Oxygen reduction reaction(ORR)has been disclosed in recent studies as a significant secondary cathodic process during magnesium corrosion.This work elaborates on the contribution of ORR to the total corrosion process ...Oxygen reduction reaction(ORR)has been disclosed in recent studies as a significant secondary cathodic process during magnesium corrosion.This work elaborates on the contribution of ORR to the total corrosion process of pure Mg at different impurity levels in NaCl electrolyte with the assistance of local techniques.A finite element based numerical model taking into account the contribution of ORR during the corrosion of the Mg test materials has been designed in this study considering the local oxygen concentration.Respective computational simulations were calibrated based on the experimental data and evaluated accordingly.Finally,the simultaneous monitoring of local concentration of H_(2) and O_(2),and the combined modeling study reveal the relation between ORR and hydrogen evolution reaction.展开更多
Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosi...Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.展开更多
In this study, aging and marine corrosion tests of a large number of rubber material and rubber bearings have been carried out. The constitutive Mooney-Rivlin model parameters for a rubber isolated bearing have been d...In this study, aging and marine corrosion tests of a large number of rubber material and rubber bearings have been carried out. The constitutive Mooney-Rivlin model parameters for a rubber isolated bearing have been determined. By applying the least-square method to the experimental data, the relationships between the aging time and the marine corrosion time with the constants in the constitutive model for a rubber beating have been derived. Next, the Mooney-Rivlin model has been modified accordingly. Further, using the modified Mooney-Rivlin model and the Abaqus software, the performance of the rubber isolated bearings has been simulated. The simulation results have been compared to the experimental results so as to verify the accuracy of the modified model. The comparison shows that the maximum errors for the vertical and horizontal stiffnesses are 16.8% and 0.49%, respectively. Since these errors are considered acceptable, the accuracy of the modified constitutive model can be considered verified. The results of this study can provide theoretical support for the performance study on rubber isolated bearings under the complex ocean environment and the life-cycle performance evaluation of bridges and other offshore structures.展开更多
Accelerated corrosion tests of the 7005-T4 aluminum alloy were conducted to determine a suitable service life prediction method by using alternating wet–dry cycles in three kinds of solutions. The morphology and comp...Accelerated corrosion tests of the 7005-T4 aluminum alloy were conducted to determine a suitable service life prediction method by using alternating wet–dry cycles in three kinds of solutions. The morphology and composition analysis of the corrosion product revealed that slight corrosion occurred on the surfaces of the samples immersed in a 0.25 wt% Na_2S_2O_8 solution. However, pitting corrosion occurred on the surfaces of the samples immersed in a 3.5 wt% NaCl solution, whereas exfoliation corrosion occurred on the surfaces of the samples immersed in a mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions. A power exponent relationship was observed between the mass loss and exposure time of the 7005-T4 aluminum alloy immersed in the three kinds of solutions. In the mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions, the mass loss of the aluminum alloy yielded the maximum value. Based on the calculation of the correlation coefficients, the alternating wet–dry procedure in a 3.5 wt% NaCl solution could be used to predict the corrosion behavior of 7005-T4 aluminum alloy exposed in the atmosphere of Qingdao, China. The prediction model is as follows: T = 104.28×t^(0.91), where T is the equivalent time and t is the exposure time.展开更多
Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been ...Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been established, in which r corr is expressed as a function of pH, temperature (T), pressure of CO 2 (P CO 2) and pressure of H 2S (P H 2S). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: (1) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the r corr in CO 2/H 2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2) The linear relationship still exists between ln r corr and ln P CO 2 in CO 2/H 2S corrosion (as same as that in CO 2 corrosion). Therefore, a correction factor as a function of P H 2S has been introduced into the predictive model in CO 2/H 2S corrosion. (3) The model is compatible with the main existing models.展开更多
Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established b...Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established by spectral tools and their purities were verified using thin-layer chromatography(TLC), displaying single-spot. The performance of corrosion protection of the prepared imidazole derivatives was examined theoretically and practically for acid steel corrosion. The experimental study was conducted by electrochemical(electrochemical impedance spectroscopy(EIS) and Tafel polarization(PPS)) tools.The findings from the used approaches concluded that the synthesized compounds were wellorganized inhibitors with an efficiency of 90.7%-98.5% at 50℃ and 0.7 mmol·L^(-1). The Tafel polarization results indicate the protective action of the additives was under mixed-monitoring. The additive adsorption on the electrode interface performed as a distinguished aspect for protection. The surface exploration on the blank and protected metal was completed by field emission scanning electron microscopy(FESEM). Computational studies by Monte Carlo(MC) simulation and quantum chemical calculation(DFT)were related to practical findings. The corrosion protection adsorption mechanism was reinforced by the preferable fitted Langmuir isotherm model. All findings from the applied-inspected approaches alternately confirm each other.展开更多
A nonlinear finite element model （FEM） of the corrosion of steel reinforcement in concrete has been successfully developed on the basis of mathematical analysis of the electrochemical process of steel corrosion in c...A nonlinear finite element model （FEM） of the corrosion of steel reinforcement in concrete has been successfully developed on the basis of mathematical analysis of the electrochemical process of steel corrosion in concrete. The influences of the area ratio and the Tafel constants of the anode and cathode on the potential and corrosion current density have been examined with the model. It has been found that the finite element calculation is more suitable for assessing the corrosion condition of steel reinforcement than ordinary electrochemical techniques due to the fact that FEM can obtain the distributions of potential and corrosion current density on the steel surface. In addition, the local corrosion of steel reinforcement in concrete is strengthened with the decrease of both the area ratio and the Tafel constants. These results provide valuable information to the researchers who investigate steel corrosion.展开更多
Iron corrosion in acidic media is a natural phenomenon that converts elemental iron to a more chemically-stable form,i.e.its oxide and hydroxide.In this study,the iron corrosion process is modeled as a completely impl...Iron corrosion in acidic media is a natural phenomenon that converts elemental iron to a more chemically-stable form,i.e.its oxide and hydroxide.In this study,the iron corrosion process is modeled as a completely implicit problem,solved by a novel finite difference model to provide insight into the ionic aspects of corrosion behavior.This new mathematical model eliminates the chemical potential parameters from the corrosion process equations,thereby reducing the need for experimental determination of chemical potentials.The eliminatedchemical-potential-parameters model predicts and quantifies key parameters(concentrations of conjugate base ion,iron(Ⅱ)ion,hydrogen ion,anodic and cathodic potentials,and the electrical current density)associated with the iron corrosion process in acidic solutions.The rigorous derivation and novel application of the eliminated-chemical-potential-parameters model and its results provide new insights into the iron corrosion process.The present model is also applicable in any industrial process which is associated with metal corrosion.The model helps to guide the design of future corrosion resistant systems,and various experimental studies pertaining to corrosion inhibition techniques.展开更多
A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethano...A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethanolamine(DEA)aqueous solutions.The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature,activator concentration,CO2 loading and pH.The study consists of two major models:Vapor–liquid Equilibrium(VLE)model and electrochemical corrosion model.The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution.The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal.An increase in concentration of activator,increases the rate of corrosion of carbon steel in mixtures of activated DEA.展开更多
A 3-dimensional finite element model was built to determine the effect of inclination angle of a corro sion defect on local mechano-electrochemical(M-E)effect in a simulated soil solution.Because of the high effect of...A 3-dimensional finite element model was built to determine the effect of inclination angle of a corro sion defect on local mechano-electrochemical(M-E)effect in a simulated soil solution.Because of the high effect of the defect inclination angle on the M-E effect,when the inclination angle is 0°(i.e.,the primary axis of the defect parallel to the longitudinal direction of the pipe),the greate st stress concentration level at the defect can be observed,which is associated with the lowest corrosion potential,the greatest anodic current density and the most serious accelerated localized corrosion.When the inclination angle is 90°,the stress concentration level reduces and the corrosion potential becomes less negative,accompanying with the decreased anodic/cathodic current densities.Besides,when the ratio(r_(ca))of the primary axial length of the defect to its secondary axial length is 1,the defect inclination does not affect the stress and the electrochemical corrosion rate at the defect.With the increase of r_(ca),the effect of the defect inclination angle is more apparent.展开更多
A model was developed to generate charts that fit the conditions as diverse temperatures and ionic strengths, and that estimate the diversified state of water. The chart can be used as a tool for controlling corrosive...A model was developed to generate charts that fit the conditions as diverse temperatures and ionic strengths, and that estimate the diversified state of water. The chart can be used as a tool for controlling corrosive waters resulted in internal corrosion and the model producing charts composed of a number of sub modules, and each module incorporated parameters including acidity, alkalinity, pH, and calcium ion. Utilizing the chart water quality of the raw water in G water purification works was estimated to be unsaturated and Langelier index becomes -1.4 which means that the water is highly corrosive and calcium carbonate would not be precipitated. Thus, the water requires treatment as the injection of water stabilizing chemicals to promote an oversaturated (protective) condition. As a result of adding 5 mg/L of lime, it is possible to be precipitated with 5 mg/L, and the water becomes noncorrosive. In addition, when 5 mg/L of caustic soda is added as a conditioning chemical, it signifies to be precipitated with 9 mg/L, and the water also turns out to be largely noncorrosive. Both chemicals are possible to use for the water to be favorable for the formation of a protective film. Optimum injection rate for controlling corrosion can be found by repeating the procedures until the well-conditioned water criteria are satisfied.展开更多
In the case of three-layered(air-seawater-seabed)model,the analytical expressions of the static electric and static magnetic field produced by the static electric dipole located in seawater were derived by using the m...In the case of three-layered(air-seawater-seabed)model,the analytical expressions of the static electric and static magnetic field produced by the static electric dipole located in seawater were derived by using the mirror image theory.Combined with the distribution of the underwater electric potential measured in laboratory,an electric dipole model for physical scale of ship was established and the distribution characteristics of an actual ship' s corrosion related magnetic field were obtained.Based on established models,theoretical analysis and calculation were made to catch out the distribution characteristics of static magnetic field related with corrosion and anticorrosion,which can not be measured directly in seawater.The results show that the static magnetic field related with corrosion and anticorrosion is a kind of noteworthy obstacle signal for degaussed ships.展开更多
An attempt has been made at unifying the resulting quadratic models from the study of the correlation behavior of the inhibition characteristics of acidified ocimum basilicum on conventional mild steel. Weight-loss co...An attempt has been made at unifying the resulting quadratic models from the study of the correlation behavior of the inhibition characteristics of acidified ocimum basilicum on conventional mild steel. Weight-loss corrosion technique was employed in obtaining the corrosion penetration rate using the equation: cpr = . Subsequently, the quadratic models were developed by using a computer-aided statistical modeling technique (International Business Machine (IBM)’s SPSS version 17.0). The results obtained showed a nearly perfect positive correlation with a correlation coefficient in the range of 0.986 ≤ R ≤ 0.996 which depicts that R ≥ 1. Also, the coefficient of determination fell within the range of 0.972 ≤ R2 ≤ 0.992 showing that approximately 97% to 99% of the total variation in passivation rate was accounted for by corresponding variation in exposure time, leaving out only between 3% and 1% to extraneous factors that are not incorporated into the model equations. The equations were further unified into a generalized form using MathCAD 7.0 and the resulting equation was y = 1.032 - 0.002t + 1.899?× 10-6t2 with a R2 value of 0.935 indicating a well-correlated relationship. With this, a new frontier on corrosion studies has emerged typifying a classical departure from previously long-held assumption that corrosion behaviours at room temperature were only logarithmic.展开更多
This paper presents a corrosion assessment of copper spent nuclear fuel disposal canisters in crystalline rock,using hydrogeological modeling.A simplified approach is considered,to avoid complex and time-consuming com...This paper presents a corrosion assessment of copper spent nuclear fuel disposal canisters in crystalline rock,using hydrogeological modeling.A simplified approach is considered,to avoid complex and time-consuming computer simulations.This simplified case is presented as a base case,with changes in the hydrogeological parameters presented as variant cases.The results show that in Taiwan’s base case,decreasing the hydraulic conductivity of the rock or decreasing the hydraulic conductivity of dikes results in a shorter transport path for sulfide and an increase in corrosion depth.However,the estimated canister failure time is still over one million years in the variant cases.展开更多
The purpose of this study was to develop an analytical model to predict the time required for cracking of concrete due to corrosion of the iron reinforcement. The concrete and cement specimens used for this study were...The purpose of this study was to develop an analytical model to predict the time required for cracking of concrete due to corrosion of the iron reinforcement. The concrete and cement specimens used for this study were batched with cover material ranging from 0.75 to 1.3 in (1.91 to 3.30 cm). The extent of cover material was not formulated into the model under the assumption that crack initiation would tend to produce visible cracking within a relatively short time period. The model was derived using both Hooke’s Law and the volume expansion induced by the corrosion oxides. Correlation achieved with specimen cracking data from the literature was relatively good with a 95% level of confidence. This model presents a key benefit to facility and infrastructure managers by enabling them to plan the time when corrosion mitigating actions are required. It also provides a significant convenience as the condition of the concrete structure or its environment changes over time. The only parameter that needs to be updated over time is the corrosion rate measurement. This single parameter captures the most influential impact that stems from several other parameters which tend to be required in models that are more mechanistically definitive.展开更多
This paper focuses on methodological issues relevant to corrosion risk prediction models.A model was developed for the prediction of corrosion rates associated with hot-dip galvanised reinforcement bar material in con...This paper focuses on methodological issues relevant to corrosion risk prediction models.A model was developed for the prediction of corrosion rates associated with hot-dip galvanised reinforcement bar material in concrete exposed to carbonation and chlorides in outdoor environment.One-year follow-up experiments,over five years,were conducted at various carbonation depths and chloride contents.The observed dependence of corrosion rate on the depth of carbonation and chloride content is complex indicating that the interaction between the carbonation and chloride influencing the corrosion.A non-linear corrosion model was proposed with statistical analysis to model the relationship between the corrosion rate and the test parameters.The main methodological contributions are(i)the proposed modeling approach able to take into account the uncertain measurement errors including unobserved systematic and random heterogeneity over different measured specimens and correlation for the same specimen across different measuring times,which best suits the measurement data;(ii)the developed model in which an interaction parameter is introduced especially to account for the contribution and the degree of the unobserved carbonation-chloride interaction.The proposed model offers greater flexibility for the modelling of measurement data than traditional models.展开更多
Fuel rod cladding waterside corrosion is one of the phenomena that limit the life time of nuclear fuel. Corrosion performance depends on the cladding material properties as well as operating conditions during the irra...Fuel rod cladding waterside corrosion is one of the phenomena that limit the life time of nuclear fuel. Corrosion performance depends on the cladding material properties as well as operating conditions during the irradiation of the fuel. As a function of temperature, power history, water chemistry, time, etc., waterside corrosion is of great concern in fuel performance evaluation, especially for high burnup fuels. This paper is dedicated to the study of the waterside corrosion phenomenon using the IFPE database by COPERNIC, which is developed for the analysis of fuel rod behaviors in normal operation and transient conditions. Different models, MATPRO, FRAMATOME and EPRI models, for example, are adopted in the simulations. The results derived from the models are compared and the unconformities are analyzed. Based on the comparative analysis, reasonable models are chosen to simulate certain irradiated fuel rods. Our analyses indicate that potential affecting factors which are not considered in COPERNIC code, such as water chemistry and alloy composition, should be responsible for discrepancies of certain rod predictions.展开更多
Mo has been widely reported as a conducive element for the corrosion resistance of massive alloy sys-tems.However,the mechanism of Mo optimizing the corrosion resistance is complicated,and in-depth studies are still r...Mo has been widely reported as a conducive element for the corrosion resistance of massive alloy sys-tems.However,the mechanism of Mo optimizing the corrosion resistance is complicated,and in-depth studies are still required.The present work comprehensively and quantitatively studied the critical influ-ences of Mo on the passivation and repassivation behavior of CoCrFeNi HEA based on the dissolution-diffusion-deposition model proposed in our previous work.The experimental results indicated that Mo remarkably eliminated the metastable pitting corrosion,significantly improved the breakdown potential and perfectly protected the CoCrFeNiMo_(0.2)HEA from pitting corrosion.The modelling and X-ray photo-electron spectroscopy(XPS)results both show that in the passivation process,MoO_(2)was the last product to deposit,thereby existing in the outer layer of the passive film.Mo addition increased the Cr content by weakening the deposition of Fe_(2)O_(3)and Fe_(3)O_(4)and also improved the Cr_(2)O_(3)/Cr(OH)3 ratio by promot-ing deprotonation of Cr(OH)_(3),thus enhancing the quality of passive film.Besides,when pitting corrosion occurred,MoO_(2),MoO_(3),and FeMoO_(4)were the first products to deposit and accelerated the repassivation process of HEA by timely covering the matrix in the pit cavity,thereby preventing further corrosion of the matrix.展开更多
基金supported by Shanghai Science and Technology Committee (No.18511109300)Science and Technology Commission of the CMC (2019JCJQZD27300)+1 种基金Foundation from Shanghai Jiao Tong University (AF0500132,AF0500149)Funding from Center of Hydrogen Science of Shanghai Jiao Tong University。
文摘Mathematical models were proposed to clarify the effect of alloying on corrosion of magnesium alloys based on film-free and film-covered status. The models are applicable to explain the “barrier effect” by cathodes and the “analogous Hall-Petch relationship” between corrosion rates and grain size. The slope of corrosion rates versus alloying content is determined by the dissolution ability of film-free substrate and the hindering effects by corrosion product film. Designing strategy for corrosion-resistant Mg alloys is established.
文摘Aiming at the problem of temperature-mechanics-chemical(T-M-C)action encountered by rocks in underground engineering,sandstone was selected as the sample for acid corrosion treatment at pH 1,3,5 and 7,the acid corrosion treated samples were then subjected to high-temperature experiments at 25,300,600,and 900℃,and triaxial compression experiments were conducted in the laboratory.The experimental results show that the superposition of chemical damage and thermal damage has a significant impact on the quality,wave velocity,porosity and compression failure characteristics of the rock.Based on the Lemaitre strain equivalent hypothesis theory,the damage degree of rock material was described by introducing damage variables,and the spatial mobilized plane(SMP)criterion was adopted.The damage constitutive model can well reflect the stress-strain characteristics of the rock triaxial compression process,which verified the rationality and reliability of the model parameters.The experiment and constitutive model analyzed the change law of mechanical properties of rock after chemical corrosion and high temperature thermal damage,which had certain practical significance for rock engineering construction.
基金the China Scholarship Council for the award of fellowship and funding(No.201806310128,201908510177)。
文摘Oxygen reduction reaction(ORR)has been disclosed in recent studies as a significant secondary cathodic process during magnesium corrosion.This work elaborates on the contribution of ORR to the total corrosion process of pure Mg at different impurity levels in NaCl electrolyte with the assistance of local techniques.A finite element based numerical model taking into account the contribution of ORR during the corrosion of the Mg test materials has been designed in this study considering the local oxygen concentration.Respective computational simulations were calibrated based on the experimental data and evaluated accordingly.Finally,the simultaneous monitoring of local concentration of H_(2) and O_(2),and the combined modeling study reveal the relation between ORR and hydrogen evolution reaction.
文摘Heat exchanger is an important equipment used in process industries for cooling and heating purposes. Its design configuration which involves the flow of cold and hot fluids within the exchanger subjects it to corrosion attack. The article utilized the principle of mass and energy conservation in the development of weight and temperature models to study the effect of corrosion on mild steel coupon inside the exchanger containing water and Mono ethanol amine (MEA). The models developed were resolved analytically using Laplace Transform and simulated using Excel as simulation tool and data obtained from experiment in the laboratory to obtain profiles of weight loss and temperature as a function of time. The weight loss and performance of mild steel under various corrosive conditions were examined which indicates the effect of corrosion on the mild steel heat exchanger in water and MEA media. The result shows that water is more corrosive than MEA at higher temperatures and at lower temperatures of 35°C and 1 atm, MEA has inhibitive properties than water as indicated by the weight loss result with time. The comparative analysis between the results obtained from the model simulation and experimental results shows that the result obtained from the model is more reliable and demonstrated better performance characteristics as it clearly shows mild steel heat exchanger experiences more corrosive effect in water medium than MEA at higher temperatures. And at lower temperatures, MEA becomes more inhibitive and less corrosive than water. The model simulation results correlate with various literatures and hence, it is valid for future referencing.
基金National Natural Science Foundation of China under Grant Nos.51578170 and 51678173National Basic Research Program of China(973 Program)under Grant No.2011CB013606+2 种基金Program for Changjiang Scholars and Innovative Research Team in University(IRT13057)Natural Science Foundation of Guangdong Province,China(2017A030313298)Science and Technology Program of Guangzhou,China(1201421152 and 201707010295)
文摘In this study, aging and marine corrosion tests of a large number of rubber material and rubber bearings have been carried out. The constitutive Mooney-Rivlin model parameters for a rubber isolated bearing have been determined. By applying the least-square method to the experimental data, the relationships between the aging time and the marine corrosion time with the constants in the constitutive model for a rubber beating have been derived. Next, the Mooney-Rivlin model has been modified accordingly. Further, using the modified Mooney-Rivlin model and the Abaqus software, the performance of the rubber isolated bearings has been simulated. The simulation results have been compared to the experimental results so as to verify the accuracy of the modified model. The comparison shows that the maximum errors for the vertical and horizontal stiffnesses are 16.8% and 0.49%, respectively. Since these errors are considered acceptable, the accuracy of the modified constitutive model can be considered verified. The results of this study can provide theoretical support for the performance study on rubber isolated bearings under the complex ocean environment and the life-cycle performance evaluation of bridges and other offshore structures.
基金supported by the National Key Research and Development Program of China (No. 2017YFB0702300)the National Natural Science Foundation of China (No. 51222106)+1 种基金the Fundamental Research Funds for the Central Universities of China (No. FRF-TP-14-011C1)the National Basic Research Program of China (973 Program, No. 2014CB643300)
文摘Accelerated corrosion tests of the 7005-T4 aluminum alloy were conducted to determine a suitable service life prediction method by using alternating wet–dry cycles in three kinds of solutions. The morphology and composition analysis of the corrosion product revealed that slight corrosion occurred on the surfaces of the samples immersed in a 0.25 wt% Na_2S_2O_8 solution. However, pitting corrosion occurred on the surfaces of the samples immersed in a 3.5 wt% NaCl solution, whereas exfoliation corrosion occurred on the surfaces of the samples immersed in a mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions. A power exponent relationship was observed between the mass loss and exposure time of the 7005-T4 aluminum alloy immersed in the three kinds of solutions. In the mixture of 0.25 wt% Na_2S_2O_8 and 3.5 wt% NaCl solutions, the mass loss of the aluminum alloy yielded the maximum value. Based on the calculation of the correlation coefficients, the alternating wet–dry procedure in a 3.5 wt% NaCl solution could be used to predict the corrosion behavior of 7005-T4 aluminum alloy exposed in the atmosphere of Qingdao, China. The prediction model is as follows: T = 104.28×t^(0.91), where T is the equivalent time and t is the exposure time.
基金TheResearchProjectofTubularGoodsRe searchCenterofChinaNationalPetroleumCorporation (No .2 3 5 2 4)andtheResearchProjectofHenanUniversityofScienceandTechnology (No .2 0 0 10 1)
文摘Based on an analysis of the existing models of CO 2 corrosion in literatures and the autoclave simulative experiments, a predictive model of corrosion rate (r corr) in CO 2/H 2S corrosion for oil tubes has been established, in which r corr is expressed as a function of pH, temperature (T), pressure of CO 2 (P CO 2) and pressure of H 2S (P H 2S). The model has been verified by experimental data obtained on N80 steel. The improved features of the predictive model include the following aspects: (1) The influence of temperature on the protectiveness of corrosion film is taken into consideration for establishment of predictive model of the r corr in CO 2/H 2S corrosion. The Equations of scale temperature and scale factor are put forward, and they fit the experimental result very well. (2) The linear relationship still exists between ln r corr and ln P CO 2 in CO 2/H 2S corrosion (as same as that in CO 2 corrosion). Therefore, a correction factor as a function of P H 2S has been introduced into the predictive model in CO 2/H 2S corrosion. (3) The model is compatible with the main existing models.
基金supported through the Annual Funding track by the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, Saudi Arabia [GRANT-415]。
文摘Five new tetrasubstituted imidazoles were designed with outstanding yields(83%-92%) in the occurrence of ionic liquid-based-pyridinium as a catalyst. The constructions of all synthesized derivatives were established by spectral tools and their purities were verified using thin-layer chromatography(TLC), displaying single-spot. The performance of corrosion protection of the prepared imidazole derivatives was examined theoretically and practically for acid steel corrosion. The experimental study was conducted by electrochemical(electrochemical impedance spectroscopy(EIS) and Tafel polarization(PPS)) tools.The findings from the used approaches concluded that the synthesized compounds were wellorganized inhibitors with an efficiency of 90.7%-98.5% at 50℃ and 0.7 mmol·L^(-1). The Tafel polarization results indicate the protective action of the additives was under mixed-monitoring. The additive adsorption on the electrode interface performed as a distinguished aspect for protection. The surface exploration on the blank and protected metal was completed by field emission scanning electron microscopy(FESEM). Computational studies by Monte Carlo(MC) simulation and quantum chemical calculation(DFT)were related to practical findings. The corrosion protection adsorption mechanism was reinforced by the preferable fitted Langmuir isotherm model. All findings from the applied-inspected approaches alternately confirm each other.
基金supported by the Opening Project of Key Laboratory of Coastal Disaster and Defence of Ministry of Education, Hohai Universitythe Natural Science Fund of Hohai University (No. 2008432111).
文摘A nonlinear finite element model （FEM） of the corrosion of steel reinforcement in concrete has been successfully developed on the basis of mathematical analysis of the electrochemical process of steel corrosion in concrete. The influences of the area ratio and the Tafel constants of the anode and cathode on the potential and corrosion current density have been examined with the model. It has been found that the finite element calculation is more suitable for assessing the corrosion condition of steel reinforcement than ordinary electrochemical techniques due to the fact that FEM can obtain the distributions of potential and corrosion current density on the steel surface. In addition, the local corrosion of steel reinforcement in concrete is strengthened with the decrease of both the area ratio and the Tafel constants. These results provide valuable information to the researchers who investigate steel corrosion.
文摘Iron corrosion in acidic media is a natural phenomenon that converts elemental iron to a more chemically-stable form,i.e.its oxide and hydroxide.In this study,the iron corrosion process is modeled as a completely implicit problem,solved by a novel finite difference model to provide insight into the ionic aspects of corrosion behavior.This new mathematical model eliminates the chemical potential parameters from the corrosion process equations,thereby reducing the need for experimental determination of chemical potentials.The eliminatedchemical-potential-parameters model predicts and quantifies key parameters(concentrations of conjugate base ion,iron(Ⅱ)ion,hydrogen ion,anodic and cathodic potentials,and the electrical current density)associated with the iron corrosion process in acidic solutions.The rigorous derivation and novel application of the eliminated-chemical-potential-parameters model and its results provide new insights into the iron corrosion process.The present model is also applicable in any industrial process which is associated with metal corrosion.The model helps to guide the design of future corrosion resistant systems,and various experimental studies pertaining to corrosion inhibition techniques.
基金the financial support provided by the Ministry of Higher Education&Scientific Research of Iraq。
文摘A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO2).Piperazine(PZ)is used as the activator in diethanolamine(DEA)aqueous solutions.The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature,activator concentration,CO2 loading and pH.The study consists of two major models:Vapor–liquid Equilibrium(VLE)model and electrochemical corrosion model.The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution.The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal.An increase in concentration of activator,increases the rate of corrosion of carbon steel in mixtures of activated DEA.
基金supported by the National Natural Science Foundation of China(No.51705077)Natural Science Foundation of Fujian Province(No.2018J01768)the University of Calgary。
文摘A 3-dimensional finite element model was built to determine the effect of inclination angle of a corro sion defect on local mechano-electrochemical(M-E)effect in a simulated soil solution.Because of the high effect of the defect inclination angle on the M-E effect,when the inclination angle is 0°(i.e.,the primary axis of the defect parallel to the longitudinal direction of the pipe),the greate st stress concentration level at the defect can be observed,which is associated with the lowest corrosion potential,the greatest anodic current density and the most serious accelerated localized corrosion.When the inclination angle is 90°,the stress concentration level reduces and the corrosion potential becomes less negative,accompanying with the decreased anodic/cathodic current densities.Besides,when the ratio(r_(ca))of the primary axial length of the defect to its secondary axial length is 1,the defect inclination does not affect the stress and the electrochemical corrosion rate at the defect.With the increase of r_(ca),the effect of the defect inclination angle is more apparent.
文摘A model was developed to generate charts that fit the conditions as diverse temperatures and ionic strengths, and that estimate the diversified state of water. The chart can be used as a tool for controlling corrosive waters resulted in internal corrosion and the model producing charts composed of a number of sub modules, and each module incorporated parameters including acidity, alkalinity, pH, and calcium ion. Utilizing the chart water quality of the raw water in G water purification works was estimated to be unsaturated and Langelier index becomes -1.4 which means that the water is highly corrosive and calcium carbonate would not be precipitated. Thus, the water requires treatment as the injection of water stabilizing chemicals to promote an oversaturated (protective) condition. As a result of adding 5 mg/L of lime, it is possible to be precipitated with 5 mg/L, and the water becomes noncorrosive. In addition, when 5 mg/L of caustic soda is added as a conditioning chemical, it signifies to be precipitated with 9 mg/L, and the water also turns out to be largely noncorrosive. Both chemicals are possible to use for the water to be favorable for the formation of a protective film. Optimum injection rate for controlling corrosion can be found by repeating the procedures until the well-conditioned water criteria are satisfied.
基金Sponsored by National Defense Pre-research Foundation(51444070105JB11)
文摘In the case of three-layered(air-seawater-seabed)model,the analytical expressions of the static electric and static magnetic field produced by the static electric dipole located in seawater were derived by using the mirror image theory.Combined with the distribution of the underwater electric potential measured in laboratory,an electric dipole model for physical scale of ship was established and the distribution characteristics of an actual ship' s corrosion related magnetic field were obtained.Based on established models,theoretical analysis and calculation were made to catch out the distribution characteristics of static magnetic field related with corrosion and anticorrosion,which can not be measured directly in seawater.The results show that the static magnetic field related with corrosion and anticorrosion is a kind of noteworthy obstacle signal for degaussed ships.
文摘An attempt has been made at unifying the resulting quadratic models from the study of the correlation behavior of the inhibition characteristics of acidified ocimum basilicum on conventional mild steel. Weight-loss corrosion technique was employed in obtaining the corrosion penetration rate using the equation: cpr = . Subsequently, the quadratic models were developed by using a computer-aided statistical modeling technique (International Business Machine (IBM)’s SPSS version 17.0). The results obtained showed a nearly perfect positive correlation with a correlation coefficient in the range of 0.986 ≤ R ≤ 0.996 which depicts that R ≥ 1. Also, the coefficient of determination fell within the range of 0.972 ≤ R2 ≤ 0.992 showing that approximately 97% to 99% of the total variation in passivation rate was accounted for by corresponding variation in exposure time, leaving out only between 3% and 1% to extraneous factors that are not incorporated into the model equations. The equations were further unified into a generalized form using MathCAD 7.0 and the resulting equation was y = 1.032 - 0.002t + 1.899?× 10-6t2 with a R2 value of 0.935 indicating a well-correlated relationship. With this, a new frontier on corrosion studies has emerged typifying a classical departure from previously long-held assumption that corrosion behaviours at room temperature were only logarithmic.
文摘This paper presents a corrosion assessment of copper spent nuclear fuel disposal canisters in crystalline rock,using hydrogeological modeling.A simplified approach is considered,to avoid complex and time-consuming computer simulations.This simplified case is presented as a base case,with changes in the hydrogeological parameters presented as variant cases.The results show that in Taiwan’s base case,decreasing the hydraulic conductivity of the rock or decreasing the hydraulic conductivity of dikes results in a shorter transport path for sulfide and an increase in corrosion depth.However,the estimated canister failure time is still over one million years in the variant cases.
文摘The purpose of this study was to develop an analytical model to predict the time required for cracking of concrete due to corrosion of the iron reinforcement. The concrete and cement specimens used for this study were batched with cover material ranging from 0.75 to 1.3 in (1.91 to 3.30 cm). The extent of cover material was not formulated into the model under the assumption that crack initiation would tend to produce visible cracking within a relatively short time period. The model was derived using both Hooke’s Law and the volume expansion induced by the corrosion oxides. Correlation achieved with specimen cracking data from the literature was relatively good with a 95% level of confidence. This model presents a key benefit to facility and infrastructure managers by enabling them to plan the time when corrosion mitigating actions are required. It also provides a significant convenience as the condition of the concrete structure or its environment changes over time. The only parameter that needs to be updated over time is the corrosion rate measurement. This single parameter captures the most influential impact that stems from several other parameters which tend to be required in models that are more mechanistically definitive.
基金study is financed by the Academy of Finland(Grant number 324023)Dr.Esko Sistonen provided the experimental data.
文摘This paper focuses on methodological issues relevant to corrosion risk prediction models.A model was developed for the prediction of corrosion rates associated with hot-dip galvanised reinforcement bar material in concrete exposed to carbonation and chlorides in outdoor environment.One-year follow-up experiments,over five years,were conducted at various carbonation depths and chloride contents.The observed dependence of corrosion rate on the depth of carbonation and chloride content is complex indicating that the interaction between the carbonation and chloride influencing the corrosion.A non-linear corrosion model was proposed with statistical analysis to model the relationship between the corrosion rate and the test parameters.The main methodological contributions are(i)the proposed modeling approach able to take into account the uncertain measurement errors including unobserved systematic and random heterogeneity over different measured specimens and correlation for the same specimen across different measuring times,which best suits the measurement data;(ii)the developed model in which an interaction parameter is introduced especially to account for the contribution and the degree of the unobserved carbonation-chloride interaction.The proposed model offers greater flexibility for the modelling of measurement data than traditional models.
文摘Fuel rod cladding waterside corrosion is one of the phenomena that limit the life time of nuclear fuel. Corrosion performance depends on the cladding material properties as well as operating conditions during the irradiation of the fuel. As a function of temperature, power history, water chemistry, time, etc., waterside corrosion is of great concern in fuel performance evaluation, especially for high burnup fuels. This paper is dedicated to the study of the waterside corrosion phenomenon using the IFPE database by COPERNIC, which is developed for the analysis of fuel rod behaviors in normal operation and transient conditions. Different models, MATPRO, FRAMATOME and EPRI models, for example, are adopted in the simulations. The results derived from the models are compared and the unconformities are analyzed. Based on the comparative analysis, reasonable models are chosen to simulate certain irradiated fuel rods. Our analyses indicate that potential affecting factors which are not considered in COPERNIC code, such as water chemistry and alloy composition, should be responsible for discrepancies of certain rod predictions.
基金funded by the National Natural Science Foun-dation of China(Grant Nos.U1960203,52004060,52325406,and 52174308)Science Fund for Distinguished Young Scholars of Liaon-ing Province(Grant No.2023JH6/100500008)Fundamental Re-search Funds for the Central Universities(Grant Nos.N2125017 and N2225031).Special thanks are due to the instrumental analysis from the Analytical and Testing Centre,Northeastern University.
文摘Mo has been widely reported as a conducive element for the corrosion resistance of massive alloy sys-tems.However,the mechanism of Mo optimizing the corrosion resistance is complicated,and in-depth studies are still required.The present work comprehensively and quantitatively studied the critical influ-ences of Mo on the passivation and repassivation behavior of CoCrFeNi HEA based on the dissolution-diffusion-deposition model proposed in our previous work.The experimental results indicated that Mo remarkably eliminated the metastable pitting corrosion,significantly improved the breakdown potential and perfectly protected the CoCrFeNiMo_(0.2)HEA from pitting corrosion.The modelling and X-ray photo-electron spectroscopy(XPS)results both show that in the passivation process,MoO_(2)was the last product to deposit,thereby existing in the outer layer of the passive film.Mo addition increased the Cr content by weakening the deposition of Fe_(2)O_(3)and Fe_(3)O_(4)and also improved the Cr_(2)O_(3)/Cr(OH)3 ratio by promot-ing deprotonation of Cr(OH)_(3),thus enhancing the quality of passive film.Besides,when pitting corrosion occurred,MoO_(2),MoO_(3),and FeMoO_(4)were the first products to deposit and accelerated the repassivation process of HEA by timely covering the matrix in the pit cavity,thereby preventing further corrosion of the matrix.
