Magnesium(Mg)alloys,the lightest metal construction material used in industry,play a vital role in future development.However,the poor corrosion resistance of Mg alloys in corrosion environments largely limits their p...Magnesium(Mg)alloys,the lightest metal construction material used in industry,play a vital role in future development.However,the poor corrosion resistance of Mg alloys in corrosion environments largely limits their potential wide applications.Therefore,a micro-arc oxidation/graphene oxide/stearic acid(MAO/GO/SA)superhydrophobic composite coating with superior corrosion resistance was fabricated on a Mg alloy AZ91D through micro-arc oxidation(MAO)technology,electrodeposition technique,and self-assembly technology.The composition and microstructure of the coating were characterized by scanning electron microscopy,X-ray diffraction,energy dispersive spectroscopy,and Raman spectroscopy.The effective protection of the MAO/GO/SA composite coating applied to a substrate was evaluated using potentiodynamic polarization,electrochemical impedance spectroscopy tests,and salt spray tests.The results showed that the MAO/GO/SA composite coating with a petal spherical structure had the best superhydrophobicity,and it attained a contact angle of 159.53°±2°.The MAO/GO/SA composite coating exhibited high resistance to corrosion,according to electrochemical and salt spray tests.展开更多
Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crossl...Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite (HEP-APU) coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.展开更多
With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary m...With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be disregarded.Therefore,it is necessary to conduct a comprehensive review in this field.In this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures.Firstly,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components.Furthermore,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating conditions.Subsequently,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail.Lastly and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs.展开更多
In this work,the influence of rolling ratios on microstructural changes and corrosion behavior of an as-rolled Mg-8 wt.%Li alloy in0.1 mol/L Na Cl solution has been investigated.It revealed that with the rolling ratio...In this work,the influence of rolling ratios on microstructural changes and corrosion behavior of an as-rolled Mg-8 wt.%Li alloy in0.1 mol/L Na Cl solution has been investigated.It revealed that with the rolling ratio being increased from 3 to 10,theα-Mg phases were elongated and fragmented,whilst the area fraction of exposedβ-Li phases increased.Meanwhile,the corrosion performance of the alloy decreased with the increased rolling ratios.For all the samples,their corrosion processes were quite similar and can have two stages.At the initial stage with the samples being immersed for less than 6 h,the corrosion mainly occurred inβ-Li phases.When the samples were immersed for longer than 6 h,the corrosion attack transferred toα-Mg phases and the hydrogen evolution rate was accelerated.展开更多
The corrosion behavior of 5 wt%Cr steel tempered at different temperatures was investigated by immersion testing and electrochemical testing in a CO_2 aqueous environment. When the tempering temperature exceeded 500℃...The corrosion behavior of 5 wt%Cr steel tempered at different temperatures was investigated by immersion testing and electrochemical testing in a CO_2 aqueous environment. When the tempering temperature exceeded 500℃, the corrosion rate increased. The corrosion layers consisted of Cr-rich compounds, which affected the corrosion behaviors of the steels immersed in the corrosive solution. The results of electrochemical experiments demonstrated that 5 wt%Cr steels with different microstructures exhibited pre-passivation characteristics that decreased their corrosion rate. Analysis by electron back-scattered diffraction showed that the frequency of high-angle grain boundaries(HAGBs) and the corrosion rate were well-correlated in specimens tempered at different temperatures. The corrosion rate increased with increasing HAGB frequency.展开更多
A high-strength AZ80 Mg alloy was prepared through multi-direction forging,thermal extrusion,and peak-aged heat treatment.The microstructure,crystallographic orientation and corrosion performance of extrusion-directio...A high-strength AZ80 Mg alloy was prepared through multi-direction forging,thermal extrusion,and peak-aged heat treatment.The microstructure,crystallographic orientation and corrosion performance of extrusion-direction,transverse-direction,and normal-direction specimens were investigated using scanning electron microscopy,electron backscatter diffraction,and atomic force microscopy,respectively.Experimental results showed that crystallographic orientation significantly influenced the corrosion performance of AZ80 Mg alloy.Corrosion rates largely increased with decreased(0001)crystallographic plane intensity,whereas the(10−10)and(2−1−10)crystallographic plane intensities increased.This study showed that the corrosion rates of alloy can be modified to some extent by controlling texture,thereby promoting the applications of high-strength AZ80 Mg alloys in the aerospace and national-defense fields.展开更多
With the loading test equipment of corrosion fatigue specially designed, the corrosion fatigue characteristics of high performance concrete (HPC) withstanding the interaction of third point fatigue loading and Na_2SO_...With the loading test equipment of corrosion fatigue specially designed, the corrosion fatigue characteristics of high performance concrete (HPC) withstanding the interaction of third point fatigue loading and Na_2SO_4 solution were investigated and analyzed. The experimental results indicate that water-binder ratio evidently influences the corrosion fatigue characteristics of HPC, and a moderate quantitative fine mineral admixture enhances the corrosion fatigue resistance of HPC. The effect is more significant when fly ash and silica fume are added.展开更多
Three kinds of NiCr-Cr 3C 2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comparison with 102G, 20G boiler...Three kinds of NiCr-Cr 3C 2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comparison with 102G, 20G boiler tube steel, FeCrAl, NiCrTi, Ni50Cr and NiCrAlMoFe-Cr 3C 2 coatings, which are widely used at present for protection of boiler tubes. Meanwhile,the influence of sealer on the hot corrosion resistance of various coatings and the mechanisms of coating corrosion were explored.展开更多
In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied. The influence of content...In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied. The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings. Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface. There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase. And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.展开更多
Pre-painted steel is one of the most important structural material of the 20th century well known for its excellent corrosion resistance and wide ranging applications.A typical pre-painted steel usually consists of a ...Pre-painted steel is one of the most important structural material of the 20th century well known for its excellent corrosion resistance and wide ranging applications.A typical pre-painted steel usually consists of a layer of metal coating system,preferably zinc or zinc alloy coating and a combination of layers of inorganic - organic coatings usually referred to as paint system.The corrosion resistance of the metal coating as well as the paint system may vary considerably based on their composition and the environment.For optimal corrosion performance of pre-painted steel,a judicious selection of both metal and inorganic-organic coating systems are essential.This paper reviews different types of possible corrosion issues in pre-painted steels and methods to optimise their performance.展开更多
The Pb-free solders have attracted a great deal of attention recently due to the environmental concerns.The present work focuses on the effect of cobalt content(0,0.5 and 3.0)on the microstructural characteristics,mel...The Pb-free solders have attracted a great deal of attention recently due to the environmental concerns.The present work focuses on the effect of cobalt content(0,0.5 and 3.0)on the microstructural characteristics,melting point and corrosion performance of extruded Sn-9Zn solder alloys.The results reveal that the Zn-rich precipitates with spherical or needle-like shape in the Sn-9Zn-xCo alloys are refined remarkably by forming the γ-Co5Zn21 and Co2Sn2Zn Co-contained intermetallic compounds,though the melting point and eutectic reaction temperature decrease slightly.It is suggested that the corrosion property of the extruded Sn-9Zn-xCo alloys is improved significantly by adding the cobalt element,while the content should be controlled reasonably.Combining the corrosion morphology,the influence of cobalt content on the corrosion behavior of the Sn-9Zn-xCo alloys is analyzed in terms of the refined microstructure and the enhanced passive film stability.展开更多
In this work, graphene-modified epoxy-based anti-corrosion coatings were prepared and the influence of graphene on the anti-corrosion performance of the epoxy-based coatings was investigated with water contact angle t...In this work, graphene-modified epoxy-based anti-corrosion coatings were prepared and the influence of graphene on the anti-corrosion performance of the epoxy-based coatings was investigated with water contact angle test ,chemical solution immersion test, and electrochemical test. The water contact angle and chemical solution resistance of the epoxy-based coatings were improved with an increase in graphene content from 0 to 0.4%. These results prove that addition of graphene can significantly improve the hydrophobicity and impermeability of epoxy- based coatings. However, when the graphene content was increased to 0.5%, the performance of the epoxy-based coatings decreased because of graphene aggregation. Tafel polarization results show that graphene addition can significantly reduce the corrosion current density and corrosion potential of epoxy-based coatings, which enhance their anti-corrosion performance.展开更多
Copper, in turn, is the most useful material in the field of electricity, especially in electrical contacts. Already, the zinc is the most useful metal in atmospheric exposure conditions which is used in sheet form as...Copper, in turn, is the most useful material in the field of electricity, especially in electrical contacts. Already, the zinc is the most useful metal in atmospheric exposure conditions which is used in sheet form as castings, but whose most important application is as a coating for corrosion protection of steel structures. Salvador, it has disadvantages as an environment conducive to corrosion, by setting up a wet surface time t4, high corrosive environment (C4). This work was proposed to study the performance of these metals compared to the effects of air pollution of an industrial site. For both atmospheric corrosion sites (ACS) were implanted natural weathering standard in order to assess the aggressiveness of atmospheric contaminants on the performance of metal specimens (galvanized steel and copper). In determining their corrosion rates which were analyzed for sulfate and chloride ions, atmospheric, given the proximity of this ACS to the seafront, due to these propitiate the acceleration of corrosion. The results allowed observation that the average local concentration of the sulfate was higher than the chloride, because of the proximity of the pollutant source, and that the corrosion rate of galvanized steel was more significant than 61.5% of copper.展开更多
One dimensional(1D) and three dimensional(3D) ultrasound sources were applied to the solidification process of Mg_(71.5)Zn_(26.1)Y_(2.4) alloy.The acoustic spectra were in-situ measured, based on which the cavitation ...One dimensional(1D) and three dimensional(3D) ultrasound sources were applied to the solidification process of Mg_(71.5)Zn_(26.1)Y_(2.4) alloy.The acoustic spectra were in-situ measured, based on which the cavitation intensities and dynamic solidification mechanism were further investigated. With the increase of ultrasonic dimension and amplitude, the primary Mg_(3)Zn_(6)Y phase was significantly refined from petals to nearly pentagonal shape. The sound field measurements showed that the transient cavitation played a decisive role in generating a high local undercooling, which facilitated the formation of icosahedral clusters and promoted the nucleation of primary Mg_(3)Zn_(6)Y phase. The morphological transition of(α-Mg+Mg_(3)Zn_(6)Y) eutectic from lamellar to anomalous structure occurred under 3D ultrasonic condition. The stable cavitation took the main responsibility because the high pressure excited by nonlinearly oscillating bubbles induced the preferential nucleation of α-Mg phase rather than Mg_(3)Zn_(6)Y phase. As compared with its static values, the tensile strength and compression plasticity of this alloy were increased by the factors of 1.9 and 2.1, and its corrosion resistance was also improved with the corrosion current density decreased by one order of magnitude.展开更多
BACKGROUND Corrosive ingestion remains an important global pathology with high morbidity and mortality.Data on the acute management of adult corrosive injuries from sub-Saharan Africa is scarce,with international inve...BACKGROUND Corrosive ingestion remains an important global pathology with high morbidity and mortality.Data on the acute management of adult corrosive injuries from sub-Saharan Africa is scarce,with international investigative algorithms,relying heavily on computed tomography(CT),having limited availability in this setting.AIM To investigate the corrosive injury spectrum in a low-resource setting and the applicability of parameters for predicting full-thickness(FT)necrosis and mortality.METHODS A retrospective analysis of a prospective corrosive injury registry(March 1,2017–October 31,2023)was performed to include all adult patients with acute corrosive ingestion managed at a single,academic referral centre in Cape Town,South Africa.Patient demographics,corrosive ingestion details,initial investigations,management,and short-term outcomes were described using descriptive statistics while multivariate analysis with receiver operator characteristic area under the curve graphs(ROC AUC)were used to identify factors predictive of FT necrosis and 30-day mortality.RESULTS One-hundred patients were included,with a mean age of 32 years(SD:11.2 years)and a male predominance(65.0%).The majority(73.0%)were intentional suicide attempts.Endoscopy on admission was the most frequent initial investigation performed(95 patients),while only 17 were assessed with CT.Seventeen patients had full thickness necrosis at surgery,of which eleven underwent emergency resection and six were palliated.Thirty-day morbidity and mortality were 27.0%and 14.0%,respectively.Patients with full thickness necrosis and those with an established perforation had a 30-day mortality of 58.8%and 91.0%,respectively.Full thickness necrosis was associated with a cumulative 2-year survival of only 17.6%.Multivariate analyses with ROC AUC showed admission endoscopy findings,CT findings,and blood gas findings(pH,base excess,lactate),to all have significant predictive value for full thickness necrosis,with endoscopy proving to have the best predictive value(AUC 0.850).CT and endoscopy findings were the only factors predictive of early mortality,with CT performing better than endoscopy(AUC 0.798 vs 0.759).CONCLUSION Intentional corrosive injuries result in devastating morbidity and mortality.Locally,early endoscopy remains the mainstay of severity assessment,but referral for CT imaging should be considered especially when blood gas findings are abnormal.展开更多
In order to study the effectiveness of combined carbon fiber-reinforced polymer (CFRP) sheets and steel jacket in strengthening the seismic performance of corrosion-damaged reinforced concrete (RC) columns, twelve...In order to study the effectiveness of combined carbon fiber-reinforced polymer (CFRP) sheets and steel jacket in strengthening the seismic performance of corrosion-damaged reinforced concrete (RC) columns, twelve reinforced concrete columns are tested under combined lateral cyclic displacement excursions and constant axial load. The variables studied in this program include effects of corrosion degree of the rebars, level of axial load, the amount of CFRP sheets and steel jacket. The results indicate that the combined CFRP and steel jacket retrofitting technique is effective in improving load-carrying, ductility and energy absorption capacity of the columns. Compared with the corrosion-damaged RC column, the lateral load and the ductility factor of many strengthened columns increase more than 90% and 100%, respectively. The formulae for the calculation of the yielding load, the maximum lateral load and the displacement ductility factor of the strengthened columns under combined constant axial load and cyclically increasing lateral loading are developed. The test results are also compared with the results obtained from the proposed formulae. A good agreement between calculated values and experimental results is observed.展开更多
The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment wassystematically studied.Electrochemical methods,including electrochemical impendence spectra,Mott–Scho...The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment wassystematically studied.Electrochemical methods,including electrochemical impendence spectra,Mott–Schottky technology,cyclicpolarization,and potentiostatic polarization,were employed to characterize the corrosion behavior of copper at different temperatures.Stereoscopic microscopy and scanning electron microscopy were used to examine the surface morphology,and X-ray photoelectronspectroscopy analysis was used to identify the composition of the passive film.The experimental results show that corrosionresistance of the passive film does not blindly decrease with the increase of temperature but increases at60°C owing to a compactouter layer;there is a potential for pitting corrosion,which decreases as the temperature increases.The main product of copper in ananaerobic aqueous sulfide solution is Cu2S but the content of CuS increases at higher temperatures.The whole passivation rangeshows p-type semiconductor characteristics and the magnitude of the acceptor density is1023cm-3,which increases with increasingtemperature.展开更多
The mixture consisted of benzotriazole (BTA), chitosan (CTS), polyacrylic acid and zinc salt has been investigated as a corrosion and scale inhibitor of A3 carbon steel in cooling water. The scale and corrosion inhibi...The mixture consisted of benzotriazole (BTA), chitosan (CTS), polyacrylic acid and zinc salt has been investigated as a corrosion and scale inhibitor of A3 carbon steel in cooling water. The scale and corrosion inhibition efficiency was evaluated by static anti-scaling teat together with rotary coupon test. Compared with the phosphorus corrosion and scale inhibitor, the corrosion inhibition rate and scale inhibition rate of it increased respectively by 2.51% and 1.16%. As the corrosion and scale inhibitor is phosphate-free, it won’t cause eutrophication, considering the product performance and environmental influence, the phosphate-free corrosion and scale inhibitor is superior to the traditional one.展开更多
The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-ce...The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-cell discharge capabilities were characterized.The results show that the corrosion rate of the Mg matrix was decreased by alloying with La,and this could be attributed to the formation of a protective La2O3-containing film on the surface of the alloy.The Mg−0.2La alloy displayed the lowest corrosion rate,i.e.,2.4 mm/a in a 3.5 wt.%NaCl solution,Furthermore,the discharge performance of Mg−0.4La alloy was superior to that of pure Mg and other Mg−La alloys;this could be associated with the modified microstructure of the Mg−0.4La alloy,which decreased the self-corrosion and accelerated the detachment of the discharge products.展开更多
Textile reinforced concrete(TRC)has good bearing capacity,crack resistance and corrosion resistance and it is suitable for repairing and reinforcing concrete structures in harsh marine environments.The four-point bend...Textile reinforced concrete(TRC)has good bearing capacity,crack resistance and corrosion resistance and it is suitable for repairing and reinforcing concrete structures in harsh marine environments.The four-point bending method was used to analyze the influence of the salt concentration,the damage degree and the coupled effect of the environment and load on the bending performance of TRC-strengthened beams with a secondary load.The results showed that as the salt concentration increased,the crack width and mid-span deflection of the beam quickly increased,and its bearing capacity decreased.As the damage degree increased,the early-stage crack development and mid-span deflection of the beam were less affected and the ultimate bearing capacity significantly decreased.In addition,the coupled effect of the environment and load on the beams with a secondary load was significant.As the sustained load increased,the ultimate bearing capacity of the strengthened beam decreased,and cracks developed faster in the later stage.In addition,the mid-span deflection of the beam decreased at the same load level because of the influence of the initial deflection due to the sustained load corrosion.展开更多
基金financially supported by the Guangxi Natural Science Foundation,China(No.2020GXNSFAA 159011)the National Natural Science Foundation of China(No.51664011).
文摘Magnesium(Mg)alloys,the lightest metal construction material used in industry,play a vital role in future development.However,the poor corrosion resistance of Mg alloys in corrosion environments largely limits their potential wide applications.Therefore,a micro-arc oxidation/graphene oxide/stearic acid(MAO/GO/SA)superhydrophobic composite coating with superior corrosion resistance was fabricated on a Mg alloy AZ91D through micro-arc oxidation(MAO)technology,electrodeposition technique,and self-assembly technology.The composition and microstructure of the coating were characterized by scanning electron microscopy,X-ray diffraction,energy dispersive spectroscopy,and Raman spectroscopy.The effective protection of the MAO/GO/SA composite coating applied to a substrate was evaluated using potentiodynamic polarization,electrochemical impedance spectroscopy tests,and salt spray tests.The results showed that the MAO/GO/SA composite coating with a petal spherical structure had the best superhydrophobicity,and it attained a contact angle of 159.53°±2°.The MAO/GO/SA composite coating exhibited high resistance to corrosion,according to electrochemical and salt spray tests.
文摘Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite (HEP-APU) coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.
文摘With the large-scale service of lithium-ion batteries(LIBs),their failures have attracted significant attentions.While the decay of active materials is the primary cause for LIB failures,the degradation of auxiliary materials,such as current collector corrosion,should not be disregarded.Therefore,it is necessary to conduct a comprehensive review in this field.In this review,from the perspectives of electrochemistry and materials,we systematically summarize the corrosion behavior of aluminum cathode current collector and propose corresponding countermeasures.Firstly,the corrosion type is clarified based on the properties of passivation layers in different organic electrolyte components.Furthermore,a thoroughgoing analysis is presented to examine the impact of various factors on aluminum corrosion,including lithium salts,organic solvents,water impurities,and operating conditions.Subsequently,strategies for electrolyte and protection layer employed to suppress corrosion are discussed in detail.Lastly and most importantly,we provide insights and recommendations to prevent corrosion of current collectors,facilitate the development of advanced current collectors and the implementation of next-generation high-voltage stable LIBs.
基金supported by the National Key Research and Development Program of China under Grant[Nos.2017YFB0702001 and 2016YFB0301105]Liaoning Province’s project of“Revitalizing Liaoning Talents”(XLYC1907062)+8 种基金National Natural Science Foundation of China Projects under Grant[Nos.5207011217,51871211 and 51701129]the Doctor Startup Fund of Natural Science Foundation Program of Liaoning Province(No.2019-BS-200)the Strategic New Industry Development Special Foundation of Shenzhen(JCYJ20170306141749970)the funds of International Joint Laboratory for Light AlloysLiaoning Bai QianWan Talents Programthe Domain Foundation of Equipment Advance Research of 13th Five-year Plan(61409220118)the Innovation Fund of Institute of Metal Research(IMR)Chinese Academy of Sciences(CAS)the National Basic Research Program of China(973 Program)project under Grant No.2013CB632205
文摘In this work,the influence of rolling ratios on microstructural changes and corrosion behavior of an as-rolled Mg-8 wt.%Li alloy in0.1 mol/L Na Cl solution has been investigated.It revealed that with the rolling ratio being increased from 3 to 10,theα-Mg phases were elongated and fragmented,whilst the area fraction of exposedβ-Li phases increased.Meanwhile,the corrosion performance of the alloy decreased with the increased rolling ratios.For all the samples,their corrosion processes were quite similar and can have two stages.At the initial stage with the samples being immersed for less than 6 h,the corrosion mainly occurred inβ-Li phases.When the samples were immersed for longer than 6 h,the corrosion attack transferred toα-Mg phases and the hydrogen evolution rate was accelerated.
基金financially supported by the National Key R & D Program of China (No. 2017YFB0304900)the National Science and Technology Major Project of China (No. 2014E-3604)
文摘The corrosion behavior of 5 wt%Cr steel tempered at different temperatures was investigated by immersion testing and electrochemical testing in a CO_2 aqueous environment. When the tempering temperature exceeded 500℃, the corrosion rate increased. The corrosion layers consisted of Cr-rich compounds, which affected the corrosion behaviors of the steels immersed in the corrosive solution. The results of electrochemical experiments demonstrated that 5 wt%Cr steels with different microstructures exhibited pre-passivation characteristics that decreased their corrosion rate. Analysis by electron back-scattered diffraction showed that the frequency of high-angle grain boundaries(HAGBs) and the corrosion rate were well-correlated in specimens tempered at different temperatures. The corrosion rate increased with increasing HAGB frequency.
基金The authors gratefully acknowledge the National Natural Science Foundation of China(grant no.51501181)
文摘A high-strength AZ80 Mg alloy was prepared through multi-direction forging,thermal extrusion,and peak-aged heat treatment.The microstructure,crystallographic orientation and corrosion performance of extrusion-direction,transverse-direction,and normal-direction specimens were investigated using scanning electron microscopy,electron backscatter diffraction,and atomic force microscopy,respectively.Experimental results showed that crystallographic orientation significantly influenced the corrosion performance of AZ80 Mg alloy.Corrosion rates largely increased with decreased(0001)crystallographic plane intensity,whereas the(10−10)and(2−1−10)crystallographic plane intensities increased.This study showed that the corrosion rates of alloy can be modified to some extent by controlling texture,thereby promoting the applications of high-strength AZ80 Mg alloys in the aerospace and national-defense fields.
文摘With the loading test equipment of corrosion fatigue specially designed, the corrosion fatigue characteristics of high performance concrete (HPC) withstanding the interaction of third point fatigue loading and Na_2SO_4 solution were investigated and analyzed. The experimental results indicate that water-binder ratio evidently influences the corrosion fatigue characteristics of HPC, and a moderate quantitative fine mineral admixture enhances the corrosion fatigue resistance of HPC. The effect is more significant when fly ash and silica fume are added.
文摘Three kinds of NiCr-Cr 3C 2 cermet coatings were designed and deposited by the subsonic velocity flame spraying, and their performances of hot corrosion performance were evaluated in comparison with 102G, 20G boiler tube steel, FeCrAl, NiCrTi, Ni50Cr and NiCrAlMoFe-Cr 3C 2 coatings, which are widely used at present for protection of boiler tubes. Meanwhile,the influence of sealer on the hot corrosion resistance of various coatings and the mechanisms of coating corrosion were explored.
基金This work was financially supported bythe Doctoral Foundation ofYanshan University(B41)theScience and Technology Foundation ofYanshan University(YDJJ0169).
文摘In order to prepare ornamental and anti-corrosive coating on aluminum alloys, preparation technology of black micro-arc ceramic coatings on Al alloys in silicate based electrolyte was studied. The influence of content of Na2WO4 and combination additive in solution on the performance of black ceramic coatings was studied; the anticorrosion performances of black ceramic coatings were evaluated through whole-immersion test and electrochemical method in 3.5% NaCl solution at different pH value; SEM and XRD were used to analyze the surface morphology and phase constitutes of the black ceramic coatings. Experimental results indicated that, without combination additives, with the increasing of Na2WO4 content in the electrolyte, ceramic coating became darker and thicker, but the color was not black; after adding combination additive, the coating turned to be black; the black ceramic coating was multi-hole form in surface. There was a small quantity of tungsten existing in the black ceramic coating beside α-Al2O3 phase and β-Al2O3 phase. And aluminum alloy with black ceramic coating exhibited excellent anti-corrosion property in acid, basic and neutral 3.5% NaCl solution.
文摘Pre-painted steel is one of the most important structural material of the 20th century well known for its excellent corrosion resistance and wide ranging applications.A typical pre-painted steel usually consists of a layer of metal coating system,preferably zinc or zinc alloy coating and a combination of layers of inorganic - organic coatings usually referred to as paint system.The corrosion resistance of the metal coating as well as the paint system may vary considerably based on their composition and the environment.For optimal corrosion performance of pre-painted steel,a judicious selection of both metal and inorganic-organic coating systems are essential.This paper reviews different types of possible corrosion issues in pre-painted steels and methods to optimise their performance.
基金Project(2017YFB0305700)supported by the Ministry of Science and Technology of ChinaProjects(51490660,51490664)supported by the National Natural Science Foundation of ChinaProject(2017YFB0305700)supported by the National Key Research and Development Project of China。
文摘The Pb-free solders have attracted a great deal of attention recently due to the environmental concerns.The present work focuses on the effect of cobalt content(0,0.5 and 3.0)on the microstructural characteristics,melting point and corrosion performance of extruded Sn-9Zn solder alloys.The results reveal that the Zn-rich precipitates with spherical or needle-like shape in the Sn-9Zn-xCo alloys are refined remarkably by forming the γ-Co5Zn21 and Co2Sn2Zn Co-contained intermetallic compounds,though the melting point and eutectic reaction temperature decrease slightly.It is suggested that the corrosion property of the extruded Sn-9Zn-xCo alloys is improved significantly by adding the cobalt element,while the content should be controlled reasonably.Combining the corrosion morphology,the influence of cobalt content on the corrosion behavior of the Sn-9Zn-xCo alloys is analyzed in terms of the refined microstructure and the enhanced passive film stability.
文摘In this work, graphene-modified epoxy-based anti-corrosion coatings were prepared and the influence of graphene on the anti-corrosion performance of the epoxy-based coatings was investigated with water contact angle test ,chemical solution immersion test, and electrochemical test. The water contact angle and chemical solution resistance of the epoxy-based coatings were improved with an increase in graphene content from 0 to 0.4%. These results prove that addition of graphene can significantly improve the hydrophobicity and impermeability of epoxy- based coatings. However, when the graphene content was increased to 0.5%, the performance of the epoxy-based coatings decreased because of graphene aggregation. Tafel polarization results show that graphene addition can significantly reduce the corrosion current density and corrosion potential of epoxy-based coatings, which enhance their anti-corrosion performance.
文摘Copper, in turn, is the most useful material in the field of electricity, especially in electrical contacts. Already, the zinc is the most useful metal in atmospheric exposure conditions which is used in sheet form as castings, but whose most important application is as a coating for corrosion protection of steel structures. Salvador, it has disadvantages as an environment conducive to corrosion, by setting up a wet surface time t4, high corrosive environment (C4). This work was proposed to study the performance of these metals compared to the effects of air pollution of an industrial site. For both atmospheric corrosion sites (ACS) were implanted natural weathering standard in order to assess the aggressiveness of atmospheric contaminants on the performance of metal specimens (galvanized steel and copper). In determining their corrosion rates which were analyzed for sulfate and chloride ions, atmospheric, given the proximity of this ACS to the seafront, due to these propitiate the acceleration of corrosion. The results allowed observation that the average local concentration of the sulfate was higher than the chloride, because of the proximity of the pollutant source, and that the corrosion rate of galvanized steel was more significant than 61.5% of copper.
基金financially supported by National Natural Science Foundation of China (nos.52088101 and 52130405)Basic Research Project of Shaanxi Natural Science Foundation (no: 2021JCW-09 and 2023-JC-JQ-28)Key R&D Plan of Shaanxi Province-Key Industrial Innovation Chain Project (no: 2020ZDLGY13-03)。
文摘One dimensional(1D) and three dimensional(3D) ultrasound sources were applied to the solidification process of Mg_(71.5)Zn_(26.1)Y_(2.4) alloy.The acoustic spectra were in-situ measured, based on which the cavitation intensities and dynamic solidification mechanism were further investigated. With the increase of ultrasonic dimension and amplitude, the primary Mg_(3)Zn_(6)Y phase was significantly refined from petals to nearly pentagonal shape. The sound field measurements showed that the transient cavitation played a decisive role in generating a high local undercooling, which facilitated the formation of icosahedral clusters and promoted the nucleation of primary Mg_(3)Zn_(6)Y phase. The morphological transition of(α-Mg+Mg_(3)Zn_(6)Y) eutectic from lamellar to anomalous structure occurred under 3D ultrasonic condition. The stable cavitation took the main responsibility because the high pressure excited by nonlinearly oscillating bubbles induced the preferential nucleation of α-Mg phase rather than Mg_(3)Zn_(6)Y phase. As compared with its static values, the tensile strength and compression plasticity of this alloy were increased by the factors of 1.9 and 2.1, and its corrosion resistance was also improved with the corrosion current density decreased by one order of magnitude.
文摘BACKGROUND Corrosive ingestion remains an important global pathology with high morbidity and mortality.Data on the acute management of adult corrosive injuries from sub-Saharan Africa is scarce,with international investigative algorithms,relying heavily on computed tomography(CT),having limited availability in this setting.AIM To investigate the corrosive injury spectrum in a low-resource setting and the applicability of parameters for predicting full-thickness(FT)necrosis and mortality.METHODS A retrospective analysis of a prospective corrosive injury registry(March 1,2017–October 31,2023)was performed to include all adult patients with acute corrosive ingestion managed at a single,academic referral centre in Cape Town,South Africa.Patient demographics,corrosive ingestion details,initial investigations,management,and short-term outcomes were described using descriptive statistics while multivariate analysis with receiver operator characteristic area under the curve graphs(ROC AUC)were used to identify factors predictive of FT necrosis and 30-day mortality.RESULTS One-hundred patients were included,with a mean age of 32 years(SD:11.2 years)and a male predominance(65.0%).The majority(73.0%)were intentional suicide attempts.Endoscopy on admission was the most frequent initial investigation performed(95 patients),while only 17 were assessed with CT.Seventeen patients had full thickness necrosis at surgery,of which eleven underwent emergency resection and six were palliated.Thirty-day morbidity and mortality were 27.0%and 14.0%,respectively.Patients with full thickness necrosis and those with an established perforation had a 30-day mortality of 58.8%and 91.0%,respectively.Full thickness necrosis was associated with a cumulative 2-year survival of only 17.6%.Multivariate analyses with ROC AUC showed admission endoscopy findings,CT findings,and blood gas findings(pH,base excess,lactate),to all have significant predictive value for full thickness necrosis,with endoscopy proving to have the best predictive value(AUC 0.850).CT and endoscopy findings were the only factors predictive of early mortality,with CT performing better than endoscopy(AUC 0.798 vs 0.759).CONCLUSION Intentional corrosive injuries result in devastating morbidity and mortality.Locally,early endoscopy remains the mainstay of severity assessment,but referral for CT imaging should be considered especially when blood gas findings are abnormal.
基金The Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (NoIRT0518)
文摘In order to study the effectiveness of combined carbon fiber-reinforced polymer (CFRP) sheets and steel jacket in strengthening the seismic performance of corrosion-damaged reinforced concrete (RC) columns, twelve reinforced concrete columns are tested under combined lateral cyclic displacement excursions and constant axial load. The variables studied in this program include effects of corrosion degree of the rebars, level of axial load, the amount of CFRP sheets and steel jacket. The results indicate that the combined CFRP and steel jacket retrofitting technique is effective in improving load-carrying, ductility and energy absorption capacity of the columns. Compared with the corrosion-damaged RC column, the lateral load and the ductility factor of many strengthened columns increase more than 90% and 100%, respectively. The formulae for the calculation of the yielding load, the maximum lateral load and the displacement ductility factor of the strengthened columns under combined constant axial load and cyclically increasing lateral loading are developed. The test results are also compared with the results obtained from the proposed formulae. A good agreement between calculated values and experimental results is observed.
基金Project(FRF-TP-14-011C1) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2014CB643300) supported by the National Basic Research Program of China
文摘The effect of temperature on the corrosion behavior of copper in simulated high-level nuclear waste environment wassystematically studied.Electrochemical methods,including electrochemical impendence spectra,Mott–Schottky technology,cyclicpolarization,and potentiostatic polarization,were employed to characterize the corrosion behavior of copper at different temperatures.Stereoscopic microscopy and scanning electron microscopy were used to examine the surface morphology,and X-ray photoelectronspectroscopy analysis was used to identify the composition of the passive film.The experimental results show that corrosionresistance of the passive film does not blindly decrease with the increase of temperature but increases at60°C owing to a compactouter layer;there is a potential for pitting corrosion,which decreases as the temperature increases.The main product of copper in ananaerobic aqueous sulfide solution is Cu2S but the content of CuS increases at higher temperatures.The whole passivation rangeshows p-type semiconductor characteristics and the magnitude of the acceptor density is1023cm-3,which increases with increasingtemperature.
文摘The mixture consisted of benzotriazole (BTA), chitosan (CTS), polyacrylic acid and zinc salt has been investigated as a corrosion and scale inhibitor of A3 carbon steel in cooling water. The scale and corrosion inhibition efficiency was evaluated by static anti-scaling teat together with rotary coupon test. Compared with the phosphorus corrosion and scale inhibitor, the corrosion inhibition rate and scale inhibition rate of it increased respectively by 2.51% and 1.16%. As the corrosion and scale inhibitor is phosphate-free, it won’t cause eutrophication, considering the product performance and environmental influence, the phosphate-free corrosion and scale inhibitor is superior to the traditional one.
基金the financial supports from the National Key Research and Development Program of China(Nos.2016YFB-0101700,2016YFB0301104)the National Natural Science Foundation of China(Nos.U1764253,51971044,U1910213)+3 种基金the National Defense Basic Scientific Research Program of Chinathe Chong-qing Science and Technology Commission,China(Nos.cstc2017zdcy-zdzxX0006,cstc2018jszx-cyzdx0082)the Chongqing Scientific&Technological Talents Program,China(No.KJXX-2017002)Qinghai Scientific&Technological Program,China(No.2018-GX-A1).
文摘The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-cell discharge capabilities were characterized.The results show that the corrosion rate of the Mg matrix was decreased by alloying with La,and this could be attributed to the formation of a protective La2O3-containing film on the surface of the alloy.The Mg−0.2La alloy displayed the lowest corrosion rate,i.e.,2.4 mm/a in a 3.5 wt.%NaCl solution,Furthermore,the discharge performance of Mg−0.4La alloy was superior to that of pure Mg and other Mg−La alloys;this could be associated with the modified microstructure of the Mg−0.4La alloy,which decreased the self-corrosion and accelerated the detachment of the discharge products.
基金Project(2017XKZD09)supported by the Fundamental Research Funds for the Central Universities,China
文摘Textile reinforced concrete(TRC)has good bearing capacity,crack resistance and corrosion resistance and it is suitable for repairing and reinforcing concrete structures in harsh marine environments.The four-point bending method was used to analyze the influence of the salt concentration,the damage degree and the coupled effect of the environment and load on the bending performance of TRC-strengthened beams with a secondary load.The results showed that as the salt concentration increased,the crack width and mid-span deflection of the beam quickly increased,and its bearing capacity decreased.As the damage degree increased,the early-stage crack development and mid-span deflection of the beam were less affected and the ultimate bearing capacity significantly decreased.In addition,the coupled effect of the environment and load on the beams with a secondary load was significant.As the sustained load increased,the ultimate bearing capacity of the strengthened beam decreased,and cracks developed faster in the later stage.In addition,the mid-span deflection of the beam decreased at the same load level because of the influence of the initial deflection due to the sustained load corrosion.