Corrosion is an essential issue limiting the application of high-strength low-carbon steel in seawater environment. The impact of retained austenite on its corrosion behavior with immersion experiments and related cor...Corrosion is an essential issue limiting the application of high-strength low-carbon steel in seawater environment. The impact of retained austenite on its corrosion behavior with immersion experiments and related corrosion sensor technology was explored. A model that clarifies the micro-galvanic effect and the heat-induced changes to the shape and composition of retained austenite was used to discuss the findings. The results indicated that retained austenite was generated following an intercritical process and demonstrated approximately 48 mV higher Volta potential than the matrix. The retained austenite content first increased and then decreased with increasing intercritical temperatures, while reaching the maximum value of 8.5% at 660℃. With the increase in retained austenite content, the corrosion rate was increased by up to 32.8% compared to “quenching + tempering” (QT) specimen. The interfaces between the retained austenite and matrix were the priority nucleation sites for corrosion. Moreover, the retained austenite reduced the corrosion resistance of the steel by increasing the micro-galvanic effect and reducing rust layer compactness.展开更多
The corrosion susceptibility of recrystallized and un-recrystallized grains in equal channel angular pressed(ECAPed)Mg-9Al-lZn(AZ91)alloys immersed in chloride containing media was investigated through immersion testi...The corrosion susceptibility of recrystallized and un-recrystallized grains in equal channel angular pressed(ECAPed)Mg-9Al-lZn(AZ91)alloys immersed in chloride containing media was investigated through immersion testing and an electrochemical microcell technique coupledwith high resolution techniques such as scanning Kelvin probe force microscopy(SKPFM),transmission electron microscopy(TEM),andelectron backscatter diffraction(EBSD).During ECAP,dynamic recrystallization(DRX)and strain-induced dynamic precipitation(SIDP)simultaneously occurred,resulting in a bimodal grain structure of original elongated coarse grains and newly formed equiaxed fine grainswith a large volume fraction ofβ-Mg17Al12 precipitates.Corrosion preferentially initiates and propagates in the DRXed grains,owing tothe greater microchemistry difference between theβ-Mg17Al12 precipitates formed at the DRXed grain boundaries and the adjacentα-Mgmatrix,which induces a strong microgalvanic coupling between these phases.Additionally,the weaker basal texture of the DRXed grainsalso makes these grains more susceptible to electrochemical reactions than the highly textured un-DRXed grains.The influence of dynamicrecrystallization and dynamic precipitation was also studied in ECAPed alloys with differenl levels of deformation strain through corrosion andelectrochemical techniques.Increasing the strain level led to a more uniform corrosion with a shallow penetration depth,lower corrosion ratevalues,and higher protective ability of the oxide film.Furthermore,higher levels of strain resulted in greater hardness values of the ECAPedalloys.The superior corrosion resistance and strength of the ECAPed alloys with increasing strain level was attributed to the combination ofsmaller DRXed grain size,higher DRX ratio,and higher volume fraction of uniformly distributed fineβ-Mg17Al12 precipitates.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.展开更多
We report that the corrosion resistance of Mg is significantly improved by adding 0.05wt%Sc.Corrosion rates evaluated from weight loss values after room-temperature immersion in 0.6 M NaCl solution for two weeks were ...We report that the corrosion resistance of Mg is significantly improved by adding 0.05wt%Sc.Corrosion rates evaluated from weight loss values after room-temperature immersion in 0.6 M NaCl solution for two weeks were 0.27 and 4.0 mm y^(-1)for the high-purity Mg samples with and without microalloyed 0.05wt%Sc,respectively.The beneficial effect of Sc microalloying on the corrosion resistance of Mg is discussed in connection with Sc-induced microstructural modifications.展开更多
When aluminum alloys are coupled with dissimilar materials,they often act as corrosion anodes and are suscepted to accelerated corrosion.Therefore,deepening our knowledge of such corrosion phenomena,related mechanisms...When aluminum alloys are coupled with dissimilar materials,they often act as corrosion anodes and are suscepted to accelerated corrosion.Therefore,deepening our knowledge of such corrosion phenomena,related mechanisms,and elaborating new prediction model is of great theoretical and practical significance.In this paper,such mechanisms are explained from both macroscopic and microscopic points of view by considering several aspects such as the second phase particle type,grain size,and environmental ions.More specifically,different perspectives on such a problem are elaborated,which take into account:the properties of the coupling pair materials,geometrical characteristics,environmental media characteristics,the corrosion regularity of different types of aluminum alloys,the influence of area ratio on anode corrosion current density,the interference of the solution primary ions represented by Cl-and the accompanying ions represented by Al3+.A review is also conducted of the standard test methods used in the study of aluminum alloys galvanic corrosion and of research methods such as the Wire Beam Electrodes Technology(WBE),the Scanning Kelvin Probe Force Microscopy(SKPFM)technology.Finally,three kinds of inhibition technologies are discussed,including the anodic oxidation treatment,the corrosion inhibitor treatment and the coating protection method.展开更多
Objective:This work aims to construct a functional titanium surface with spontaneous electrical stimulation for immune osteogenesis and antibacteria.Impact Statement:A silver–calcium microgalvanic cell was engineered...Objective:This work aims to construct a functional titanium surface with spontaneous electrical stimulation for immune osteogenesis and antibacteria.Impact Statement:A silver–calcium microgalvanic cell was engineered on the titanium implant surface to spontaneously generate microcurrents for osteoimmunomodulation and bacteria killing,which provides a promising strategy for the design of a multifunctional electroactive titanium implant.Introduction:Titanium-based implants are usually bioinert,which often leads to inflammation-induced loosening.Electrical stimulation has therapeutic potential;however,its dependence on external devices limits its clinical application.Therefore,designing an electroactive titanium surface with endogenous electrical stimulation capability is a promising strategy to overcome implant failure induced by inflammation.Methods:The silver–calcium micro-galvanic cell was constructed on titanium substrate surfaces by the ion implantation technique.RAW264.7 and MC3T3-E1 were used for cell culture studies with the material to evaluate immunomodulatory and osteogenic abilities of the implant.The expression levels of inflammatory genes and voltage-gated Ca2+channel-related genes were tested for investigating the mechanism of immunoregulation.The antibacterial properties of the modified titanium were assessed.Finally,its immunomodulatory effects in vivo were verified by a mouse subcutaneous inflammation model.Results:The silver–calcium micro-galvanic modified titanium surface generates microcurrents and releases Ca^(2+),which induces macrophage polarization toward the M2 phenotype and promotes osteogenic differentiation via paracrine signaling,exhibiting excellent antibacterial activity.Conclusion:The silver–calcium micro-galvanic cell on titanium could regulate the immune response to promote bone repair and exhibit antibacterial capabilities through noninvasive electrical stimulation,providing a promising strategy for the design of multifunctional electroactive implant surfaces.展开更多
文摘Corrosion is an essential issue limiting the application of high-strength low-carbon steel in seawater environment. The impact of retained austenite on its corrosion behavior with immersion experiments and related corrosion sensor technology was explored. A model that clarifies the micro-galvanic effect and the heat-induced changes to the shape and composition of retained austenite was used to discuss the findings. The results indicated that retained austenite was generated following an intercritical process and demonstrated approximately 48 mV higher Volta potential than the matrix. The retained austenite content first increased and then decreased with increasing intercritical temperatures, while reaching the maximum value of 8.5% at 660℃. With the increase in retained austenite content, the corrosion rate was increased by up to 32.8% compared to “quenching + tempering” (QT) specimen. The interfaces between the retained austenite and matrix were the priority nucleation sites for corrosion. Moreover, the retained austenite reduced the corrosion resistance of the steel by increasing the micro-galvanic effect and reducing rust layer compactness.
基金This research did not receive any specific grant from funding agencies in the public,commercial,or not-for-profit sectors.
文摘The corrosion susceptibility of recrystallized and un-recrystallized grains in equal channel angular pressed(ECAPed)Mg-9Al-lZn(AZ91)alloys immersed in chloride containing media was investigated through immersion testing and an electrochemical microcell technique coupledwith high resolution techniques such as scanning Kelvin probe force microscopy(SKPFM),transmission electron microscopy(TEM),andelectron backscatter diffraction(EBSD).During ECAP,dynamic recrystallization(DRX)and strain-induced dynamic precipitation(SIDP)simultaneously occurred,resulting in a bimodal grain structure of original elongated coarse grains and newly formed equiaxed fine grainswith a large volume fraction ofβ-Mg17Al12 precipitates.Corrosion preferentially initiates and propagates in the DRXed grains,owing tothe greater microchemistry difference between theβ-Mg17Al12 precipitates formed at the DRXed grain boundaries and the adjacentα-Mgmatrix,which induces a strong microgalvanic coupling between these phases.Additionally,the weaker basal texture of the DRXed grainsalso makes these grains more susceptible to electrochemical reactions than the highly textured un-DRXed grains.The influence of dynamicrecrystallization and dynamic precipitation was also studied in ECAPed alloys with differenl levels of deformation strain through corrosion andelectrochemical techniques.Increasing the strain level led to a more uniform corrosion with a shallow penetration depth,lower corrosion ratevalues,and higher protective ability of the oxide film.Furthermore,higher levels of strain resulted in greater hardness values of the ECAPedalloys.The superior corrosion resistance and strength of the ECAPed alloys with increasing strain level was attributed to the combination ofsmaller DRXed grain size,higher DRX ratio,and higher volume fraction of uniformly distributed fineβ-Mg17Al12 precipitates.c 2020 Published by Elsevier B.V.on behalf of Chongqing University.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea Government(MSIT)(No.2019R1A2C1003905)
文摘We report that the corrosion resistance of Mg is significantly improved by adding 0.05wt%Sc.Corrosion rates evaluated from weight loss values after room-temperature immersion in 0.6 M NaCl solution for two weeks were 0.27 and 4.0 mm y^(-1)for the high-purity Mg samples with and without microalloyed 0.05wt%Sc,respectively.The beneficial effect of Sc microalloying on the corrosion resistance of Mg is discussed in connection with Sc-induced microstructural modifications.
基金This work is supported by the Natural Science Foundation of Shaanxi Province of China(No.2022JM-243)Youth Fund Project of University(2021QN-B026).
文摘When aluminum alloys are coupled with dissimilar materials,they often act as corrosion anodes and are suscepted to accelerated corrosion.Therefore,deepening our knowledge of such corrosion phenomena,related mechanisms,and elaborating new prediction model is of great theoretical and practical significance.In this paper,such mechanisms are explained from both macroscopic and microscopic points of view by considering several aspects such as the second phase particle type,grain size,and environmental ions.More specifically,different perspectives on such a problem are elaborated,which take into account:the properties of the coupling pair materials,geometrical characteristics,environmental media characteristics,the corrosion regularity of different types of aluminum alloys,the influence of area ratio on anode corrosion current density,the interference of the solution primary ions represented by Cl-and the accompanying ions represented by Al3+.A review is also conducted of the standard test methods used in the study of aluminum alloys galvanic corrosion and of research methods such as the Wire Beam Electrodes Technology(WBE),the Scanning Kelvin Probe Force Microscopy(SKPFM)technology.Finally,three kinds of inhibition technologies are discussed,including the anodic oxidation treatment,the corrosion inhibitor treatment and the coating protection method.
基金supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang(2024C03080)the National Natural Science Foundation of China(52450110,52501320,and 52401310)the Science and Technology Commission of Shanghai Municipality(24ZR1475600).
文摘Objective:This work aims to construct a functional titanium surface with spontaneous electrical stimulation for immune osteogenesis and antibacteria.Impact Statement:A silver–calcium microgalvanic cell was engineered on the titanium implant surface to spontaneously generate microcurrents for osteoimmunomodulation and bacteria killing,which provides a promising strategy for the design of a multifunctional electroactive titanium implant.Introduction:Titanium-based implants are usually bioinert,which often leads to inflammation-induced loosening.Electrical stimulation has therapeutic potential;however,its dependence on external devices limits its clinical application.Therefore,designing an electroactive titanium surface with endogenous electrical stimulation capability is a promising strategy to overcome implant failure induced by inflammation.Methods:The silver–calcium micro-galvanic cell was constructed on titanium substrate surfaces by the ion implantation technique.RAW264.7 and MC3T3-E1 were used for cell culture studies with the material to evaluate immunomodulatory and osteogenic abilities of the implant.The expression levels of inflammatory genes and voltage-gated Ca2+channel-related genes were tested for investigating the mechanism of immunoregulation.The antibacterial properties of the modified titanium were assessed.Finally,its immunomodulatory effects in vivo were verified by a mouse subcutaneous inflammation model.Results:The silver–calcium micro-galvanic modified titanium surface generates microcurrents and releases Ca^(2+),which induces macrophage polarization toward the M2 phenotype and promotes osteogenic differentiation via paracrine signaling,exhibiting excellent antibacterial activity.Conclusion:The silver–calcium micro-galvanic cell on titanium could regulate the immune response to promote bone repair and exhibit antibacterial capabilities through noninvasive electrical stimulation,providing a promising strategy for the design of multifunctional electroactive implant surfaces.
