Passivation by the inorganic-rich solid electrolyte interphase(SEI),especially the LiF-rich SEI,is highly desirable to guarantee the durable lifespan of Li metal batteries(LMBs).Here,we report a diluent with the capab...Passivation by the inorganic-rich solid electrolyte interphase(SEI),especially the LiF-rich SEI,is highly desirable to guarantee the durable lifespan of Li metal batteries(LMBs).Here,we report a diluent with the capability to facilitate the formation of LiF-rich SEI while avoiding the excess consumption of Li salts.Dissimilar to most of reported inert diluents,heptafluoro-l-methoxypropane(HM) is firstly demonstrated to cooperate with the decomposition of anions to generate LiF-rich SEI via releasing Fcontaining species near Li surface.The designed electrolyte consisting of 1.8 M LiFSI in the mixture of1,2-dimethoxyethane(DME)/HM(2:1 by vol.) achieves excellent compatibility with both Li metal anodes(Coulombic efficiency~99.8%) and high-voltage cathodes(4.4 V LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) and 4.5 V LiCoO_(2)(LCO) vs Li^(+)/Li).The 4.4 V Li(20μm)‖NMC811(2.5 mA h cm^(-2)) and 4.5 V Li(20μm)‖LCO(2.5 mA h cm^(-2)) cells achieve capacity retentions of 80% over 560 cycles and 80% over 505 cycles,respectively.Meanwhile,the anode-free pouch cell delivers an energy density of~293 W h kg^(-1)initially and retains 70% of capacity after 100 deep cycles.This work highlights the critical impact of diluent on the SEI formation,and opens up a new direction for designing desirable interfacial chemistries to enable high-performance LMBs.展开更多
In-situ incorporation of layered double hydroxides(LDH)nanocontainers into plasma electrolytic oxidation(PEO)coatings on AZ91 Mg alloy has been achieved in the present study.Fumarate was selected as Mg corrosion inhib...In-situ incorporation of layered double hydroxides(LDH)nanocontainers into plasma electrolytic oxidation(PEO)coatings on AZ91 Mg alloy has been achieved in the present study.Fumarate was selected as Mg corrosion inhibitor for exchange and intercalation into the nanocontainers,which were subsequently incorporated into the coating.It was found that the thickness and compactness of the coatings were increased in the presence of LDH nanocontainers.The corrosion protection performance of the blank PEO,LDH containing PEO and inhibitor loaded coatings was evaluated by means of polarization test and electrochemical impedance spectroscopy(EIS).The degradation process and corrosion resistance of PEO coating were found to be greatly affected by the loaded inhibitor and nanocontainers by means of ion-exchange when corrosion occurs,leading to enhanced and stable corrosion resistance of the substrate.展开更多
This study investigated the effect of sealing treatment on the corrosion performance of plasma electrolytic oxidation(PEO)coated AZ91D Mg alloy with and without addition of corrosion inhibitor.The microstructure,phase...This study investigated the effect of sealing treatment on the corrosion performance of plasma electrolytic oxidation(PEO)coated AZ91D Mg alloy with and without addition of corrosion inhibitor.The microstructure,phase composition and corrosion property of the sealed and unsealed coatings were evaluated by using scanning electron microscopy(SEM),energy dispersion spectroscopy(EDS),x-ray diffraction(XRD),x-ray photoelectron spectroscopy(XPS),polarization,and electrochemical impedance spectroscopy(EIS)tests.Electrochemical experiments and salt spray tests showed that,after sealing in phosphate solution containing corrosion inhibitor,the corrosion current density of PEO-coated AZ91D decreased more than 10-fold and the anti-corrosion time in a salt spray environment increased more than three-fold.The corrosion rate of the PEO coating slowed down due to the releasing and adsorbing of the corrosion inhibitors in the pores and cracks of the coating during the corrosion process.展开更多
The influence of Al content on the Mg-Al alloys corrosion performance during sodium chloride induced at- mospheric corrosion has been studied. It was found that the corrosion rate of three Mg-Al alloys was accelerated...The influence of Al content on the Mg-Al alloys corrosion performance during sodium chloride induced at- mospheric corrosion has been studied. It was found that the corrosion rate of three Mg-Al alloys was accelerated with increasing Al content. The poor corrosion resistance was attributed to the galvanic coupling between the β phase and eutectic phase or α phase and the formation of porous corrosion products.展开更多
Cracking and low thickness are major obstacles to the high corrosion performance of conversion coating on magnesium alloy.In this work,the ratio of total acidity to p H(TA/p H)was applied as an indicator,and new princ...Cracking and low thickness are major obstacles to the high corrosion performance of conversion coating on magnesium alloy.In this work,the ratio of total acidity to p H(TA/p H)was applied as an indicator,and new principles regarding the design of conversion bath were proposed.The treatment bath should be composed of species that can be categorized into two groups:the first group of species that react with Mg substrate to increase the local p H at the interface;the second group that precipitate and contributes to the growth of coating.The species belong to second group exists in a supersaturated state and its precipitation process is almost independent on the reactions of the species in first group.By this way,a thick and crack-free two-layered conversion coating is obtained.Moreover,the nature of the adjustment of TA/p H and the roles of the oxidizing agent and catalyst were discussed.展开更多
The sputtered nanocrystalline coating of K38G alloy was obtained by magnetron sput-tering. The hot corrosion behaviors of cast K38G alloy and its sputtered nanocrys-talline coating by pre-deposited 75wt%Na2SO4+25wt%K2...The sputtered nanocrystalline coating of K38G alloy was obtained by magnetron sput-tering. The hot corrosion behaviors of cast K38G alloy and its sputtered nanocrys-talline coating by pre-deposited 75wt%Na2SO4+25wt%K2SO4 at 900℃ were studied.The results indicated the occurrence of internal sulfidation in the cast K38G alloy withpre-deposited sulfattes of 0.8 and 3.0mg/cm2. However, the internal sulfidation wasnot observed in the coating with pre-deposited 0. 8mg/cm2 sulfate. The hot corrosionresistance of K38G alloy was clearly enhanced through nanocrystallinzation, althoughthe internal sulfides were still formed for the coating with sulfate deposit of 3mg/cm2.The relevant hot corrosion mechanism was also discussed.展开更多
The preparation of pH-responsive nanocontainers by typical silane modification of the mesoporous silica nanoparticle(MSN)surface is usually high-cost,complex,and time-consuming,which remains a great challenge for effe...The preparation of pH-responsive nanocontainers by typical silane modification of the mesoporous silica nanoparticle(MSN)surface is usually high-cost,complex,and time-consuming,which remains a great challenge for effective corrosion protection of magnesium alloy.Here,a new strategy to construct pH-responsive nanocontainers(MSN-MBT@LDH)is demonstrated.The nanocontainers consist of corrosion inhibitor(2-mercaptobenzothiazole,MBT)loaded MSN core and layered double hydroxide(LDH)nanosheet shell serving as gatekeepers.The successful loading of MBT and encapsulation by LDH nanosheets were confirmed by a series of characterization such as scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy(STEM-EDS)and N2 adsorption/desorption isotherms.The pH-responsive feature of the nanocontainers was demonstrated by determination of the MBT concentration in buffer solutions with different pH values.A smart corrosion protection system on Mg alloy is obtained by incorporating the synthesized nanocontainers into a self-assembled nanophase particle(SNAP)coating.The electrochemical tests and visual observations show that the hybrid coating has the best barrier properties and robustness in corrosion protection in NaCl corrosive solutions in comparison with the control coatings.The present method simplifies the synthesis processes of nanocontainers and eliminates the potential detrimental effect of excess gatekeepers on the coating.The findings provide new insights into the preparation of scalable nanocontainers.The self-healing coatings are expected to have widespread applications for corrosion protection of Mg alloy and other metals.展开更多
The influence of sodium dodecyl sulfate(SDS)on morphology and chemical composition of corrosion product layer formed onα-Mg matrix and cathodic Al-Mn intermetallic was systematically investigated by using FIB and TEM...The influence of sodium dodecyl sulfate(SDS)on morphology and chemical composition of corrosion product layer formed onα-Mg matrix and cathodic Al-Mn intermetallic was systematically investigated by using FIB and TEM analysis for the first time to disclose the underlying inhibition mechanism.A porous corrosion bi-layer composed of crystalline MgO and Mg(OH)_(2)was observed on both ofα-Mg and Al-Mn intermetallic.It was found that a passive inner layer was deposited onα-Mg after immersion in SDS-containing NaCl solution,which can be ascribed to steady-state growth of magnesium and aluminum oxide under the protection of hydrophobic group of SDS.The inhibition mechanism of the inhibitor was mainly associated with formation of dense oxide layer onα-Mg matrix and preferential adsorption of SDS on the corrosion layer deposited on Al-Mn intermetallic.展开更多
Surface rumpling is detrimental to high temperature protective coatings as it shortens their lifetime and leads to adhesion losses and unexpected corrosion degradation.The driving force and mass transport mechanism be...Surface rumpling is detrimental to high temperature protective coatings as it shortens their lifetime and leads to adhesion losses and unexpected corrosion degradation.The driving force and mass transport mechanism behind of rumpling remains to be clarified.In the present investigation,we subjected two types of nanocrystalline coating systems to avoid the influence of interdiffusion on rumpling study.One group was an ordinary nanocrystalline coating,and the other group was designed and prepared with trace oxygen by reactive magnetron sputtering.Systematic cyclic oxidation test at 1100°C was also car-ried out.Results show the ordinary nanocrystalline coating oxidized rapidly,which leads to the fast consumption of Al and the acceleration of phase transition in the coating.Meanwhile,severe surface rumpling is observed due to the stress release of nanocrystals through plastic deformation.Besides,the reactive doping of oxygen can significantly reduce the consumption process of Al in nanocrystalline coat-ing.The rumpling is controlled due to the improvement of coefficient of thermal expansion and Young’s modulus of the coating.Thereafter,the cyclic oxidation resistance is improved.展开更多
Planting on mulched soil is the main cultivation mode for sweet potato slips in spring in northern China.The‘boatbottom’planting method can bring high quantity and similar size for sweet potatoes.In this study,a mec...Planting on mulched soil is the main cultivation mode for sweet potato slips in spring in northern China.The‘boatbottom’planting method can bring high quantity and similar size for sweet potatoes.In this study,a mechanism for transplanting sweet potato seedlings on mulched was proposed,which could realize‘boat-bottom’transplanting trajectory and improve the planting efficiency.The virtual prototype model of the transplanting mechanism was constructed using ADAMS software,a soil particle model and a flexible body model of sweet potato seedling were established using EDEM software,and then a joint simulation was carried out to find out the interaction of mechanism,seedling and soil.By simulation,the trajectory of the clamping point,the sweet potato seedling posture,soil particles,pits,and relative force were all analyzed,which verified the rationality of the transplanting mechanism design.Finally,three kinds of sweet potato seedlings,watermelon red,Yan-25,and purple sweet potato seedlings were selected,and transplanting experiments were carried out on the mulch to verify that the theoretical trajectory,the simulated trajectory,and the actual trajectory were consistent.The transplanting success rates of the three kinds of sweet potato seedlings were all above 85%,indicating that different varieties of sweet potato seedlings had little effect on the transplanting effect of the mechanism,which reflected that the transplanting mechanism had good practicability and adaptability.展开更多
Corrosion-resistant high nitrogen high entropy alloys(HEAs)were manufactured by pressurized metal-lurgy.This work revealed the inhibitory effect of nitrogen on pitting corrosion of HEAs caused by sul-fate reducing bac...Corrosion-resistant high nitrogen high entropy alloys(HEAs)were manufactured by pressurized metal-lurgy.This work revealed the inhibitory effect of nitrogen on pitting corrosion of HEAs caused by sul-fate reducing bacterium Desulfovibrio vulgaris.Results indicated that HEA-0 N was susceptible to pitting corrosion and sulfidation under attack of D.vulgaris,whereas the addition of nitrogen significantly de-creased the pitting sensitivity.Pitting potentials of HEA-0.52 N and HEA-1.23 N increased by 133%and 171%,respectively compared to HEA-0 N in the presence of SRB.X-ray photoelectron spectroscopy results unveiled that nitrogen enriched in passive film and strengthened it by increasing fraction of Cr_(2)O_(3)and Fe^(3+)_(ox).Surface of the nitrogen-alloyed HEAs exhibited less defective passive films as revealed by Mott-Schottky results.Nitrogen doping provides a novel insight into the design of microbial corrosion resistant HEA.展开更多
Cariogenic Streptococcus mutans(S.mutans)is a leading cause of bacterial-induced oral diseases.Current strategies to kill bacteria based on Host defense peptide(HDP)mimicking polymers hold promise to treat oral bacter...Cariogenic Streptococcus mutans(S.mutans)is a leading cause of bacterial-induced oral diseases.Current strategies to kill bacteria based on Host defense peptide(HDP)mimicking polymers hold promise to treat oral bacterial infection.Here,we explore the impact of hydrophobic subunit and chain length variation on the antibacterial and antibiofilm activity ofβ-peptide polymers.The physicochemical and biological prop-erties,such as the toxicity,the antibacterial activity,and the effect on bacterial transcription ofβ-peptide polymers,were systematically investigated with numerous techniques.The results exhibited that the op-timalβ-peptide polymer has low toxicity towards human periodontal ligament fibroblasts,andβ-peptide polymers(especially P3)have more excellent antibacterial activity against S.mutans than metronidazole.In addition,β-peptide polymers inhibited the reversible and irreversible bacterial adhesion during the formation of biofilms.The polymer can promote biofilm dispersion by decreasing the hydrophobicity of bacterial cells after adhering to cell surfaces.Analysis of the transcriptome for S.mutans treated withβ-peptide polymers demonstrated thatβ-peptide polymers could reduce the cariogenicity of S.mutans by impacting the transcription of the energy and acid metabolism-related genes.β-peptide polymers are promising antimicrobial agents in clinical dentistry due to their high antibacterial efficiency and low tox-icity.展开更多
Nanocrystalline coating with the same chemical composition as the nickel-based superalloys was proved to possess high resistance to oxidation and scale spallation,meanwhile avoid notable elements inter-diffusion.It op...Nanocrystalline coating with the same chemical composition as the nickel-based superalloys was proved to possess high resistance to oxidation and scale spallation,meanwhile avoid notable elements inter-diffusion.It opens up a new direction for the development of protective coatings.However,in a worse environment containing chlorine and water vapor,the ultrafine grains act like a double-edged sword,which can promote the formation of a protective scale of Al_(2)O_(3)or Cr_(2)O_(3),but also favor the inward dif-fusion of Cl and H_(2)O to accelerate corrosion.In order to solve this problem,moderate amount of oxygen was doped into nanocrystalline coating during magnetron sputtering.Then,corrosion behavior of the two nanocrystalline coatings with or without oxygen doping was studied in the O_(2)+38%H_(2)O environment with solid NaCl deposit.Results indicated that the doped oxygen can attract active elements of Ti and Al to form TiO_(2)andθ-Al_(2)O_(3),which pinned at grain boundaries to keep the ultrafine grains stable at high temperature while prevent inward diffusion of the corrosive media.Accordingly,a dense and pure chromia scale was formed quickly at surface,ensuring that the oxygen-doped nanocrystalline coating provided the highest corrosion resistance under the synergy of solid NaCl deposit and water vapor.In contrast,the coating without oxygen doping suffered from severe internal corrosion.展开更多
Microbiologically influenced corrosion(MIC) is a major cause of corrosion damages, facility failures, and financial losses, making MIC an important research topic. Due to complex microbiological activities and a lack ...Microbiologically influenced corrosion(MIC) is a major cause of corrosion damages, facility failures, and financial losses, making MIC an important research topic. Due to complex microbiological activities and a lack of deep understanding of the interactions between biofilms and metal surfaces, MIC occurrences and mechanisms are difficult to predict and interpret. Many theories and mechanisms have been proposed to explain MIC. In this review, the mechanisms of MIC are discussed using bioenergetics, microbial respiration types, and biofilm extracellular electron transfer(EET). Two main MIC types, namely EET-MIC and metabolite MIC(M-MIC), are discussed. This brief review provides a state of the art insight into MIC mechanisms and it helps the diagnosis and prediction of occurrences of MIC under anaerobic conditions in the oil and gas industry.展开更多
The corrosion behavior of 2 A02 Al alloy under simulated marine atmospheric environment has been studied using mass-gain, scanning electron microscope/energy dispersive spectroscopy(SEM/EDS), laser scanning confocal m...The corrosion behavior of 2 A02 Al alloy under simulated marine atmospheric environment has been studied using mass-gain, scanning electron microscope/energy dispersive spectroscopy(SEM/EDS), laser scanning confocal microscopy, X-ray diffraction spectroscopy and localized electrochemical methods. The results demonstrate that the relationship between the corrosion induced mass-gain and the corrosion time is in accordance with the power rule. The mass-gain increases gradually during the corrosion time,while the corrosion rate decreases. With ongoing of the corrosion, corrosion products film changed from a porous to a compact structure. The various spectroscopic data show that the corrosion products films composed mainly of Al(OH)_3, Al_2O_3 and AlCl_3. The electrochemical corrosion behavior of the 2 A02 Al alloy was studied by electrochemical impedance spectroscopy(EIS).展开更多
The corrosion behavior of 316L stainless steel(316L SS) has been investigated in solutions containing various concentrations of chloride ions by using potentiodynamic polarization, capacitance measurement and Motte Sc...The corrosion behavior of 316L stainless steel(316L SS) has been investigated in solutions containing various concentrations of chloride ions by using potentiodynamic polarization, capacitance measurement and Motte Schottky relationship analysis(Me S). The result indicates that passive currents change slightly with the addition of chloride ions. The pitting potential(Epit) decreases linearly with log[Cl ]. Correspondingly, the point defect diffusion coefficient(Do) of the passive film increases linearly with increasing log[Cl ]. The results also indicate that the pitting corrosion of 316L SS follows the adsorption mechanism in NaCl solution.展开更多
The isothermal and cyclic oxidation behaviors in air and hot corrosion behaviors in Na2SO4t 25 wt%K2SO4salt of M951 cast superalloy and a sputtered nanocrystalline coating of the same material were studied.Scanning el...The isothermal and cyclic oxidation behaviors in air and hot corrosion behaviors in Na2SO4t 25 wt%K2SO4salt of M951 cast superalloy and a sputtered nanocrystalline coating of the same material were studied.Scanning electron microscopy,energy dispersive X-ray spectroscope,X-ray diffraction,and transmission electron microscopy were employed to examine the morphologies and phase composition of the M951 alloy and nanocrystalline coating before and after oxidation and hot corrosion.The as-sputtered nanocrystalline layer has a homogeneous g phase structure of very fine grain size(30e200 nm)with the preferential growth texture of(111)parallel to the interface.Adherent Al2O3rich oxide scale formed on the cast M951 alloy and its sputtered coating after isothermal oxidation at 900 and 1000 C.However,when being isothermal oxidized at 1100 C and cyclic oxidized at 1000 C,the oxide scale formed on the cast alloy was a mixture of NiO,NiAl2O4,Al2O3and Nb2O5and spalled seriously,while that formed on the sputtered coating mainly consisted of Al2O3and was very adherent.Nanocrystallization promoted rapid formation of Al2O3scale during the early stage of oxidation and enhanced the adhesion of the oxide scale,thus improved the oxidation resistance of the substrate alloy.Serious corrosion occurred for the cast alloy.The sputtered nanocrystalline coating apparently improved the hot corrosion resistance of the cast alloy in the mixed sulfate by the formation of a continuous Al2O3and Cr2O3mixed oxide layer on the surface of the coating,and the preoxidation treatment of the coating led to an even better effect.展开更多
基金supported by the National Natural Science Foundation of China(22072134,22161142017,and U21A2081)the Natural Science Foundation of Zhejiang Province(LZ21B030002)+2 种基金the Fundamental Research Funds for the Zhejiang Provincial Universities(2021XZZX010)the Fundamental Research Funds for the Central Universities(2021FZZX001-09)“Hundred Talents Program” of Zhejiang University。
文摘Passivation by the inorganic-rich solid electrolyte interphase(SEI),especially the LiF-rich SEI,is highly desirable to guarantee the durable lifespan of Li metal batteries(LMBs).Here,we report a diluent with the capability to facilitate the formation of LiF-rich SEI while avoiding the excess consumption of Li salts.Dissimilar to most of reported inert diluents,heptafluoro-l-methoxypropane(HM) is firstly demonstrated to cooperate with the decomposition of anions to generate LiF-rich SEI via releasing Fcontaining species near Li surface.The designed electrolyte consisting of 1.8 M LiFSI in the mixture of1,2-dimethoxyethane(DME)/HM(2:1 by vol.) achieves excellent compatibility with both Li metal anodes(Coulombic efficiency~99.8%) and high-voltage cathodes(4.4 V LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) and 4.5 V LiCoO_(2)(LCO) vs Li^(+)/Li).The 4.4 V Li(20μm)‖NMC811(2.5 mA h cm^(-2)) and 4.5 V Li(20μm)‖LCO(2.5 mA h cm^(-2)) cells achieve capacity retentions of 80% over 560 cycles and 80% over 505 cycles,respectively.Meanwhile,the anode-free pouch cell delivers an energy density of~293 W h kg^(-1)initially and retains 70% of capacity after 100 deep cycles.This work highlights the critical impact of diluent on the SEI formation,and opens up a new direction for designing desirable interfacial chemistries to enable high-performance LMBs.
基金support from National Natural Science Foundation of China(No.52071067 and U1737102)Mobility Programme of the Sino-German Center(M-0056)+1 种基金the Fundamental Research Funds for the Central Universities(N2002009)FUNCOAT project(H2020-MSCA-RISE-2018,Grant Agreement N 823942).
文摘In-situ incorporation of layered double hydroxides(LDH)nanocontainers into plasma electrolytic oxidation(PEO)coatings on AZ91 Mg alloy has been achieved in the present study.Fumarate was selected as Mg corrosion inhibitor for exchange and intercalation into the nanocontainers,which were subsequently incorporated into the coating.It was found that the thickness and compactness of the coatings were increased in the presence of LDH nanocontainers.The corrosion protection performance of the blank PEO,LDH containing PEO and inhibitor loaded coatings was evaluated by means of polarization test and electrochemical impedance spectroscopy(EIS).The degradation process and corrosion resistance of PEO coating were found to be greatly affected by the loaded inhibitor and nanocontainers by means of ion-exchange when corrosion occurs,leading to enhanced and stable corrosion resistance of the substrate.
基金the National Natural Science Foundation of China(No.U1737102,51531007,51371059)Young Elite Scientists Sponsorship Program by CAST(2017QNRC001)+3 种基金Guangxi Natural Science Foundation of China(Nos.2016GXNSFDA380022)Major Science and Technology Projects in Guangxi(No.AA18118030 and AA17204100)Project of Development of Science and Technology of Nanning(No.20181191-2)the Fundamental Research Funds for the Central Universities(N170203006).
文摘This study investigated the effect of sealing treatment on the corrosion performance of plasma electrolytic oxidation(PEO)coated AZ91D Mg alloy with and without addition of corrosion inhibitor.The microstructure,phase composition and corrosion property of the sealed and unsealed coatings were evaluated by using scanning electron microscopy(SEM),energy dispersion spectroscopy(EDS),x-ray diffraction(XRD),x-ray photoelectron spectroscopy(XPS),polarization,and electrochemical impedance spectroscopy(EIS)tests.Electrochemical experiments and salt spray tests showed that,after sealing in phosphate solution containing corrosion inhibitor,the corrosion current density of PEO-coated AZ91D decreased more than 10-fold and the anti-corrosion time in a salt spray environment increased more than three-fold.The corrosion rate of the PEO coating slowed down due to the releasing and adsorbing of the corrosion inhibitors in the pores and cracks of the coating during the corrosion process.
基金support by the National Natural ScienceFoundation of China (Grant No. 50571105) is acknowl-edged.
文摘The influence of Al content on the Mg-Al alloys corrosion performance during sodium chloride induced at- mospheric corrosion has been studied. It was found that the corrosion rate of three Mg-Al alloys was accelerated with increasing Al content. The poor corrosion resistance was attributed to the galvanic coupling between the β phase and eutectic phase or α phase and the formation of porous corrosion products.
基金financial support from the National Natural Science Foundation of China(51531007 and 51771050)China Postdoctoral Science Foundation(2019M651128)+1 种基金the National Program for Young Top-notch Professionalsthe Fundamental Research Funds for the Central Universities(N170205002)
文摘Cracking and low thickness are major obstacles to the high corrosion performance of conversion coating on magnesium alloy.In this work,the ratio of total acidity to p H(TA/p H)was applied as an indicator,and new principles regarding the design of conversion bath were proposed.The treatment bath should be composed of species that can be categorized into two groups:the first group of species that react with Mg substrate to increase the local p H at the interface;the second group that precipitate and contributes to the growth of coating.The species belong to second group exists in a supersaturated state and its precipitation process is almost independent on the reactions of the species in first group.By this way,a thick and crack-free two-layered conversion coating is obtained.Moreover,the nature of the adjustment of TA/p H and the roles of the oxidizing agent and catalyst were discussed.
文摘The sputtered nanocrystalline coating of K38G alloy was obtained by magnetron sput-tering. The hot corrosion behaviors of cast K38G alloy and its sputtered nanocrys-talline coating by pre-deposited 75wt%Na2SO4+25wt%K2SO4 at 900℃ were studied.The results indicated the occurrence of internal sulfidation in the cast K38G alloy withpre-deposited sulfattes of 0.8 and 3.0mg/cm2. However, the internal sulfidation wasnot observed in the coating with pre-deposited 0. 8mg/cm2 sulfate. The hot corrosionresistance of K38G alloy was clearly enhanced through nanocrystallinzation, althoughthe internal sulfides were still formed for the coating with sulfate deposit of 3mg/cm2.The relevant hot corrosion mechanism was also discussed.
基金Sichuan Science and Technology Program(2018JY0483)Young Elite Scientists Sponsorship Program by China Association for Science and Technology(YESS,2018QNRC001)+4 种基金Natural Science Foundation of Hunan Province(2020JJ4073)Open Project of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province(CSPC202004)Foundation of Huaihua University Double First-rate Applied Characteristic Discipline Construction Projects of Materials Science and Engineering(19CKA002)the Fundamental Research Funds of China West Normal University(CXTD2020-1)the support from the National Science Foundation(CHE 1566283)。
文摘The preparation of pH-responsive nanocontainers by typical silane modification of the mesoporous silica nanoparticle(MSN)surface is usually high-cost,complex,and time-consuming,which remains a great challenge for effective corrosion protection of magnesium alloy.Here,a new strategy to construct pH-responsive nanocontainers(MSN-MBT@LDH)is demonstrated.The nanocontainers consist of corrosion inhibitor(2-mercaptobenzothiazole,MBT)loaded MSN core and layered double hydroxide(LDH)nanosheet shell serving as gatekeepers.The successful loading of MBT and encapsulation by LDH nanosheets were confirmed by a series of characterization such as scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy(STEM-EDS)and N2 adsorption/desorption isotherms.The pH-responsive feature of the nanocontainers was demonstrated by determination of the MBT concentration in buffer solutions with different pH values.A smart corrosion protection system on Mg alloy is obtained by incorporating the synthesized nanocontainers into a self-assembled nanophase particle(SNAP)coating.The electrochemical tests and visual observations show that the hybrid coating has the best barrier properties and robustness in corrosion protection in NaCl corrosive solutions in comparison with the control coatings.The present method simplifies the synthesis processes of nanocontainers and eliminates the potential detrimental effect of excess gatekeepers on the coating.The findings provide new insights into the preparation of scalable nanocontainers.The self-healing coatings are expected to have widespread applications for corrosion protection of Mg alloy and other metals.
基金financial support from National Natural Science Foundation of China(No.52071067)the Fundamental Research Funds for the Central Universities(N2002009)。
文摘The influence of sodium dodecyl sulfate(SDS)on morphology and chemical composition of corrosion product layer formed onα-Mg matrix and cathodic Al-Mn intermetallic was systematically investigated by using FIB and TEM analysis for the first time to disclose the underlying inhibition mechanism.A porous corrosion bi-layer composed of crystalline MgO and Mg(OH)_(2)was observed on both ofα-Mg and Al-Mn intermetallic.It was found that a passive inner layer was deposited onα-Mg after immersion in SDS-containing NaCl solution,which can be ascribed to steady-state growth of magnesium and aluminum oxide under the protection of hydrophobic group of SDS.The inhibition mechanism of the inhibitor was mainly associated with formation of dense oxide layer onα-Mg matrix and preferential adsorption of SDS on the corrosion layer deposited on Al-Mn intermetallic.
基金supported by the National Natu-ral Science Foundation of China under Grant(Nos.51671053 and 51801021)the National Key R&D Program of China under Grant(No.2017YFB0306100)+1 种基金the Fundamental Research Funds for the Central Universities(No.N2102015)by the Ministry of Indus-try and Information Technology Project(No.MJ-2017-J-99).
文摘Surface rumpling is detrimental to high temperature protective coatings as it shortens their lifetime and leads to adhesion losses and unexpected corrosion degradation.The driving force and mass transport mechanism behind of rumpling remains to be clarified.In the present investigation,we subjected two types of nanocrystalline coating systems to avoid the influence of interdiffusion on rumpling study.One group was an ordinary nanocrystalline coating,and the other group was designed and prepared with trace oxygen by reactive magnetron sputtering.Systematic cyclic oxidation test at 1100°C was also car-ried out.Results show the ordinary nanocrystalline coating oxidized rapidly,which leads to the fast consumption of Al and the acceleration of phase transition in the coating.Meanwhile,severe surface rumpling is observed due to the stress release of nanocrystals through plastic deformation.Besides,the reactive doping of oxygen can significantly reduce the consumption process of Al in nanocrystalline coat-ing.The rumpling is controlled due to the improvement of coefficient of thermal expansion and Young’s modulus of the coating.Thereafter,the cyclic oxidation resistance is improved.
基金The work was financially supported by the National Natural Science Foundation of China(Grant No.31701325,31671632)the Potato innovation team of Shandong modern agricultural industry technology system(Grant No.SDAIT-16-10)+2 种基金Ningbo Public Welfare Science and Technology Project(Grant No.202002N3011)Green Farming and Mechanical Innovation Team of Fruit Harvesting under Soilthe Key Laboratory of Modern Agricultural Equipment,Ministry of Agriculture and Rural Affairs,China.
文摘Planting on mulched soil is the main cultivation mode for sweet potato slips in spring in northern China.The‘boatbottom’planting method can bring high quantity and similar size for sweet potatoes.In this study,a mechanism for transplanting sweet potato seedlings on mulched was proposed,which could realize‘boat-bottom’transplanting trajectory and improve the planting efficiency.The virtual prototype model of the transplanting mechanism was constructed using ADAMS software,a soil particle model and a flexible body model of sweet potato seedling were established using EDEM software,and then a joint simulation was carried out to find out the interaction of mechanism,seedling and soil.By simulation,the trajectory of the clamping point,the sweet potato seedling posture,soil particles,pits,and relative force were all analyzed,which verified the rationality of the transplanting mechanism design.Finally,three kinds of sweet potato seedlings,watermelon red,Yan-25,and purple sweet potato seedlings were selected,and transplanting experiments were carried out on the mulch to verify that the theoretical trajectory,the simulated trajectory,and the actual trajectory were consistent.The transplanting success rates of the three kinds of sweet potato seedlings were all above 85%,indicating that different varieties of sweet potato seedlings had little effect on the transplanting effect of the mechanism,which reflected that the transplanting mechanism had good practicability and adaptability.
基金This work was financially supported by the National Natural Science Foundation of China(No.U2006219)the National Key Re-search and Development Program of China(No.2020YFA0907300)+1 种基金the Fundamental Research Funds for the Central Universities of the Ministry of Education of China(Nos.N2102009 and N2002019)Liaoning Revitalization Talents Program(No.XLYC1907158).
文摘Corrosion-resistant high nitrogen high entropy alloys(HEAs)were manufactured by pressurized metal-lurgy.This work revealed the inhibitory effect of nitrogen on pitting corrosion of HEAs caused by sul-fate reducing bacterium Desulfovibrio vulgaris.Results indicated that HEA-0 N was susceptible to pitting corrosion and sulfidation under attack of D.vulgaris,whereas the addition of nitrogen significantly de-creased the pitting sensitivity.Pitting potentials of HEA-0.52 N and HEA-1.23 N increased by 133%and 171%,respectively compared to HEA-0 N in the presence of SRB.X-ray photoelectron spectroscopy results unveiled that nitrogen enriched in passive film and strengthened it by increasing fraction of Cr_(2)O_(3)and Fe^(3+)_(ox).Surface of the nitrogen-alloyed HEAs exhibited less defective passive films as revealed by Mott-Schottky results.Nitrogen doping provides a novel insight into the design of microbial corrosion resistant HEA.
基金supported by the National Natural Science Foundation of China(No.51871050)the National Natural Science Foundation of China(No.U2106206)+3 种基金the Natural Science Foundation of Liaoning Province(No.20180510041)the Liaon-ing Revitalization Talents Program(No.XLYC1907158)the Gen-eral Project of Natural Science Foundation of Science and Tech-nology Department of Liaoning Province(No.2021-MS-308)the Fundamental Research Funds for the Central Universities(No.N2120007).
文摘Cariogenic Streptococcus mutans(S.mutans)is a leading cause of bacterial-induced oral diseases.Current strategies to kill bacteria based on Host defense peptide(HDP)mimicking polymers hold promise to treat oral bacterial infection.Here,we explore the impact of hydrophobic subunit and chain length variation on the antibacterial and antibiofilm activity ofβ-peptide polymers.The physicochemical and biological prop-erties,such as the toxicity,the antibacterial activity,and the effect on bacterial transcription ofβ-peptide polymers,were systematically investigated with numerous techniques.The results exhibited that the op-timalβ-peptide polymer has low toxicity towards human periodontal ligament fibroblasts,andβ-peptide polymers(especially P3)have more excellent antibacterial activity against S.mutans than metronidazole.In addition,β-peptide polymers inhibited the reversible and irreversible bacterial adhesion during the formation of biofilms.The polymer can promote biofilm dispersion by decreasing the hydrophobicity of bacterial cells after adhering to cell surfaces.Analysis of the transcriptome for S.mutans treated withβ-peptide polymers demonstrated thatβ-peptide polymers could reduce the cariogenicity of S.mutans by impacting the transcription of the energy and acid metabolism-related genes.β-peptide polymers are promising antimicrobial agents in clinical dentistry due to their high antibacterial efficiency and low tox-icity.
基金supported by the National Natural Science Foundation of China(No.51871051).
文摘Nanocrystalline coating with the same chemical composition as the nickel-based superalloys was proved to possess high resistance to oxidation and scale spallation,meanwhile avoid notable elements inter-diffusion.It opens up a new direction for the development of protective coatings.However,in a worse environment containing chlorine and water vapor,the ultrafine grains act like a double-edged sword,which can promote the formation of a protective scale of Al_(2)O_(3)or Cr_(2)O_(3),but also favor the inward dif-fusion of Cl and H_(2)O to accelerate corrosion.In order to solve this problem,moderate amount of oxygen was doped into nanocrystalline coating during magnetron sputtering.Then,corrosion behavior of the two nanocrystalline coatings with or without oxygen doping was studied in the O_(2)+38%H_(2)O environment with solid NaCl deposit.Results indicated that the doped oxygen can attract active elements of Ti and Al to form TiO_(2)andθ-Al_(2)O_(3),which pinned at grain boundaries to keep the ultrafine grains stable at high temperature while prevent inward diffusion of the corrosive media.Accordingly,a dense and pure chromia scale was formed quickly at surface,ensuring that the oxygen-doped nanocrystalline coating provided the highest corrosion resistance under the synergy of solid NaCl deposit and water vapor.In contrast,the coating without oxygen doping suffered from severe internal corrosion.
基金supported by Science Foundation of China University of Petroleum,Beijing(Nos.2462017YJRC038 and 2462018BJC005)supported by the National Natural Science Foundation of China(Grant U1660118)+1 种基金the National Basic Research Program of China(973 Program,No.2014CB643300)the National Environmental Corrosion Platform(NECP)
文摘Microbiologically influenced corrosion(MIC) is a major cause of corrosion damages, facility failures, and financial losses, making MIC an important research topic. Due to complex microbiological activities and a lack of deep understanding of the interactions between biofilms and metal surfaces, MIC occurrences and mechanisms are difficult to predict and interpret. Many theories and mechanisms have been proposed to explain MIC. In this review, the mechanisms of MIC are discussed using bioenergetics, microbial respiration types, and biofilm extracellular electron transfer(EET). Two main MIC types, namely EET-MIC and metabolite MIC(M-MIC), are discussed. This brief review provides a state of the art insight into MIC mechanisms and it helps the diagnosis and prediction of occurrences of MIC under anaerobic conditions in the oil and gas industry.
基金supported by the National Natural Science Fund of China (Nos.51622106 and 5167010950)the National Key Basic Research and Development Plan of China (No.2014CB643303)the International S&T Cooperation Program of China (ISTCP) (No.2014DFR50560)
文摘The corrosion behavior of 2 A02 Al alloy under simulated marine atmospheric environment has been studied using mass-gain, scanning electron microscope/energy dispersive spectroscopy(SEM/EDS), laser scanning confocal microscopy, X-ray diffraction spectroscopy and localized electrochemical methods. The results demonstrate that the relationship between the corrosion induced mass-gain and the corrosion time is in accordance with the power rule. The mass-gain increases gradually during the corrosion time,while the corrosion rate decreases. With ongoing of the corrosion, corrosion products film changed from a porous to a compact structure. The various spectroscopic data show that the corrosion products films composed mainly of Al(OH)_3, Al_2O_3 and AlCl_3. The electrochemical corrosion behavior of the 2 A02 Al alloy was studied by electrochemical impedance spectroscopy(EIS).
基金the financial support from the National Natural Science Foundation of China (Nos. 50971050 and 50771038)the Ministry of Science and Technology of China (No. 2012FY113000)the Fundamental Research Founds for the Central Universities (No. HEUCF101005).
文摘The corrosion behavior of 316L stainless steel(316L SS) has been investigated in solutions containing various concentrations of chloride ions by using potentiodynamic polarization, capacitance measurement and Motte Schottky relationship analysis(Me S). The result indicates that passive currents change slightly with the addition of chloride ions. The pitting potential(Epit) decreases linearly with log[Cl ]. Correspondingly, the point defect diffusion coefficient(Do) of the passive film increases linearly with increasing log[Cl ]. The results also indicate that the pitting corrosion of 316L SS follows the adsorption mechanism in NaCl solution.
基金financially supported by the National Natural Science Foundation of China(No.51071163)the National Key Basic Research and Development Program("973 Program",Nos.2010CB631206 and 2012CB625100)the National High Technology Research and Development Program of China(No.2012AA03A512)
文摘The isothermal and cyclic oxidation behaviors in air and hot corrosion behaviors in Na2SO4t 25 wt%K2SO4salt of M951 cast superalloy and a sputtered nanocrystalline coating of the same material were studied.Scanning electron microscopy,energy dispersive X-ray spectroscope,X-ray diffraction,and transmission electron microscopy were employed to examine the morphologies and phase composition of the M951 alloy and nanocrystalline coating before and after oxidation and hot corrosion.The as-sputtered nanocrystalline layer has a homogeneous g phase structure of very fine grain size(30e200 nm)with the preferential growth texture of(111)parallel to the interface.Adherent Al2O3rich oxide scale formed on the cast M951 alloy and its sputtered coating after isothermal oxidation at 900 and 1000 C.However,when being isothermal oxidized at 1100 C and cyclic oxidized at 1000 C,the oxide scale formed on the cast alloy was a mixture of NiO,NiAl2O4,Al2O3and Nb2O5and spalled seriously,while that formed on the sputtered coating mainly consisted of Al2O3and was very adherent.Nanocrystallization promoted rapid formation of Al2O3scale during the early stage of oxidation and enhanced the adhesion of the oxide scale,thus improved the oxidation resistance of the substrate alloy.Serious corrosion occurred for the cast alloy.The sputtered nanocrystalline coating apparently improved the hot corrosion resistance of the cast alloy in the mixed sulfate by the formation of a continuous Al2O3and Cr2O3mixed oxide layer on the surface of the coating,and the preoxidation treatment of the coating led to an even better effect.
