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
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
In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion perform...In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion performance in simulated body fluid of Mg65Zn30Ca5 alloy were studied through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and electrochemical and immersion tests. Results show that with the Mn addition increasing, all the ribbon samples are completely in amorphous state. However, the microstructure of 2-mm rod samples transfers from fully amorphous for the Mn-free alloy to almost polycrystalline state with precipitated Mg, Mn, and MgZn phases. Glass-forming ability of Mg65Zn30Ca5 alloy is decreased by Mn addition. Results of electrochemical and immersion tests demon- strate that the Mn-doped samples exhibit more negative corrosion potential and larger corrosion current density, suggesting that the corrosion resistance decreases with doping amount of Mn element increasing.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
Recently it is a hot topic to make full use of high abundant Y element in Nd_(2)Fe_(14)B-type permanent magnets.In contrast to Pr and Nd elements,Y shows different metallurgical behaviors during preparation process.In...Recently it is a hot topic to make full use of high abundant Y element in Nd_(2)Fe_(14)B-type permanent magnets.In contrast to Pr and Nd elements,Y shows different metallurgical behaviors during preparation process.In this paper,we have explored the magnetic properties,microstructures and corrosion performance of Pr-Nd-Y-Fe-B magnets fabricated by spark plasma sintering(SPS)technique from the ribbons of nanocrystalline and amorphous precursors,respectively.The coercivity and maximum energy product were improved for the magnets prepared from amorphous precursor materials(denoted as SPS-A hereafter)compared with the magnets prepared from crystalline precursor materials(denoted as SPS-C hereafter).Magnetic properties of Jr=0.79 T,Hci=864 k A/m,and(BH)_(max)=102 k J/m^(3)were obtained for SPS-A magnets.In contrast with SPS-C magnets,the magnetic properties of SPS-A magnets are not so sensitive to the preparation conditions,which is quite beneficial to the homogeneity of microstructure and enhancement of coercivity for large-scale production of the designated magnets.Aggregated(Pr,Nd,Y)-rich phase was found out in SPS-C magnets.Pr and Nd elements are rich at grain boundary while Y is distributed uniformly at main phase and grain boundary phase.The strip grains and equiaxed grains exist in SPS-C and SPS-A magnets,respectively.The enhanced magnetic properties for SPS-A magnets are accredited to the uniform distribution of rare-earth-rich phase and low demagnetization factor.It is revealed by electrochemical test and dipping test that the corrosion potential is more positive and the corrosion rate is slower for the SPS-A magnets in 3.5 wt.%Na Cl solution.The work is also expected to shed light on developing the nanocrystalline Pr-Nd-Y-Fe-B SPSed high-performance magnets in industry.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
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
High-pressure die cast(HPDC)AZ91 magnesium alloy is widely used in automotive components such as transmission housings and brackets for its excellent strength-to-weight ratio.Zinc-based cold spray coatings can be appl...High-pressure die cast(HPDC)AZ91 magnesium alloy is widely used in automotive components such as transmission housings and brackets for its excellent strength-to-weight ratio.Zinc-based cold spray coatings can be applied selectively to vulnerable areas to enhance corrosion resistance,minimize galvanic coupling with dissimilar metals,and eliminate the need for full-surface oxide coatings,making the process more efficient and targeted.A comprehensive evaluation of 16 combinations of nitrogen carrier gas temperatures and pressures led to the identification of an optimal range of process parameters,yielding Zn coatings with porosity<0.5% by area,wear rates reduced by a factor of two compared to uncoated AZ91,and adhesion strengths up to 35 MPa.The enhanced mechanical performance of the coating is attributed to the low porosity and the formation of a metallurgical bond at the coating-substrate interface.Corrosion studies using macroscale potentiodynamic polarization(PDP)and electrochemical impedance spectroscopy(EIS)revealed a significant decrease in corrosion rate and a shift to more noble corrosion potentials(ZCP)for coated substrates.Furthermore,the Zn cold-sprayed samples exhibited significantly lower corrosioninduced evolved hydrogen content compared to the base AZ91 substrate and AZ91 coated with industrial coatings,demonstrating that the Zn layer effectively protects the substrate from the corrosive environment.Overall,cold spray Zn coatings significantly improve the mechanical and corrosion performance of AZ91 Mg alloys,addressing key material challenges and enabling their broader use in automotive applications.展开更多
The impact of cryorolling(CR)and room temperature rolling(RTR)followed by artificial aging on the corrosion characteristics of 2195 Al−Li alloy(AA2195)was studied.Transmission electron microscope,scanning electron mic...The impact of cryorolling(CR)and room temperature rolling(RTR)followed by artificial aging on the corrosion characteristics of 2195 Al−Li alloy(AA2195)was studied.Transmission electron microscope,scanning electron microscope,optical microscope,intergranular corrosion experiment,and electrochemical experiment were used.Throughout different stages of aging treatment,the corrosion behavior of both CR and RTR samples exhibited a sequential progression of pitting corrosion,followed by intergranular corrosion,and then pitting corrosion again.The corrosion rates of both samples initially showed an increase,followed by a gradual stabilization over time.The size and density of T1 phase significantly influenced the corrosion performance of the alloy.During the peak aging and over-aging stages,the CR sample exhibited superior corrosion resistance to the RTR sample,attributed to its finer T1 phase.展开更多
Magnesium alloys hold promise as biodegradable orthopedic implants but suffer from rapid corrosion and poor corrosion fatigue performance.This study evaluates the efficacy of a micro-arc oxidation(MAO)layer combined w...Magnesium alloys hold promise as biodegradable orthopedic implants but suffer from rapid corrosion and poor corrosion fatigue performance.This study evaluates the efficacy of a micro-arc oxidation(MAO)layer combined with 3-glycidyloxypropyltrimethoxysilane(GPTMS)sealing in enhancing the corrosion fatigue behavior of ZE21B magnesium alloy in Hanks’Balanced Salt Solution(HBSS).Electrochemical testing revealed a two-order-of-magnitude reduction in corrosion current density compared to bare alloy,while immersion tests demonstrated sustained protection against degradation.Corrosion fatigue experiments under cyclic loading showed stress-dependent performance:the composite coating improved fatigue life at low stress amplitudes(60 MPa)by mitigating corrosion pit formation,but interfacial weakness between GPTMS and MAO layers reduced performance at high stresses(90-80 MPa).Fractographic analysis identified asynchronous deformation and stress gradient-dependent coating spallation as key failure modes.These results provide mechanistic insights into coating degradation pathways and offer design strategies for developing robust surface modification systems to advance magnesium-based orthopedic applications.展开更多
Copper is a versatile material,commonly utilized in power transmission and electronic devices,but its relative high reactivity necessitates a long-lasting protective technique.Here,we report a method that combines pla...Copper is a versatile material,commonly utilized in power transmission and electronic devices,but its relative high reactivity necessitates a long-lasting protective technique.Here,we report a method that combines plasma-enhanced non-equilibrium magnetron sputtering physical vapor deposition(PEUMS-PVD)and anodization to construct a self-healing three-dimensional Ti/Al-doped TiO_(2)nanotubes/Ti_(3)AlC_(2)coating on the surface of Cu substrates.This novel strategy enhances the corrosion resistance of copper substrates in marine environments,with corrosion current densities of up to 4.5643×10^(−8)A/cm^(2).Among them,the doping of nano-aluminum particles makes the coating self-healing.The mechanistic analysis of the corrosion behaviors during early immersion experiments was conducted using electrochemical noise,and revealed that during the initial stages of coating immersion,uniform corrosion predominates,with a minor occurrence of localized corrosion.展开更多
The rust layer plays an important role in the corrosion of steel in chlorinated environments. Salt spray, po- tentiodynamic polarization curve and tensile test were conducted in laboratory for the specimens after two-...The rust layer plays an important role in the corrosion of steel in chlorinated environments. Salt spray, po- tentiodynamic polarization curve and tensile test were conducted in laboratory for the specimens after two-stage heat treatment. The influence of the alloying elements on mechanical properties and corrosion resistance of three kinds of steels was investigated by observing the microstructure and the morphologies of rust layer. The results show that the highest value （29%） of total elongation for steel A is obtained. The mechanical property of the specimen for steel C exhibits best strength ductility balance （21 384 MPa ·%） because of the presence of the multiphase microstructures after a two-stage heat treatment and the addition of the alloying elements. The corrosion products are known to be a complex mixture of Fe3O4 , Fe2O3 and α-FeOOH for steel C. The presence of the alloying elements results in the for mation of compact and dense rust layers in steel B and C. Passive film protects the substrate of TRIP （transformation induced plasticity） steel containing a complex mix of multiphase. Superior corrosion performance is exhibited for steel C with low alloying contents due to the enrichment of alloying elements within the rust layers.展开更多
To improve the surface performance of TB2 alloy,pack boriding was performed at 1100℃ for 20 h with 4 wt.%La_(2)O_(3).The composition and thickness of boride layer and corrosion and wear properties of borided TB2 allo...To improve the surface performance of TB2 alloy,pack boriding was performed at 1100℃ for 20 h with 4 wt.%La_(2)O_(3).The composition and thickness of boride layer and corrosion and wear properties of borided TB2 alloy were measured.The results show that La_(2)O_(3) can promote the growth,continuity,and compactness of boride layer,and the length of TiB whisker increases from 16.80 to 21.84μm.The reason is that La_(2)O_(3) can react with B to form La−B active groups and further to improve the growth of the boride layer.The wear and corrosion resistances of TB2 alloy are enhanced by boriding with La_(2)O_(3).The wear mechanisms are adhesive wear and abrasive wear for unborided and borided TB2 alloys,respectively,and the corrosion mechanism is changed from local corrosion(unborided TB2 alloy)to uniform corrosion(borided TB2 alloy).展开更多
The Mo-N surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo-N modified Ti6Al4V alloy were investigated by X-ray diffraction （XRD） a...The Mo-N surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo-N modified Ti6Al4V alloy were investigated by X-ray diffraction （XRD） and glow discharge optical emission spectroscopy （GDOES）. The Mo-N modified layer contains Mo-N coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo-N modified Ti6Al4V alloy reveals that the outmost surface of the Mo-N modified Ti6Al4V alloy is composed of phase Mo2N （fcc） and Mo2N （tetr）. The electrochemical corrosion performance of the Mo-N modified Ti6Al4V alloy in 0.5 mol/L HCl solution was investigated and compared with that of Ti6Al4V alloy. The chemical corrosion performance of the Mo-N modified Ti6Al4V alloy in boiling 37% HCl solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that self-corroding electric potentials and corrosion-rate of the Mo-N modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 0.5 mol/L HCl solution. The corrosion-rate of the Mo-N modified Ti6Al4V alloy is lower than that of Ti6Al4V alloy in boiling 37% HCl solution.展开更多
Although magnesium(Mg)alloys are the lightest among structural metals,their inadequate corrosion resistance makes them difficult to be used in energy-saving lightweight structures.Moreover,the improvement in corrosion...Although magnesium(Mg)alloys are the lightest among structural metals,their inadequate corrosion resistance makes them difficult to be used in energy-saving lightweight structures.Moreover,the improvement in corrosion resistance by the conventional surface treatments is always achieved at the expense of sacrificing the fatigue lifetime.In this study,high purity aluminum(Al)and AlMgSi alloy coatings were deposited on Mg alloys via an in-situ micro-forging(MF)assisted cold spray(MFCS)process for simultaneous higher corrosion resistance and longer fatigue lifetime.Besides contributing to a highly dense microstructure,the in-situ MF also greatly refines the grain of the deposited Al alloy coating to the sub-micrometer range due to the enhanced dynamic recrystallization and also generates notable compressive residual stress up to 210 MPa within the AlMgSi coating.The absence of secondary phases in the AlMgSi alloy coatings enable the coated Mg alloy with corrosion resistance,which is even better than its bulk AlMgSi counterparts.The unique combination of refined microstructure and the prominent compressive residual stress within the AlMgSi coatings,effectively delayed the crack initiation upon repeated dynamic loading,thereby leading to∼10 times increase in the fatigue lifetime of the Mg Alloy.However,although residual stress is also generated in the submmicro-sized grained pure Al coating,the low intrinsic strength of the coating layer leads to a lower fatigue lifetime than the uncoated Mg alloy substrate.The present work is aimed to provide a facile approach to break the trade-off between corrosion resistance improvement and fatigue lifetime of the coated Mg alloys.展开更多
Three kinds of rare earth nitrates were adopted to sodium molybdate to get three kinds of LnN-M compounded inhibitors （La（NO3）3＋Na2MoOa（LaN-M）, Ce（NO3）3＋Na2MoOn（CeN-M）, Pr（NO3）3＋Na2MoO4（PrN-M））. The c...Three kinds of rare earth nitrates were adopted to sodium molybdate to get three kinds of LnN-M compounded inhibitors （La（NO3）3＋Na2MoOa（LaN-M）, Ce（NO3）3＋Na2MoOn（CeN-M）, Pr（NO3）3＋Na2MoO4（PrN-M））. The combination of weight-loss method and the electrochemical test, was used to evaluate and analyze the corrosion inhibition efficiency of these LnN-M inhibitors to make the research on their corrosion inhibition performance, and the sequential order of their performance was found as follows： CeN-M〉 LaN-M〉PrN-M, among which, the inhibition efficiency of CeN-M for the X70 steel could reach 98.21%. The synergism parameters were calculated by weight-loss method, these computational data indicated that the synergistic effect between rare earth nitrates and sodium molybdate was obvious and significant. Surface morphology, chemical composition and phase components of the precipitation films were tested for discussing the mechanism of LnN-M inhibitors. The outer electronic configuration of the lanthanide was found to have an important influence on the inhibition efficiency. The CeN-M inhibitor was discovered to have the best inhibition effect with the amorphous cerium oxides. The results of this research revealed that the precipitation films formed on the surface of the steel samples had a crucial influence on the inhibition efficiencies after adding LnN-M inhibitors.展开更多
Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and biocompatibility.In the present study,Mg–3Zn-x Ag（w...Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and biocompatibility.In the present study,Mg–3Zn-x Ag（wt%,x=0.2,0.5 and0.8）alloys with single-phase crystal structure were prepared by backward extrusion at 340°C.The addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag concentration.The tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present work.The extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.展开更多
A kind of environmental friendly anodizing routine for AZ91D magnesium alloy,based on an alkaline borate-potassium acid phthalate（KAP） electrolyte,was studied.The effect of KAP on the properties of the anodized film...A kind of environmental friendly anodizing routine for AZ91D magnesium alloy,based on an alkaline borate-potassium acid phthalate（KAP） electrolyte,was studied.The effect of KAP on the properties of the anodized film was investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,energy dispersive spectrometry（EDS）,potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）,respectively.The results showed that the anodizing process,surface morphology,thickness,phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of KAP.In the presence of adequate KAP,a compact and smooth anodized film with excellent corrosion resistance was obtained.展开更多
Multiphase TRIP(Transformation Induced Plasticity)steels are known to combine higher strength with higher ductility.In this paper,the corrosion resistance of this steel has been has been investigated by accelerated co...Multiphase TRIP(Transformation Induced Plasticity)steels are known to combine higher strength with higher ductility.In this paper,the corrosion resistance of this steel has been has been investigated by accelerated corrosion tests,such as wet/dry cyclic corrosion and the weight loss in laboratory.The morphologies of their rust layers were observed by using scanning electron microscopy,and the corrosion performance of these steels was discussed by analyzing the protective mechanism.The results show that the corrosion rate of steel A is significantly greater than that of steels B and C in wet/dry cyclic corrosion and weight loss tests.The corrosion performance of conventional C-Mn-Si TRIP steel is deteriorated in both NaHSO 3 and 3.5 wt.%NaCl aqueous solutions.And superior corrosion performance is exhibited for TRIP steel with low alloying contents due to its high thermodynamic stability.The enhancement of corrosion performance of TRIP steel is attributed to the additions of alloying elements,such as Al,Cu,Cr,Mo,Ni,etc.The alloying elements increase the compactness of rust layers,so electrochemical characteristic of TRIP steel is improved.展开更多
AA7085 aluminum alloys with different Cu/Mg ratios （0.67, 1.0, 1.06, 1.6） were prepared by ingot metallurgy method. The effects of Cu/Mg ratio on the microstructure, mechanical properties and corrosion behavior of t...AA7085 aluminum alloys with different Cu/Mg ratios （0.67, 1.0, 1.06, 1.6） were prepared by ingot metallurgy method. The effects of Cu/Mg ratio on the microstructure, mechanical properties and corrosion behavior of the AA7085 alloys were investigated by optical microscope, scanning electron microscope （SEM）, mechanical properties and corrosion testing. The results indicate that a better recrystallization inhibition and corrosion resistance can be achieved when Cu/Mg ratio is 1.6. When Cu/Mg ratio is 0.67, the alloy reveals better mechanical properties, and the tensile strength and yield strength of AA7085 alloys are 586 and 550 MPa, respectively. Moreover, both the mechanical properties and corrosion resistance of the alloy are reduced when Cu/Mg ratio is equal to 1.0.展开更多
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.
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 Natural Science Foundation of China (Nos. 51201120 and 51401155)the Science & Technology Coordination & Innovation Project of Shaanxi Province(No. 2016KTZDGY-04-01)the Key Laboratory Program Funded by Shaanxi Provincial Education Department(No.17JS053)
文摘In the present work, ribbon and 2-mm rod samples of Mg-Zn-Ca-Mn alloys were prepared by meltspinning and copper mold injection methods, respectively. Effects of Mn doping on glass-forming ability and corrosion performance in simulated body fluid of Mg65Zn30Ca5 alloy were studied through X-ray diffraction, scanning electron microscopy, differential scanning calorimeter, and electrochemical and immersion tests. Results show that with the Mn addition increasing, all the ribbon samples are completely in amorphous state. However, the microstructure of 2-mm rod samples transfers from fully amorphous for the Mn-free alloy to almost polycrystalline state with precipitated Mg, Mn, and MgZn phases. Glass-forming ability of Mg65Zn30Ca5 alloy is decreased by Mn addition. Results of electrochemical and immersion tests demon- strate that the Mn-doped samples exhibit more negative corrosion potential and larger corrosion current density, suggesting that the corrosion resistance decreases with doping amount of Mn element increasing.
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.
基金supported by the National Natural Science Foundation of China(Nos.51901089 and 51671097)the Foundation of Jiangxi Educational Committee(No.GJJ180472)+2 种基金the Science and Technology Program of Fujian Province(No.2017T3001)the Key Research and Development Program of Jinagxi Province(No.20201BBE51010)the Ph D.Start-up Foundation of Jiangxi University of Science and Technology(No.JXXJBS18052)。
文摘Recently it is a hot topic to make full use of high abundant Y element in Nd_(2)Fe_(14)B-type permanent magnets.In contrast to Pr and Nd elements,Y shows different metallurgical behaviors during preparation process.In this paper,we have explored the magnetic properties,microstructures and corrosion performance of Pr-Nd-Y-Fe-B magnets fabricated by spark plasma sintering(SPS)technique from the ribbons of nanocrystalline and amorphous precursors,respectively.The coercivity and maximum energy product were improved for the magnets prepared from amorphous precursor materials(denoted as SPS-A hereafter)compared with the magnets prepared from crystalline precursor materials(denoted as SPS-C hereafter).Magnetic properties of Jr=0.79 T,Hci=864 k A/m,and(BH)_(max)=102 k J/m^(3)were obtained for SPS-A magnets.In contrast with SPS-C magnets,the magnetic properties of SPS-A magnets are not so sensitive to the preparation conditions,which is quite beneficial to the homogeneity of microstructure and enhancement of coercivity for large-scale production of the designated magnets.Aggregated(Pr,Nd,Y)-rich phase was found out in SPS-C magnets.Pr and Nd elements are rich at grain boundary while Y is distributed uniformly at main phase and grain boundary phase.The strip grains and equiaxed grains exist in SPS-C and SPS-A magnets,respectively.The enhanced magnetic properties for SPS-A magnets are accredited to the uniform distribution of rare-earth-rich phase and low demagnetization factor.It is revealed by electrochemical test and dipping test that the corrosion potential is more positive and the corrosion rate is slower for the SPS-A magnets in 3.5 wt.%Na Cl solution.The work is also expected to shed light on developing the nanocrystalline Pr-Nd-Y-Fe-B SPSed high-performance magnets in industry.
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.
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the support of the U.S.Department of Energy’s Vehicle Technologies Office.
文摘High-pressure die cast(HPDC)AZ91 magnesium alloy is widely used in automotive components such as transmission housings and brackets for its excellent strength-to-weight ratio.Zinc-based cold spray coatings can be applied selectively to vulnerable areas to enhance corrosion resistance,minimize galvanic coupling with dissimilar metals,and eliminate the need for full-surface oxide coatings,making the process more efficient and targeted.A comprehensive evaluation of 16 combinations of nitrogen carrier gas temperatures and pressures led to the identification of an optimal range of process parameters,yielding Zn coatings with porosity<0.5% by area,wear rates reduced by a factor of two compared to uncoated AZ91,and adhesion strengths up to 35 MPa.The enhanced mechanical performance of the coating is attributed to the low porosity and the formation of a metallurgical bond at the coating-substrate interface.Corrosion studies using macroscale potentiodynamic polarization(PDP)and electrochemical impedance spectroscopy(EIS)revealed a significant decrease in corrosion rate and a shift to more noble corrosion potentials(ZCP)for coated substrates.Furthermore,the Zn cold-sprayed samples exhibited significantly lower corrosioninduced evolved hydrogen content compared to the base AZ91 substrate and AZ91 coated with industrial coatings,demonstrating that the Zn layer effectively protects the substrate from the corrosive environment.Overall,cold spray Zn coatings significantly improve the mechanical and corrosion performance of AZ91 Mg alloys,addressing key material challenges and enabling their broader use in automotive applications.
基金supported by the High-tech Industry Technology Innovation Leading Plan of Hunan Province,China(No.2022GK4032)the State Key Laboratory of Precision Manufacturing for Extreme Service Performance at Central South University,China.
文摘The impact of cryorolling(CR)and room temperature rolling(RTR)followed by artificial aging on the corrosion characteristics of 2195 Al−Li alloy(AA2195)was studied.Transmission electron microscope,scanning electron microscope,optical microscope,intergranular corrosion experiment,and electrochemical experiment were used.Throughout different stages of aging treatment,the corrosion behavior of both CR and RTR samples exhibited a sequential progression of pitting corrosion,followed by intergranular corrosion,and then pitting corrosion again.The corrosion rates of both samples initially showed an increase,followed by a gradual stabilization over time.The size and density of T1 phase significantly influenced the corrosion performance of the alloy.During the peak aging and over-aging stages,the CR sample exhibited superior corrosion resistance to the RTR sample,attributed to its finer T1 phase.
基金the National Natural Science Foundation of China(52301107)the Joint Fund Project of Henan Provincial Science and Technology Research and Development Plan(242301420036).
文摘Magnesium alloys hold promise as biodegradable orthopedic implants but suffer from rapid corrosion and poor corrosion fatigue performance.This study evaluates the efficacy of a micro-arc oxidation(MAO)layer combined with 3-glycidyloxypropyltrimethoxysilane(GPTMS)sealing in enhancing the corrosion fatigue behavior of ZE21B magnesium alloy in Hanks’Balanced Salt Solution(HBSS).Electrochemical testing revealed a two-order-of-magnitude reduction in corrosion current density compared to bare alloy,while immersion tests demonstrated sustained protection against degradation.Corrosion fatigue experiments under cyclic loading showed stress-dependent performance:the composite coating improved fatigue life at low stress amplitudes(60 MPa)by mitigating corrosion pit formation,but interfacial weakness between GPTMS and MAO layers reduced performance at high stresses(90-80 MPa).Fractographic analysis identified asynchronous deformation and stress gradient-dependent coating spallation as key failure modes.These results provide mechanistic insights into coating degradation pathways and offer design strategies for developing robust surface modification systems to advance magnesium-based orthopedic applications.
基金Projects(42106051,42006046,U2106206) supported by the National Natural Science Foundation of ChinaProject(22373501D) supported by Hebei Provincial Key R&D Program,China。
文摘Copper is a versatile material,commonly utilized in power transmission and electronic devices,but its relative high reactivity necessitates a long-lasting protective technique.Here,we report a method that combines plasma-enhanced non-equilibrium magnetron sputtering physical vapor deposition(PEUMS-PVD)and anodization to construct a self-healing three-dimensional Ti/Al-doped TiO_(2)nanotubes/Ti_(3)AlC_(2)coating on the surface of Cu substrates.This novel strategy enhances the corrosion resistance of copper substrates in marine environments,with corrosion current densities of up to 4.5643×10^(−8)A/cm^(2).Among them,the doping of nano-aluminum particles makes the coating self-healing.The mechanistic analysis of the corrosion behaviors during early immersion experiments was conducted using electrochemical noise,and revealed that during the initial stages of coating immersion,uniform corrosion predominates,with a minor occurrence of localized corrosion.
基金Sponsored by National Natural Science Foundation of China(50334010)Shenyang City Application Basic Research Project of China(1071198-1-00)
文摘The rust layer plays an important role in the corrosion of steel in chlorinated environments. Salt spray, po- tentiodynamic polarization curve and tensile test were conducted in laboratory for the specimens after two-stage heat treatment. The influence of the alloying elements on mechanical properties and corrosion resistance of three kinds of steels was investigated by observing the microstructure and the morphologies of rust layer. The results show that the highest value （29%） of total elongation for steel A is obtained. The mechanical property of the specimen for steel C exhibits best strength ductility balance （21 384 MPa ·%） because of the presence of the multiphase microstructures after a two-stage heat treatment and the addition of the alloying elements. The corrosion products are known to be a complex mixture of Fe3O4 , Fe2O3 and α-FeOOH for steel C. The presence of the alloying elements results in the for mation of compact and dense rust layers in steel B and C. Passive film protects the substrate of TRIP （transformation induced plasticity） steel containing a complex mix of multiphase. Superior corrosion performance is exhibited for steel C with low alloying contents due to the enrichment of alloying elements within the rust layers.
基金the financial support from the National Natural Science Foundation of China (No. 51761023)。
文摘To improve the surface performance of TB2 alloy,pack boriding was performed at 1100℃ for 20 h with 4 wt.%La_(2)O_(3).The composition and thickness of boride layer and corrosion and wear properties of borided TB2 alloy were measured.The results show that La_(2)O_(3) can promote the growth,continuity,and compactness of boride layer,and the length of TiB whisker increases from 16.80 to 21.84μm.The reason is that La_(2)O_(3) can react with B to form La−B active groups and further to improve the growth of the boride layer.The wear and corrosion resistances of TB2 alloy are enhanced by boriding with La_(2)O_(3).The wear mechanisms are adhesive wear and abrasive wear for unborided and borided TB2 alloys,respectively,and the corrosion mechanism is changed from local corrosion(unborided TB2 alloy)to uniform corrosion(borided TB2 alloy).
基金Funded by the 863 Program(No.2007AA03Z521)the National Natural Science Foundation of China(No.50771070)the Program for the Top Young and Middle-aged Innovative Talents of Higher Learning Institutions of Shanxi and the Scientific Foundationfor Returned Overseas Scholars of Shanxi Province(No.2006-27)
文摘The Mo-N surface modified layer on Ti6Al4V alloy was obtained by the plasma surface alloying technique. The structure and composition of the Mo-N modified Ti6Al4V alloy were investigated by X-ray diffraction （XRD） and glow discharge optical emission spectroscopy （GDOES）. The Mo-N modified layer contains Mo-N coating on subsurface and diffusion layers between the subsurface and substrate. The X- ray diffraction analysis of the Mo-N modified Ti6Al4V alloy reveals that the outmost surface of the Mo-N modified Ti6Al4V alloy is composed of phase Mo2N （fcc） and Mo2N （tetr）. The electrochemical corrosion performance of the Mo-N modified Ti6Al4V alloy in 0.5 mol/L HCl solution was investigated and compared with that of Ti6Al4V alloy. The chemical corrosion performance of the Mo-N modified Ti6Al4V alloy in boiling 37% HCl solution was investigated and compared with that of Ti6Al4V alloy. Results indicate that self-corroding electric potentials and corrosion-rate of the Mo-N modified Ti6Al4V alloy are higher than that of Ti6Al4V alloy in 0.5 mol/L HCl solution. The corrosion-rate of the Mo-N modified Ti6Al4V alloy is lower than that of Ti6Al4V alloy in boiling 37% HCl solution.
基金supported by the National Natural Science Foundation of China(51875443)Guangdong Basic and Applied Basic Research Foundation(2019B1515120016,202002030290).
文摘Although magnesium(Mg)alloys are the lightest among structural metals,their inadequate corrosion resistance makes them difficult to be used in energy-saving lightweight structures.Moreover,the improvement in corrosion resistance by the conventional surface treatments is always achieved at the expense of sacrificing the fatigue lifetime.In this study,high purity aluminum(Al)and AlMgSi alloy coatings were deposited on Mg alloys via an in-situ micro-forging(MF)assisted cold spray(MFCS)process for simultaneous higher corrosion resistance and longer fatigue lifetime.Besides contributing to a highly dense microstructure,the in-situ MF also greatly refines the grain of the deposited Al alloy coating to the sub-micrometer range due to the enhanced dynamic recrystallization and also generates notable compressive residual stress up to 210 MPa within the AlMgSi coating.The absence of secondary phases in the AlMgSi alloy coatings enable the coated Mg alloy with corrosion resistance,which is even better than its bulk AlMgSi counterparts.The unique combination of refined microstructure and the prominent compressive residual stress within the AlMgSi coatings,effectively delayed the crack initiation upon repeated dynamic loading,thereby leading to∼10 times increase in the fatigue lifetime of the Mg Alloy.However,although residual stress is also generated in the submmicro-sized grained pure Al coating,the low intrinsic strength of the coating layer leads to a lower fatigue lifetime than the uncoated Mg alloy substrate.The present work is aimed to provide a facile approach to break the trade-off between corrosion resistance improvement and fatigue lifetime of the coated Mg alloys.
基金Foundation of Material Corrosion and Protection Key Laboratory of Sichuan Province(2012CL04)Innovative Research Team of Southwest Petroleum University(2012XJZT002) for financial support
文摘Three kinds of rare earth nitrates were adopted to sodium molybdate to get three kinds of LnN-M compounded inhibitors （La（NO3）3＋Na2MoOa（LaN-M）, Ce（NO3）3＋Na2MoOn（CeN-M）, Pr（NO3）3＋Na2MoO4（PrN-M））. The combination of weight-loss method and the electrochemical test, was used to evaluate and analyze the corrosion inhibition efficiency of these LnN-M inhibitors to make the research on their corrosion inhibition performance, and the sequential order of their performance was found as follows： CeN-M〉 LaN-M〉PrN-M, among which, the inhibition efficiency of CeN-M for the X70 steel could reach 98.21%. The synergism parameters were calculated by weight-loss method, these computational data indicated that the synergistic effect between rare earth nitrates and sodium molybdate was obvious and significant. Surface morphology, chemical composition and phase components of the precipitation films were tested for discussing the mechanism of LnN-M inhibitors. The outer electronic configuration of the lanthanide was found to have an important influence on the inhibition efficiency. The CeN-M inhibitor was discovered to have the best inhibition effect with the amorphous cerium oxides. The results of this research revealed that the precipitation films formed on the surface of the steel samples had a crucial influence on the inhibition efficiencies after adding LnN-M inhibitors.
基金supported by the National Natural Science Foundation of China (Nos. 51371046 and 51525101)the National Key Research and Development Program of China (No. 2016YFB0701202)the Fundamental Research Funds of the Central Universities (No. N141008001)
文摘Mg–Zn–Ag alloys have been extensively studied in recent years for potential biodegradable implants due to their unique mechanical properties,biodegradability and biocompatibility.In the present study,Mg–3Zn-x Ag（wt%,x=0.2,0.5 and0.8）alloys with single-phase crystal structure were prepared by backward extrusion at 340°C.The addition of Ag element into Mg–3Zn slightly influences the ultimate tensile strength and microstructure,but the elongation firstly increases from12%to 19.8%and then decreases from 19.8%to 9.9%with the increment of Ag concentration.The tensile yield strength,ultimate tensile strength and elongation of Mg–3Zn–0.2Ag alloy reach up to 142,234 MPa and 19.8%,respectively,which are the best mechanical performance of Mg–Zn–Ag alloys in the present work.The extruded Mg–3Zn–0.2Ag alloy also possesses the best corrosion behavior with the corresponding corrosion rate of 3.2 mm/year in immersion test,which could be explained by the single-phase and uniformly distributed grain structure,and the fewer twinning.
基金Projects (50771092,21073162) supported by the National Natural Science Foundation of ChinaProject (08JC1421600) supported by the Science and Technology Commission of Shanghai,ChinaProject (2008AZ2018) supported by the Science and Technology Bureau of Jiaxing,China
文摘A kind of environmental friendly anodizing routine for AZ91D magnesium alloy,based on an alkaline borate-potassium acid phthalate（KAP） electrolyte,was studied.The effect of KAP on the properties of the anodized film was investigated by scanning electron microscopy（SEM）,X-ray diffraction（XRD）,energy dispersive spectrometry（EDS）,potentiodynamic polarization and electrochemical impedance spectroscopy（EIS）,respectively.The results showed that the anodizing process,surface morphology,thickness,phase structure and corrosion resistance of the anodized film were strongly dependent on the concentration of KAP.In the presence of adequate KAP,a compact and smooth anodized film with excellent corrosion resistance was obtained.
文摘Multiphase TRIP(Transformation Induced Plasticity)steels are known to combine higher strength with higher ductility.In this paper,the corrosion resistance of this steel has been has been investigated by accelerated corrosion tests,such as wet/dry cyclic corrosion and the weight loss in laboratory.The morphologies of their rust layers were observed by using scanning electron microscopy,and the corrosion performance of these steels was discussed by analyzing the protective mechanism.The results show that the corrosion rate of steel A is significantly greater than that of steels B and C in wet/dry cyclic corrosion and weight loss tests.The corrosion performance of conventional C-Mn-Si TRIP steel is deteriorated in both NaHSO 3 and 3.5 wt.%NaCl aqueous solutions.And superior corrosion performance is exhibited for TRIP steel with low alloying contents due to its high thermodynamic stability.The enhancement of corrosion performance of TRIP steel is attributed to the additions of alloying elements,such as Al,Cu,Cr,Mo,Ni,etc.The alloying elements increase the compactness of rust layers,so electrochemical characteristic of TRIP steel is improved.
基金Projects(51271152,51021063)supported by the National Natural Science Foundation of ChinaProject(13JJ6006)supported by Hunan Provincial Natural Science Foundation,ChinaProject(2012CB619502)supported by National Basic Research Program of China
文摘AA7085 aluminum alloys with different Cu/Mg ratios （0.67, 1.0, 1.06, 1.6） were prepared by ingot metallurgy method. The effects of Cu/Mg ratio on the microstructure, mechanical properties and corrosion behavior of the AA7085 alloys were investigated by optical microscope, scanning electron microscope （SEM）, mechanical properties and corrosion testing. The results indicate that a better recrystallization inhibition and corrosion resistance can be achieved when Cu/Mg ratio is 1.6. When Cu/Mg ratio is 0.67, the alloy reveals better mechanical properties, and the tensile strength and yield strength of AA7085 alloys are 586 and 550 MPa, respectively. Moreover, both the mechanical properties and corrosion resistance of the alloy are reduced when Cu/Mg ratio is equal to 1.0.
