A Cr/Cr2N/CrN multilayer coating with a thickness of 24.4 μm was deposited by multi-arc ion plating. The coating was systematically characterized by field emission scanning electron microscopy(FESEM), X-ray photoelec...A Cr/Cr2N/CrN multilayer coating with a thickness of 24.4 μm was deposited by multi-arc ion plating. The coating was systematically characterized by field emission scanning electron microscopy(FESEM), X-ray photoelectron spectrometry(XPS), energy dispersive spectroscopy(EDS), X-ray diffraction(XRD) and transmission electron microscopy(TEM). Hardness and adhesion were tested by nanoindentation and scratch tester, respectively. The friction properties were investigated by a reciprocating UMT-3MT ball-on-disk tribometer in air and seawater. The results showed that the multilayer coating consisted of three different layers, with Cr,Cr2N and CrN phases, respectively. Compared with CrN single layer coating, the adhesion of the multilayer coating was improved significantly, the hardness of the multilayer coating was(21±2) GPa. The corrosion resistance of the multilayer coating was also improved in artificial seawater. The friction coefficient of multilayer coating was lower than that of CrN single layer coating both in air and seawater.展开更多
Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-s...Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm.展开更多
A composite ceramic coating containing Y2O3-ZrO2-MgO(YSZ-MgO) was prepared on AZ91D magnesium alloy,which was immersed in Y(NO3)3 aqueous solution as pretreatment,by micro-arc oxidation(MAO) process.The morpholo...A composite ceramic coating containing Y2O3-ZrO2-MgO(YSZ-MgO) was prepared on AZ91D magnesium alloy,which was immersed in Y(NO3)3 aqueous solution as pretreatment,by micro-arc oxidation(MAO) process.The morphology,elemental and phase compositions,corrosion behavior and thermal stability of the coatings were studied by SEM,EDX,XRD,electrochemical corrosion test,high temperature oxidation and thermal shock test.The results show that the coating mainly consists of ZrO2,Y2O3,MgO,Mg2SiO4,and MgF2.Among these compounds,Y2O3 accounts for 26.7% of(Y2O3 + ZrO2).The thickness of YSZ-MgO coating is smaller than that of ZrO2-MgO coating,but its compactness and surface roughness are better than those of ZrO2-MgO coating.YSZ-MgO coating has a good corrosion resistance,and its corrosion rate in 5% NaCl aqueous solution is lower than that of ZrO2-MgO and only about 8.5% of that of AZ91D magnesium alloy.After oxidation at 410 °C,the mass gain of AZ91D magnesium alloy presents a linear increase with the oxidation time.The YSZ-MgO coating and ZrO2-MgO coating can remarkably decrease the oxidation mass gain.The oxidation mass gain of YSZ-MgO coating is lower than that of ZrO2-MgO coating,especially during a long oxidation period.The thermal shock resistance of YSZ-MgO coating is superior to ZrO2-MgO coating.展开更多
The effects of Sr and Y with different contents on the microstructure and corrosion resistance of AZ31 alloy were investigated. The results indicate that the addition of Sr can obviously reduce the grain size of AZ31 ...The effects of Sr and Y with different contents on the microstructure and corrosion resistance of AZ31 alloy were investigated. The results indicate that the addition of Sr can obviously reduce the grain size of AZ31 alloy and transform β-Mg 17 Al 12 phase from continuous network to scattered form. Simultaneously, Al 4 Sr phase distributed along the boundaries of grains is formed in AZ31-Sr magnesium alloys. The addition of Sr is not as effective as the simultaneous addition of Sr+Y for the refinement of grains, and Al 2 Y and Al 3 Y phases are distributed both in intracrystalline and along grain boundaries. The corrosion resistance is improved slightly in AZ31 alloy with simultaneous addition of 0.5%Sr+Y. Due to its smallest corrosion current density and corrosion rate, the corrosion resistance of AZ31-0.5%Sr-1.5%Y magnesium alloy is proved the best.展开更多
The selection and application of salt tolerance varieties in peanut is impor- tant for the exploitation of saline soil. In this study, 41 peanut varieties were select- ed for the evaluation of salt tolerance in both g...The selection and application of salt tolerance varieties in peanut is impor- tant for the exploitation of saline soil. In this study, 41 peanut varieties were select- ed for the evaluation of salt tolerance in both germination and young seedling stage. The results showed the germination and growth of peanut were significantly inhibited by salt stress, which were enhanced by salt concentration increasing. The 0.5% NaCI was selected as the most suitable concentration for further identification, and the characters in germination stage (including the relative germination potential, relative germination rate and germination index) and young seedling stage (including relative main root length, seedling height, fresh weight, dry weight, et aL) were measured. Cluster analysis showed the varieties could be divided into different groups, and 9 and 3 salt-tolerant varieties were identified in the two stages, respec- tively, including two varieties performed well in both two stages, which could be useful for the breeding of new salt tolerance varieties and the study of salt toler- ance mechanism.展开更多
hi a survey of plant population, Sedum alfredii Hance, a new lead (Pb)-tolerant and lead (Pb)accumulating ecotype, was found in an old Pb/Zn mining area in Zhejiang Province of China. The growth and Pb content of plan...hi a survey of plant population, Sedum alfredii Hance, a new lead (Pb)-tolerant and lead (Pb)accumulating ecotype, was found in an old Pb/Zn mining area in Zhejiang Province of China. The growth and Pb content of plant ecotypes being able to and unable to accumulate Pb were studied by hydroponic culture with different concentrations of Pb(NO3)(2). Growth of shoots of accumulating ecotype was not affected by Ph treatments up to 320 mg/L, whereas that of non-accumulating ecotype was inhibited in all Ph treatments. The Ph concentrations in the roots and shoots of accumulating ecotype increased with increasing of Pb level in the nutrient solution. The maximum Ph concentrations in the shoots and roots of accumulating ecotype were 514 mg/kg and 13 922 mg/kg, 2.27 times and 2.62 times as much as that of non-accumulating ecotype, respectively. The highest rate of Pb accumulation of accumulating ecotype was 8.62 mug/plant/d, 7.16 times as much as that of non-accumulating ecotype. Due to its fast growth rate and high Pb-accumulating ability, from a phytoremediation perspective, accumulating ecotype of S. alfredii is a potential plant species for Pb removal from contaminated soils.展开更多
To enhance the corrosion resistance of magnesium(Mg) alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg(OH)2 films were fabricated on AZ31 magnes...To enhance the corrosion resistance of magnesium(Mg) alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg(OH)2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate(GS) and poly(sodium 4-styrene sulfonate)(PSS), were prepared via layer-by-layer(Lb L) assembly. The morphologies, chemical compositions and corrosion resistance of the obtained(PSS/GS)n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of(PSS/GS)n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.展开更多
In order to improve the corrosion resistance and microhardness of AZ91D magnesium alloy, TiN nanoparticles were addedto fabricate Ni-P-TiN composite coating by electrodeposition. The surface, cross-section morphology ...In order to improve the corrosion resistance and microhardness of AZ91D magnesium alloy, TiN nanoparticles were addedto fabricate Ni-P-TiN composite coating by electrodeposition. The surface, cross-section morphology and composition wereexamined using SEM, EDS and XRD, and the corrosion resistance was checked by electrochemical technology. The results indicatethat TiN nanoparticles were doped successfully in the Ni-P matrix after a series of complex pretreatments including activation, zincimmersion and pre-electroplating, which enhances the stability of magnesium alloy in electrolyte and the adhesion betweenmagnesium alloy and composite coating. The microhardness of the Ni-P coating increases dramatically by adding TiN nanoparticlesand subsequent heat treatment. The corrosion experimental results indicate that the corrosion resistance of Ni-P-TiN compositecoating is much higher than that of uncoated AZ91D magnesium alloy and similar with Ni-P coating in short immersion time.However, TiN nanoparticles play a significant role in long-term corrosion resistance of composite coatings.展开更多
Efficient use of timber is a vital concern problem, especially in these regions where the forestry coverage ratio is decreasing. Studies on physical modification of wood have been taken more attention due to the incre...Efficient use of timber is a vital concern problem, especially in these regions where the forestry coverage ratio is decreasing. Studies on physical modification of wood have been taken more attention due to the increasing attentions on environmental protection. Thermal modification is emphasized and developed quickly in developing countries, especially in European countries. A large number of researches have been conducted and some industrial production plants have been built. This paper reviewed the history of heat treatment, exemplifies the industrial developments in several European countries, summarized the basic principle of heat treatment and describes the environmental characteristics. The properties of heat-treated wood and its usage are also summed up.展开更多
Magnesium alloy wires were processed by micro-arc oxidation (MAO) in a modified silicate-phosphate composite electrolyte containing hydroxyapatite (HA) nanopowders and NaOH. Effects of NaOH content in the composit...Magnesium alloy wires were processed by micro-arc oxidation (MAO) in a modified silicate-phosphate composite electrolyte containing hydroxyapatite (HA) nanopowders and NaOH. Effects of NaOH content in the composite electrolyte on the microstructure and properties of the MAO ceramic coatings on magnesium alloy wires were studied. It is found that the arc voltage of magnesium alloy wires in the micro-arc oxidation process is significantly reduced while the oxidation rate is accelerated. Addition of 2 g/L NaOH in the composite electrolyte is a better choice for improving corrosion resistance of magnesium alloy wires. During early simulated body fluids (SBF) immersion, the micro-arc oxidized magnesium alloy wires undergo a slow and stable degradation. After soaking for 28 d, the protective ceramic coating still shows no damage but significant degradation is observed for magnesium alloy wires after immersion for more than 60 d.展开更多
A series of electrochemical and long-term corrosion tests were carried out in a neutral saline (5%NaCl) vapor of 35 °C on thermal sprayed WC cermet coatings containing different kinds of metallic binders in ord...A series of electrochemical and long-term corrosion tests were carried out in a neutral saline (5%NaCl) vapor of 35 °C on thermal sprayed WC cermet coatings containing different kinds of metallic binders in order to examine the effect of composition of binder materials on the corrosion behavior. The experimental results revealed that the overall corrosion resistance of WC-Co coating was inferior to that of WC-Co-Cr coating. For the coatings without Cr, WC-Co, general corrosion occurred in binder materials in addition to galvanic corrosion between WC particles and metallic binders in the neutral environment. By contrast, the formation of passive film in the form of surface oxide in the coatings containing Cr, WC-Co-Cr, suppressed the binder and metallic binders to be eroded. It is found that the chemical composition of metallic binder materials is one of the important factors influencing the corrosion resistance of HVOF sprayed WC cermet coatings in the neutral vapor.展开更多
Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe...Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9%NaCl and 0.2%NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.展开更多
Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crossl...Hydroxyl-epoxy phosphate (HEP) as a reactive corrosion inhibitor was innovatively synthe- sized by the reaction of bisphenol A epoxy resin with phosphoric acid. HEP was mixed with hydroxyl acrylate resin, and crosslinked with waterborne isocyanate curing agent, which was used to form waterborne HEP/acrylic polyurethane composite (HEP-APU) coatings on Q235 steel surfaces. Electrochemical impedance spectroscopy and polarization curves were applied to analyze the corrosion behavior of the HEP-APU coatings in 3.5wt% NaCl solutions. The results indicated that the HEP-APU coatings show a superior passivation property and efficient corrosion protection of Q235 steel. The waterborne acrylic polyurethane coating containing 0.5wt% HEP exhibited the best corrosion performance among all the coating specimens. The improved flash-rust resistance can be attributed to the introduction of the phosphate group which could form phosphate film on the steel substrate.展开更多
Laser surface melting(LSM) is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In the present work, an attempt of LSM on magnesium alloy with liquid...Laser surface melting(LSM) is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In the present work, an attempt of LSM on magnesium alloy with liquid nitrogen-assisted cooling(LNSC) was carried out to get the higher cooling rate and improve the surface properties. The experimental results were compared with those of Ar gas protection at room temperature. The samples after LSM with LNSC resulted in a thinner melted layer, a highly homogeneous, refined melted microstructure and formed a lot of worm-like nanocrystals and local amorphous structures. Microhardness of the melted layer with LNAC was improved to HV 90-148 as compared to HV 65-105 of the samples with Ar gas protection. The corrosion resistance of the melted layer in a 3.5% Na Cl solution(mass fraction) was improved because of the grain refinement and redistribution of β-Mg17Al12 phases following rapid quenching associated with the process.展开更多
xCu/(10NiO-NiFe2O4) cermet and 1BaO-xCu/(10NiO-NiFe2O4) cermet(x=5,10,17) inert anodes were prepared as potential inert anodes for aluminum electrolysis and their corrosion resistance to traditional electrolyte ...xCu/(10NiO-NiFe2O4) cermet and 1BaO-xCu/(10NiO-NiFe2O4) cermet(x=5,10,17) inert anodes were prepared as potential inert anodes for aluminum electrolysis and their corrosion resistance to traditional electrolyte was studied with anodic current density of 1.0 A/cm2 in laboratory electrolysis.The substantial corrosion of metal Cu was observed,many pores appeared on the surface of anode and electrolytes infiltrated inside anodes during the electrolysis.The wear rates of 5Cu/(10NiO-NiFe2O4),10Cu/(10NiO-NiFe2O4),17Cu/(10NiO-NiFe2O4),1BaO-5Cu/(10NiO-NiFe2O4),1BaO-10Cu/(10NiO-NiFe2O4) and 1BaO-17Cu/(10NiO-NiFe2O4) are 2.15,6.50,8.30,4.88,4.70 and 4.48 cm/a,respectively.The addition of BaO to 10Cu/(10NiO-NiFe2O4) cermet and 17Cu/(10NiO-NiFe2O4) cermet is advantageous because BaO can effectively promote densification and thus improve corrosion resistance.But the addition of BaO to 5Cu/(10NiO-NiFe2O4) cermet is unfavorable to corrosion resistance because additive BaO at the grain boundary of anode accelerates possibly the corrosion of cermet.展开更多
A FeCrSiBMn amorphous/nanocrystalline coating with 700 μm in thickness and 0.65% in porosity, was prepared by high velocity oxygen fuel(HVOF) spraying process. The long-term corrosion behavior of the FeCrSiBMn coatin...A FeCrSiBMn amorphous/nanocrystalline coating with 700 μm in thickness and 0.65% in porosity, was prepared by high velocity oxygen fuel(HVOF) spraying process. The long-term corrosion behavior of the FeCrSiBMn coating was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) tests in a 3.5% NaCl solution with a hard chromium coating as a reference. The FeCrSiBMn coating exhibited higher corrosion potential and lower corrosion current density than the hard chromium coating. The pore resistance(Rp) and charge transfer resistance(Rct) of FeCrSiBMn coating were higher than those of the hard chromium coating. In addition, after immersion in the Na Cl solution for 28 d, only small pores in the FeCrSiBMn coating were observed. All the results indicated that the FeCrSiBMn coating held superior corrosion resistance to the hard chromium coating. This could be attributed to the dense structure, low porosity and amorphous/nanocrystalline phases of the FeCrSiBMn coating.展开更多
Boronizing was applied to Inconel 718. In order to obtain the optimal combination of strength and ductility, the borided Inconel 718 was subjected to standard heat treatment. This consists of solution treatment and th...Boronizing was applied to Inconel 718. In order to obtain the optimal combination of strength and ductility, the borided Inconel 718 was subjected to standard heat treatment. This consists of solution treatment and then a two-step aging treatment. The borided layer is composed of the compound layer and the boron diffusion zone. Because of the superior hardness of borides, the borided Inconel 718 exhibits a significant reduction in its wear rate and relatively low coefficient of friction (COF) compared with the unborided Inconel 718. The standard heat treatment efficiently promotes the diffusion of boron into the interior of the material and the generation of new borides (Fe2B, CrB). The borided layer with standard heat treatment shows much better wear resistance due to the thicker borided layer (313.76 μm).展开更多
A comparative study on the corrosion resistance of 17Ni/(NiFe2O4-10NiO) cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rate...A comparative study on the corrosion resistance of 17Ni/(NiFe2O4-10NiO) cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 (volume fraction) are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer (about 50 μm) is thicker than that (about 30 μm) formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe(II) in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.展开更多
基金Project(51475449)supported by the National Natural Science Foundation of China
文摘A Cr/Cr2N/CrN multilayer coating with a thickness of 24.4 μm was deposited by multi-arc ion plating. The coating was systematically characterized by field emission scanning electron microscopy(FESEM), X-ray photoelectron spectrometry(XPS), energy dispersive spectroscopy(EDS), X-ray diffraction(XRD) and transmission electron microscopy(TEM). Hardness and adhesion were tested by nanoindentation and scratch tester, respectively. The friction properties were investigated by a reciprocating UMT-3MT ball-on-disk tribometer in air and seawater. The results showed that the multilayer coating consisted of three different layers, with Cr,Cr2N and CrN phases, respectively. Compared with CrN single layer coating, the adhesion of the multilayer coating was improved significantly, the hardness of the multilayer coating was(21±2) GPa. The corrosion resistance of the multilayer coating was also improved in artificial seawater. The friction coefficient of multilayer coating was lower than that of CrN single layer coating both in air and seawater.
基金Project(2011B050400007)supported by the International Cooperation Program of Guangdong Province,China
文摘Ti/TiN/Zr/ZrN multilayer coatings were deposited on Cr_17Ni_2 steel substrates with different surface roughnesses by vacuum cathodic arc deposition method. Microstructure, micro-hardness, adhesion strength and cross-sectional morphology of the obtained multilayer coatings were investigated. The results show that the Vickers hardness of Ti/TiN/Zr/ZrN multilayer coating, with a film thickness of 11.37 μm, is 29.36 GPa. The erosion and salt spray resistance performance of Cr_17Ni_2 steel substrates can be evidently improved by Ti/TiN/Zr/ZrN multilayer coating. The surface roughness of Cr_17Ni_2 steel substrates plays an important role in determining the mechanical and erosion performances of Ti/TiN/Zr/ZrN multilayer coatings. Overall, a low value of the surface roughness of substrates corresponds to an improved performance of erosion and salt spray resistance of multilayer coatings. The optimized performance of Ti/TiN/Zr/ZrN multilayer coatings can be achieved provided that the surface roughness of Cr_17Ni_2 steel substrates is lower than 0.4μm.
基金Project (gf200901002) support by the National Defense Key Disciplines Laboratory of Light Alloy Processing Science and Technology of Nanchang Hangkong University,China
文摘A composite ceramic coating containing Y2O3-ZrO2-MgO(YSZ-MgO) was prepared on AZ91D magnesium alloy,which was immersed in Y(NO3)3 aqueous solution as pretreatment,by micro-arc oxidation(MAO) process.The morphology,elemental and phase compositions,corrosion behavior and thermal stability of the coatings were studied by SEM,EDX,XRD,electrochemical corrosion test,high temperature oxidation and thermal shock test.The results show that the coating mainly consists of ZrO2,Y2O3,MgO,Mg2SiO4,and MgF2.Among these compounds,Y2O3 accounts for 26.7% of(Y2O3 + ZrO2).The thickness of YSZ-MgO coating is smaller than that of ZrO2-MgO coating,but its compactness and surface roughness are better than those of ZrO2-MgO coating.YSZ-MgO coating has a good corrosion resistance,and its corrosion rate in 5% NaCl aqueous solution is lower than that of ZrO2-MgO and only about 8.5% of that of AZ91D magnesium alloy.After oxidation at 410 °C,the mass gain of AZ91D magnesium alloy presents a linear increase with the oxidation time.The YSZ-MgO coating and ZrO2-MgO coating can remarkably decrease the oxidation mass gain.The oxidation mass gain of YSZ-MgO coating is lower than that of ZrO2-MgO coating,especially during a long oxidation period.The thermal shock resistance of YSZ-MgO coating is superior to ZrO2-MgO coating.
基金Project(2007CB613702)supported by the National Basic Research Program of ChinaProject(2006AA4012)supported by the Research Program Foundation of CQ CSTC, ChinaProject(2008BB4323)supported by the Natural Science Foundation of CQ CSTC, China
文摘The effects of Sr and Y with different contents on the microstructure and corrosion resistance of AZ31 alloy were investigated. The results indicate that the addition of Sr can obviously reduce the grain size of AZ31 alloy and transform β-Mg 17 Al 12 phase from continuous network to scattered form. Simultaneously, Al 4 Sr phase distributed along the boundaries of grains is formed in AZ31-Sr magnesium alloys. The addition of Sr is not as effective as the simultaneous addition of Sr+Y for the refinement of grains, and Al 2 Y and Al 3 Y phases are distributed both in intracrystalline and along grain boundaries. The corrosion resistance is improved slightly in AZ31 alloy with simultaneous addition of 0.5%Sr+Y. Due to its smallest corrosion current density and corrosion rate, the corrosion resistance of AZ31-0.5%Sr-1.5%Y magnesium alloy is proved the best.
文摘The selection and application of salt tolerance varieties in peanut is impor- tant for the exploitation of saline soil. In this study, 41 peanut varieties were select- ed for the evaluation of salt tolerance in both germination and young seedling stage. The results showed the germination and growth of peanut were significantly inhibited by salt stress, which were enhanced by salt concentration increasing. The 0.5% NaCI was selected as the most suitable concentration for further identification, and the characters in germination stage (including the relative germination potential, relative germination rate and germination index) and young seedling stage (including relative main root length, seedling height, fresh weight, dry weight, et aL) were measured. Cluster analysis showed the varieties could be divided into different groups, and 9 and 3 salt-tolerant varieties were identified in the two stages, respec- tively, including two varieties performed well in both two stages, which could be useful for the breeding of new salt tolerance varieties and the study of salt toler- ance mechanism.
文摘hi a survey of plant population, Sedum alfredii Hance, a new lead (Pb)-tolerant and lead (Pb)accumulating ecotype, was found in an old Pb/Zn mining area in Zhejiang Province of China. The growth and Pb content of plant ecotypes being able to and unable to accumulate Pb were studied by hydroponic culture with different concentrations of Pb(NO3)(2). Growth of shoots of accumulating ecotype was not affected by Ph treatments up to 320 mg/L, whereas that of non-accumulating ecotype was inhibited in all Ph treatments. The Ph concentrations in the roots and shoots of accumulating ecotype increased with increasing of Pb level in the nutrient solution. The maximum Ph concentrations in the shoots and roots of accumulating ecotype were 514 mg/kg and 13 922 mg/kg, 2.27 times and 2.62 times as much as that of non-accumulating ecotype, respectively. The highest rate of Pb accumulation of accumulating ecotype was 8.62 mug/plant/d, 7.16 times as much as that of non-accumulating ecotype. Due to its fast growth rate and high Pb-accumulating ability, from a phytoremediation perspective, accumulating ecotype of S. alfredii is a potential plant species for Pb removal from contaminated soils.
基金Project(2014TDJH104)supported by Shandong University of Science and Technology(SDUST)Research FundChina+3 种基金Project(2013RCJJ006)supported by Scientific Research Foundation of Shandong University of Science and Technology for Recruited TalentsChinaProject(BS2013CL009)supported by Scientific Research Foundation of Shandong for Outstanding Young ScientistChina
文摘To enhance the corrosion resistance of magnesium(Mg) alloy and to impart its surface with antibacterial functionality for inhibiting biofilm formation and biocorrosion, Mg(OH)2 films were fabricated on AZ31 magnesium alloy substrates by an in-situ hydrothermal method and well-defined multilayer coatings, consisting of gentamicin sulfate(GS) and poly(sodium 4-styrene sulfonate)(PSS), were prepared via layer-by-layer(Lb L) assembly. The morphologies, chemical compositions and corrosion resistance of the obtained(PSS/GS)n/Mg sample were investigated using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, electrochemical methods and immersion tests. Finally, the bactericidal activity of(PSS/GS)n/Mg samples against Staphylococcus aureus was assessed by the zone of inhibition methods and plate-counting method. The so-synthesized composite coating on the Mg alloy substrates exhibits good corrosion resistance and antibacterial performance, which make them attractive as coatings for medical implanted devices.
基金Projects(51171172,51131005)supported by the National Natural Science Foundation of ChinaProject(R16E010001)supported by Zhejiang Provincial Natural Science Foundation of China+1 种基金Project(2015QNA3011)supported by Fundamental Research Funds for the Central Universities,ChinaProject(14DZ2261000)supported by Science and Technology Commission of Shanghai Municipality,China
文摘In order to improve the corrosion resistance and microhardness of AZ91D magnesium alloy, TiN nanoparticles were addedto fabricate Ni-P-TiN composite coating by electrodeposition. The surface, cross-section morphology and composition wereexamined using SEM, EDS and XRD, and the corrosion resistance was checked by electrochemical technology. The results indicatethat TiN nanoparticles were doped successfully in the Ni-P matrix after a series of complex pretreatments including activation, zincimmersion and pre-electroplating, which enhances the stability of magnesium alloy in electrolyte and the adhesion betweenmagnesium alloy and composite coating. The microhardness of the Ni-P coating increases dramatically by adding TiN nanoparticlesand subsequent heat treatment. The corrosion experimental results indicate that the corrosion resistance of Ni-P-TiN compositecoating is much higher than that of uncoated AZ91D magnesium alloy and similar with Ni-P coating in short immersion time.However, TiN nanoparticles play a significant role in long-term corrosion resistance of composite coatings.
文摘Efficient use of timber is a vital concern problem, especially in these regions where the forestry coverage ratio is decreasing. Studies on physical modification of wood have been taken more attention due to the increasing attentions on environmental protection. Thermal modification is emphasized and developed quickly in developing countries, especially in European countries. A large number of researches have been conducted and some industrial production plants have been built. This paper reviewed the history of heat treatment, exemplifies the industrial developments in several European countries, summarized the basic principle of heat treatment and describes the environmental characteristics. The properties of heat-treated wood and its usage are also summed up.
基金Project (BE2011778) supported by Science and Technology Support Program of Jiangsu Province,ChinaProjects (CityU 112510,112212) supported by Hong Kong Research Grants Council (RGC) General Research Funds (GRF) ,China
文摘Magnesium alloy wires were processed by micro-arc oxidation (MAO) in a modified silicate-phosphate composite electrolyte containing hydroxyapatite (HA) nanopowders and NaOH. Effects of NaOH content in the composite electrolyte on the microstructure and properties of the MAO ceramic coatings on magnesium alloy wires were studied. It is found that the arc voltage of magnesium alloy wires in the micro-arc oxidation process is significantly reduced while the oxidation rate is accelerated. Addition of 2 g/L NaOH in the composite electrolyte is a better choice for improving corrosion resistance of magnesium alloy wires. During early simulated body fluids (SBF) immersion, the micro-arc oxidized magnesium alloy wires undergo a slow and stable degradation. After soaking for 28 d, the protective ceramic coating still shows no damage but significant degradation is observed for magnesium alloy wires after immersion for more than 60 d.
文摘A series of electrochemical and long-term corrosion tests were carried out in a neutral saline (5%NaCl) vapor of 35 °C on thermal sprayed WC cermet coatings containing different kinds of metallic binders in order to examine the effect of composition of binder materials on the corrosion behavior. The experimental results revealed that the overall corrosion resistance of WC-Co coating was inferior to that of WC-Co-Cr coating. For the coatings without Cr, WC-Co, general corrosion occurred in binder materials in addition to galvanic corrosion between WC particles and metallic binders in the neutral environment. By contrast, the formation of passive film in the form of surface oxide in the coatings containing Cr, WC-Co-Cr, suppressed the binder and metallic binders to be eroded. It is found that the chemical composition of metallic binder materials is one of the important factors influencing the corrosion resistance of HVOF sprayed WC cermet coatings in the neutral vapor.
基金Projects(N100702001,N120310001)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(20131036)supported by Doctoral Fund of Liaoning Province,ChinaProject(51301037)supported by the National Natural Science Foundation of China
文摘Surface mechanical attrition treatment (SMAT) was performed on biomedicalβ-type TiNbZrFe alloy for 60 min at room temperature to study the effect of surface nanocrystallization on the corrosion resistance of TiNbZrFe alloy in physiological environment. The surface nanostructure was characterized by TEM, and the electrochemical behaviors of the samples with nanocrystalline layer and coarse grain were comparatively investigated in 0.9% NaCl and 0.2% NaF solutions, respectively. The results indicate that nanocrystallines with the size of 10-30 nm are formed within the surface layer of 30 μm in depth. The nanocrystallized surface behaves higher impedance, more positive corrosion potential and lower corrosion current density in 0.9%NaCl and 0.2%NaF solutions as compared with the coarse grain surface. The improvement of the corrosion resistance is attributed to the rapid formation of stable and dense passive film on the nanocrystallized surface of TiNbZrFe alloy.
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Project(51305292)supported by the National Natural Science Foundation of ChinaProject(2014-024)supported by Shanxi Scholarship Council of China
文摘Laser surface melting(LSM) is a high-energy surface treatment that allows modification of the microstructure and surface properties of Mg alloys. In the present work, an attempt of LSM on magnesium alloy with liquid nitrogen-assisted cooling(LNSC) was carried out to get the higher cooling rate and improve the surface properties. The experimental results were compared with those of Ar gas protection at room temperature. The samples after LSM with LNSC resulted in a thinner melted layer, a highly homogeneous, refined melted microstructure and formed a lot of worm-like nanocrystals and local amorphous structures. Microhardness of the melted layer with LNAC was improved to HV 90-148 as compared to HV 65-105 of the samples with Ar gas protection. The corrosion resistance of the melted layer in a 3.5% Na Cl solution(mass fraction) was improved because of the grain refinement and redistribution of β-Mg17Al12 phases following rapid quenching associated with the process.
基金Project(2005CB623703)supported by the National Basic Research Program of ChinaProject(50721003)supported by the National Natural Science Foundation for Innovation Group of China+1 种基金Project(2008AA030501)supported by the National High-tech Research and Development Program of ChinaProject(201012200021)supported by the Basic Scientific Research Program of Central South University,China
文摘xCu/(10NiO-NiFe2O4) cermet and 1BaO-xCu/(10NiO-NiFe2O4) cermet(x=5,10,17) inert anodes were prepared as potential inert anodes for aluminum electrolysis and their corrosion resistance to traditional electrolyte was studied with anodic current density of 1.0 A/cm2 in laboratory electrolysis.The substantial corrosion of metal Cu was observed,many pores appeared on the surface of anode and electrolytes infiltrated inside anodes during the electrolysis.The wear rates of 5Cu/(10NiO-NiFe2O4),10Cu/(10NiO-NiFe2O4),17Cu/(10NiO-NiFe2O4),1BaO-5Cu/(10NiO-NiFe2O4),1BaO-10Cu/(10NiO-NiFe2O4) and 1BaO-17Cu/(10NiO-NiFe2O4) are 2.15,6.50,8.30,4.88,4.70 and 4.48 cm/a,respectively.The addition of BaO to 10Cu/(10NiO-NiFe2O4) cermet and 17Cu/(10NiO-NiFe2O4) cermet is advantageous because BaO can effectively promote densification and thus improve corrosion resistance.But the addition of BaO to 5Cu/(10NiO-NiFe2O4) cermet is unfavorable to corrosion resistance because additive BaO at the grain boundary of anode accelerates possibly the corrosion of cermet.
文摘A FeCrSiBMn amorphous/nanocrystalline coating with 700 μm in thickness and 0.65% in porosity, was prepared by high velocity oxygen fuel(HVOF) spraying process. The long-term corrosion behavior of the FeCrSiBMn coating was evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy(EIS) tests in a 3.5% NaCl solution with a hard chromium coating as a reference. The FeCrSiBMn coating exhibited higher corrosion potential and lower corrosion current density than the hard chromium coating. The pore resistance(Rp) and charge transfer resistance(Rct) of FeCrSiBMn coating were higher than those of the hard chromium coating. In addition, after immersion in the Na Cl solution for 28 d, only small pores in the FeCrSiBMn coating were observed. All the results indicated that the FeCrSiBMn coating held superior corrosion resistance to the hard chromium coating. This could be attributed to the dense structure, low porosity and amorphous/nanocrystalline phases of the FeCrSiBMn coating.
基金Projects(2011CB013402,201303002,2014028002)supported by the National Basic Research Program of China
文摘Boronizing was applied to Inconel 718. In order to obtain the optimal combination of strength and ductility, the borided Inconel 718 was subjected to standard heat treatment. This consists of solution treatment and then a two-step aging treatment. The borided layer is composed of the compound layer and the boron diffusion zone. Because of the superior hardness of borides, the borided Inconel 718 exhibits a significant reduction in its wear rate and relatively low coefficient of friction (COF) compared with the unborided Inconel 718. The standard heat treatment efficiently promotes the diffusion of boron into the interior of the material and the generation of new borides (Fe2B, CrB). The borided layer with standard heat treatment shows much better wear resistance due to the thicker borided layer (313.76 μm).
基金Project(51474238)supported by the National Natural Science Foundation of China
文摘A comparative study on the corrosion resistance of 17Ni/(NiFe2O4-10NiO) cermet inert anode prepared in differentsintering atmospheres was conducted in Na3AlF6-Al2O3 melt. The results indicate that the corrosion rates of NiFe2O4-based cermetanodes prepared in the vacuum and the atmosphere with oxygen content of 2×10^-3 (volume fraction) are 6.46 and 2.71 cm/a,respectively. Though there is a transition layer with lots of holes or pores, a densified layer is formed on the surface of anode due tosome reactions producing aluminates. For the anode prepared in the atmosphere with oxygen content of 2×10^-3, the thickness of thedensification layer (about 50 μm) is thicker than that (about 30 μm) formed on the surface of anode prepared in the vacuum. Thecontents of NiO and Fe(II) in NiFe2xO4-y-z increase with the decrease of oxygen content in sintering atmosphere, which reduces thecorrosion resistance of the material.