In this study, series of novel composite phase change materials(PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs.The meso-porous carbon materia...In this study, series of novel composite phase change materials(PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs.The meso-porous carbon material was prepared through one-pot co-assembly method, using resorcinol and formaldehyde as carbon precursor, tetraethoxysilane as silica sources and triblock copolymer F127 as a template. And the phase behaviors of n-octadcane confined in the nano-porous structure of the meso-porous carbon were further investigated. Fourier transform-infrared spectroscopy spectra show that n-octadecane was effectively encapsulated in the porous structure of mesoporous carbon and the composite PCMs were successfully prepared. Differential scanning calorimetry results confirm that the composite PCMs possess a good phase change behavior, fast thermal-response rate and excellent thermal cycling stability. In addition, the composite PCMs possess expected heat storage and heat release properties. All these results demonstrate that the composite PCMs possess good comprehensive property so that they can be used widely in energy storage systems.展开更多
Defects of cement-based materials can be restored by microbial carbonate precipitation, but in order to accelerate the completion of the mineralization process, previous studies all adopt the approach of immersion in ...Defects of cement-based materials can be restored by microbial carbonate precipitation, but in order to accelerate the completion of the mineralization process, previous studies all adopt the approach of immersion in bacterial liquid, which can not be applied for in situ repair. We investigated micro-environment, basophil-domestication of microorganism and effective absorption of micro-organisms by cement-based materials, and adopted spray technology to conduct in situ repairs on the defects on the surface of cement-based materials and enhance the repair process operability. Through microbial carbonate precipitation in the defects by spraying bacteria liquid, 100 μm thickness of calcium carbonate film can be deposited on sample surface and in defects holes＇ microenvironment within 3 to 5 days. The capillary water absorption coefficient of specimen surface is 77% lower than the value before repair. The repairing effect is remarkable which makes it possible to conduct on-site repairs.展开更多
In this paper, preparation of nano-biphasic calcium phosphate （nBCP）, mechanical behavior and load-bearing of poly （lactide-co-glycolide） （PLGA） and PLGA/nBCP are presented. The nBCP with composition of 63/37 （...In this paper, preparation of nano-biphasic calcium phosphate （nBCP）, mechanical behavior and load-bearing of poly （lactide-co-glycolide） （PLGA） and PLGA/nBCP are presented. The nBCP with composition of 63/37 （w/w） HA/-TCP （hydroxyapatite/fl-tricalcium phosphate） was produced by heating of bovine bone at 700℃. Composite scaffolds were made by using PLGA matrix and 10-50 wt% nBCP powders as reinforcement material. All scaffolds were prepared by thermally induced solid-liquid phase separation （TIPS） at -60~C under 4 Pa （0.04 mbar） vacuum. The results of elastic modulus testing were adjusted with Ishai-Cohen and Narkis models for rigid polymeric matrix and compared to each other. PLGA/nBCP scaffolds with 30 wt% nBCP showed the highest value of yield strength among the scaffolds. In addition, it was found that by increasing the nBCP in scaffolds to 50 wt%, the modulus of elasticity was highly enhanced. However, the optimum value of yield strength was obtained at 30 wt% nBCP, and the agglomeration of reinforcing particles at higher percentages caused a reduction in yield strength. It is clear that the elastic modulus of matrix has the significant role in elastic modulus of scaffolds, as also the size of the filler particles in the matrix.展开更多
Rare earth compounds as modifiers used widely in modern friction materials can enhance the interfacial binding of constituents of materials and improve the comprehensive properties of materials evidently. However, the...Rare earth compounds as modifiers used widely in modern friction materials can enhance the interfacial binding of constituents of materials and improve the comprehensive properties of materials evidently. However, there are still few reports on application of rare earth in automotive friction materials. In order to study the effect mechanism of rare earths in friction materials, a rare earth compound was selected as additive and the effects of materials doped with or without rare earth on friction and wear properties of materials were studied. The microstructure and worn surface morphology were observed by scanning electron microscopy and the macro performance was discussed. Worn surface element constitution of materials was analyzed by energy dispersive spectroscopy. Effect mechanism of rare earths on friction and wear behaviors of friction materials were discussed. The results show that doping rare earths in friction materials can stabilize friction coefficient, lower the wear rate of materials and increase the impact strength of materials. The flexibility and fracture resistance of materials is greatly improved. Worn surface of materials doped with rare earth is compact and the surface adhesion is greatly enhanced.展开更多
The relationship between isothermal magnetic entropy change DELTA S andadiabatic temperature change DELTA T_(ad) was deduced according to the principles of thermodynamics.The MCE and the engineering application were d...The relationship between isothermal magnetic entropy change DELTA S andadiabatic temperature change DELTA T_(ad) was deduced according to the principles of thermodynamics.The MCE and the engineering application were discussed for Gd and several new kinds of magneticrefrigerating materials near room temperature, Gd_5Si_2Ge_2, MnFeP_(0.45)As_(0.55) and LaFe_(11.2)Co_(0.7)Si_(1.1). Isothermal entropy change is proportional to adiabatic temperature change with afactor of T/C (T is temperature, C is heat capacity). When the comparison of magnetacoloric effectis made for two different materials, we should consider isothermal entropy change as well asadiabatic temperature change.展开更多
Graphene, the thinnest and hardest nano-material in the world, is non-toxic, sustainable and with minimal environmental footprint. As one of the most important carbon materials, it is composed of a monolayer of carbon...Graphene, the thinnest and hardest nano-material in the world, is non-toxic, sustainable and with minimal environmental footprint. As one of the most important carbon materials, it is composed of a monolayer of carbon atoms with a honeycomb structure. Nowadays, scientists have tried to use it in the biomedicine subject because of its superior physical and chemical properties and excellent biocompatibility.展开更多
Bacterial infection plays an important role in the initiation of biliary sludge formation. Bacterial adherence and biofilm formation on the surface of a material have been considered as one of the main factors of sten...Bacterial infection plays an important role in the initiation of biliary sludge formation. Bacterial adherence and biofilm formation on the surface of a material have been considered as one of the main factors of stent re-occlusion in clinic. This work reported preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stent material using chitosan film. The chitosan film was deposited on 316 L stainless steel （SS） plate by electrophoresis method and was characterized by X-ray diffraction （XRD）, Fourier Transform infrared spectroscopy （FTIR） and atomic force microscopy （AFM）. The ability of inhibiting bacterial adherence was investigated by incubating in human fresh bile adding E. coli and Enterobacter at 37±1 ℃ . Scanning electron microscopy （SEM） and fluorescence staining were used for observing bacterial colonization and biofilm formation. The results show that chitosan film was uniformly deposited on material surface, and the composition of the film did not change through cross-linking, but the crystallinity of chitosan film become well. Comparing to un-modified sample, the E. coli and Enterococcus adhesion amount and colonization on the surface of modified sample were significantly decreased by fluorescence staining and SEM. It is suggested that chitosan could be applied to biliary stent in clinical because of its antimicrobial activities.展开更多
Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impede...Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impedes the commercial application. The initial nucleation and low Li ions diffusion rate in the electrolyte/electrode interface dominate the deposition behavior. Therefore, a uniform and flexible interface is urgently needed. Here, a facile method is proposed to prepare a thin and porous LiF-rich layer (TPL) by the in-situ reaction of small amount of ammonium hydrogen difluoride (NH4HF2) and Li metal. The deposition morphology on Li metal anode with LiF layer is significantly flat and homogeneous owning to low lateral diffusion barrier on LiF crystals and the porous structure of TPL film. Additionally, the symmetrical cells made with such TPL Li anodes show significantly stable cycling over 100 cycles at high current density of 6 mA/cm^2. The TPL Li|LiFePO4 full cells keep over 99% capacity retention after 100 cycles at 2.0 C. This approach serves as a facile and controllable way of adjusting the protective layer on Li metal.展开更多
Interactions between microwaves and certain catalysts can lead to efficient, energy-directed convergence of a relatively dispersed microwave field onto the reactive sites of the catalyst,which produces thermal or disc...Interactions between microwaves and certain catalysts can lead to efficient, energy-directed convergence of a relatively dispersed microwave field onto the reactive sites of the catalyst,which produces thermal or discharge effects around the catalyst. These interactions form"high-energy sites"(HeS) that promote energy efficient utilization and enhanced in situ degradation of organic pollutants. This article focuses on the processes occurring between microwaves and absorbing catalysts, and presents a critical review of microwave-absorbing mechanisms. This article also discusses aqueous phase applications of relevant catalysts(ironbased, carbon-based, soft magnetic, rare earth, and other types) and microwaves, special effects caused by the dimensions and structures of catalytic materials, and the optimization and design of relevant reactors for microwave-assisted catalysis of wastewater. The results of this study demonstrate that microwave-assisted catalysis can effectively enhance the degradation rate of organic compounds in an aqueous phase and has potential applications to a variety of engineering fields such as microwave-assisted pyrolysis, pollutant removal,material synthesis, and water treatment.展开更多
Aging treatment and various heat input conditions and mechanical properties of TIG welded 606I-T6 alloy joints were adopted to investigate the microstructural evolution by microstructural observations, microhardness t...Aging treatment and various heat input conditions and mechanical properties of TIG welded 606I-T6 alloy joints were adopted to investigate the microstructural evolution by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone （HAZ） increases and grains in the fusion zone （FZ） coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175℃ for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.展开更多
Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabil...Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabilizer and dopant source,respectively.Structure and microstructure of the films were characterized with X-ray diffraction(XRD),field emission-scanning electron microscopy(FE-SEM) and the energy dispersive X-ray spectrometry(EDS).The infrared properties were also investigated.It was found that Ce-...展开更多
MXene has shown distinctive advantages as anode materials of lithium-ion batteries. However, local surface chemistry, which was confirmed that can block ion transfer and limit redox reaction, has a significant effect ...MXene has shown distinctive advantages as anode materials of lithium-ion batteries. However, local surface chemistry, which was confirmed that can block ion transfer and limit redox reaction, has a significant effect on electrochemical performance. Herein, annealing MXene under hydrogen was employed for removing-F and turning-OH to-O terminations. We demonstrate that it improves the kinetics of Li-ion transport between the electrolyte and electrode. As a result, a lower interfacial charge transfer impedance was obtained. The electrochemical measurement exhibited that a nearly 2-fold increase of specific capacity was achieved for the annealed MXene.展开更多
As a β stabilizing element in Ti-based alloys,the effect of Mo on phase constitution,microstructure,mechanical and shape memory properties was investigated.Different compositions of Ti-xMo-3Sn alloys(where x=2,4,6,at...As a β stabilizing element in Ti-based alloys,the effect of Mo on phase constitution,microstructure,mechanical and shape memory properties was investigated.Different compositions of Ti-xMo-3Sn alloys(where x=2,4,6,at.%) were prepared by arc melting.A binary composition of Ti-6 Mo alloy was also prepared for comparison.Ti-xMo-3Sn alloys show low hardness and high ductility with 90% reduction in thickness while Ti-6 Mo alloy shows high hardness,brittle behavior,and poor ductility.Field emission scanning electron microscopy(FESEM) reveals round morphology of athermal ω(ωath) precipitates.The presence of ωath phase is also confirmed by X-ray diffraction(XRD)in both as-cast and solution-treated and quenched conditions.The optical microscopy(OM) and FESEM show that the amount of martensite forming during quenching decreases with an increase in Mo content,which is also due to β→ω transformation.The hardness trends reinforce the presence of ωath too.The shape memory effect(SME) of 9% is the highest for Ti-6 Mo-3Sn alloy.The SME is trivial due to ωath phase formation;however,the increase in SME is observed with an increase in Mo content,which is due to the reverse transformation from ωath and the stress-induced martensitic transformation.In addition,a new and very simple method was designed and used for shape memory effect measurement.展开更多
A 1040°C-hot-deformed Ti_2AlNb-based alloy solution-treated at 950°C and aged at different temperatures was quantitatively investigated. The microstructure, size of the phase, and microhardness of the deform...A 1040°C-hot-deformed Ti_2AlNb-based alloy solution-treated at 950°C and aged at different temperatures was quantitatively investigated. The microstructure, size of the phase, and microhardness of the deformed alloys were measured. The results indicated that the microstructure of the deformed Ti_2AlNb-based alloy specimens comprise coarse O lath, fine O lath, equiaxed O/α_2, and acicular O phase. More O phase was generated in the deformed alloy after heat treatment because the acicular O phase was more likely to nucleate and grow along the deformation-induced crystal defects such as dislocations and subgrain boundaries. After deformation and subsequent heat treatment, the acicular O phase of the resultant alloy became finer compared to that of the undeformed alloy, and the acicular O phase became coarser and longer with the elevated aging temperature, while the width of the O lath exhibited unobvious variations. The hot deformation facilitated the dissolution of the O lath but accelerated the precipitation of the acicular O phase. When the 950°C-solution-treated deformed Ti_2AlNb-based alloy was then aged at 750°C for different periods, the phase content was nearly invariable, O and B2 phases eventually reached equilibrium, and the microstructure became stable and homogeneous.展开更多
A highly branched polycarbosilane bearing allyl groups has been prepared by a one-pot synthesis with chloromethyltrichlorosilane, chloromethylmethyldichlorosilane and allyl chloride as the starting materials. The resu...A highly branched polycarbosilane bearing allyl groups has been prepared by a one-pot synthesis with chloromethyltrichlorosilane, chloromethylmethyldichlorosilane and allyl chloride as the starting materials. The resultant polymer, with the approximate formula [SiH1.2(CH3)0.71(CH2CHCH2)0.09CH2]n, has been characterized by 1H, 13C, and 29Si NMR, GPC, TG and elemental analysis. It could be cross-linked thermally at 170 °C in the absence of oxygen. Pyrolysis of the polymer gave a ceramic with a yield of about 70%.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant Nos. 51102230, 51462006, 51361005, 51863005, U1501242, 51371060 and 51671062)the Guangxi Natural Science Foundation (Nos. 2014GXNSFAA118401, 2013GXNSFBA019244, 2014GXNSFAA118319 and 2014GXNAFDA118005)+2 种基金Guangxi Key Laboratory of Information Materials (Nos. 161002-Z, 171027-Z and 161002-K)Guangxi Scientific Technology Team (No. 2012GXNSFGA06002, AA17202030)the Program for Postgraduate Joint Training Base of GUET-CJYRE (No. 20160513-14-Z)
文摘In this study, series of novel composite phase change materials(PCMs) were prepared through vacuum impregnation by using meso-porous carbon as a supporting matrix and n-octadcane as PCMs.The meso-porous carbon material was prepared through one-pot co-assembly method, using resorcinol and formaldehyde as carbon precursor, tetraethoxysilane as silica sources and triblock copolymer F127 as a template. And the phase behaviors of n-octadcane confined in the nano-porous structure of the meso-porous carbon were further investigated. Fourier transform-infrared spectroscopy spectra show that n-octadecane was effectively encapsulated in the porous structure of mesoporous carbon and the composite PCMs were successfully prepared. Differential scanning calorimetry results confirm that the composite PCMs possess a good phase change behavior, fast thermal-response rate and excellent thermal cycling stability. In addition, the composite PCMs possess expected heat storage and heat release properties. All these results demonstrate that the composite PCMs possess good comprehensive property so that they can be used widely in energy storage systems.
基金Funded by the National Natural Science Foundation of China(No.51202029)
文摘Defects of cement-based materials can be restored by microbial carbonate precipitation, but in order to accelerate the completion of the mineralization process, previous studies all adopt the approach of immersion in bacterial liquid, which can not be applied for in situ repair. We investigated micro-environment, basophil-domestication of microorganism and effective absorption of micro-organisms by cement-based materials, and adopted spray technology to conduct in situ repairs on the defects on the surface of cement-based materials and enhance the repair process operability. Through microbial carbonate precipitation in the defects by spraying bacteria liquid, 100 μm thickness of calcium carbonate film can be deposited on sample surface and in defects holes＇ microenvironment within 3 to 5 days. The capillary water absorption coefficient of specimen surface is 77% lower than the value before repair. The repairing effect is remarkable which makes it possible to conduct on-site repairs.
基金supported by Isfahan University of Technology and Ministry of Sciences, Research & Technology in Iran and Materials Science & Engineering School of Nanyang Technological University in Singapore
文摘In this paper, preparation of nano-biphasic calcium phosphate （nBCP）, mechanical behavior and load-bearing of poly （lactide-co-glycolide） （PLGA） and PLGA/nBCP are presented. The nBCP with composition of 63/37 （w/w） HA/-TCP （hydroxyapatite/fl-tricalcium phosphate） was produced by heating of bovine bone at 700℃. Composite scaffolds were made by using PLGA matrix and 10-50 wt% nBCP powders as reinforcement material. All scaffolds were prepared by thermally induced solid-liquid phase separation （TIPS） at -60~C under 4 Pa （0.04 mbar） vacuum. The results of elastic modulus testing were adjusted with Ishai-Cohen and Narkis models for rigid polymeric matrix and compared to each other. PLGA/nBCP scaffolds with 30 wt% nBCP showed the highest value of yield strength among the scaffolds. In addition, it was found that by increasing the nBCP in scaffolds to 50 wt%, the modulus of elasticity was highly enhanced. However, the optimum value of yield strength was obtained at 30 wt% nBCP, and the agglomeration of reinforcing particles at higher percentages caused a reduction in yield strength. It is clear that the elastic modulus of matrix has the significant role in elastic modulus of scaffolds, as also the size of the filler particles in the matrix.
文摘Rare earth compounds as modifiers used widely in modern friction materials can enhance the interfacial binding of constituents of materials and improve the comprehensive properties of materials evidently. However, there are still few reports on application of rare earth in automotive friction materials. In order to study the effect mechanism of rare earths in friction materials, a rare earth compound was selected as additive and the effects of materials doped with or without rare earth on friction and wear properties of materials were studied. The microstructure and worn surface morphology were observed by scanning electron microscopy and the macro performance was discussed. Worn surface element constitution of materials was analyzed by energy dispersive spectroscopy. Effect mechanism of rare earths on friction and wear behaviors of friction materials were discussed. The results show that doping rare earths in friction materials can stabilize friction coefficient, lower the wear rate of materials and increase the impact strength of materials. The flexibility and fracture resistance of materials is greatly improved. Worn surface of materials doped with rare earth is compact and the surface adhesion is greatly enhanced.
文摘The relationship between isothermal magnetic entropy change DELTA S andadiabatic temperature change DELTA T_(ad) was deduced according to the principles of thermodynamics.The MCE and the engineering application were discussed for Gd and several new kinds of magneticrefrigerating materials near room temperature, Gd_5Si_2Ge_2, MnFeP_(0.45)As_(0.55) and LaFe_(11.2)Co_(0.7)Si_(1.1). Isothermal entropy change is proportional to adiabatic temperature change with afactor of T/C (T is temperature, C is heat capacity). When the comparison of magnetacoloric effectis made for two different materials, we should consider isothermal entropy change as well asadiabatic temperature change.
文摘Graphene, the thinnest and hardest nano-material in the world, is non-toxic, sustainable and with minimal environmental footprint. As one of the most important carbon materials, it is composed of a monolayer of carbon atoms with a honeycomb structure. Nowadays, scientists have tried to use it in the biomedicine subject because of its superior physical and chemical properties and excellent biocompatibility.
基金Supported by Key Basic Research Project of China (No. 2005CB623904)National Natural Science Foundation of China (No.RGC30831160509)Program for New Century Excellent Talents in University (No.06-0800)
文摘Bacterial infection plays an important role in the initiation of biliary sludge formation. Bacterial adherence and biofilm formation on the surface of a material have been considered as one of the main factors of stent re-occlusion in clinic. This work reported preventing bacterial adherence and bacterial biofilm formation on the surface of biliary stent material using chitosan film. The chitosan film was deposited on 316 L stainless steel （SS） plate by electrophoresis method and was characterized by X-ray diffraction （XRD）, Fourier Transform infrared spectroscopy （FTIR） and atomic force microscopy （AFM）. The ability of inhibiting bacterial adherence was investigated by incubating in human fresh bile adding E. coli and Enterobacter at 37±1 ℃ . Scanning electron microscopy （SEM） and fluorescence staining were used for observing bacterial colonization and biofilm formation. The results show that chitosan film was uniformly deposited on material surface, and the composition of the film did not change through cross-linking, but the crystallinity of chitosan film become well. Comparing to un-modified sample, the E. coli and Enterococcus adhesion amount and colonization on the surface of modified sample were significantly decreased by fluorescence staining and SEM. It is suggested that chitosan could be applied to biliary stent in clinical because of its antimicrobial activities.
基金supported by the National Basic Research Program of China (Grant no. 2015CB251100)Beijing Natural Science Foundation (No. L182023)
文摘Lithium metal is supposed to be critical material for constructing next-generation batteries due to extremely high capacity and ultralow redox potential. However, the perplexing issue of lithium dendrite growth impedes the commercial application. The initial nucleation and low Li ions diffusion rate in the electrolyte/electrode interface dominate the deposition behavior. Therefore, a uniform and flexible interface is urgently needed. Here, a facile method is proposed to prepare a thin and porous LiF-rich layer (TPL) by the in-situ reaction of small amount of ammonium hydrogen difluoride (NH4HF2) and Li metal. The deposition morphology on Li metal anode with LiF layer is significantly flat and homogeneous owning to low lateral diffusion barrier on LiF crystals and the porous structure of TPL film. Additionally, the symmetrical cells made with such TPL Li anodes show significantly stable cycling over 100 cycles at high current density of 6 mA/cm^2. The TPL Li|LiFePO4 full cells keep over 99% capacity retention after 100 cycles at 2.0 C. This approach serves as a facile and controllable way of adjusting the protective layer on Li metal.
基金the support of the Natural Science Foundation of Shandong Province(No.ZR2018MEE030)the National Natural Science Foundation of China(Nos.51506116,51576118,51376112)+1 种基金the Young Scholars Program of Shandong University(No.2016WLJH37)the Fundamental Research Funds of Shandong University(No.2016JC004)
文摘Interactions between microwaves and certain catalysts can lead to efficient, energy-directed convergence of a relatively dispersed microwave field onto the reactive sites of the catalyst,which produces thermal or discharge effects around the catalyst. These interactions form"high-energy sites"(HeS) that promote energy efficient utilization and enhanced in situ degradation of organic pollutants. This article focuses on the processes occurring between microwaves and absorbing catalysts, and presents a critical review of microwave-absorbing mechanisms. This article also discusses aqueous phase applications of relevant catalysts(ironbased, carbon-based, soft magnetic, rare earth, and other types) and microwaves, special effects caused by the dimensions and structures of catalytic materials, and the optimization and design of relevant reactors for microwave-assisted catalysis of wastewater. The results of this study demonstrate that microwave-assisted catalysis can effectively enhance the degradation rate of organic compounds in an aqueous phase and has potential applications to a variety of engineering fields such as microwave-assisted pyrolysis, pollutant removal,material synthesis, and water treatment.
基金financially supported by the Natural Science Foundation Project of Chongqing City (No.cstc2012jjA50002)
文摘Aging treatment and various heat input conditions and mechanical properties of TIG welded 606I-T6 alloy joints were adopted to investigate the microstructural evolution by microstructural observations, microhardness tests, and tensile tests. With an increase in heat input, the width of the heat-affected zone （HAZ） increases and grains in the fusion zone （FZ） coarsen. Moreover, the hardness of the HAZ decreases, whereas that of the FZ decreases initially and then increases with an increase in heat input. Low heat input results in the low ultimate tensile strength of the welded joints due to the presence of partial penetrations and pores in the welded joints. After a simple artificial aging treatment at 175℃ for 8 h, the microstructure of the welded joints changes slightly. The mechanical properties of the welded joints enhance significantly after the aging process as few precipitates distribute in the welded seam.
基金supported by the National 863 Research Project (2006AA03Z219)Natural Science Foundation of Jiangsu Province (BK2007199)Foundation for "Liu Da Ren Cai" of Jiangsu Province (06-E-021)
文摘Ce-doped ZnO films were prepared by the sol-gel method with spin coating onto glass substrates.Zinc acetate dihydrate,ethanol,diethanolamine and cerium nitrate hexahydrate were used as starting material,solvent,stabilizer and dopant source,respectively.Structure and microstructure of the films were characterized with X-ray diffraction(XRD),field emission-scanning electron microscopy(FE-SEM) and the energy dispersive X-ray spectrometry(EDS).The infrared properties were also investigated.It was found that Ce-...
基金financial support provided by the National Key R&D Program of China (2016YFA0200400)the Jilin Province/Jilin University co-Construction Project-Funds for New Materials (SXGJSF2017-3, Branch-2/440050316A36)+4 种基金the National Natural Science Foundation of China (Grant nos. 91545119, 21761132025, 21773269 and 51372095)the Youth Innovation Promotion Association CAS (Grant no. 2015152)Strategic Priority Research Program of the Chinese Academy of Sciences Chinese Academy of Sciences (Grant nos. XDA09030103 and XDA09040203)the Program for JLU Science and Technology Innovative Research Team (JLUSTIRT)"Double-First Class" Discipline for Materials Science & Engineering
文摘MXene has shown distinctive advantages as anode materials of lithium-ion batteries. However, local surface chemistry, which was confirmed that can block ion transfer and limit redox reaction, has a significant effect on electrochemical performance. Herein, annealing MXene under hydrogen was employed for removing-F and turning-OH to-O terminations. We demonstrate that it improves the kinetics of Li-ion transport between the electrolyte and electrode. As a result, a lower interfacial charge transfer impedance was obtained. The electrochemical measurement exhibited that a nearly 2-fold increase of specific capacity was achieved for the annealed MXene.
基金the Higher Education Commission (HЕС) Pakistan for provision of research funding (Project No. 20-3844/R&D/HEC/14) under National Research Program for Universities (NRPU)
文摘As a β stabilizing element in Ti-based alloys,the effect of Mo on phase constitution,microstructure,mechanical and shape memory properties was investigated.Different compositions of Ti-xMo-3Sn alloys(where x=2,4,6,at.%) were prepared by arc melting.A binary composition of Ti-6 Mo alloy was also prepared for comparison.Ti-xMo-3Sn alloys show low hardness and high ductility with 90% reduction in thickness while Ti-6 Mo alloy shows high hardness,brittle behavior,and poor ductility.Field emission scanning electron microscopy(FESEM) reveals round morphology of athermal ω(ωath) precipitates.The presence of ωath phase is also confirmed by X-ray diffraction(XRD)in both as-cast and solution-treated and quenched conditions.The optical microscopy(OM) and FESEM show that the amount of martensite forming during quenching decreases with an increase in Mo content,which is also due to β→ω transformation.The hardness trends reinforce the presence of ωath too.The shape memory effect(SME) of 9% is the highest for Ti-6 Mo-3Sn alloy.The SME is trivial due to ωath phase formation;however,the increase in SME is observed with an increase in Mo content,which is due to the reverse transformation from ωath and the stress-induced martensitic transformation.In addition,a new and very simple method was designed and used for shape memory effect measurement.
基金the National Natural Science Foundation of China(Nos.51474156 and U1660201)the National Magnetic Confinement Fusion Energy Research Program of China(No.2015GB119001)for their grants and financial supports
文摘A 1040°C-hot-deformed Ti_2AlNb-based alloy solution-treated at 950°C and aged at different temperatures was quantitatively investigated. The microstructure, size of the phase, and microhardness of the deformed alloys were measured. The results indicated that the microstructure of the deformed Ti_2AlNb-based alloy specimens comprise coarse O lath, fine O lath, equiaxed O/α_2, and acicular O phase. More O phase was generated in the deformed alloy after heat treatment because the acicular O phase was more likely to nucleate and grow along the deformation-induced crystal defects such as dislocations and subgrain boundaries. After deformation and subsequent heat treatment, the acicular O phase of the resultant alloy became finer compared to that of the undeformed alloy, and the acicular O phase became coarser and longer with the elevated aging temperature, while the width of the O lath exhibited unobvious variations. The hot deformation facilitated the dissolution of the O lath but accelerated the precipitation of the acicular O phase. When the 950°C-solution-treated deformed Ti_2AlNb-based alloy was then aged at 750°C for different periods, the phase content was nearly invariable, O and B2 phases eventually reached equilibrium, and the microstructure became stable and homogeneous.
文摘A highly branched polycarbosilane bearing allyl groups has been prepared by a one-pot synthesis with chloromethyltrichlorosilane, chloromethylmethyldichlorosilane and allyl chloride as the starting materials. The resultant polymer, with the approximate formula [SiH1.2(CH3)0.71(CH2CHCH2)0.09CH2]n, has been characterized by 1H, 13C, and 29Si NMR, GPC, TG and elemental analysis. It could be cross-linked thermally at 170 °C in the absence of oxygen. Pyrolysis of the polymer gave a ceramic with a yield of about 70%.
