Heavy metal pollution and remediation of soils have drawn much attention. More and more scholars tend to remediate soil heavy metals without affecting the normal agricultural production. By analyzing the mechanism of ...Heavy metal pollution and remediation of soils have drawn much attention. More and more scholars tend to remediate soil heavy metals without affecting the normal agricultural production. By analyzing the mechanism of action of organic materials to remediate Pb pollution in soil,the effect of different organic materials on the passivation of available Pb in soil was summarized,and the prospect was proposed for the future application of organic materials,in order to provide reference for the remediation of Pb and other heavy metals by organic materials.展开更多
The oilseed cake, vetch, rapeseed straw, wheat straw and corn straw were buried in tobacco-planted soil. The decomposition rates, the variation of active organic C and N contents in the residues and the relationship b...The oilseed cake, vetch, rapeseed straw, wheat straw and corn straw were buried in tobacco-planted soil. The decomposition rates, the variation of active organic C and N contents in the residues and the relationship between active organic C and N contents and decomposition rate were investigated. The results showed the decomposition rates of different organic materials were all high in the early period and then low in the late period. Among the organic materials, the decomposition rates ranked as oilseed cake 〉 vetch 〉 wheat straw and rapeseed straw 〉 corn straw. The decomposition rate was positively related to total N content （P〈0.01）, but was negatively related to the active organic C/N ratio （P〈0.01）. However, there was no significant relationship between decomposition ratio and active organic C content. With the proceeding of decomposition, the active organic C content and the total N content in rapeseed straw, vetch, wheat straw and corn straw all trended to increase, but the active organic C/N ratio trended to decrease. However, the variation of active organic C content, total N content and active organic C/N ratio in oilseed cake was on the contrary.展开更多
In order to enhance electrochemical properties of LiFePO4 （LFP） cathode materials, spherical porous nano/micro structured LFP/C cathode materials were synthesized by spray drying, followed by calcination. The result...In order to enhance electrochemical properties of LiFePO4 （LFP） cathode materials, spherical porous nano/micro structured LFP/C cathode materials were synthesized by spray drying, followed by calcination. The results show that the spherical precursors with the sizes of 0.5-5 μm can be completely converted to LFP/C when the calcination temperature is higher than 500 ℃. The LFP/C microspheres obtained at calcination temperature of 700 ℃ are composed of numerous particles with sizes of -20 nm, and have well-developed interconnected pore structure and large specific surface area of 28.77 mE/g. The specific discharge capacities of the LFP/C obtained at 700 ℃ are 162.43, 154.35 and 144.03 mA.h/g at 0.5C, 1C and 2C, respectively. Meanwhile, the capacity retentions can reach up to 100% after 50 cycles. The improved electrochemical properties of the materials are ascribed to a small Li＋ diffusion resistance and special structure of LFP/C microspheres.展开更多
Hunan Province is rich in red tourism resources, and many scenic spots in the region proudly echo the glory of China's revolutionary history. Publicity materials of red tourism in Hunan Province play the role of p...Hunan Province is rich in red tourism resources, and many scenic spots in the region proudly echo the glory of China's revolutionary history. Publicity materials of red tourism in Hunan Province play the role of publicizing and promoting historical sites and places linked with China's revolutionary history. However, at present the C-E translation of publicity materials of red tourism in Hunan province is far from satisfaction. Reasonable application of eco-translatology in C-E translation of publicity materials of red tourism in Hunan Province will allow the translator to enjoy a much greater degree of flexibility in translating and produce appropriate translation which produce functionally the same effect on the target readers as the original on the readers.展开更多
Spherical LiFePO4 and LiFePO4/C composite powders for lithium ion batteries were synthesized by a novel processing route of co-precipitation and subsequent calcinations in a nitrogen and hydrogen atmosphere. The precu...Spherical LiFePO4 and LiFePO4/C composite powders for lithium ion batteries were synthesized by a novel processing route of co-precipitation and subsequent calcinations in a nitrogen and hydrogen atmosphere. The precursors of LiFePO4, LiFePO4/C composite and the resultant products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and the electrochemical performances were investigated by galvanostatic charge and discharge tests. The precursors composed of amorphous Fe3(PO4)2·xH2O and crystalline Li3PO4 obtained in the co-precipitation processing have a sphere-like morphology. The spherical LiFePO4 derived from the calcinations of the precursor at 700 ℃ for 10 h in a reduction atmosphere shows a discharge capacity of 119 mAh·g-1 at the C/10 rate, while the LiFePO4/C composite with 10wt.% carbon addition exhibits a discharge capacity of 140 mAh·g-1. The electrochemical performances indicate that the LiFePO4/C composite has a higher specific capacity and a more stable cycling performance than the bare olivine LiFePO4 due to the carbon addition enhancing the electronic conductivity.展开更多
Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be...Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.展开更多
Thermal deformation of aluminum alloy casting materials for manufacturing the tire mold was numerically investigated.The AC7A and AC4C casting material was selected as casting material and the metal casting device was...Thermal deformation of aluminum alloy casting materials for manufacturing the tire mold was numerically investigated.The AC7A and AC4C casting material was selected as casting material and the metal casting device was used in order to manufacture the mold product of automobile tire in the actual industrial field.The temperature distribution and the cooling time of casting materials were numerically calculated by finite element analysis (FEA).Also,the thermal deformation such as displacement and stress distribution was calculated from the temperature results.The thermal deformation was closely related to the temperature difference between the surface and inside of the casting.The numerical analysis results reveal that the thermal deformation of AC7A casting material is higher than that of AC4C casting material.Also,the thermal deformation results at the central part are larger than that on the side of casting because of the shrinkage caused by the cooling speed difference.展开更多
The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial...The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu（Ⅱ）. These results are important to achieve better understanding of the behavior of Cu（Ⅱ） in soil and water bodies in the presence of organic materials.展开更多
The 3D needled C/SiC brake materials modified with graphite were prepared by a combined process of the chemical vapor infiltration,slurry infiltration and liquid silicon infiltration process.The microstructure and fri...The 3D needled C/SiC brake materials modified with graphite were prepared by a combined process of the chemical vapor infiltration,slurry infiltration and liquid silicon infiltration process.The microstructure and frictional properties of the brake materials were investigated.The density and open porosity of the materials as-received were about(2.1±0.1)g/cm3and(5±1)%,respectively.The brake materials were composed of 59%C,39%SiC,and 2%Si(mass fraction).The content of Si in the C/SiC brake materials modified with graphite was far less than that in the C/SiC brake materials without being modified with graphite,and the Si was dispersed.The braking curve of the 3D needled C/SiC modified with graphite was smooth,which can ensure the smooth and comfortable braking.The frictional properties under wet condition of the 3D needled C/SiC modified with graphite showed no fading.And the linear wear rate of the C/SiC modified with graphite was lower than that of the C/SiC unmodified.展开更多
There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic t...There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic tiles. The average production of EBP is about Ig million tons per year. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks. The maximal amount of CFA should be up to 50%.展开更多
Natural radioactivity radionuclides in building materials, such as^(226)Ra,^(232)Th and^(40)K, cause indoor exposure due to their gamma-rays. In this research, in a standard dwelling room(5.0 m 9 4.0 m 9 2.8 m), with ...Natural radioactivity radionuclides in building materials, such as^(226)Ra,^(232)Th and^(40)K, cause indoor exposure due to their gamma-rays. In this research, in a standard dwelling room(5.0 m 9 4.0 m 9 2.8 m), with the floor covered by various granite stones, was set up to simulate the dose rates from the radionuclides using MCNP4 C code. Using samples of granite building products in Iran, activities of the^(226)Ra,^(232)Th and^(40)K were measured at 3.8–94.2, 6.5–172.2 and 556.9–1529.2 Bq kg^(-1),respectively. The simulated dose rates were26.31–184.36 n Gy h^(-1), while the measured dose rates were 27.70–204.17 n Gy h^(-1). With the results in good agreement, the simulation is suitable for any kind of dwelling places.展开更多
B4C, SiC and C, Cu functionally graded-materials (FGMs) have been developed by plasma spraying and hot pressing. Their high-heat flux properties have been investigated by high energy laser and electron beam for the si...B4C, SiC and C, Cu functionally graded-materials (FGMs) have been developed by plasma spraying and hot pressing. Their high-heat flux properties have been investigated by high energy laser and electron beam for the simulation of plasma disruption process of the future fusion reactors, And a study on eroded products of B4C/Cu FGM under transient thermal load of electron beam was performed. In the experiment, SEM and EDS analysis indicated that B4C and SiC were decomposed, carbon was preferentially evaporated under high thermal load, and a part of Si and Cu were melted, in addition, the splash of melted metal and the particle emission of brittle destruction were also found. Different erosive behaviors of carbon-based materials (CBMs) caused by laser and electron beam were also discussed.展开更多
In this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2F...In this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2FeSi04 was synthesized by a facile hydrothermal method with（NH4）2Fe（SO4）2 as the iron source.The spindle-like Li2FeSiO4 was sintered at 600 ℃ for 6 h in Ar atmosphere.Li2FeSiO4-C composite was obtained by the hydrothermal treatment of spindle-like Li2FeSiO4 in glucose solution at 190 ℃ for 3 h.Electrochemical measurements show that after carbon coating,the electrode performances such as discharge capacity and high-rate capability are greatly enhanced.In particular.Li2FeSiO4-C with carbon content of 7.21 wt%delivers the discharge capacities of 160.9 mAh·g-1 at room temperature and 213 mAh·g-1 at45℃（0.1 C）,revealing the potential application in lithium-ion batteries.展开更多
Smart Materials are along with Innovation attributes and Artificial Intelligence among the most used “buzz” words in all media. Central to their practical occurrence, many talents are to be gathered within new conte...Smart Materials are along with Innovation attributes and Artificial Intelligence among the most used “buzz” words in all media. Central to their practical occurrence, many talents are to be gathered within new contextual data influxes. Has this, in the last 20 years, changed some of the essential fundamental dimensions and the required skills of the actors such as providers, users, insiders, etc.? This is a preliminary focus and prelude of this review. As an example, polysaccharide materials are the most abundant macromolecules present as an integral part of the natural system of our planet. They are renewable, biodegradable, carbon neutral with low environmental, health and safety risks and serve as structural materials in the cell walls of plants. Most of them are used, for many years, as engineering materials in many important industrial processes, such as pulp and papermaking and manufacture of synthetic textile fibres. They are also used in other domains such as conversion into biofuels and, more recently, in the design of processes using polysaccharide nanoparticles. The main properties of polysaccharides (e.g. low density, thermal stability, chemical resistance, high mechanical strength…), together with their biocompatibility, biodegradability, functionality, durability and uniformity, allow their use for manufacturing smart materials such as blends and composites, electroactive polymers and hydrogels which can be obtained 1) through direct utilization and/or 2) after chemical or physical modifications of the polysaccharides. This paper reviews recent works developed on polysaccharides, mainly on cellulose, hemicelluloses, chitin, chitosans, alginates, and their by-products (blends and composites), with the objectives of manufacturing smart materials. It is worth noting that, today, the fundamental understanding of the molecular level interactions that confer smartness to polysaccharides remains poor and one can predict that new experimental and theoretical tools will emerge to develop the necessary understanding of the structure-property-function relationships that will enable polysaccharide-smartness to be better understood and controlled, giving rise to the development of new and innovative applications such as nanotechnology, foods, cosmetics and medicine (e.g. controlled drug release and regenerative medicine) and so, opening up major commercial markets in the context of green chemistry.展开更多
基金Supported by the Key Technology Research and Development Program of Guizhou Province(Qiankehe Support[2017]2580)the Major Project of Science and Technology Fund of Guizhou Province(Qiankehe JZ[2014]No.2012)
文摘Heavy metal pollution and remediation of soils have drawn much attention. More and more scholars tend to remediate soil heavy metals without affecting the normal agricultural production. By analyzing the mechanism of action of organic materials to remediate Pb pollution in soil,the effect of different organic materials on the passivation of available Pb in soil was summarized,and the prospect was proposed for the future application of organic materials,in order to provide reference for the remediation of Pb and other heavy metals by organic materials.
基金Supported by National Key Technology Research and Development Program(2012BAD40B02Yunnan Provincial Tobacco Company Plan Project(2012YN48)~~
文摘The oilseed cake, vetch, rapeseed straw, wheat straw and corn straw were buried in tobacco-planted soil. The decomposition rates, the variation of active organic C and N contents in the residues and the relationship between active organic C and N contents and decomposition rate were investigated. The results showed the decomposition rates of different organic materials were all high in the early period and then low in the late period. Among the organic materials, the decomposition rates ranked as oilseed cake 〉 vetch 〉 wheat straw and rapeseed straw 〉 corn straw. The decomposition rate was positively related to total N content （P〈0.01）, but was negatively related to the active organic C/N ratio （P〈0.01）. However, there was no significant relationship between decomposition ratio and active organic C content. With the proceeding of decomposition, the active organic C content and the total N content in rapeseed straw, vetch, wheat straw and corn straw all trended to increase, but the active organic C/N ratio trended to decrease. However, the variation of active organic C content, total N content and active organic C/N ratio in oilseed cake was on the contrary.
基金Project(2013AA050901)supported by the National High-tech Research and Development Program of China
文摘In order to enhance electrochemical properties of LiFePO4 （LFP） cathode materials, spherical porous nano/micro structured LFP/C cathode materials were synthesized by spray drying, followed by calcination. The results show that the spherical precursors with the sizes of 0.5-5 μm can be completely converted to LFP/C when the calcination temperature is higher than 500 ℃. The LFP/C microspheres obtained at calcination temperature of 700 ℃ are composed of numerous particles with sizes of -20 nm, and have well-developed interconnected pore structure and large specific surface area of 28.77 mE/g. The specific discharge capacities of the LFP/C obtained at 700 ℃ are 162.43, 154.35 and 144.03 mA.h/g at 0.5C, 1C and 2C, respectively. Meanwhile, the capacity retentions can reach up to 100% after 50 cycles. The improved electrochemical properties of the materials are ascribed to a small Li＋ diffusion resistance and special structure of LFP/C microspheres.
文摘Hunan Province is rich in red tourism resources, and many scenic spots in the region proudly echo the glory of China's revolutionary history. Publicity materials of red tourism in Hunan Province play the role of publicizing and promoting historical sites and places linked with China's revolutionary history. However, at present the C-E translation of publicity materials of red tourism in Hunan province is far from satisfaction. Reasonable application of eco-translatology in C-E translation of publicity materials of red tourism in Hunan Province will allow the translator to enjoy a much greater degree of flexibility in translating and produce appropriate translation which produce functionally the same effect on the target readers as the original on the readers.
基金This work was financially supported by the National Natural Science Foundation of China (No.50134020)
文摘Spherical LiFePO4 and LiFePO4/C composite powders for lithium ion batteries were synthesized by a novel processing route of co-precipitation and subsequent calcinations in a nitrogen and hydrogen atmosphere. The precursors of LiFePO4, LiFePO4/C composite and the resultant products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and the electrochemical performances were investigated by galvanostatic charge and discharge tests. The precursors composed of amorphous Fe3(PO4)2·xH2O and crystalline Li3PO4 obtained in the co-precipitation processing have a sphere-like morphology. The spherical LiFePO4 derived from the calcinations of the precursor at 700 ℃ for 10 h in a reduction atmosphere shows a discharge capacity of 119 mAh·g-1 at the C/10 rate, while the LiFePO4/C composite with 10wt.% carbon addition exhibits a discharge capacity of 140 mAh·g-1. The electrochemical performances indicate that the LiFePO4/C composite has a higher specific capacity and a more stable cycling performance than the bare olivine LiFePO4 due to the carbon addition enhancing the electronic conductivity.
基金National Natural Science Foundation of China with Grant No.21905304Natural Science Foundation of Shandong Province(No.ZR2019BEM031)the Fundamental Research Funds for the Central Universities(Nos.18CX02158A and 19CX05001A).
文摘Ti3C2Tx,a novel two-dimensional layer material,is widely used as electrode materials of supercapacitor due to its good metal conductivity,redox reaction active surface,and so on.However,there are many challenges to be addressed which impede Ti3C2Tx obtaining the ideal specific capacitance,such as restacking,re-crushing,and oxidation of titanium.Recently,many advances have been proposed to enhance capacitance performance of Ti3C2Tx.In this review,recent strategies for improving specific capacitance are summarized and compared,for example,film formation,surface modification,and composite method.Furthermore,in order to comprehend the mechanism of those efforts,this review analyzes the energy storage performance in different electrolytes and influencing factors.This review is expected to predict redouble research direction of Ti3C2Tx materials in supercapacitors.
基金Project supported by Research Funds from Chosun University(2009),Korea
文摘Thermal deformation of aluminum alloy casting materials for manufacturing the tire mold was numerically investigated.The AC7A and AC4C casting material was selected as casting material and the metal casting device was used in order to manufacture the mold product of automobile tire in the actual industrial field.The temperature distribution and the cooling time of casting materials were numerically calculated by finite element analysis (FEA).Also,the thermal deformation such as displacement and stress distribution was calculated from the temperature results.The thermal deformation was closely related to the temperature difference between the surface and inside of the casting.The numerical analysis results reveal that the thermal deformation of AC7A casting material is higher than that of AC4C casting material.Also,the thermal deformation results at the central part are larger than that on the side of casting because of the shrinkage caused by the cooling speed difference.
基金supported by the Key Technologies R&D Program of China (2013BAD07B02 and 2013BAC09B01)the Special Fund for Agro-Scientific Research in the Public Interest of China (201103003)+1 种基金the Postdoctoral Project of Jilin Province, China (01912)the Doctoral Initiative Foundation of Jilin Agricultural University, China (201216)
文摘The adsorption of Cu（Ⅱ） from aqueous solution onto humic acid （HA） which was isolated from cattle manure （CHA）, peat （PHA）, and leaf litter （LHA） as a function of contact time, pH, ion strength, and initial concentration was studied using the batch method. X-ray absorption spectroscopy （XAS） was used to examine the coordination environment of the Cu（ll） adsorbed by HA at a molecular level. Moreover, the chemical compositions of the isolated HA were characterized by elemental analysis and solid-state 13C nuclear magnetic resonance spectroscopy （NMR）. The kinetic data showed that the adsorption equilibrium can be achieved within 8 h. The adsorption kinetics followed the pseudo-second-order equation. The adsorption isotherms could be well fitted by the Langmuir model, and the maximum adsorption capacities of Cu（ll） on CHA, PHA, and LHA were 229.4,210.4, and 197.7 mg g-1, respectively. The adsorption of Cu（Ⅱ） on HA increased with the increase in pH from 2 to 7, and maintained a high level at pH〉7. The adsorption of Cu（Ⅱ） was also strongly influenced by the low ionic strength of 0.01 to 0.2 mol L-1 NaNO3, but was weakly influenced by high ionic strength of 0.4 to 1 mol L-1 NaNO3. The Cu（Ⅱ） adsorption on HA may be mainly attributed to ion exchange and surface complexation. XAS results revealed that the binding site and oxidation state of Cu adsorbed on HA surface did not change at the initial Cu（Ⅱ） concentrations of 15 to 40 mg L 1. For all the Cu（Ⅱ） adsorption samples, each Cu atom was surrounded by 40/N atoms at a bond distance of 1.95 A in the first coordination shell. The presence of the higher Cu coordination shells proved that Cu（Ⅱ） was adsorbed via an inner-sphere covalent bond onto the HA surface. Among the three HA samples, the adsorption capacity and affinity of CHA for Cu（Ⅱ） was the greatest, followed by that of PHA and LHA. All the three HA samples exhibited similar types of elemental and functional groups, but different contents of elemental and functional groups. CHA contained larger proportions of methoxyl C, phenolic C and carbonyl C, and smaller proportions of alkyl C and carbohydrate C than PHA and LHA. The structural differences of the three HA samples are responsible for their distinct adsorption capacity and affinity toward Cu（Ⅱ）. These results are important to achieve better understanding of the behavior of Cu（Ⅱ） in soil and water bodies in the presence of organic materials.
基金Project(46-QP-2009)supported by the Research Fund of State Key Laboratory of Solidification Processing(NWPU),ChinaProject supported by the Program for Changjiang Scholars and Innovative Research Team in Chinese University
文摘The 3D needled C/SiC brake materials modified with graphite were prepared by a combined process of the chemical vapor infiltration,slurry infiltration and liquid silicon infiltration process.The microstructure and frictional properties of the brake materials were investigated.The density and open porosity of the materials as-received were about(2.1±0.1)g/cm3and(5±1)%,respectively.The brake materials were composed of 59%C,39%SiC,and 2%Si(mass fraction).The content of Si in the C/SiC brake materials modified with graphite was far less than that in the C/SiC brake materials without being modified with graphite,and the Si was dispersed.The braking curve of the 3D needled C/SiC modified with graphite was smooth,which can ensure the smooth and comfortable braking.The frictional properties under wet condition of the 3D needled C/SiC modified with graphite showed no fading.And the linear wear rate of the C/SiC modified with graphite was lower than that of the C/SiC unmodified.
文摘There have been increasing efforts to utilize energy by-products （EBP） all over the world. In the Czech Re- public fly ash is usually used in ceramic technology, es- pecially in brick manufacturing and for ceramic tiles. The average production of EBP is about Ig million tons per year. The range of potential products, where EBP could be used, is very wide and energy by-products have become an important raw material source. In this paper the attention was focused on class C fly ash and its usage in field of refractory materials. Experimental works were carried out on mixtures with fly ash and clay. There were also tested batches for lightweight fireclay bricks. The maximal amount of CFA should be up to 50%.
文摘Natural radioactivity radionuclides in building materials, such as^(226)Ra,^(232)Th and^(40)K, cause indoor exposure due to their gamma-rays. In this research, in a standard dwelling room(5.0 m 9 4.0 m 9 2.8 m), with the floor covered by various granite stones, was set up to simulate the dose rates from the radionuclides using MCNP4 C code. Using samples of granite building products in Iran, activities of the^(226)Ra,^(232)Th and^(40)K were measured at 3.8–94.2, 6.5–172.2 and 556.9–1529.2 Bq kg^(-1),respectively. The simulated dose rates were26.31–184.36 n Gy h^(-1), while the measured dose rates were 27.70–204.17 n Gy h^(-1). With the results in good agreement, the simulation is suitable for any kind of dwelling places.
文摘B4C, SiC and C, Cu functionally graded-materials (FGMs) have been developed by plasma spraying and hot pressing. Their high-heat flux properties have been investigated by high energy laser and electron beam for the simulation of plasma disruption process of the future fusion reactors, And a study on eroded products of B4C/Cu FGM under transient thermal load of electron beam was performed. In the experiment, SEM and EDS analysis indicated that B4C and SiC were decomposed, carbon was preferentially evaporated under high thermal load, and a part of Si and Cu were melted, in addition, the splash of melted metal and the particle emission of brittle destruction were also found. Different erosive behaviors of carbon-based materials (CBMs) caused by laser and electron beam were also discussed.
基金supported by the Programs of National 973(2011CB935900)NSFC(21231005)+1 种基金MOE(B12015 and 113016A)the Fundamental Research Funds for the Central Universities
文摘In this paper,we report on the preparation of Li2FeSiO4,sintered Li2FeSiO4,and Li2FeSiO4-C composite with spindle-like morphologies and their application as cathode materials of lithium-ion batteries.Spindle-like Li2FeSi04 was synthesized by a facile hydrothermal method with（NH4）2Fe（SO4）2 as the iron source.The spindle-like Li2FeSiO4 was sintered at 600 ℃ for 6 h in Ar atmosphere.Li2FeSiO4-C composite was obtained by the hydrothermal treatment of spindle-like Li2FeSiO4 in glucose solution at 190 ℃ for 3 h.Electrochemical measurements show that after carbon coating,the electrode performances such as discharge capacity and high-rate capability are greatly enhanced.In particular.Li2FeSiO4-C with carbon content of 7.21 wt%delivers the discharge capacities of 160.9 mAh·g-1 at room temperature and 213 mAh·g-1 at45℃（0.1 C）,revealing the potential application in lithium-ion batteries.
文摘Smart Materials are along with Innovation attributes and Artificial Intelligence among the most used “buzz” words in all media. Central to their practical occurrence, many talents are to be gathered within new contextual data influxes. Has this, in the last 20 years, changed some of the essential fundamental dimensions and the required skills of the actors such as providers, users, insiders, etc.? This is a preliminary focus and prelude of this review. As an example, polysaccharide materials are the most abundant macromolecules present as an integral part of the natural system of our planet. They are renewable, biodegradable, carbon neutral with low environmental, health and safety risks and serve as structural materials in the cell walls of plants. Most of them are used, for many years, as engineering materials in many important industrial processes, such as pulp and papermaking and manufacture of synthetic textile fibres. They are also used in other domains such as conversion into biofuels and, more recently, in the design of processes using polysaccharide nanoparticles. The main properties of polysaccharides (e.g. low density, thermal stability, chemical resistance, high mechanical strength…), together with their biocompatibility, biodegradability, functionality, durability and uniformity, allow their use for manufacturing smart materials such as blends and composites, electroactive polymers and hydrogels which can be obtained 1) through direct utilization and/or 2) after chemical or physical modifications of the polysaccharides. This paper reviews recent works developed on polysaccharides, mainly on cellulose, hemicelluloses, chitin, chitosans, alginates, and their by-products (blends and composites), with the objectives of manufacturing smart materials. It is worth noting that, today, the fundamental understanding of the molecular level interactions that confer smartness to polysaccharides remains poor and one can predict that new experimental and theoretical tools will emerge to develop the necessary understanding of the structure-property-function relationships that will enable polysaccharide-smartness to be better understood and controlled, giving rise to the development of new and innovative applications such as nanotechnology, foods, cosmetics and medicine (e.g. controlled drug release and regenerative medicine) and so, opening up major commercial markets in the context of green chemistry.
