Nickel-plated graphite particles and unmodified graphite particles with different contents were added to the Fe-based diamond composites.The basic properties of those specimens were measured,including relative density...Nickel-plated graphite particles and unmodified graphite particles with different contents were added to the Fe-based diamond composites.The basic properties of those specimens were measured,including relative density,hardness,bending strength,abrasion ratio and holding force coefficient.And also,SEM,XRD and EDS were used to carry out microstructure characterization,phase analysis and element distribution of these specimens.The results show that nickel plating effectively improves the surface wettability of graphite particles.And it is determined that an element diffusion zone is formed on the transition interface between the nickel-plated graphite and the matrix materials,effectively enhancing the interfacial bonding strength.Also,the pores and cracks in the matrix generated by adding the graphite particles are reduced after nickel plating.Thus,the loss of basic properties of the specimens is restrained.But it is found the higher the graphite content is,the weaker the positive effect of nickel plating is.In addition,it is revealed that nickel plating plays a conducive part in the formation of graphite lubricants on the working surface,and nickel-plated graphites can slow down the thermal corrosion of the diamond particles inside the high-temperature sintered specimens.展开更多
In this paper new criteria for designing of temporary architectures, which can be used as a uniform coverage for open spaces, are discussed. Frequently temporary architectures use building techniques and materials lig...In this paper new criteria for designing of temporary architectures, which can be used as a uniform coverage for open spaces, are discussed. Frequently temporary architectures use building techniques and materials lightweight. In the case of temporary architectures the theme of sustainability requires that the structure can be reused in different occasions and contexts. The solution to these issues, developed in this paper, makes use of a innovative constructive procedure of prestressed masonry in blocks of natural stone. This procedure is used for the construction of the vertical supports of the cover, consisting of a tensostructure with shape of hyperboloid, obtained by products standard （steel profiles and membrane）. The columns with prestressed blocks of natural stone, dry assembled, allow you to have a modular structure, easily assembled and disassembled, with full recovery of all elements; the stone columns, due to their weight, are able to stabilize the whole structure, even to the dynamic stresses, without using any type of foundation structure fixed to the ground. This paper shows the description of all the elements that make up the new type of temporary architecture designed.展开更多
The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimen...The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimensional (2D)nanomaterials and their heterostructures are an intense area of study and promise great potential in electrochemical lithium storage owing to their unique properties that result from structural planar confinement.Here we report a microwave chemistry strategy to integrate ultrathin SnO2 nanosheets into graphene layer to construct surface-to-surface 2D heterostructured architectures,which can provide unique structural planar confinement for highly reversible electrochemical lithium storage.The as-synthesized 2D SnO2/graphene heterostructures can exhibit high reversible capacity of 688.5mAh g^-1 over 500cycles with excellent long-term cycling stability and good rate capability when used as anode materials for lithium ion batteries.The present work definitely reveals the advantages of 2D heterostructures featured with a surface-to-surface stack between two different nanosheets in energy storage and conversion devices.展开更多
Ni1-xZnxFe2O4(0≤x≤1,in steps of 0.1) nanocrystallines were synthesized by sol-gel route.The doping effects of zinc on structural,magnetic and microwave absorption properties were investigated in detail.X-ray diffrac...Ni1-xZnxFe2O4(0≤x≤1,in steps of 0.1) nanocrystallines were synthesized by sol-gel route.The doping effects of zinc on structural,magnetic and microwave absorption properties were investigated in detail.X-ray diffraction(XRD) results show that all the samples are single-phase spinel structure.The magnetic and microwave absorption properties are strongly dependent on the zinc content,which can be understood in terms of the cations redistribution in spinel tetrahedral and octahedral sites with the increase of zinc content.The magnetic measurement shows the antiferromagnetic nature of the samples for x=0.9 and x=1.0.The saturation magnetization reaches the maximum of 3.35μB/f.u.at x=0.5.The optimal reflection loss(RL) of-29.6 dB is found at 6.5 GHz for an absorber thickness of 5 mm.The RL values exceeding 10 dB are obtained for the absorber in the range of 3.9-8.9 GHz.These Ni1-xZnxFe2O4 nanocrystallines may be attractive candidates for electromagnetic wave absorption materials.展开更多
The development of materials with unique nanostructures is an effective strategy for the improvement of sodium storage in sodium ion batteries to achieve stable cycling performance and good rate capability. In this wo...The development of materials with unique nanostructures is an effective strategy for the improvement of sodium storage in sodium ion batteries to achieve stable cycling performance and good rate capability. In this work, SnSb- core/carbon-shell nanocables directly anchored on graphene sheets （GS） were synthesized by the hydrothermal technique and chemical vapor deposition. The simultaneous carbon coating and the encapsulation of SnSb alloy is effective for alleviating the volume-change problem in sodium ion batteries. After optimizing the electrolyte for SnSb in the sodium ion batteries, the optimized coaxial SnSb/carbon nanocable/GS （SnSb/CNT@GS） nanostructure demonstrated stable cycling capability and rate performance in 1 M NaClO4 with propylene carbonate （PC） ＋ 5% fluoroethylene carbonate （FEC）. The SnSb/CNT@GS electrode can retain a capacity of 360 mAh/g for up to 100 cycles, which is 71% of the theoretical capacity. This is higher than in the other three electrolytes tested （1 M NaClO4 in PC, 1 M NaC104 in PC/FEC （1：1 v/v） and 1 M NaPF6 ＋ PC）, and higher than that of the sample without the addition of graphene. The good electrochemical performance can be attributed to the efficient buffering provided by the outer carbon nanocable layer and the graphene inhibiting the agglomeration of SnSb particles, as well as its high conductivity.展开更多
Light-weight and high-strength materials have attracted considerable attention owing to their outstanding properties, such as weight-reducing, acoustic absorption, thermal insulation, shock and vibration damping. Diam...Light-weight and high-strength materials have attracted considerable attention owing to their outstanding properties, such as weight-reducing, acoustic absorption, thermal insulation, shock and vibration damping. Diamond possesses specific stiffness and strength arising from its special crystal structure. In this work, inspired by the diamond crystal structure, hollow-tube nickel materials with the diamond structure were fabricated using a diamond structured polymer template based on the Stereo Lithography Appearance technology. The diamond structured template was coated with Ni-P by electroless plating. Finally, the template was removed by high temperature calcinations. The density of the hollow tube nickel materials is about 20 mg/cm3. The morphology and composition of the resultant materials were characterized by scanning electron microscope, energy-dispersive spectrometry, and X-ray diffraction. The results showed that the surface of the Ni film was uniform with the thickness of 4 gm. The mechanical property was also measured by stress and strain tester. The maximum compression stress can be reached to 40.6 KPa.展开更多
文摘Nickel-plated graphite particles and unmodified graphite particles with different contents were added to the Fe-based diamond composites.The basic properties of those specimens were measured,including relative density,hardness,bending strength,abrasion ratio and holding force coefficient.And also,SEM,XRD and EDS were used to carry out microstructure characterization,phase analysis and element distribution of these specimens.The results show that nickel plating effectively improves the surface wettability of graphite particles.And it is determined that an element diffusion zone is formed on the transition interface between the nickel-plated graphite and the matrix materials,effectively enhancing the interfacial bonding strength.Also,the pores and cracks in the matrix generated by adding the graphite particles are reduced after nickel plating.Thus,the loss of basic properties of the specimens is restrained.But it is found the higher the graphite content is,the weaker the positive effect of nickel plating is.In addition,it is revealed that nickel plating plays a conducive part in the formation of graphite lubricants on the working surface,and nickel-plated graphites can slow down the thermal corrosion of the diamond particles inside the high-temperature sintered specimens.
文摘In this paper new criteria for designing of temporary architectures, which can be used as a uniform coverage for open spaces, are discussed. Frequently temporary architectures use building techniques and materials lightweight. In the case of temporary architectures the theme of sustainability requires that the structure can be reused in different occasions and contexts. The solution to these issues, developed in this paper, makes use of a innovative constructive procedure of prestressed masonry in blocks of natural stone. This procedure is used for the construction of the vertical supports of the cover, consisting of a tensostructure with shape of hyperboloid, obtained by products standard （steel profiles and membrane）. The columns with prestressed blocks of natural stone, dry assembled, allow you to have a modular structure, easily assembled and disassembled, with full recovery of all elements; the stone columns, due to their weight, are able to stabilize the whole structure, even to the dynamic stresses, without using any type of foundation structure fixed to the ground. This paper shows the description of all the elements that make up the new type of temporary architecture designed.
基金supported by China Ministry of Science and Technology under Contract of 2016YFA(0202801)the National Natural Science Foundation of China(21521091,21390393,U1463202,21471089,21671117,21703219 and 21371023)China Postdoctoral Science Foundation(2017M620738)
文摘The ever-growing market demands for lithium ion batteries have stimulated numerous research efforts aiming at the exploration of novel electrode materials with higher capacity and long-term cycling stability.Two-dimensional (2D)nanomaterials and their heterostructures are an intense area of study and promise great potential in electrochemical lithium storage owing to their unique properties that result from structural planar confinement.Here we report a microwave chemistry strategy to integrate ultrathin SnO2 nanosheets into graphene layer to construct surface-to-surface 2D heterostructured architectures,which can provide unique structural planar confinement for highly reversible electrochemical lithium storage.The as-synthesized 2D SnO2/graphene heterostructures can exhibit high reversible capacity of 688.5mAh g^-1 over 500cycles with excellent long-term cycling stability and good rate capability when used as anode materials for lithium ion batteries.The present work definitely reveals the advantages of 2D heterostructures featured with a surface-to-surface stack between two different nanosheets in energy storage and conversion devices.
基金supported by the National Natural Science Foundation of China (Grant Nos.10874051,51002156,and 11104098)the Natural Science Major Foundation of Anhui Provincial Higher Education Institutions of China (Grant No. KJ2012ZD14)
文摘Ni1-xZnxFe2O4(0≤x≤1,in steps of 0.1) nanocrystallines were synthesized by sol-gel route.The doping effects of zinc on structural,magnetic and microwave absorption properties were investigated in detail.X-ray diffraction(XRD) results show that all the samples are single-phase spinel structure.The magnetic and microwave absorption properties are strongly dependent on the zinc content,which can be understood in terms of the cations redistribution in spinel tetrahedral and octahedral sites with the increase of zinc content.The magnetic measurement shows the antiferromagnetic nature of the samples for x=0.9 and x=1.0.The saturation magnetization reaches the maximum of 3.35μB/f.u.at x=0.5.The optimal reflection loss(RL) of-29.6 dB is found at 6.5 GHz for an absorber thickness of 5 mm.The RL values exceeding 10 dB are obtained for the absorber in the range of 3.9-8.9 GHz.These Ni1-xZnxFe2O4 nanocrystallines may be attractive candidates for electromagnetic wave absorption materials.
文摘The development of materials with unique nanostructures is an effective strategy for the improvement of sodium storage in sodium ion batteries to achieve stable cycling performance and good rate capability. In this work, SnSb- core/carbon-shell nanocables directly anchored on graphene sheets （GS） were synthesized by the hydrothermal technique and chemical vapor deposition. The simultaneous carbon coating and the encapsulation of SnSb alloy is effective for alleviating the volume-change problem in sodium ion batteries. After optimizing the electrolyte for SnSb in the sodium ion batteries, the optimized coaxial SnSb/carbon nanocable/GS （SnSb/CNT@GS） nanostructure demonstrated stable cycling capability and rate performance in 1 M NaClO4 with propylene carbonate （PC） ＋ 5% fluoroethylene carbonate （FEC）. The SnSb/CNT@GS electrode can retain a capacity of 360 mAh/g for up to 100 cycles, which is 71% of the theoretical capacity. This is higher than in the other three electrolytes tested （1 M NaClO4 in PC, 1 M NaC104 in PC/FEC （1：1 v/v） and 1 M NaPF6 ＋ PC）, and higher than that of the sample without the addition of graphene. The good electrochemical performance can be attributed to the efficient buffering provided by the outer carbon nanocable layer and the graphene inhibiting the agglomeration of SnSb particles, as well as its high conductivity.
基金support of the National Basic Research Program of China(2010CB934700)the National Natural Science Foundation of China(51372010)
文摘Light-weight and high-strength materials have attracted considerable attention owing to their outstanding properties, such as weight-reducing, acoustic absorption, thermal insulation, shock and vibration damping. Diamond possesses specific stiffness and strength arising from its special crystal structure. In this work, inspired by the diamond crystal structure, hollow-tube nickel materials with the diamond structure were fabricated using a diamond structured polymer template based on the Stereo Lithography Appearance technology. The diamond structured template was coated with Ni-P by electroless plating. Finally, the template was removed by high temperature calcinations. The density of the hollow tube nickel materials is about 20 mg/cm3. The morphology and composition of the resultant materials were characterized by scanning electron microscope, energy-dispersive spectrometry, and X-ray diffraction. The results showed that the surface of the Ni film was uniform with the thickness of 4 gm. The mechanical property was also measured by stress and strain tester. The maximum compression stress can be reached to 40.6 KPa.
