Low carbon Al2O3 - C refractories specimens were prepared with tabular alumina （3. 0 - 1.0, 1.0 - 0. 5, 0.6-0.2, ≤0.3, ≤0. 045 and ≤0. 02 mm）, active alumina micropowder （≤2 μm ） and silicon （ 〈≤0. 045 mm ...Low carbon Al2O3 - C refractories specimens were prepared with tabular alumina （3. 0 - 1.0, 1.0 - 0. 5, 0.6-0.2, ≤0.3, ≤0. 045 and ≤0. 02 mm）, active alumina micropowder （≤2 μm ） and silicon （ 〈≤0. 045 mm ） as main raw materials. Nano carbon black （N220） and natural graphite flake （ 〈≤0. 074 mm ） were adopted as the carbon sources. The specimens were treated at 800, 1 000, 1 200 and 1 400 ℃ under coke embedded atmosphere. The effects of additions of nano carbon black and graphite flake on mechanical properties and thermal shock resistance of the specimens were stud- ied. Their mechanical properties were measured by three- point bending test and thermal shock resistance was de- termined by water quenching method. The phase compo- sition of the specimens was analyzed with X-ray diffrac- tion and microstruetures were observed through FESEM. The results reveal that： （1） the strengths of A1203 - C refractories with these two carbon sources show no big differences when coked at lower than 1 000 ℃ ; when coked at over 1 200 ℃ , the strengths of the specimens with graphite added are much higher than those of the specimens containing carbon black due to much more sil- icon carbide whiskers formed; （2） since the nano carbon black has small particle size, they can be filled into in- terstice of Al2O3 particles to form the nano carbon net- work structure, absorbing and relieving the thermal stressgenerated from expansion and contraction and reducing the thermal expansion coefficient of the specimens, thus their thermal shock resistance is better than that of the specimens containing graphite ; （ 3 ） low carbon Al2 O3 - C refractories with good mechanical properties and excellent thermal shock resistance can be prepared with combi- nation of nano carbon black and graphite flake.展开更多
Nano ZVI particles supported on micro-scale exfoliated graphite were prepared by using KBH4 as reducing agent in the H2O/ethanol system. The supported ZVI materials generally have higher activity and greater flexibili...Nano ZVI particles supported on micro-scale exfoliated graphite were prepared by using KBH4 as reducing agent in the H2O/ethanol system. The supported ZVI materials generally have higher activity and greater flexibility for environmental remediation applications. The exfoliated graphite as the support was treated beforehand to hydrophilic material. Nano iron particles are deposited onto the rough graphite surface while those were formed by borohydride reduction. The possible nitrate reduction pathways were proposed. The TEM image shows that iron particles are highly dispersed on the surface of graphite and several of iron particles are imbedded in the pit of support surface. In this synthesis, iron particles have a nearly spherical shape with a grain size of 50?100 nm. The surface areas of materials with different iron loadings of 3.5%, 7.0%, 10.0%, 15.0% and 20.0%(mass fraction) are 2.89, 9.55, 8.45, 23.8 and 6.18 m2·g?1 by BET surface analyzer. The chemical reduction of nitrate by supported nano ZVI in aqueous solution were tested in series batch experiments. Experiment results suggest that NO3? can be more rapidly reduced to NH4+ at neutral pH and anaerobic conditions by supported nano ZVI than unsupported nano ZVI or ZVI scraps. The 15% nano Fe/graphite shows the best reduction efficiency contrasted with other Fe loading particles.展开更多
A new material is prepared by impregnating the expanded graphite(EG) into ethanol solutions of metal acetate and then drying and reducing it in H2.It contains the EG and the nanoparticles of the magnetic Ni–Fe alloy ...A new material is prepared by impregnating the expanded graphite(EG) into ethanol solutions of metal acetate and then drying and reducing it in H2.It contains the EG and the nanoparticles of the magnetic Ni–Fe alloy for the electromagnetic shielding.Its morphology,phase structure,magnetic properties,and electromagnetic shielding effectiveness(SE) are investigated in our experiment.It shows that the morphology,the phase structure,and the magnetic property of the composite can be modified by altering the Ni content in the alloy nanoparticles.Interestingly,the SE can be enhanced to 54–70 d B at low frequencies(300 kHz–10 MHz) by dispersing the magnetic nanoparticles onto EG.展开更多
The role of nano-SiO 2 and ultra-fine boron carbide on the properties of alumina-graphite materials was investigated. The study showed that the ultra-fine boron carbide added modified the microstructure of residual c...The role of nano-SiO 2 and ultra-fine boron carbide on the properties of alumina-graphite materials was investigated. The study showed that the ultra-fine boron carbide added modified the microstructure of residual carbon and promoted the chemical bond between residual carbon from phenolic resin and flake graphite. The carbon white could strengthen the residual carbon from phenolic resin. These two additives improved the mechanical properties of AG refractories at both room temperature and high temperature, and thermal shock resistance was improved noticeably. When the two additives were doped together, carbon white could retard the evaporation of B 2O 3. Thermal shock resistance was guaranteed with a smaller amount of ultra-fine boron carbide.展开更多
A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid...A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peaks by 230 mV. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine and ascorbic acid can be determined simultaneously with the modified electrode. The electrode shows good sensitivity, selectivity and stability.展开更多
Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a ...Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.展开更多
A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidificatio...A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. Nitrogen adsorption and mercury porosimetry show that mixed nanopores and micropores coexist in MNC with a high specific surface area of 1978 m2·g-1 and a total pore volume of 0.99 cm3·g-1. In addition, the MNC is found to consist of EG and activated carbon with the latter deposited on the interior and the exterior surfaces of the EG pores. The thickness of the activated carbon layer is calculated to be about one hundred nanometers and is further confirmed by scanning electron microscope (SEM) and transmission election microscope (TEM). A maximum static phenol adsorption of 241.2 mg·g-1 was obtained by using MNC, slightly higher than that of 220.4 mg·g-1 by using commercial activated carbon (CAC). The phenol adsorption kinetics were investigated and the data fitted well to a pseudo-second-order model. Also, an intra-particle diffusion mechanism was proposed. Furthermore, it is found that the dynamic adsorption capacity of MNC is nearly three times that of CAC. The results suggest that the MNC is a more efficient adsorbent than CAC for the removal of phenol from aqueous solution.展开更多
The mechanical behavior of highly oriented pyrolyti c graphite (HOPG) has been investigated in this paper, by simulating a machining p rocess in a nano-indent test with the method of molecular dynamics (MD) and by doi...The mechanical behavior of highly oriented pyrolyti c graphite (HOPG) has been investigated in this paper, by simulating a machining p rocess in a nano-indent test with the method of molecular dynamics (MD) and by doing an experiment directly using the probe tip of atomic force microscope (AFM ) as tool. The characteristics and properties of graphite crystal lattice are di scussed firstly, then, three potentials are selected for different interaction b etween graphite atoms according to the graphite properties, and molecular dynami c calculations of nano-indent test are carried out. After that, an experiments for nano-indentation of graphite crystal and its observation, directly by using an AFM tip as indent tool and consequential measurement, are introduced and don e. The topography of the hole indented by the tip, the profile, surface of the g raphite, as well the indented force and the strength of HOPG are measured and ca lculated. Results show the indentation experiment and the MD calculation consist ent with each other, that MD may be a good tool for comprehending the micro-mac hining behavior and the mechanism of materials.展开更多
This paper reports that bunchy flake-like nano-graphite crystallite films （BNGCFs） were deposited on Si substrates by using the microwave chemical vapour deposition technique. Furthermore the BNGCFs were characteriz...This paper reports that bunchy flake-like nano-graphite crystallite films （BNGCFs） were deposited on Si substrates by using the microwave chemical vapour deposition technique. Furthermore the BNGCFs were characterized by x-ray diffraction spectra, scanning electron microscopy, Raman spectra and field emission （FE） I-V measurements, and a lowest turn-on field of 1.5 V/μm, and a high average emission current density of 30 mA/cm2 at a macroscopic electric field of 8.0V/μm were obtained. The J-E data did not follow the original Fowler-Nordheim （F-N） relation since they were not well represented in the F-N plot by a straight line. A model considering the F-N mechanism, and the statistic effects of FE tip structures has been applied successfully to explain all the FE data observed for E 〈 8.SV/μm.展开更多
文摘Low carbon Al2O3 - C refractories specimens were prepared with tabular alumina （3. 0 - 1.0, 1.0 - 0. 5, 0.6-0.2, ≤0.3, ≤0. 045 and ≤0. 02 mm）, active alumina micropowder （≤2 μm ） and silicon （ 〈≤0. 045 mm ） as main raw materials. Nano carbon black （N220） and natural graphite flake （ 〈≤0. 074 mm ） were adopted as the carbon sources. The specimens were treated at 800, 1 000, 1 200 and 1 400 ℃ under coke embedded atmosphere. The effects of additions of nano carbon black and graphite flake on mechanical properties and thermal shock resistance of the specimens were stud- ied. Their mechanical properties were measured by three- point bending test and thermal shock resistance was de- termined by water quenching method. The phase compo- sition of the specimens was analyzed with X-ray diffrac- tion and microstruetures were observed through FESEM. The results reveal that： （1） the strengths of A1203 - C refractories with these two carbon sources show no big differences when coked at lower than 1 000 ℃ ; when coked at over 1 200 ℃ , the strengths of the specimens with graphite added are much higher than those of the specimens containing carbon black due to much more sil- icon carbide whiskers formed; （2） since the nano carbon black has small particle size, they can be filled into in- terstice of Al2O3 particles to form the nano carbon net- work structure, absorbing and relieving the thermal stressgenerated from expansion and contraction and reducing the thermal expansion coefficient of the specimens, thus their thermal shock resistance is better than that of the specimens containing graphite ; （ 3 ） low carbon Al2 O3 - C refractories with good mechanical properties and excellent thermal shock resistance can be prepared with combi- nation of nano carbon black and graphite flake.
基金Project(20477019) supported by the National Natural Science Foundation of China
文摘Nano ZVI particles supported on micro-scale exfoliated graphite were prepared by using KBH4 as reducing agent in the H2O/ethanol system. The supported ZVI materials generally have higher activity and greater flexibility for environmental remediation applications. The exfoliated graphite as the support was treated beforehand to hydrophilic material. Nano iron particles are deposited onto the rough graphite surface while those were formed by borohydride reduction. The possible nitrate reduction pathways were proposed. The TEM image shows that iron particles are highly dispersed on the surface of graphite and several of iron particles are imbedded in the pit of support surface. In this synthesis, iron particles have a nearly spherical shape with a grain size of 50?100 nm. The surface areas of materials with different iron loadings of 3.5%, 7.0%, 10.0%, 15.0% and 20.0%(mass fraction) are 2.89, 9.55, 8.45, 23.8 and 6.18 m2·g?1 by BET surface analyzer. The chemical reduction of nitrate by supported nano ZVI in aqueous solution were tested in series batch experiments. Experiment results suggest that NO3? can be more rapidly reduced to NH4+ at neutral pH and anaerobic conditions by supported nano ZVI than unsupported nano ZVI or ZVI scraps. The 15% nano Fe/graphite shows the best reduction efficiency contrasted with other Fe loading particles.
基金supported by the National Natural Science Foundation of China(Nos.50977042 and 10904061)the“863”program of MSTC(No.2006AA03Z458)the research funds for Nanjing Institute of Technology(No.YKJ201002)
文摘A new material is prepared by impregnating the expanded graphite(EG) into ethanol solutions of metal acetate and then drying and reducing it in H2.It contains the EG and the nanoparticles of the magnetic Ni–Fe alloy for the electromagnetic shielding.Its morphology,phase structure,magnetic properties,and electromagnetic shielding effectiveness(SE) are investigated in our experiment.It shows that the morphology,the phase structure,and the magnetic property of the composite can be modified by altering the Ni content in the alloy nanoparticles.Interestingly,the SE can be enhanced to 54–70 d B at low frequencies(300 kHz–10 MHz) by dispersing the magnetic nanoparticles onto EG.
文摘The role of nano-SiO 2 and ultra-fine boron carbide on the properties of alumina-graphite materials was investigated. The study showed that the ultra-fine boron carbide added modified the microstructure of residual carbon and promoted the chemical bond between residual carbon from phenolic resin and flake graphite. The carbon white could strengthen the residual carbon from phenolic resin. These two additives improved the mechanical properties of AG refractories at both room temperature and high temperature, and thermal shock resistance was improved noticeably. When the two additives were doped together, carbon white could retard the evaporation of B 2O 3. Thermal shock resistance was guaranteed with a smaller amount of ultra-fine boron carbide.
文摘A novel nano-SnO2/graphite electrode has been prepared via polishing procedure to produce active and stable surface. The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peaks by 230 mV. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine and ascorbic acid can be determined simultaneously with the modified electrode. The electrode shows good sensitivity, selectivity and stability.
基金the National Natural Science Fund(50774071） ；the Natural Science Foundation of Hubei Province(2004ABA090）.
文摘Superfine graphite powder was prepared by ball-milling exfoliated graphite containing anhydrous CuCl2 in planetary ball milling systems. Nano-scale CuCl2 graphite intercalation compounds were synthesized by heating a mixture of anhydrous CuCl2 and graphite nanosheets. Scanning electron microscopy, energy-dispersive X-ray spectroscopy and high-resolution transmission electron microscopy were performed to characterize the microstructures of stage-1 nano-scale CuCl2 graphite intercalation compounds. The structure and components of the domain wall and core in the nano-scale CuCl2 graphite intercalation compounds are described. The results show that the content of CuCl2 in the mixture plays a crucial role in the size of the nano-scale CuCl2 graphite intercalation compound.
基金financially supported by the Fundamental Research Funds for the National Natural Science Foundation of China(Nos.21071107,21277094,and21103119)Production and Research Collaborative Innovation Project of Jiangsu Province(No.BY2012123)+9 种基金Natural Science Foundation of Jiangsu Province(No.BK2012167)Scienceand Technology Pillar Program(Industry)of Jiangsu Province(No.BE2012101)Collegiate Natural Science Fund of Jiangsu Province(Nos.12KJA430005,09KJB30003,and11KJB430012)Key Laboratory for Environment Functional Materials of Suzhou(No.SZS201008)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),Applied Basic Research Project of Suzhou(No.SYG201242)Industrial Surport Project of Suzhou(No.SG201138)Jiangsu Key Laboratory of Material Tribology(No.Kjsmcx2011001)Jiangsu Key Laboratory for Photon Manufacturing(No.GZ201111)Jiangsu Provincial Key Laboratory for Interventional Medical Devices(No.Jr1210)Creative Project of Postgraduate of Jiangsu Province(No.CXZZ11_0954)
文摘A hierarchical micro-nano porous carbon material (MNC) was prepared using expanded graphite (EG), sucrose, and phosphoric acid as raw materials, followed by sucrose-phosphoric acid solution impregnation, solidification, carbonization and activation. Nitrogen adsorption and mercury porosimetry show that mixed nanopores and micropores coexist in MNC with a high specific surface area of 1978 m2·g-1 and a total pore volume of 0.99 cm3·g-1. In addition, the MNC is found to consist of EG and activated carbon with the latter deposited on the interior and the exterior surfaces of the EG pores. The thickness of the activated carbon layer is calculated to be about one hundred nanometers and is further confirmed by scanning electron microscope (SEM) and transmission election microscope (TEM). A maximum static phenol adsorption of 241.2 mg·g-1 was obtained by using MNC, slightly higher than that of 220.4 mg·g-1 by using commercial activated carbon (CAC). The phenol adsorption kinetics were investigated and the data fitted well to a pseudo-second-order model. Also, an intra-particle diffusion mechanism was proposed. Furthermore, it is found that the dynamic adsorption capacity of MNC is nearly three times that of CAC. The results suggest that the MNC is a more efficient adsorbent than CAC for the removal of phenol from aqueous solution.
文摘The mechanical behavior of highly oriented pyrolyti c graphite (HOPG) has been investigated in this paper, by simulating a machining p rocess in a nano-indent test with the method of molecular dynamics (MD) and by doing an experiment directly using the probe tip of atomic force microscope (AFM ) as tool. The characteristics and properties of graphite crystal lattice are di scussed firstly, then, three potentials are selected for different interaction b etween graphite atoms according to the graphite properties, and molecular dynami c calculations of nano-indent test are carried out. After that, an experiments for nano-indentation of graphite crystal and its observation, directly by using an AFM tip as indent tool and consequential measurement, are introduced and don e. The topography of the hole indented by the tip, the profile, surface of the g raphite, as well the indented force and the strength of HOPG are measured and ca lculated. Results show the indentation experiment and the MD calculation consist ent with each other, that MD may be a good tool for comprehending the micro-mac hining behavior and the mechanism of materials.
基金supported by the Shanghai Education Committee of China(Grant No 07ZZ95)
文摘This paper reports that bunchy flake-like nano-graphite crystallite films （BNGCFs） were deposited on Si substrates by using the microwave chemical vapour deposition technique. Furthermore the BNGCFs were characterized by x-ray diffraction spectra, scanning electron microscopy, Raman spectra and field emission （FE） I-V measurements, and a lowest turn-on field of 1.5 V/μm, and a high average emission current density of 30 mA/cm2 at a macroscopic electric field of 8.0V/μm were obtained. The J-E data did not follow the original Fowler-Nordheim （F-N） relation since they were not well represented in the F-N plot by a straight line. A model considering the F-N mechanism, and the statistic effects of FE tip structures has been applied successfully to explain all the FE data observed for E 〈 8.SV/μm.
