The hexagonal BaGd x Fe 12- x O 19 ( x =0.1~1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of...The hexagonal BaGd x Fe 12- x O 19 ( x =0.1~1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the molar ratio of nitrate/citric acid and the calcination temperature on the synthesis of the ferrites were investigated. The crystal structure, grain size, shape and magnetic properties were studied by means of XRD, TEM and vibrating sample magnetometer.The results show that under the conditions of pH 7.0 or so, mole ratio of citrate/nitrate (1~3) and calcination temperature of 850 ℃ for 1 h, M type BaGd x Fe 12- x O 19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA·m -1 at x =1.0, which is far greater than that of barium ferrite (BaFe 12 O 19 ).展开更多
The radiation of material surface by high intensity laser beams is used to produce the uhrafine powder of pure Fe and ZrO_2.The morphology,size and phases of the powder were examined by X-ray diffraetometer,scanning e...The radiation of material surface by high intensity laser beams is used to produce the uhrafine powder of pure Fe and ZrO_2.The morphology,size and phases of the powder were examined by X-ray diffraetometer,scanning electron microscopy as well as transmission electron microscopy.In pure Fe a considerable quantity of γ-phase was found in the powder.In ZrO_2 powder,instead of stable phase,two metastable phases appeared.展开更多
A simple and rapid process for synthesizing lead zirconate titanate,Pb(Zr0.52Ti0.48)O3(PZT),ferroclectric powders was developed.This process,combining the sol-gel and combustion process.offers several advantages o...A simple and rapid process for synthesizing lead zirconate titanate,Pb(Zr0.52Ti0.48)O3(PZT),ferroclectric powders was developed.This process,combining the sol-gel and combustion process.offers several advantages over conventional methods.including rapid solution synthesis,use of commercially available materials lower synthesis temperature and ease of obtaining ultrafine powders.The precursor solution for synthesizing powders was prepared from lead nitrate.zireonium nitrate.titanium oxynitrate,citric acid and deionized water.The precarsor was investigated by DSC-TG,and the PZT powders were investigated by powder-XRD,IR spectra and TEM.XRD analysis shous that the powders possess a single phase perovskite type structure,no pyrochlore phase exists.and TEM image shows that the grain size of the powders is about 40nm.展开更多
The precursor of ultrafine In 2O 3 powder was prepared by the hydrolysis, peptization and gelation of InCl 3·4H 2O used as raw material. After calcination, ultrafine In 2O 3 powder was obtained. The particl...The precursor of ultrafine In 2O 3 powder was prepared by the hydrolysis, peptization and gelation of InCl 3·4H 2O used as raw material. After calcination, ultrafine In 2O 3 powder was obtained. The particles were characterized by the methods of thermo gravimetric and differential thermal analysis (TG DTA), X ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively.展开更多
The ultrafine powders of YBa2Cu3O7-x with the size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to adjust pH of solu-tion. The process of Sol formation and Gel polymeri...The ultrafine powders of YBa2Cu3O7-x with the size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to adjust pH of solu-tion. The process of Sol formation and Gel polymerization of YBa2Cu3O7-x in the Sol-Gel synthetic reaction has bee studied. The particle size ,pruity, sintering activity and superconducting properties of YBa2Cu3O7-x prepared by Sol-Gel method are better than by solid state reaction.展开更多
[Objective] This paper aimed to observe the effects of Qishen ultrafine powder on immune efficacy of infectious bursal disease vaccine in chickens. [ Method] 360 1-day-old chickens were randomly divided into six group...[Objective] This paper aimed to observe the effects of Qishen ultrafine powder on immune efficacy of infectious bursal disease vaccine in chickens. [ Method] 360 1-day-old chickens were randomly divided into six groups equally, and group I -V were vaccinated with IBD live virus vaccine on the 21 th and 35th day, respectively. From 14th to 21th day, group I - Ⅲ were added with 1%, 0.5% of Qishen ultrafine powder and 2% of Qishan powder in basel diet, respectively, group IV was given Yupingfeng oral liquid and group VI was as a control group without vaccination. Be- fore the expedment (14-day-old chickens as DO ) and 7 ( D7 ), 14 ( D14 ), 21 ( D21 ), 28 ( D26 ), 35 ( D36 ), 42 ( D42 ) days after the experiment, the dynamic change of serum IBD specific antibody was determined, respectively. On D7, D21 and D36, the dynamic change of peripheral T lymphocyte proliferation and IL-2 in serum were determined, respectively. The weight change was also observed. [Results] Compared with the immune control group, the immune effects of IBD vaccine of each administration group were significantly improved, and there was no significant difference between each other. [ Condusion] Qishen ultrafine powder could increase immune function of chickens at lower dosage.展开更多
Using 9200 laser particle size analyzer and KYKY-2800 scanning electron microscope, particle sizes and cellular morphology of Radix Astragalus and Radix Isatidis ultrafine powders were observed. According to the resu...Using 9200 laser particle size analyzer and KYKY-2800 scanning electron microscope, particle sizes and cellular morphology of Radix Astragalus and Radix Isatidis ultrafine powders were observed. According to the results, the particle size of 89. 1 % of Radix Astragalus ultrafine powders ranged from 1.729 [xm to 44.938 |xm, Z )50 =4.368 |xm; the particle size of 93.411% of Radix Isatidis ultrafine powders ranged from 1.510 [xm to 44.938 |xm, Z )50 = 8 .7 2 6 [xm. Radix As-tragalus and Radix Isatidis ultrafine powders were pulverized completely without intact cellular morphology. The antibacterial activity of Radix Astragalus and Radix Isatidis ultrafine powders against chicken-derived E. coli (078) was investigated. The results indicated that Radix Astragalus and Radix Isatidis ultrafine powders exhibited higher antibacterial activity against chicken-derived E. coli (078 ) compared with the corresponding coarse powders. This study laid a solid foundation for the development and application of Chinese medicine ultrafine powder preparations.展开更多
Ultrafine amorphous alloy powders of spherical shape with diameters from 10 to 50nm for Fe-Ni-B and Fe-Cr-B were prepared by chemical reduction. The amorphous structure of two powders was identified by X-ray diffracti...Ultrafine amorphous alloy powders of spherical shape with diameters from 10 to 50nm for Fe-Ni-B and Fe-Cr-B were prepared by chemical reduction. The amorphous structure of two powders was identified by X-ray diffraction. The B concentrations for the two alloy systems did not change dramatically, as the preparation condition changed. An oxide film covered up the powders. The maximum magnetization decreased as increasing the content of Ni or Cr.展开更多
The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics.The results show that the Rushton disk turbine impeller is more conducive to maintai...The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics.The results show that the Rushton disk turbine impeller is more conducive to maintaining suspended homogeneity and circulation of slurry compared with the pitch blade turbine pumping up impeller and the pitch blade turbine pumping down impeller.And the increase in stirring speed enhances turbulent fluctuation and anisotropic velocity of the fluid at the cost of more power consumption,which improves dispersibility and suspensibility of the particles.Meanwhile,the change of impeller clearance has a weak influence on the flow pattern,and the impeller clearance of 0.32T(T is the diameter of the bottom of the reactor)can achieve better dispersivity and suspensibility of the particles with lower power consumption and larger axial velocity.The experiments of surface coating modification of ultrafine titanium dioxide(TiO2)were carried out under the same conditions for those of the simulation system.The surface film morphology and photocatalytic properties of the modified TiO2 were analyzed,and the obtained data are well consistent with the simulation results.展开更多
In this paper, Pyrolysis Gas Chromatography Mass Spectroscopy is adopted to measure heating release curve of Si 3N 4 ultrafine powder at different temperatures. The results demonstrate that Si 3N 4 mainly adsorbs...In this paper, Pyrolysis Gas Chromatography Mass Spectroscopy is adopted to measure heating release curve of Si 3N 4 ultrafine powder at different temperatures. The results demonstrate that Si 3N 4 mainly adsorbs O 2, N 2, CO 2, NH 3 and H 2O during the storage at room temperature, of which O 2 and N 2 are physisorped and H 2O chemisorped. Hydrolysis reaction is the reason for oxygen increasement and the different states of oxygen can be determined by improved heat extraction. The mechanisms of the reaction speed as well as the formation of different states of oxygen are also discussed.展开更多
INVESTIGAORS recognized the role of finely divided insoluble solid particles in stabilizing oil-water emulsions in the 1920s. The work has been extensively done since the 1980s. Butthe studies only focused on particle...INVESTIGAORS recognized the role of finely divided insoluble solid particles in stabilizing oil-water emulsions in the 1920s. The work has been extensively done since the 1980s. Butthe studies only focused on particles with the parameter up to micrometer size rather than thoseof nanometer size. In this letter, emulsive properties, including the type, ability and mecha-展开更多
An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has be...An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has been made.展开更多
The ultrafine alloy powders,CuRh,γ-Ni_(0.33)Fe_(0.66) and α-Fe_(0.66)Co_(0.33) of size less than 35 nm were prepared by reduction of complex metallic oxides under atmosphere of 15% H_2 and 85%Ar.
The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reductio...The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reduction technology were investigated. In comparison to the conventional HE sintering processing, microwave sintering to W-15Cu can be achieved at lower sintering temperature and shorter sintering time. Furthermore, higher performances in microwave sintered compacts were obtained, but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.展开更多
An efficient and recyclable cadmium removal adsorbent was prepared by molding and sintering of ultrafine silica powder produced from ferroalloy plant as the main raw materials, with the addition of a certain amount of...An efficient and recyclable cadmium removal adsorbent was prepared by molding and sintering of ultrafine silica powder produced from ferroalloy plant as the main raw materials, with the addition of a certain amount of AI(OH)3 and CaO for modification. XRD and SEM were used to characterize the crystal phases and microstructures of the adsorbent. The influences of different pH, initial cadmium concentration and contacting time on the cadmium adsorption capacity were investigated. The results show that the cadmium removal capacity is up to 0.239 mg/g at the initial Cd2+ concentration of 5 g/L, pH value of 7 and contacting time of 120 rain when the optimum, mass ratio is 70(ultrafine silica powder):30(Al(OH)3 and CaO mixture). The corresponding adsorbent has a porous structure with main crystalline phases of CazAI2SiO7 and CaSiO3. Cadmium is adsorbed and removed mainly by physical adsorption, assisted by chemical adsorption.展开更多
High quality ultrafine Si powders have been synthesized from SiH4 by laser induced gas phase reaction. The powders prduced under different synthesis conditions have mean particle size of 10-120nm in diam. with narrow ...High quality ultrafine Si powders have been synthesized from SiH4 by laser induced gas phase reaction. The powders prduced under different synthesis conditions have mean particle size of 10-120nm in diam. with narrow particle size distribution, and free of hard agglomerates.The powders are polycrystalline with the ratio of mean grain to particle diameter being between 0.3-0.7. The size of the powder increases with increasing laser power and reaction pressure,but decreases with increasing silane gas flow rate and the addition of Ar diluent. Grain sizes drop distinctly with the rise of the addition of Ar gas and laser power, but change little with the gas flow rate and reaction temperature. The formation of Si particles under different synthesis conditions is discussed展开更多
The γ-ray radiation technique combined with hydrothermal crystallization was firstly used to prepare ultrafine metallic particles of An,Cu and Au-Cu alloy.Particle size for Au in average is about 10 nm.The morphologi...The γ-ray radiation technique combined with hydrothermal crystallization was firstly used to prepare ultrafine metallic particles of An,Cu and Au-Cu alloy.Particle size for Au in average is about 10 nm.The morphologies were observed by TEM.The nucleation mechanism of metal particles and their stability are discussed.展开更多
Coprecipitation supercritical fluid drying technology has been employed to synthesize calcia-stabilized zirconia ultrafine powder with low-cost inorganic salts as the starting materials. The sintering behaviors of the...Coprecipitation supercritical fluid drying technology has been employed to synthesize calcia-stabilized zirconia ultrafine powder with low-cost inorganic salts as the starting materials. The sintering behaviors of these powders were also investigated. The results showed that supercritical fluid drying could effectively alleviate the hard agglomeration of grains during the gel drying process, and the morphology of the powder retained the network texture of the original gel. The resulting particles were characterized by small particle size (5-20 nm), better monodispersity and high surface area, which gave rise to high activity and sinterability. Consequently, these powders could readily be compacted into the desired shape and their densification could be carried out in shorter time and at lower temperatures. For instance, nanometer-sized powder calcined at 600癈 for 2 h could be cold-pressed into a green body and sintered at 1100?for 0.5 h to attain a dense body with bulk density of 5.9718 g/cm3 and specific pore volume of 0.0008 cm3/g.展开更多
Ultrafine particles of Al_(2)O_(3),MoO_(3),TiO_(2)and SiO_(2)were prepared by irradiate high power laser beams on material surface in O_(2)atmosphere as well as TiN in N_(2) atmosphere.X-ray diffractometer analysis id...Ultrafine particles of Al_(2)O_(3),MoO_(3),TiO_(2)and SiO_(2)were prepared by irradiate high power laser beams on material surface in O_(2)atmosphere as well as TiN in N_(2) atmosphere.X-ray diffractometer analysis identified that all oxides and nitrides powder obtained are crystalline except SiO_(2) particles which have amorphous struc-ture.展开更多
With InCl 3·4H 2O being used as raw materials, the precursor of nano sized In 2O 3 powder was prepared by hydrolysis, peptization and gelation of InCl 3·4H 2O. After calcination, nano sized In 2O 3...With InCl 3·4H 2O being used as raw materials, the precursor of nano sized In 2O 3 powder was prepared by hydrolysis, peptization and gelation of InCl 3·4H 2O. After calcination, nano sized In 2O 3 powder was obtained. The powder was characterized by thermo gravimetric and differential thermal analysis (TG DTA), X ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively. Calculation revealed that the mean crystalline size increased with increasing the calcination temperature, but crystal lattice distortion rate decreased with the increasing in the average crystalline size. This indicated that the smaller the particle size, the bigger the crystal lattice distortion, the worse the crystal growing. The activation energies for growth of nano sized In 2O 3 were calculated to be 4.75 kJ·mol -1 at the calcination temperature up to 500℃ and 66.40 kJ·mol -1 at the calcination temperature over 600℃. TEM photos revealed that the addition of the chemical additive (OP-10) greatly influenced the morphology and size of In 2O 3 particles.展开更多
文摘The hexagonal BaGd x Fe 12- x O 19 ( x =0.1~1.0) nano sized powders with M type structure were synthesized by the sol gel auto combustion high temperature synthesis method. The effects of pH of the solution, the molar ratio of nitrate/citric acid and the calcination temperature on the synthesis of the ferrites were investigated. The crystal structure, grain size, shape and magnetic properties were studied by means of XRD, TEM and vibrating sample magnetometer.The results show that under the conditions of pH 7.0 or so, mole ratio of citrate/nitrate (1~3) and calcination temperature of 850 ℃ for 1 h, M type BaGd x Fe 12- x O 19 ultrafine powders with a particle size of less than 100 nm can be obtained, and the coercive force reaches 430 kA·m -1 at x =1.0, which is far greater than that of barium ferrite (BaFe 12 O 19 ).
文摘The radiation of material surface by high intensity laser beams is used to produce the uhrafine powder of pure Fe and ZrO_2.The morphology,size and phases of the powder were examined by X-ray diffraetometer,scanning electron microscopy as well as transmission electron microscopy.In pure Fe a considerable quantity of γ-phase was found in the powder.In ZrO_2 powder,instead of stable phase,two metastable phases appeared.
文摘A simple and rapid process for synthesizing lead zirconate titanate,Pb(Zr0.52Ti0.48)O3(PZT),ferroclectric powders was developed.This process,combining the sol-gel and combustion process.offers several advantages over conventional methods.including rapid solution synthesis,use of commercially available materials lower synthesis temperature and ease of obtaining ultrafine powders.The precursor solution for synthesizing powders was prepared from lead nitrate.zireonium nitrate.titanium oxynitrate,citric acid and deionized water.The precarsor was investigated by DSC-TG,and the PZT powders were investigated by powder-XRD,IR spectra and TEM.XRD analysis shous that the powders possess a single phase perovskite type structure,no pyrochlore phase exists.and TEM image shows that the grain size of the powders is about 40nm.
文摘The precursor of ultrafine In 2O 3 powder was prepared by the hydrolysis, peptization and gelation of InCl 3·4H 2O used as raw material. After calcination, ultrafine In 2O 3 powder was obtained. The particles were characterized by the methods of thermo gravimetric and differential thermal analysis (TG DTA), X ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively.
文摘The ultrafine powders of YBa2Cu3O7-x with the size of 100nm were synthesized by Sol-Gel process using cit-rate as complex and ammonium hydroxide to adjust pH of solu-tion. The process of Sol formation and Gel polymerization of YBa2Cu3O7-x in the Sol-Gel synthetic reaction has bee studied. The particle size ,pruity, sintering activity and superconducting properties of YBa2Cu3O7-x prepared by Sol-Gel method are better than by solid state reaction.
基金funded by the Henan Provincial Key Scientific and Technological Project(122102110185)
文摘[Objective] This paper aimed to observe the effects of Qishen ultrafine powder on immune efficacy of infectious bursal disease vaccine in chickens. [ Method] 360 1-day-old chickens were randomly divided into six groups equally, and group I -V were vaccinated with IBD live virus vaccine on the 21 th and 35th day, respectively. From 14th to 21th day, group I - Ⅲ were added with 1%, 0.5% of Qishen ultrafine powder and 2% of Qishan powder in basel diet, respectively, group IV was given Yupingfeng oral liquid and group VI was as a control group without vaccination. Be- fore the expedment (14-day-old chickens as DO ) and 7 ( D7 ), 14 ( D14 ), 21 ( D21 ), 28 ( D26 ), 35 ( D36 ), 42 ( D42 ) days after the experiment, the dynamic change of serum IBD specific antibody was determined, respectively. On D7, D21 and D36, the dynamic change of peripheral T lymphocyte proliferation and IL-2 in serum were determined, respectively. The weight change was also observed. [Results] Compared with the immune control group, the immune effects of IBD vaccine of each administration group were significantly improved, and there was no significant difference between each other. [ Condusion] Qishen ultrafine powder could increase immune function of chickens at lower dosage.
基金Oupported by Spark Program of the Ministry of Science and Technology of China(2015GA620002)Science and Technology Support Program of Science and Technology Department of Hebei Province(12220408D,14966610D)+2 种基金Post-award Grant Program from the Department of Science and Technology of Hebei Province(15926620H)Project of Shijiazhuang Municipal Science and Technology Bureau(141200603A)Project of Chengde Municipal Science and Technology Bureau(2015N0001)
文摘Using 9200 laser particle size analyzer and KYKY-2800 scanning electron microscope, particle sizes and cellular morphology of Radix Astragalus and Radix Isatidis ultrafine powders were observed. According to the results, the particle size of 89. 1 % of Radix Astragalus ultrafine powders ranged from 1.729 [xm to 44.938 |xm, Z )50 =4.368 |xm; the particle size of 93.411% of Radix Isatidis ultrafine powders ranged from 1.510 [xm to 44.938 |xm, Z )50 = 8 .7 2 6 [xm. Radix As-tragalus and Radix Isatidis ultrafine powders were pulverized completely without intact cellular morphology. The antibacterial activity of Radix Astragalus and Radix Isatidis ultrafine powders against chicken-derived E. coli (078) was investigated. The results indicated that Radix Astragalus and Radix Isatidis ultrafine powders exhibited higher antibacterial activity against chicken-derived E. coli (078 ) compared with the corresponding coarse powders. This study laid a solid foundation for the development and application of Chinese medicine ultrafine powder preparations.
文摘Ultrafine amorphous alloy powders of spherical shape with diameters from 10 to 50nm for Fe-Ni-B and Fe-Cr-B were prepared by chemical reduction. The amorphous structure of two powders was identified by X-ray diffraction. The B concentrations for the two alloy systems did not change dramatically, as the preparation condition changed. An oxide film covered up the powders. The maximum magnetization decreased as increasing the content of Ni or Cr.
基金financially supported by the National Natural Science Foundation of China(Nos.21838003,91834301 and 21878092)the Shanghai Scientific and Technological Innovation Project(No.18JC1410600)+2 种基金the Social Development Program of Shanghai(Nos.17DZ1200900 and 18DZ2252400)the Innovation Program of Shanghai Municipal Education Commissionthe Fundamental Research Funds for the Central Universities(No.222201718002)。
文摘The suspension characteristics of ultrafine powder slurry in the stirred vessel were simulated by using computational fluid dynamics.The results show that the Rushton disk turbine impeller is more conducive to maintaining suspended homogeneity and circulation of slurry compared with the pitch blade turbine pumping up impeller and the pitch blade turbine pumping down impeller.And the increase in stirring speed enhances turbulent fluctuation and anisotropic velocity of the fluid at the cost of more power consumption,which improves dispersibility and suspensibility of the particles.Meanwhile,the change of impeller clearance has a weak influence on the flow pattern,and the impeller clearance of 0.32T(T is the diameter of the bottom of the reactor)can achieve better dispersivity and suspensibility of the particles with lower power consumption and larger axial velocity.The experiments of surface coating modification of ultrafine titanium dioxide(TiO2)were carried out under the same conditions for those of the simulation system.The surface film morphology and photocatalytic properties of the modified TiO2 were analyzed,and the obtained data are well consistent with the simulation results.
文摘In this paper, Pyrolysis Gas Chromatography Mass Spectroscopy is adopted to measure heating release curve of Si 3N 4 ultrafine powder at different temperatures. The results demonstrate that Si 3N 4 mainly adsorbs O 2, N 2, CO 2, NH 3 and H 2O during the storage at room temperature, of which O 2 and N 2 are physisorped and H 2O chemisorped. Hydrolysis reaction is the reason for oxygen increasement and the different states of oxygen can be determined by improved heat extraction. The mechanisms of the reaction speed as well as the formation of different states of oxygen are also discussed.
文摘INVESTIGAORS recognized the role of finely divided insoluble solid particles in stabilizing oil-water emulsions in the 1920s. The work has been extensively done since the 1980s. Butthe studies only focused on particles with the parameter up to micrometer size rather than thoseof nanometer size. In this letter, emulsive properties, including the type, ability and mecha-
文摘An intensive study of the particle size distribution of four commercial ultrafine alumina powders to obtain information about the powder agglomeration and relate them to the compactibility and the sinterability has been made.
文摘The ultrafine alloy powders,CuRh,γ-Ni_(0.33)Fe_(0.66) and α-Fe_(0.66)Co_(0.33) of size less than 35 nm were prepared by reduction of complex metallic oxides under atmosphere of 15% H_2 and 85%Ar.
基金Funded by the Project for Science and Technology Plan of Wuhan City(200910321092)the Youth Science Plan for Light of the Morning Sun of Wuhan City (200750731270)
文摘The effects of microwave sintering and conventional H2 sintering on the microstructure and properties of W-15Cu alloy using ultrafine W-15Cu composite powder fabricated by spray drying & calcining-continuous reduction technology were investigated. In comparison to the conventional HE sintering processing, microwave sintering to W-15Cu can be achieved at lower sintering temperature and shorter sintering time. Furthermore, higher performances in microwave sintered compacts were obtained, but high microwave sintering temperature or long microwave sintering time could result in coarser microstructures.
基金Supported by the National Natural Science Foundation of China (No. 21201035)
文摘An efficient and recyclable cadmium removal adsorbent was prepared by molding and sintering of ultrafine silica powder produced from ferroalloy plant as the main raw materials, with the addition of a certain amount of AI(OH)3 and CaO for modification. XRD and SEM were used to characterize the crystal phases and microstructures of the adsorbent. The influences of different pH, initial cadmium concentration and contacting time on the cadmium adsorption capacity were investigated. The results show that the cadmium removal capacity is up to 0.239 mg/g at the initial Cd2+ concentration of 5 g/L, pH value of 7 and contacting time of 120 rain when the optimum, mass ratio is 70(ultrafine silica powder):30(Al(OH)3 and CaO mixture). The corresponding adsorbent has a porous structure with main crystalline phases of CazAI2SiO7 and CaSiO3. Cadmium is adsorbed and removed mainly by physical adsorption, assisted by chemical adsorption.
文摘High quality ultrafine Si powders have been synthesized from SiH4 by laser induced gas phase reaction. The powders prduced under different synthesis conditions have mean particle size of 10-120nm in diam. with narrow particle size distribution, and free of hard agglomerates.The powders are polycrystalline with the ratio of mean grain to particle diameter being between 0.3-0.7. The size of the powder increases with increasing laser power and reaction pressure,but decreases with increasing silane gas flow rate and the addition of Ar diluent. Grain sizes drop distinctly with the rise of the addition of Ar gas and laser power, but change little with the gas flow rate and reaction temperature. The formation of Si particles under different synthesis conditions is discussed
文摘The γ-ray radiation technique combined with hydrothermal crystallization was firstly used to prepare ultrafine metallic particles of An,Cu and Au-Cu alloy.Particle size for Au in average is about 10 nm.The morphologies were observed by TEM.The nucleation mechanism of metal particles and their stability are discussed.
基金the National Natural Science Foundation of China under grant No.20133040
文摘Coprecipitation supercritical fluid drying technology has been employed to synthesize calcia-stabilized zirconia ultrafine powder with low-cost inorganic salts as the starting materials. The sintering behaviors of these powders were also investigated. The results showed that supercritical fluid drying could effectively alleviate the hard agglomeration of grains during the gel drying process, and the morphology of the powder retained the network texture of the original gel. The resulting particles were characterized by small particle size (5-20 nm), better monodispersity and high surface area, which gave rise to high activity and sinterability. Consequently, these powders could readily be compacted into the desired shape and their densification could be carried out in shorter time and at lower temperatures. For instance, nanometer-sized powder calcined at 600癈 for 2 h could be cold-pressed into a green body and sintered at 1100?for 0.5 h to attain a dense body with bulk density of 5.9718 g/cm3 and specific pore volume of 0.0008 cm3/g.
文摘Ultrafine particles of Al_(2)O_(3),MoO_(3),TiO_(2)and SiO_(2)were prepared by irradiate high power laser beams on material surface in O_(2)atmosphere as well as TiN in N_(2) atmosphere.X-ray diffractometer analysis identified that all oxides and nitrides powder obtained are crystalline except SiO_(2) particles which have amorphous struc-ture.
文摘With InCl 3·4H 2O being used as raw materials, the precursor of nano sized In 2O 3 powder was prepared by hydrolysis, peptization and gelation of InCl 3·4H 2O. After calcination, nano sized In 2O 3 powder was obtained. The powder was characterized by thermo gravimetric and differential thermal analysis (TG DTA), X ray diffractometry (XRD) and transmission electron microscopy (TEM), respectively. Calculation revealed that the mean crystalline size increased with increasing the calcination temperature, but crystal lattice distortion rate decreased with the increasing in the average crystalline size. This indicated that the smaller the particle size, the bigger the crystal lattice distortion, the worse the crystal growing. The activation energies for growth of nano sized In 2O 3 were calculated to be 4.75 kJ·mol -1 at the calcination temperature up to 500℃ and 66.40 kJ·mol -1 at the calcination temperature over 600℃. TEM photos revealed that the addition of the chemical additive (OP-10) greatly influenced the morphology and size of In 2O 3 particles.