The ultrafine silver powders were prepared by liquid reduction method using Arabic gum as dispersant.The effects of different dispersants,pH values,and temperature on the morphology and particle size of silver powders...The ultrafine silver powders were prepared by liquid reduction method using Arabic gum as dispersant.The effects of different dispersants,pH values,and temperature on the morphology and particle size of silver powders were investigated.It is found that Arabic gum can better adsorb on silver particles via chemical adsorption,and it shows the best dispersive effect among all the selected dispersants.The particle size of silver powders can be finely tuned from 0.34 to 4.09μm by adjusting pH values,while the morphology of silver powders can be tuned by changing the temperature.The silver powders with high tap density higher than 4.0 g/cm3 were successfully prepared in a wide temperature range of 21.8-70°C.Especially,the tap density is higher than 5.0 g/cm3 when the temperature is optimized to be 50°C.The facile process and high silver concentration of this method make it a promising way to prepare high quality silver powders for electronic paste.展开更多
The Williamson-Hall and uniaxial compression methods were used to study the variations of the micro-strain and stress-strain relations in WC powders after jet milling and ball milling, respectively. The rupture behavi...The Williamson-Hall and uniaxial compression methods were used to study the variations of the micro-strain and stress-strain relations in WC powders after jet milling and ball milling, respectively. The rupture behavior of agglomerates in WC powders was investigated. Meanwhile, the as-obtained WC powders treated by different milling methods were used to fabricate WC-10%Co cemented carbides, followed by the performance assessment of cemented carbides. The results show that the micro-strain of the jet-milled WC powders decreases significantly compared with that of the ball-milled WC powders, and that the cemented carbides prepared by jet-milled WC powders exhibit excellent properties with a transverse-rupture strength of 4260 MPa, due to the elimination of agglomerates and the reduction of lattice strain.展开更多
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 continuously dynamic-controlled combustion synthesis (CDCCS) was developed based on the continuous fluidization and combustion synthesis technologies. CoC2O4·2H2O powders were transformed to Co3O4 in a gas-...The continuously dynamic-controlled combustion synthesis (CDCCS) was developed based on the continuous fluidization and combustion synthesis technologies. CoC2O4·2H2O powders were transformed to Co3O4 in a gas-solid fluid bed unit designed and build independently, where the reactant of CoC2O4·2H2O powders and the reactant of air were poured and introduced from the top and the bottom of the bed at a certain rates respectively. The reagents met in the bed and ignited at a given low temperature, resulting in formation of Co3O4. The results show a significant difference in combustion wave models. In the case of CDCCS, there was an immobile combustion wave, floating in the combustion zone located in the middle of the bed, instead of propagating of the combustion wave. The temperature of the combustion wave can be controlled by adjusting the flow rate of carrier gas. The resultant Co3O4 powders (diameter size ≤0.8 μm) have a narrow particle size distribution and spherical or quasi-spherical shape. This novel technique has many advantages, such as continuation, efficiency, energy conservation and environmental friendly and has been used in mass production.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
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
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 hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic pro...The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd x Fe12?x O19(x=0.1?1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m?1 at x=1, which is far greater than that of barium permanent ferrite (BaFe12O19).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
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
Seven Shenfu coal powders different in particle size obtained by sieving and ball milling were used to probe their adsorption properties to phenol from water. The results show that the kinetics of phenol on coal powde...Seven Shenfu coal powders different in particle size obtained by sieving and ball milling were used to probe their adsorption properties to phenol from water. The results show that the kinetics of phenol on coal powders follow the second-order adsorption kinetic model well. Adsorption processes are governed by film diffusion and the kinetic parameters and the effective diffusion coefficients were calculated through plotting. Adsorption capacities to phenol increase exponentially with decreasing of diameter of coal powders. The phenol adsorption equilibrium for coal powder with d50 of 9.30 μm can be described in terms of Freundlich isotherm, while for ultrafine coal powders with d50 of 4.28 and 4.82 μm fit Langmuir isotherm well.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
The adsorption of methyl orange onto ultrafine coal powder (UCP) and modified ultrafine coal powder (MUCP) from aqueous solutions were studied, in which the influence of contact time, dosage, temperature, pH, and ...The adsorption of methyl orange onto ultrafine coal powder (UCP) and modified ultrafine coal powder (MUCP) from aqueous solutions were studied, in which the influence of contact time, dosage, temperature, pH, and methyl orange concentration in the solution were investigated. The adsorption kinetics of methyl orange by UCP and MUCP can be described by the Lagergren first-order and pseudo second-order kinetic models, respectively. The adsorption isotherms of methyl orange onto MUCP at 303, 313 and 323 K follow the Freundlich and Langmuir isotherm equation. Values of △G^0 for methyl orange adsorption onto MUCP are -22.55, -23.10 and -23.79 kJ·mol^-1 at 303, 313, and 323 K, respectively. The values of △H^0 and △S^0 are -3.74 kJ· mol^-1 and 61.99 J·mol^-1, respectively. The adsorption process is spontaneous and exothermic.展开更多
A new hydrometallurgical process of chlorination-distillation at low temperatures about 100 °C was developed for recovery of valuable metal and environmental protection. This process was used to treat flue dust c...A new hydrometallurgical process of chlorination-distillation at low temperatures about 100 °C was developed for recovery of valuable metal and environmental protection. This process was used to treat flue dust containing arsenic and antimony and satisfactory results were obtained. Over 99% of arsenic and antimony were recovered, and high purity As2O3 and SbCl3 were produced. A metallic alcoholate technique was developed and proved to be of significant to the utilization of antimony resources. Using this technique, a number of antimony oxide powders were prepared, such as high purity and ultrafine Sb2O3, ultrafine Sb2O3-Sb2O5 and Sb2O3-SnO2 composite powders.展开更多
The present study evaluated ef fects of ultrafine powder of the green macroalgae E nteromopha prolifera as dietary supplement on growth performance, digestive enzyme activities and serum nonspecific immune responses o...The present study evaluated ef fects of ultrafine powder of the green macroalgae E nteromopha prolifera as dietary supplement on growth performance, digestive enzyme activities and serum nonspecific immune responses of the red tilapia(O reochromis mossambicus × Oreochromis niloticus). The red tilapia were fed five diets supplemented with different levels of E. prolifera ultrafine powder as well as a control diet containing no E. prolifera for seven weeks(Diets 0–6 contained 0(control), 10, 20, 30, 40 and 50 g/kg of E. prolifera ultrafine powder, respectively). The results showed that diets supplemented with E. prolifera ultrafine powder generally improved growth, immunity and digestive enzyme activities of the red tilapia. In particular, the fish fed the diet incorporated 50 g/kg (5%) E. prolifera ultrafine powder(Diet 5) achieved the highest percentage weight gain, specific growth rate and the condition factor(increased by 15.4%, 8.0% and 5.7%, respectively when compared to the control). Feeding the diet also led to significantly increases( P <0.05) in serum nonspecific immune responses, including total superoxide dismutase, acid phosphatase, alkaline phosphatase, lysozyme activities and serum total protein(increased by 19.4%, 48.1%, 29.5%, 30.3% and 8.7%, respectively) as well as digestive enzyme activities of erepsin, gastric amylase, gastric lipase, pepsin, intestinal amylase and gastric lipase(increased by 15.7%, 33.3%, 16.3%, 21.3%, 52.3% and 28.2%, respectively) than those of the control. Based on these results, it is recommended that the inclusion level of E. prolifera ultrafine powder in the diet of the red tilapia should be 50 g/kg(or 5%).展开更多
Ultrafine alumina power was obtained by calcining the precursor at 1 200 ℃ for 2 h, which was prepared by homogeneous precipitation method using aluminium salts and urea as raw materials. The effects of anions on the...Ultrafine alumina power was obtained by calcining the precursor at 1 200 ℃ for 2 h, which was prepared by homogeneous precipitation method using aluminium salts and urea as raw materials. The effects of anions on the morphology, particle size, surface area and configuration of the precursors were studied. The results show that the reactions of urea with aluminium nitrate and aluminium chloride result in agglomerates gels with bad filtering performance, the morphology is fibrillar. Aluminium sulphate-urea reactions result in the direct formation of amorphous powders with good filtering performance, of which morphology are regular spherical particles with larger granularity and smaller surface area. The reaction of mutual compound of aluminium sulphate and aluminium nitrate with molar ratio of 40:60 with urea can produce precursor with good filtering performance, spherical morphology, and uniform granularity distribution in the particle size range of 2-3 μm.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
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
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
基金Project(2014DFA90520)supported by the International Cooperation Program of Ministry of Science and Technology of ChinaProject(2013A090100003)supported by the Production,Teaching and Research Program of Guangdong Province,ChinaProject(2013DY048)supported by the Science and Technology Cooperation Program of Daye Nonferrous Metals Group,China
文摘The ultrafine silver powders were prepared by liquid reduction method using Arabic gum as dispersant.The effects of different dispersants,pH values,and temperature on the morphology and particle size of silver powders were investigated.It is found that Arabic gum can better adsorb on silver particles via chemical adsorption,and it shows the best dispersive effect among all the selected dispersants.The particle size of silver powders can be finely tuned from 0.34 to 4.09μm by adjusting pH values,while the morphology of silver powders can be tuned by changing the temperature.The silver powders with high tap density higher than 4.0 g/cm3 were successfully prepared in a wide temperature range of 21.8-70°C.Especially,the tap density is higher than 5.0 g/cm3 when the temperature is optimized to be 50°C.The facile process and high silver concentration of this method make it a promising way to prepare high quality silver powders for electronic paste.
基金Project(2016GZ0290) supported by the Key Technology R&D Program of Sichuan Province,ChinaProject(2019CDXYCL0031) supported by the Fundamental Research Funds for the Central Universities,China
文摘The Williamson-Hall and uniaxial compression methods were used to study the variations of the micro-strain and stress-strain relations in WC powders after jet milling and ball milling, respectively. The rupture behavior of agglomerates in WC powders was investigated. Meanwhile, the as-obtained WC powders treated by different milling methods were used to fabricate WC-10%Co cemented carbides, followed by the performance assessment of cemented carbides. The results show that the micro-strain of the jet-milled WC powders decreases significantly compared with that of the ball-milled WC powders, and that the cemented carbides prepared by jet-milled WC powders exhibit excellent properties with a transverse-rupture strength of 4260 MPa, due to the elimination of agglomerates and the reduction of lattice strain.
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 ).
基金Project (2007BAE05B01) supported by the National Key Technologies R & D Program of China
文摘The continuously dynamic-controlled combustion synthesis (CDCCS) was developed based on the continuous fluidization and combustion synthesis technologies. CoC2O4·2H2O powders were transformed to Co3O4 in a gas-solid fluid bed unit designed and build independently, where the reactant of CoC2O4·2H2O powders and the reactant of air were poured and introduced from the top and the bottom of the bed at a certain rates respectively. The reagents met in the bed and ignited at a given low temperature, resulting in formation of Co3O4. The results show a significant difference in combustion wave models. In the case of CDCCS, there was an immobile combustion wave, floating in the combustion zone located in the middle of the bed, instead of propagating of the combustion wave. The temperature of the combustion wave can be controlled by adjusting the flow rate of carrier gas. The resultant Co3O4 powders (diameter size ≤0.8 μm) have a narrow particle size distribution and spherical or quasi-spherical shape. This novel technique has many advantages, such as continuation, efficiency, energy conservation and environmental friendly and has been used in mass production.
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.
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.
文摘The hexagonal BaNd x Fe12?x O19(x=0.1?1.0) fine powders with M-type structure were synthesized by sol-gel auto-combustion high-temperature synthesis method. The structure of powders, gels’ combustion and magnetic properties of powders were respectively studied by means of X-ray diffractometer (XRD), differential thermal analysis-thermogravimetric analysis (DTA-TG) and vibrating sample magnetometer (VSM). The powders before and after combustion and calcination at 450–850 °C with different mole ratio of Nd to Ba (0.1–1.0) were compared in terms of XRD. In addition, the effects of different synthesis conditions on magnetic properties of powders were also discussed. The results show that at pH 7.0 or so, mole ratio of citrate to nitrate (1–3) and calcination temperature of 850 °C for 1 h, M-type BaNd x Fe12?x O19(x=0.1?1.0) fine powders can be obtained, and the coercive force reaches 436880 A·m?1 at x=1, which is far greater than that of barium permanent ferrite (BaFe12O19).
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.
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Seven Shenfu coal powders different in particle size obtained by sieving and ball milling were used to probe their adsorption properties to phenol from water. The results show that the kinetics of phenol on coal powders follow the second-order adsorption kinetic model well. Adsorption processes are governed by film diffusion and the kinetic parameters and the effective diffusion coefficients were calculated through plotting. Adsorption capacities to phenol increase exponentially with decreasing of diameter of coal powders. The phenol adsorption equilibrium for coal powder with d50 of 9.30 μm can be described in terms of Freundlich isotherm, while for ultrafine coal powders with d50 of 4.28 and 4.82 μm fit Langmuir isotherm well.
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Supported by the National Science Foundation for Post Doctoral Scientists of China (20070411124), Scientific and Technological Key Project of Shaanxi Province (2006k07-G19), and Industrialization Project of Shaanxi Provincial Department of Education (06JC 11).
文摘The adsorption of methyl orange onto ultrafine coal powder (UCP) and modified ultrafine coal powder (MUCP) from aqueous solutions were studied, in which the influence of contact time, dosage, temperature, pH, and methyl orange concentration in the solution were investigated. The adsorption kinetics of methyl orange by UCP and MUCP can be described by the Lagergren first-order and pseudo second-order kinetic models, respectively. The adsorption isotherms of methyl orange onto MUCP at 303, 313 and 323 K follow the Freundlich and Langmuir isotherm equation. Values of △G^0 for methyl orange adsorption onto MUCP are -22.55, -23.10 and -23.79 kJ·mol^-1 at 303, 313, and 323 K, respectively. The values of △H^0 and △S^0 are -3.74 kJ· mol^-1 and 61.99 J·mol^-1, respectively. The adsorption process is spontaneous and exothermic.
文摘A new hydrometallurgical process of chlorination-distillation at low temperatures about 100 °C was developed for recovery of valuable metal and environmental protection. This process was used to treat flue dust containing arsenic and antimony and satisfactory results were obtained. Over 99% of arsenic and antimony were recovered, and high purity As2O3 and SbCl3 were produced. A metallic alcoholate technique was developed and proved to be of significant to the utilization of antimony resources. Using this technique, a number of antimony oxide powders were prepared, such as high purity and ultrafine Sb2O3, ultrafine Sb2O3-Sb2O5 and Sb2O3-SnO2 composite powders.
基金Supported by the Natural Science Foundation of Fujian Province(No.2017J01638)the Science and Technology Project Grant of Xiamen City,China(No.3502Z20113029)the Key Project of Technology Grant of Fujian Province(No.2012N0018)
文摘The present study evaluated ef fects of ultrafine powder of the green macroalgae E nteromopha prolifera as dietary supplement on growth performance, digestive enzyme activities and serum nonspecific immune responses of the red tilapia(O reochromis mossambicus × Oreochromis niloticus). The red tilapia were fed five diets supplemented with different levels of E. prolifera ultrafine powder as well as a control diet containing no E. prolifera for seven weeks(Diets 0–6 contained 0(control), 10, 20, 30, 40 and 50 g/kg of E. prolifera ultrafine powder, respectively). The results showed that diets supplemented with E. prolifera ultrafine powder generally improved growth, immunity and digestive enzyme activities of the red tilapia. In particular, the fish fed the diet incorporated 50 g/kg (5%) E. prolifera ultrafine powder(Diet 5) achieved the highest percentage weight gain, specific growth rate and the condition factor(increased by 15.4%, 8.0% and 5.7%, respectively when compared to the control). Feeding the diet also led to significantly increases( P <0.05) in serum nonspecific immune responses, including total superoxide dismutase, acid phosphatase, alkaline phosphatase, lysozyme activities and serum total protein(increased by 19.4%, 48.1%, 29.5%, 30.3% and 8.7%, respectively) as well as digestive enzyme activities of erepsin, gastric amylase, gastric lipase, pepsin, intestinal amylase and gastric lipase(increased by 15.7%, 33.3%, 16.3%, 21.3%, 52.3% and 28.2%, respectively) than those of the control. Based on these results, it is recommended that the inclusion level of E. prolifera ultrafine powder in the diet of the red tilapia should be 50 g/kg(or 5%).
基金Project(5JJ3010) supported by the Natural Science Foundation of Hunan Province, China
文摘Ultrafine alumina power was obtained by calcining the precursor at 1 200 ℃ for 2 h, which was prepared by homogeneous precipitation method using aluminium salts and urea as raw materials. The effects of anions on the morphology, particle size, surface area and configuration of the precursors were studied. The results show that the reactions of urea with aluminium nitrate and aluminium chloride result in agglomerates gels with bad filtering performance, the morphology is fibrillar. Aluminium sulphate-urea reactions result in the direct formation of amorphous powders with good filtering performance, of which morphology are regular spherical particles with larger granularity and smaller surface area. The reaction of mutual compound of aluminium sulphate and aluminium nitrate with molar ratio of 40:60 with urea can produce precursor with good filtering performance, spherical morphology, and uniform granularity distribution in the particle size range of 2-3 μm.
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.