Alumina sols with a molar ratio of 1 ： 50 between aluminum sec-batoxide（ ASB ） aud H2 O were fabricated by adding various amounts of nitric acid. The particle shape, zeta potential, polydispersity and effective par...Alumina sols with a molar ratio of 1 ： 50 between aluminum sec-batoxide（ ASB ） aud H2 O were fabricated by adding various amounts of nitric acid. The particle shape, zeta potential, polydispersity and effective particle size of alumina sol were examined by a TEM, a zeta PALS granularity analyzer and a zetaPALS zeta potential analyzer, respectively. By analyzing the change of zeta potential and doable-layer thickness with nitric acid concentration, the potential energy curves of colloidal particles were mapped on the basis of DLVO theory, and the effects of nitric acid concentration on the stability of alumina sols were intensively studied. The results show that for the alumina sols with a mol ratio of 1 ： 50 between ASB and H2O, the total interaction energy of the colloidal particle is at a maximum when the nitric acid concentration is 0.22 mol/ L. Therefore, the stability of the colloid reaches optimum at the nitric acid concentration of 0.22 mol / L.展开更多
Long alumina fibers were prepared by sol-gel method.The spinning sol was obtained by mixing aluminum nitrate,tartaric acid,and polyvinylpyrrolidone with a mass ratio of 10∶3∶1.5.Thermogravimetry-differential scannin...Long alumina fibers were prepared by sol-gel method.The spinning sol was obtained by mixing aluminum nitrate,tartaric acid,and polyvinylpyrrolidone with a mass ratio of 10∶3∶1.5.Thermogravimetry-differential scanning calorimetry （TG-DSC）,Fourier transform infrared （FT-IR） spectra,X-ray diffraction （XRD）,and scanning electron microscopy （SEM） were used to characterize the properties of the gel and ceramic fibers.A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K.The fibers with a uniform diameter can be obtained when sintered at 1473 K,and its main phase is also indentified as α-Al2O3.展开更多
Hydroxyapatite/alumina nanocrystalline composite powders needed for various biomedical applications were successfully synthe- sized by sol-gel process. Structural and morphological investigations of the prepared compo...Hydroxyapatite/alumina nanocrystalline composite powders needed for various biomedical applications were successfully synthe- sized by sol-gel process. Structural and morphological investigations of the prepared composite powders were performed using X-ray dif- fractometer （XRD）, scanning electron microscopy （SEM）, X＇Pert HighScore software, and Clemex Vision image analysis software. The re- suits show that the crystallite size of the obtained composite powders is in the range of 25 to 90 nm. SEM evaluation shows that the obtained composite powders have a porous structure, which is very useful for biomedical applications. The spherical nanoparticles in the range of 60 to 800 nm are embedded in the agglomerated clusters of the prepared composite powders.展开更多
The microstructures of nanosized alumina powders prepared by sol gel routine were systematically studied with transmission electron microscopy and X ray diffractometer. It was found that the morphologies of alumina ge...The microstructures of nanosized alumina powders prepared by sol gel routine were systematically studied with transmission electron microscopy and X ray diffractometer. It was found that the morphologies of alumina gel powders change in the orders of caterpillar thorn granular dumbbell shaped structures during calcining at temperatures from 20?℃ to 800?℃, 1?200?℃ and 1?300?℃. The caterpillar shaped structure composed of strings with a diameter of 5?nm.展开更多
A stable colloidal boehmite sol was made with the aluminium iso propoxide made in China and used to prepare the supported γ alumina membrane using sol gel method. The γ alumina thin layer was characterized by SE...A stable colloidal boehmite sol was made with the aluminium iso propoxide made in China and used to prepare the supported γ alumina membrane using sol gel method. The γ alumina thin layer was characterized by SEM, N 2 sorption method and permeation measurement. The γ alumina membrane was prepared with uniform surface, thickness of 3 μm and average diameter of about 5 nm. The permeabilities of the single gases of H 2, N 2, Ar and their separation factors were measured. The experimental data explained a behavior of Knudsen diffusion for the gas transport through the thin membrane.展开更多
Long alumina .fibers with 60 cm in length were pre- pared by sol - gel method. The spinning sol was ob- tained by mixing aluminum nitrate, oxalic acid, and polyvinylpyrrolidone with a mass ratio of 10： 3： 2. Fourier...Long alumina .fibers with 60 cm in length were pre- pared by sol - gel method. The spinning sol was ob- tained by mixing aluminum nitrate, oxalic acid, and polyvinylpyrrolidone with a mass ratio of 10： 3： 2. Fourier transform infrared （ FTIR ） spectra, X-ray diffraction （XRD） , and scanning electron microscopy （SEM） were used to characterize the properties of the gel and ce- ramic fibers. The fibers with uniform diameter and smooth surface were obtained by sintering at 1 200℃ for 1 h, and their main phase was indentified as α-Al2O3.展开更多
The supported membranes of Al 2O 3 and its modification membranes were prepared.Al 2O 3,Al 2O 3 SiO 2 TiO 2 and Al 2O 3 SiO 2 TiO 2 ZrO 2 membranes were mamufatured by the slip casting process using...The supported membranes of Al 2O 3 and its modification membranes were prepared.Al 2O 3,Al 2O 3 SiO 2 TiO 2 and Al 2O 3 SiO 2 TiO 2 ZrO 2 membranes were mamufatured by the slip casting process using mixing boehmite,silicate,titania and zirconia sols under proper conditions,then the composite membrane was prepared.The structure and characteristics of the membrane were determined by XRD,SEM and AFM measurement.The conditions of preparation of the membrane are discussed.The thickness of the layer is about 1-2μm,the diameter of an average pore is 200-300nm and has a narrow pore distribution without crack forming.By changing the ratios of Al∶Si∶Ti∶Zr(mol),variations of surface pore size of Al 2O 3 SiO 2 TiO 2 ZrO 2 membrane can be gained.展开更多
The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using ...The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using aluminum tri-sec-butoxide and zirconium n-propoxide as precursors. Ethanol (EtOH), isopropanol (iPrOH) and isobutanol (iBuOH) were used as solvents. The Al2O3-ZrO2 powders were characterized by nitrogen physisorption (SBET), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Prepared oxides calcined at 700℃ showed high specific surface area (200 - 240 m2/g). Obtained results suggest that the homogeneity of the mixed oxides is favored by using a water addition rate of 0.06 and 0.10 mL/min with ethanol as solvent.展开更多
Optimizing highly porous fibrous ceramics, like bird’s nest structure, were obtained by vacuum impregnation method with mullite fibers and alumina sol as raw material. The influences of impregnation cycles on the pro...Optimizing highly porous fibrous ceramics, like bird’s nest structure, were obtained by vacuum impregnation method with mullite fibers and alumina sol as raw material. The influences of impregnation cycles on the property of the sample, such as porosity, compressive strength and room-temperature thermal conductivity were explored. The experimental results show that the 3D skeleton structure of the sample was constructed by the randomly arranged mullite fibers and inorganic particles. The content of alumina can be adjusted effectively by impregnation times and it increases with increasing impregnation cycles. The thermal conductivity and compressive strength can also be controlled via tailored impregnation cycles. The compressive strength of fibrous ceramic ranged from 1.03 MPa to 5.31 MPa, while the porosity decrease slightly from 85.3% to 73.8%. In the same time, the thermal conductivity increase from 0.037 W/(m·K) to 0.217 W/(m·K), indicating that the fibrous ceramic with high impressive and low thermal conductivity can be fabricated by impregnation method.展开更多
基金Supported by the Foundation for University Key Teacher of theMinistry of Education,the Key Research Project of the Ministry ofEducation (No.99087)
文摘Alumina sols with a molar ratio of 1 ： 50 between aluminum sec-batoxide（ ASB ） aud H2 O were fabricated by adding various amounts of nitric acid. The particle shape, zeta potential, polydispersity and effective particle size of alumina sol were examined by a TEM, a zeta PALS granularity analyzer and a zetaPALS zeta potential analyzer, respectively. By analyzing the change of zeta potential and doable-layer thickness with nitric acid concentration, the potential energy curves of colloidal particles were mapped on the basis of DLVO theory, and the effects of nitric acid concentration on the stability of alumina sols were intensively studied. The results show that for the alumina sols with a mol ratio of 1 ： 50 between ASB and H2O, the total interaction energy of the colloidal particle is at a maximum when the nitric acid concentration is 0.22 mol/ L. Therefore, the stability of the colloid reaches optimum at the nitric acid concentration of 0.22 mol / L.
基金supported by the Natural Science Foundation of Shaanxi Province,China (No.2010K10-21)
文摘Long alumina fibers were prepared by sol-gel method.The spinning sol was obtained by mixing aluminum nitrate,tartaric acid,and polyvinylpyrrolidone with a mass ratio of 10∶3∶1.5.Thermogravimetry-differential scanning calorimetry （TG-DSC）,Fourier transform infrared （FT-IR） spectra,X-ray diffraction （XRD）,and scanning electron microscopy （SEM） were used to characterize the properties of the gel and ceramic fibers.A little of α-Al2O3 phase is observed in the alumina precursor gel fibers sintered at 1273 K.The fibers with a uniform diameter can be obtained when sintered at 1473 K,and its main phase is also indentified as α-Al2O3.
文摘Hydroxyapatite/alumina nanocrystalline composite powders needed for various biomedical applications were successfully synthe- sized by sol-gel process. Structural and morphological investigations of the prepared composite powders were performed using X-ray dif- fractometer （XRD）, scanning electron microscopy （SEM）, X＇Pert HighScore software, and Clemex Vision image analysis software. The re- suits show that the crystallite size of the obtained composite powders is in the range of 25 to 90 nm. SEM evaluation shows that the obtained composite powders have a porous structure, which is very useful for biomedical applications. The spherical nanoparticles in the range of 60 to 800 nm are embedded in the agglomerated clusters of the prepared composite powders.
文摘The microstructures of nanosized alumina powders prepared by sol gel routine were systematically studied with transmission electron microscopy and X ray diffractometer. It was found that the morphologies of alumina gel powders change in the orders of caterpillar thorn granular dumbbell shaped structures during calcining at temperatures from 20?℃ to 800?℃, 1?200?℃ and 1?300?℃. The caterpillar shaped structure composed of strings with a diameter of 5?nm.
文摘A stable colloidal boehmite sol was made with the aluminium iso propoxide made in China and used to prepare the supported γ alumina membrane using sol gel method. The γ alumina thin layer was characterized by SEM, N 2 sorption method and permeation measurement. The γ alumina membrane was prepared with uniform surface, thickness of 3 μm and average diameter of about 5 nm. The permeabilities of the single gases of H 2, N 2, Ar and their separation factors were measured. The experimental data explained a behavior of Knudsen diffusion for the gas transport through the thin membrane.
基金supported by the Natural Science Foundation of Shaanxi in China ( No. 2010K10 - 21)
文摘Long alumina .fibers with 60 cm in length were pre- pared by sol - gel method. The spinning sol was ob- tained by mixing aluminum nitrate, oxalic acid, and polyvinylpyrrolidone with a mass ratio of 10： 3： 2. Fourier transform infrared （ FTIR ） spectra, X-ray diffraction （XRD） , and scanning electron microscopy （SEM） were used to characterize the properties of the gel and ce- ramic fibers. The fibers with uniform diameter and smooth surface were obtained by sintering at 1 200℃ for 1 h, and their main phase was indentified as α-Al2O3.
基金Project cooperated with College of Environment Engineering,Huazhong University of Technology
文摘The supported membranes of Al 2O 3 and its modification membranes were prepared.Al 2O 3,Al 2O 3 SiO 2 TiO 2 and Al 2O 3 SiO 2 TiO 2 ZrO 2 membranes were mamufatured by the slip casting process using mixing boehmite,silicate,titania and zirconia sols under proper conditions,then the composite membrane was prepared.The structure and characteristics of the membrane were determined by XRD,SEM and AFM measurement.The conditions of preparation of the membrane are discussed.The thickness of the layer is about 1-2μm,the diameter of an average pore is 200-300nm and has a narrow pore distribution without crack forming.By changing the ratios of Al∶Si∶Ti∶Zr(mol),variations of surface pore size of Al 2O 3 SiO 2 TiO 2 ZrO 2 membrane can be gained.
文摘The influence of solvent and the rate of addition of water on the characteristics of alumina-zirconia powders obtained by sol-gel method were investigated. The Al2O3-ZrO2 powders (1:1 molar ratio) were prepared using aluminum tri-sec-butoxide and zirconium n-propoxide as precursors. Ethanol (EtOH), isopropanol (iPrOH) and isobutanol (iBuOH) were used as solvents. The Al2O3-ZrO2 powders were characterized by nitrogen physisorption (SBET), Fourier transformed infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Prepared oxides calcined at 700℃ showed high specific surface area (200 - 240 m2/g). Obtained results suggest that the homogeneity of the mixed oxides is favored by using a water addition rate of 0.06 and 0.10 mL/min with ethanol as solvent.
基金Funded by the National Natural Science Foundation of China(No.51772139)
文摘Optimizing highly porous fibrous ceramics, like bird’s nest structure, were obtained by vacuum impregnation method with mullite fibers and alumina sol as raw material. The influences of impregnation cycles on the property of the sample, such as porosity, compressive strength and room-temperature thermal conductivity were explored. The experimental results show that the 3D skeleton structure of the sample was constructed by the randomly arranged mullite fibers and inorganic particles. The content of alumina can be adjusted effectively by impregnation times and it increases with increasing impregnation cycles. The thermal conductivity and compressive strength can also be controlled via tailored impregnation cycles. The compressive strength of fibrous ceramic ranged from 1.03 MPa to 5.31 MPa, while the porosity decrease slightly from 85.3% to 73.8%. In the same time, the thermal conductivity increase from 0.037 W/(m·K) to 0.217 W/(m·K), indicating that the fibrous ceramic with high impressive and low thermal conductivity can be fabricated by impregnation method.
