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
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
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
With alumina sol as binder and Ni metal as sintering aids,the Ni-TiB_(2)/Al_(2)O_(3) composite cathode material for aluminum electrolysis was prepared by coldpressed sintering.The mechanical properties of the composit...With alumina sol as binder and Ni metal as sintering aids,the Ni-TiB_(2)/Al_(2)O_(3) composite cathode material for aluminum electrolysis was prepared by coldpressed sintering.The mechanical properties of the composite cathode material were measured.Its electrolytic properties were identified by a 20-A electrolysis test.Cathode samples before and after electrolysis test were measured by energy-dispersive spectroscopy(EDS).The migration behavior of various elements in the electrolysis process was studied by phase analysis.The result shows that Ni metal can effectively fill the gap between the aggregate during the sintering process,which can improve the sintering density of the composite cathode material significantly.The voltage of the 20-A electrolysis test is stable.The impurity of aluminum liquid is 0.42%.The aluminum liquid can wet the cathode surface effectively,and the Ni-TiB_(2)/Al_(2)O_(3) composite is an ideal wettable cathode material.In the process of electrolysis,the alkali elements in the electrolyte penetrate the electrode,where K goes deeper than Na.Al generated on the cathode surface will also penetrate the cathode through the gap of the composite material,while Ni in the electrode will spread into the aluminum liquid layer.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.
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financially supported by the Major Science and Technology Projects of Henan Province(No.131100210700)the Major Science and Technology Programs of CHALCO(No.ZB2013CBBCe1)。
文摘With alumina sol as binder and Ni metal as sintering aids,the Ni-TiB_(2)/Al_(2)O_(3) composite cathode material for aluminum electrolysis was prepared by coldpressed sintering.The mechanical properties of the composite cathode material were measured.Its electrolytic properties were identified by a 20-A electrolysis test.Cathode samples before and after electrolysis test were measured by energy-dispersive spectroscopy(EDS).The migration behavior of various elements in the electrolysis process was studied by phase analysis.The result shows that Ni metal can effectively fill the gap between the aggregate during the sintering process,which can improve the sintering density of the composite cathode material significantly.The voltage of the 20-A electrolysis test is stable.The impurity of aluminum liquid is 0.42%.The aluminum liquid can wet the cathode surface effectively,and the Ni-TiB_(2)/Al_(2)O_(3) composite is an ideal wettable cathode material.In the process of electrolysis,the alkali elements in the electrolyte penetrate the electrode,where K goes deeper than Na.Al generated on the cathode surface will also penetrate the cathode through the gap of the composite material,while Ni in the electrode will spread into the aluminum liquid layer.
