Cerium is one of the most abundant rare earth elements in both bastnasite and monazite. Ceria has been widely used in optical, catalytic, electrolyte, and sensor materials, with unique performances. With the developme...Cerium is one of the most abundant rare earth elements in both bastnasite and monazite. Ceria has been widely used in optical, catalytic, electrolyte, and sensor materials, with unique performances. With the development of functional materials, great interest has been focused on the synthesis and characterization of specific fine/mesoporous ceria powder. In this study, the modified precipitation and recrystallization processes combined with a controlled calcination process for fabricating the ceria with large particle size and high appearance density was reported. During precipitation, a certain amount of mineral acid such as nitric acid served as an additive, to adjust the precipitation and crystallization processes of cerium oxalates. An appropriate acidic condition could lead the process into the Oswald ripening stage and made the particles become bigger. Thus, the appearance density of powder was increased. The optimized conditions, such as the temperature, feeding speed, type and concentration of mineral acids, and the concentration of cerium-contained stock solution, were investigated and evaluated.展开更多
The surface flashover of epoxy resin(EP) composites is a pivotal problem in the field of highvoltage insulation.The regulation of the interface between the filler and matrix is an effective means to suppress flashover...The surface flashover of epoxy resin(EP) composites is a pivotal problem in the field of highvoltage insulation.The regulation of the interface between the filler and matrix is an effective means to suppress flashover.In this work,nano ZnO was fluorinated and grafted using lowtemperature plasma technology,and the fluorinated filler was doped into EP to study the DC surface flashover performance of the composite.The results show that plasma fluorination can effectively inhibit the agglomeration by grafting –CFxgroups onto the surface of nano-ZnO particles.The fluorine-containing groups at the interface provide higher charge binding traps and enhance the insulation strength at the interface.At the same time,the interface bond cooperation caused by plasma treatment also promoted the accelerating effect of nano ZnO on charge dissipation.The two effects synergistically improve the surface flashover performance of epoxy composites.When the concentration of fluorinated ZnO filler is 20%,the flashover voltage has the highest increase,which is 31.52% higher than that of pure EP.In addition,fluorinated ZnO can effectively reduce the dielectric constant and dielectric loss of epoxy composites.The interface interaction mechanism was further analyzed using molecular dynamics simulation and density functional theory simulation.展开更多
基金Project supported by the Ministry of Science and Technology of China (2006BAC02A06)
文摘Cerium is one of the most abundant rare earth elements in both bastnasite and monazite. Ceria has been widely used in optical, catalytic, electrolyte, and sensor materials, with unique performances. With the development of functional materials, great interest has been focused on the synthesis and characterization of specific fine/mesoporous ceria powder. In this study, the modified precipitation and recrystallization processes combined with a controlled calcination process for fabricating the ceria with large particle size and high appearance density was reported. During precipitation, a certain amount of mineral acid such as nitric acid served as an additive, to adjust the precipitation and crystallization processes of cerium oxalates. An appropriate acidic condition could lead the process into the Oswald ripening stage and made the particles become bigger. Thus, the appearance density of powder was increased. The optimized conditions, such as the temperature, feeding speed, type and concentration of mineral acids, and the concentration of cerium-contained stock solution, were investigated and evaluated.
基金supported by Beijing Natural Science Foundation (No. 3222057)National Natural Science Foundation of China (Nos. 52277147 and 52007065)。
文摘The surface flashover of epoxy resin(EP) composites is a pivotal problem in the field of highvoltage insulation.The regulation of the interface between the filler and matrix is an effective means to suppress flashover.In this work,nano ZnO was fluorinated and grafted using lowtemperature plasma technology,and the fluorinated filler was doped into EP to study the DC surface flashover performance of the composite.The results show that plasma fluorination can effectively inhibit the agglomeration by grafting –CFxgroups onto the surface of nano-ZnO particles.The fluorine-containing groups at the interface provide higher charge binding traps and enhance the insulation strength at the interface.At the same time,the interface bond cooperation caused by plasma treatment also promoted the accelerating effect of nano ZnO on charge dissipation.The two effects synergistically improve the surface flashover performance of epoxy composites.When the concentration of fluorinated ZnO filler is 20%,the flashover voltage has the highest increase,which is 31.52% higher than that of pure EP.In addition,fluorinated ZnO can effectively reduce the dielectric constant and dielectric loss of epoxy composites.The interface interaction mechanism was further analyzed using molecular dynamics simulation and density functional theory simulation.
