We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of...We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of （Sr, Bi, Si, Ta）-doped TiO2- based varistor ceramics sintered at 1 250℃ for 0.5 h, 1.0 h, 2.0 h, 3.0 h, 4.0 h, and 5.0 h, respectively. The samples were characterized by X-ray diffraction, breakdown voltage, and complex impedance. The results show that as the soaking time increases from 0.5 h to 5.0 h, the breakdown voltage drops before rising while the nonlinear coefficient increases and then decreases. We suggest that, considering both grain semi-conductivity and nonlinear electrical properties of the TiO2-based varistor ceramics, the optimal soaking time is between 2.0 h and 3.0 h.展开更多
In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent ...In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiC np advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vo1% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730＋ 95 MPa and fracture toughness is 5.6 ± 0.6 MPa.m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.展开更多
The development of low-voltage ZnO varistor ceramics containing TiO2 is presented in this report. The varistor properties of ZnO ceramics with different compositions were measured, and microstructure of the ceramics w...The development of low-voltage ZnO varistor ceramics containing TiO2 is presented in this report. The varistor properties of ZnO ceramics with different compositions were measured, and microstructure of the ceramics was investigated by XRD and SEM. The results show that the addition of TiO2 is beneficial to the decrease of varistor voltage (V1mA). whereas it leads to the recession of nonlinear coefficient (α) and leakage current (lL). The varistor properties of ZnO ceramics containing TiO2 can be effectively improved by introducing moderate amount of pre-fabricated ZnO seed grains. The behaviors of TiO2 and seed grains, as well as the mechanisms by which TiO2 and seed grains influence varistor properties, are discussed.展开更多
Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar...Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar-driven VOC degradation.Conventional batch-type photoreactors have low efficiency while continuous-flow photoreactors suffer from the problem of incomplete removal of VOCs.Herein,aiming for continuous and complete degradation of toluene gas as the target contaminant,continuous-flow pho-tocatalytic degradation reactors were made by adhering the vanadium and nitrogen codoped TiO_(2)on honeycomb ceramics(V/N-TiO_(2)@HC)by a simple sol-gel method.In such a reactor,the rich ordered pores in the HC accelerate mass transport of toluene,and the introduction of V/N dopants narrows the bandgap and widens the light absorption range of TiO_(2),together resulting in continuous and nearly-complete pho-tocatalytic degradation of toluene.The unique and stable structure of HC allows the photocatalysts to be reused.The degradation rate of toluene gas can reach 97.8%,and after 24 rounds of photocatalytic degra-dation,there is still a degradation rate of 96.7%.The impacts of loading times and gaseous flow rate on the photocatalytic performance of V/N-TiO_(2)@HC are studied in detail.Our study provides a practical so-lution for the continuous and complete photocatalytic degradation of VOCs and opens a new application field for HC.展开更多
Reticulated ceramic foam filters provide an effective way to purify molten steel by removing non-metallic inclusions.We proposed a novel strategy to improve the purification performance of Al_(2)O_(3)-based ceramic fi...Reticulated ceramic foam filters provide an effective way to purify molten steel by removing non-metallic inclusions.We proposed a novel strategy to improve the purification performance of Al_(2)O_(3)-based ceramic filters by using microporous corundum-spinel raw materials to replace dense raw materials.Three kinds of Al_(2)O_(3)-based ceramic filters fabricated from dense α-Al_(2)O_(3) micro-powder or microporous corundum-spinel powder were selected to carry out the immersion tests with molten steel.On the one hand,the higher surface roughness of the filter skeleton prepared from microporous raw materials increased the adsorption capacity of skeleton surface on inclusions in molten steel.On the other hand,the higher apparent porosity and larger pore size of the filter skeleton were more beneficial to the penetration of molten steel in the micropores of skeleton.The reaction process at the solid-liquid interface also improved the wettability of the interface between skeleton and molten steel,resulting in a larger penetration depth and a better adsorption effect on the inclusions.In summary,the novel Al_(2)O_(3)-based ceramic filter prepared with microporous corundum-spinel powder and addition of 5 wt.% nano-Al_(2)O_(3) powder reduced the total oxygen content of the steel from 40.2×10^(-4) to 12.7×10^(-4) wt.% by 68.4% and the Al content from 0.46 to 0.18 wt.% by 60.9% after immersion test,presenting the most excellent purification performance on molten steel.展开更多
Research on doping modification of ZnTiO_(3) ceramics to enhance microwave dielectric properties has been hindered by poor performance,unclear structure-function mechanisms.To expand the applicability of ZnTiO_(3) cer...Research on doping modification of ZnTiO_(3) ceramics to enhance microwave dielectric properties has been hindered by poor performance,unclear structure-function mechanisms.To expand the applicability of ZnTiO_(3) ceramics,this study explores Zn_(1-x)Li_(2x)TiO_(3)(O≤×≤1)ceramics using a phase engineering strategy.Our findings reveal that the introduction of Lit into the ZnTiO_(3) system initiates a multiple phase transition,starting at x=0.1.Initially,ilmenite ZnTiO_(3) transforms into a cubic ordered spinel phase(space group P4332).Subsequently,a transition to a disordered spinel phase(space group Fd3m)occurs at x=0.5,culminating in the formation of a monoclinic rock salt-structured LizTiO3 phase.Significantly,two sets of ceramics with near-zero temperature coefficients of resonance frequency(t:)were obtained at x=0.1 and 0.75.Moreover,the quality factor(Qxf)demonstrated a 4.4-fold increase compared to that of ZnTiO_(3) ceramics at x=0.25(105,013 GHz).Additionally,it was observed that the Ti4 polarization in Zn_(1-x)Li_(2x)TiO_(3) ceramics was underestimated by 11.3%-13.3%,causing the measured dielectric constant(e.)exceeding the theoretical dielectric constant(eth).The ionic polarizability of Ti*was adjusted to stabilize around 3.29 A.Evaluation using multiple methods,including Phillips-van Vechten-Levine(P-V-L)theory,Raman vibrational mode analysis,bond valence,bond energy theory,and octahedral distortion,confirms that the Ti-O bonds within the octahedron predominantly affect&r,the increasing lattice energy(U)contributes to the enhancement of Qxf,and the strengthened Li-O bond energy effectively regulates Tr.展开更多
Early research mainly studies the performance of TiO2 power condition.As a result of using power condition TiO2,its power is slight,not easy to precipitate,and creates another pollutants.Therefore,the ceramic granulat...Early research mainly studies the performance of TiO2 power condition.As a result of using power condition TiO2,its power is slight,not easy to precipitate,and creates another pollutants.Therefore,the ceramic granulated substance carrier material was used to prepare the TiO2 thin film to carry on the water treatment to obtain the good effect.The gangue of coal was used to make the ceramic granulated substance basis,then in a ceramic granulated basis place TiO2 thin film was painted,advancing together the running water processing experiment.The test result is as follows:The TOC content reduces by above 80%,and used to filter the material to be possible to replace at will,which has obtained good effect.In the testing,using the scanning electron microscope analyzer,carrying on the superficial appearance view to the TiO2 ceramic sand leach material to scratch,finally indicated,it has some turtle crack in the TiO2 ceramic granulated substance surface,has crystal boundary surface flaw,causes it to have bigger catalytic activity.展开更多
The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi...The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xCa(Mg_(1/3)Nb_(2/3))O_(3) ceramics were synthesized by the solid-state reaction method.The 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramic exhibited a high recoverable energy storage density of 8.1 J/cm3 and energy storage efficiency of 82.4% at 550 kV/cm.The introduction of Ca(Mg_(1/3)Nb_(2/3))O_(3) reduced the grain size and increased the band gap,thereby enhancing the breakdown field strength of the ceramic materials.The method also resulted in good temperature stability(20–140℃),frequency stability(1–200 Hz),and fatigue stability over 106 cycles.In addition,an ultrahigh power density of 187 MW/cm^(3) and a fast charge-discharge rate(t0.9=57.2 ns)can be obtained simultaneously.Finite element method analysis revealed that the decrease of grain size was beneficial to the increase of breakdown field strength.Therefore,the 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramics resulted in high energy storage properties with good stability and were promising environment-friendly materials for advanced pulsed power systems applications.展开更多
基金Funded by the Natural Science Foundation of China (No. 50872001 and No. 50642038)the Scientific Research Foundation of Education Ministry of Anhui Province (No. 2005KJ224 and No. KJ2007B132)the Graduate Student Innovation Programs of Anhui University (No. 20072006)
文摘We investigated the influence of soaking time on the semi-conductivity and nonlinear electrical properties of TiO2- based varistor ceramic samples. We used a single sintering process and fabricated six disk samples of （Sr, Bi, Si, Ta）-doped TiO2- based varistor ceramics sintered at 1 250℃ for 0.5 h, 1.0 h, 2.0 h, 3.0 h, 4.0 h, and 5.0 h, respectively. The samples were characterized by X-ray diffraction, breakdown voltage, and complex impedance. The results show that as the soaking time increases from 0.5 h to 5.0 h, the breakdown voltage drops before rising while the nonlinear coefficient increases and then decreases. We suggest that, considering both grain semi-conductivity and nonlinear electrical properties of the TiO2-based varistor ceramics, the optimal soaking time is between 2.0 h and 3.0 h.
基金Supported by National Natural Science Foundation of China(Grant No.51175305)
文摘In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiC np advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vo1% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730＋ 95 MPa and fracture toughness is 5.6 ± 0.6 MPa.m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.
基金Funded by the science fund of Wuhan University of Technology.
文摘The development of low-voltage ZnO varistor ceramics containing TiO2 is presented in this report. The varistor properties of ZnO ceramics with different compositions were measured, and microstructure of the ceramics was investigated by XRD and SEM. The results show that the addition of TiO2 is beneficial to the decrease of varistor voltage (V1mA). whereas it leads to the recession of nonlinear coefficient (α) and leakage current (lL). The varistor properties of ZnO ceramics containing TiO2 can be effectively improved by introducing moderate amount of pre-fabricated ZnO seed grains. The behaviors of TiO2 and seed grains, as well as the mechanisms by which TiO2 and seed grains influence varistor properties, are discussed.
基金financial support of this work from the Key Research and Development Project of Gansu Province(No.20YF3GA008)the Lanzhou Science and Technology Lanzhou Science and Technology Bureau Project(No.2022-2-15)+1 种基金Gansu Provincial Science and Technology Commissioner Special Project(No.22CX8GA106)Key Research and Development Project of Gansu Natural Energy Institute(No.2019YF-02).
文摘Photocatalytic degradation of volatile organic compounds(VOCs)is a significant applying aspect of pho-tocatalysis.Both the modulation of photocatalysts and the rational dispersion of them on supports are key for solar-driven VOC degradation.Conventional batch-type photoreactors have low efficiency while continuous-flow photoreactors suffer from the problem of incomplete removal of VOCs.Herein,aiming for continuous and complete degradation of toluene gas as the target contaminant,continuous-flow pho-tocatalytic degradation reactors were made by adhering the vanadium and nitrogen codoped TiO_(2)on honeycomb ceramics(V/N-TiO_(2)@HC)by a simple sol-gel method.In such a reactor,the rich ordered pores in the HC accelerate mass transport of toluene,and the introduction of V/N dopants narrows the bandgap and widens the light absorption range of TiO_(2),together resulting in continuous and nearly-complete pho-tocatalytic degradation of toluene.The unique and stable structure of HC allows the photocatalysts to be reused.The degradation rate of toluene gas can reach 97.8%,and after 24 rounds of photocatalytic degra-dation,there is still a degradation rate of 96.7%.The impacts of loading times and gaseous flow rate on the photocatalytic performance of V/N-TiO_(2)@HC are studied in detail.Our study provides a practical so-lution for the continuous and complete photocatalytic degradation of VOCs and opens a new application field for HC.
基金financially supported by the National Natural Science Foundation of China(Grant No.51974214).
文摘Reticulated ceramic foam filters provide an effective way to purify molten steel by removing non-metallic inclusions.We proposed a novel strategy to improve the purification performance of Al_(2)O_(3)-based ceramic filters by using microporous corundum-spinel raw materials to replace dense raw materials.Three kinds of Al_(2)O_(3)-based ceramic filters fabricated from dense α-Al_(2)O_(3) micro-powder or microporous corundum-spinel powder were selected to carry out the immersion tests with molten steel.On the one hand,the higher surface roughness of the filter skeleton prepared from microporous raw materials increased the adsorption capacity of skeleton surface on inclusions in molten steel.On the other hand,the higher apparent porosity and larger pore size of the filter skeleton were more beneficial to the penetration of molten steel in the micropores of skeleton.The reaction process at the solid-liquid interface also improved the wettability of the interface between skeleton and molten steel,resulting in a larger penetration depth and a better adsorption effect on the inclusions.In summary,the novel Al_(2)O_(3)-based ceramic filter prepared with microporous corundum-spinel powder and addition of 5 wt.% nano-Al_(2)O_(3) powder reduced the total oxygen content of the steel from 40.2×10^(-4) to 12.7×10^(-4) wt.% by 68.4% and the Al content from 0.46 to 0.18 wt.% by 60.9% after immersion test,presenting the most excellent purification performance on molten steel.
基金This work was supported by the National Natural Science Foundation of China(No.52102129)the Hunan Provincial Natural Science Foundation of China(No.2023JJ30138)the science and technology innovation Program of Hunan Province(No.2023RC3094).
文摘Research on doping modification of ZnTiO_(3) ceramics to enhance microwave dielectric properties has been hindered by poor performance,unclear structure-function mechanisms.To expand the applicability of ZnTiO_(3) ceramics,this study explores Zn_(1-x)Li_(2x)TiO_(3)(O≤×≤1)ceramics using a phase engineering strategy.Our findings reveal that the introduction of Lit into the ZnTiO_(3) system initiates a multiple phase transition,starting at x=0.1.Initially,ilmenite ZnTiO_(3) transforms into a cubic ordered spinel phase(space group P4332).Subsequently,a transition to a disordered spinel phase(space group Fd3m)occurs at x=0.5,culminating in the formation of a monoclinic rock salt-structured LizTiO3 phase.Significantly,two sets of ceramics with near-zero temperature coefficients of resonance frequency(t:)were obtained at x=0.1 and 0.75.Moreover,the quality factor(Qxf)demonstrated a 4.4-fold increase compared to that of ZnTiO_(3) ceramics at x=0.25(105,013 GHz).Additionally,it was observed that the Ti4 polarization in Zn_(1-x)Li_(2x)TiO_(3) ceramics was underestimated by 11.3%-13.3%,causing the measured dielectric constant(e.)exceeding the theoretical dielectric constant(eth).The ionic polarizability of Ti*was adjusted to stabilize around 3.29 A.Evaluation using multiple methods,including Phillips-van Vechten-Levine(P-V-L)theory,Raman vibrational mode analysis,bond valence,bond energy theory,and octahedral distortion,confirms that the Ti-O bonds within the octahedron predominantly affect&r,the increasing lattice energy(U)contributes to the enhancement of Qxf,and the strengthened Li-O bond energy effectively regulates Tr.
文摘Early research mainly studies the performance of TiO2 power condition.As a result of using power condition TiO2,its power is slight,not easy to precipitate,and creates another pollutants.Therefore,the ceramic granulated substance carrier material was used to prepare the TiO2 thin film to carry on the water treatment to obtain the good effect.The gangue of coal was used to make the ceramic granulated substance basis,then in a ceramic granulated basis place TiO2 thin film was painted,advancing together the running water processing experiment.The test result is as follows:The TOC content reduces by above 80%,and used to filter the material to be possible to replace at will,which has obtained good effect.In the testing,using the scanning electron microscope analyzer,carrying on the superficial appearance view to the TiO2 ceramic sand leach material to scratch,finally indicated,it has some turtle crack in the TiO2 ceramic granulated substance surface,has crystal boundary surface flaw,causes it to have bigger catalytic activity.
基金This work is supported by the Natural Science Foundation of Shandong Province of China(Nos.ZR2020ME035,ZR2020QE043 and ZR2020QE044)National Natural Science Foundation of China(Nos.51872166 and 52102132)+1 种基金Postdoctoral Research Foundation of China(2017M622196)Opening Project of Key Laboratory of Inorganic Functional Materials and Devices,Chinese Academy of Sciences(KLIFMD201705).
文摘The increase in energy consumption and its collateral damage on the environment has encouraged the development of environment-friendly ceramic materials with good energy storage properties.In this work,(1-x)Na_(0.5)Bi_(0.5)TiO_(3)-xCa(Mg_(1/3)Nb_(2/3))O_(3) ceramics were synthesized by the solid-state reaction method.The 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramic exhibited a high recoverable energy storage density of 8.1 J/cm3 and energy storage efficiency of 82.4% at 550 kV/cm.The introduction of Ca(Mg_(1/3)Nb_(2/3))O_(3) reduced the grain size and increased the band gap,thereby enhancing the breakdown field strength of the ceramic materials.The method also resulted in good temperature stability(20–140℃),frequency stability(1–200 Hz),and fatigue stability over 106 cycles.In addition,an ultrahigh power density of 187 MW/cm^(3) and a fast charge-discharge rate(t0.9=57.2 ns)can be obtained simultaneously.Finite element method analysis revealed that the decrease of grain size was beneficial to the increase of breakdown field strength.Therefore,the 0.88Na_(0.5)Bi_(0.5)TiO_(3)-0.12Ca(Mg_(1/3)Nb_(2/3))O_(3) ceramics resulted in high energy storage properties with good stability and were promising environment-friendly materials for advanced pulsed power systems applications.
