CaBi_(4)Ti_(4)O_(15)(CBT)-based Aurivillius high-temperature piezoceramics with different Sb-Mn co-doping amounts were synthesized via the conventional sintering technique.The influences of doping amount on the produc...CaBi_(4)Ti_(4)O_(15)(CBT)-based Aurivillius high-temperature piezoceramics with different Sb-Mn co-doping amounts were synthesized via the conventional sintering technique.The influences of doping amount on the product were studied via their crystal structure,microstructure,and piezoelectric performance.It is found that an appropriate Sb-Mn co-doping amount can effectively optimize the crystal structure and decrease the oxygen vacancy concentration in CBT ceramics,leading to enhanced electrical properties.Optimized electrical performance with a high Curie temperature(TC)of 792℃and a remarkable piezoelectric coefficient(d33)of 25 p C/N were achieved at a doping amount(x)of 0.05.Furthermore,this ceramic is found to exhibit an excellent thermal stability,with d33 retaining 88%of its original value after annealing at 600℃for 2 h.Moreover,this ceramic shows a high electrical resistivity(ρ)of 1.35×10^(8)Ω·cm with a small dielectric loss(tanδ)of 1.7%at 400℃.Because of such outstanding piezoelectric performance,it is believed that these Sb-Mn co-doped CBT ceramics could be potential candidates for high-temperature piezoelectric applications.展开更多
Lanthanum titanate （La2/3 TiO3） powders were synthesized by hydrothermal method based on the reaction of TiO2, La（NO3）3 and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure, mor...Lanthanum titanate （La2/3 TiO3） powders were synthesized by hydrothermal method based on the reaction of TiO2, La（NO3）3 and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure, morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope, transmission electron microscope and impedance method. The results show that the La2/3TiO3 particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1150℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.展开更多
Based on the FEA software ANSYS,a model was developed to simulate the thermal stress distribution of inert anode.In order to reduce its thermal stress,the effect of some parameters on thermal stress distribution was i...Based on the FEA software ANSYS,a model was developed to simulate the thermal stress distribution of inert anode.In order to reduce its thermal stress,the effect of some parameters on thermal stress distribution was investigated,including the temperature of electrolyte,the current,the anode cathode distance,the anode immersion depth,the surrounding temperature and the convection coefficient between anode and circumstance.The results show that there exists a large axial tensile stress near the tangent interface between the anode and bath,which is the major cause of anode breaking.Increasing the temperature of electrolyte or the anode immersion depth will deteriorate the stress distribution of inert anode.When the bath temperature increases from 750 to 970 ℃,the maximal value and absolute minimal value of the 1st principal stress increase by 29.7% and 29.6%,respectively.When the anode immersion depth is changed from 1 to 10 cm,the maximal value and absolute minimal value of the 1st principal stress increase by 52.1% and 65.0%,respectively.The effects of other parameters on stress distribution are not significant.展开更多
Glass-ceramics obtained from the electric arc furnace molten slag of incinerator fly ash was produced by applying nucleation and crystallization through heat treatment process. The effects of nucleating agent （TiO2 a...Glass-ceramics obtained from the electric arc furnace molten slag of incinerator fly ash was produced by applying nucleation and crystallization through heat treatment process. The effects of nucleating agent （TiO2 and Cr2O3） on the crystallization kinetics and heat treatment schedule of the slag were investigated. The results show that the nucleating agents changed the crystallization phase and morphology of the obtained glass-ceramics. The optimum heat treatment schedule of the glass with TiO2 was determined as nucleation at 952 K for 1.5 h and crystal growth at 1 258 K for 1.5 h, while those values with Cr203 were estimated at 971 K for 2 h and at 1 238 K for 2 h. TiO2 acting as nucleating agent could decrease the activation energy of the slag and shorten the total thermal treatment time in comparison with Cr2O3. The glass-ceramics obtained under the optimum heat treatment condition was environmentfriendly and had remarkable physical/mechanical properties and chemical durability.展开更多
The electrocaloric effect(ECE) of multilayer ceramic capacitor(MLCC) of Y5 V type was directly measured via a differential scanning calorimetry(DSC) method and a reference resistor was used to calibrate the heat flow ...The electrocaloric effect(ECE) of multilayer ceramic capacitor(MLCC) of Y5 V type was directly measured via a differential scanning calorimetry(DSC) method and a reference resistor was used to calibrate the heat flow due to the heat dissipation. The results are compared with those calculated from Maxwell relations by using the polarization data obtained from the polarization–electric field hysteresis loops. The direct method shows a larger ECE temperature change, which is accounted for the situation approaches an ideal condition. For the indirect method using Maxwell relations, only the polarization projection along the electric field was taken into account, which will be less than the randomly distributed real polarizations that contribute to the ECE. The MLCCs exhibit a broad peak of ECE around 80 C, which will be favorite for the practical ECE cooling devices.展开更多
The thermal diffusivity and heat capacity of β-SiAION ceramics with different Z values （0.6, 1.5, 3.0） were measured by laser flash technique and differential scanning calorimetry （DSC）, respectively. The thermal...The thermal diffusivity and heat capacity of β-SiAION ceramics with different Z values （0.6, 1.5, 3.0） were measured by laser flash technique and differential scanning calorimetry （DSC）, respectively. The thermal conductivity of β-SiAION was calculated from thermal diffusivity, heat capacity and density and it decreased and then kept almost constant with increasing of temperature. Two different models representing effective thermal conductivity were established and the various parameters of these models were simulated based on the results from the present work. The fitted regression lines were in good agreement with the experimental values.展开更多
基金financial support from the Key Research and Development Project of Zhejiang Province,China(No.2017C01056)。
文摘CaBi_(4)Ti_(4)O_(15)(CBT)-based Aurivillius high-temperature piezoceramics with different Sb-Mn co-doping amounts were synthesized via the conventional sintering technique.The influences of doping amount on the product were studied via their crystal structure,microstructure,and piezoelectric performance.It is found that an appropriate Sb-Mn co-doping amount can effectively optimize the crystal structure and decrease the oxygen vacancy concentration in CBT ceramics,leading to enhanced electrical properties.Optimized electrical performance with a high Curie temperature(TC)of 792℃and a remarkable piezoelectric coefficient(d33)of 25 p C/N were achieved at a doping amount(x)of 0.05.Furthermore,this ceramic is found to exhibit an excellent thermal stability,with d33 retaining 88%of its original value after annealing at 600℃for 2 h.Moreover,this ceramic shows a high electrical resistivity(ρ)of 1.35×10^(8)Ω·cm with a small dielectric loss(tanδ)of 1.7%at 400℃.Because of such outstanding piezoelectric performance,it is believed that these Sb-Mn co-doped CBT ceramics could be potential candidates for high-temperature piezoelectric applications.
文摘Lanthanum titanate （La2/3 TiO3） powders were synthesized by hydrothermal method based on the reaction of TiO2, La（NO3）3 and KOH at 160℃ for 24 h followed by the treatment of acidification. The microstructure, morphology and dielectric properties were investigated by using X-ray diffraction, scanning electron microscope, transmission electron microscope and impedance method. The results show that the La2/3TiO3 particles consist of nearly homogenous and lamellar grains. The particles can be sintered into porous ceramics above 1150℃. The dielectric properties of La2/3 TiO3 show that both the dielectric constant and the dielectric loss tangent decrease with the increase of frequency.
基金Project (2005CB623703) supported by the National Basic Research and Development Program of ChinaProject (50474051) supported by the National Natural Science Foundation of China
文摘Based on the FEA software ANSYS,a model was developed to simulate the thermal stress distribution of inert anode.In order to reduce its thermal stress,the effect of some parameters on thermal stress distribution was investigated,including the temperature of electrolyte,the current,the anode cathode distance,the anode immersion depth,the surrounding temperature and the convection coefficient between anode and circumstance.The results show that there exists a large axial tensile stress near the tangent interface between the anode and bath,which is the major cause of anode breaking.Increasing the temperature of electrolyte or the anode immersion depth will deteriorate the stress distribution of inert anode.When the bath temperature increases from 750 to 970 ℃,the maximal value and absolute minimal value of the 1st principal stress increase by 29.7% and 29.6%,respectively.When the anode immersion depth is changed from 1 to 10 cm,the maximal value and absolute minimal value of the 1st principal stress increase by 52.1% and 65.0%,respectively.The effects of other parameters on stress distribution are not significant.
基金Supported by the National Natural Science Foundation of China(No.51378332 and No.20806051)Science and Technology Project of Housing and Urban-Rural Ministry(No.2014-K4-014)Chinese Postdoctoral Science Foundation(No.2013M530872)
文摘Glass-ceramics obtained from the electric arc furnace molten slag of incinerator fly ash was produced by applying nucleation and crystallization through heat treatment process. The effects of nucleating agent （TiO2 and Cr2O3） on the crystallization kinetics and heat treatment schedule of the slag were investigated. The results show that the nucleating agents changed the crystallization phase and morphology of the obtained glass-ceramics. The optimum heat treatment schedule of the glass with TiO2 was determined as nucleation at 952 K for 1.5 h and crystal growth at 1 258 K for 1.5 h, while those values with Cr203 were estimated at 971 K for 2 h and at 1 238 K for 2 h. TiO2 acting as nucleating agent could decrease the activation energy of the slag and shorten the total thermal treatment time in comparison with Cr2O3. The glass-ceramics obtained under the optimum heat treatment condition was environmentfriendly and had remarkable physical/mechanical properties and chemical durability.
基金supported by the National Natural Science Foundation of China(Grant No.51372042)the Department of Education of Guangdong Province of People’s Republic of China(Grant No.2014GKXM039)+1 种基金Guangdong Provincial Natural Science Foundation(Grant No.2015A030308004)the NSFC-Guangdong Joint Fund(Grant NoU1501246)
文摘The electrocaloric effect(ECE) of multilayer ceramic capacitor(MLCC) of Y5 V type was directly measured via a differential scanning calorimetry(DSC) method and a reference resistor was used to calibrate the heat flow due to the heat dissipation. The results are compared with those calculated from Maxwell relations by using the polarization data obtained from the polarization–electric field hysteresis loops. The direct method shows a larger ECE temperature change, which is accounted for the situation approaches an ideal condition. For the indirect method using Maxwell relations, only the polarization projection along the electric field was taken into account, which will be less than the randomly distributed real polarizations that contribute to the ECE. The MLCCs exhibit a broad peak of ECE around 80 C, which will be favorite for the practical ECE cooling devices.
基金supported by the National Natural Science Foundation of China(Grant No. 50332010)the National Basic Research Program of China ("973"Program)(Grant No. 2007CB613608)the National Science and Technology Supporting Program (Grant Nos. 2006BAC21B02-1,2007BAB24B03)
文摘The thermal diffusivity and heat capacity of β-SiAION ceramics with different Z values （0.6, 1.5, 3.0） were measured by laser flash technique and differential scanning calorimetry （DSC）, respectively. The thermal conductivity of β-SiAION was calculated from thermal diffusivity, heat capacity and density and it decreased and then kept almost constant with increasing of temperature. Two different models representing effective thermal conductivity were established and the various parameters of these models were simulated based on the results from the present work. The fitted regression lines were in good agreement with the experimental values.
