Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explo...Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density,phase composition,microstructure,bulk conductivity,and total conductivity.In the impedance test under frequency of 1-10^(6) Hz,the bulk conductivity of the samples increased with increasing sintering temperature,and the total conductivity first increased and then decreased.SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature,which increased from(0.54±0.01)μm to(1.21±0.01)μm when the temperature changed from 750 to 950°C.The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased.The holding time had little effect on the grain size growth or sample density,but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte.展开更多
The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order ...The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order to ascertain the effects of these two factors on the structure refinement by the ECP technique,three groups of experiments were performed with different types of electrodes or various thermal insulators.By the comparison between solidification structures under different conditions,it is followed that the electrode and the thermal insulator have an obvious influence on the grain refinement under an applied ECP,and further analysis demonstrates that the thermal conditions of the liquid surface play a vital role in the modification of solidification structure.Also,the results support the viewpoint that most of the equiaxed grains originate from the liquid surface subjected to an ECP.展开更多
The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98（K0.sNa0.5）NbO3-0.02LaFeO3 ceramics （abbreviated as 0.98KNN-0.02LF）. All the ceramics sinte...The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98（K0.sNa0.5）NbO3-0.02LaFeO3 ceramics （abbreviated as 0.98KNN-0.02LF）. All the ceramics sintered for different dwell time are of pure phase and the peak intensity of the 0.98KNN-0.02LF ceramics becomes stronger with a longer dwell time. Denser microstructures with larger grain size are developed for the sample with a longer dwell time. The maximum dielectric permittivity decreases with increasing the dwell time, and the deteriorative dielectric properties are due to the increasing grain size and the domain wall motion. Ferroelectric properties results indicate that 2Pr value slightly decreases with increasing the dwell time, while the 2Ec value increases. Consequently, the 0.98KNN-0.02LF ceramic sintered at 1150 ℃ for 2 h shows optimum dielectric properties （er=2253 and tan fi〈5%） and ferroelectric properties （2Pr=34.51 gC/cm2 and 2Ec=5.07 kV/mm）.展开更多
Temperature distribution and weld bead profiles of constant current and pulsed current gas tungsten arc welded aluminium alloy joints were compared. The effects of pulsed current welding on tensile properties, hardnes...Temperature distribution and weld bead profiles of constant current and pulsed current gas tungsten arc welded aluminium alloy joints were compared. The effects of pulsed current welding on tensile properties, hardness profiles, microstructural features and residual stress distribution of aluminium alloy joints were reported. The use of pulsed current technique is found to improve the tensile properties of the weld compared with continuous current welding due to grain refinement occurring in the fusion zone.展开更多
基金funded by the National Natural Science Foundation of China(Nos.51672310,51272288,51972344)。
文摘Li_(1.5)Ga_(0.5)Ti_(1.5)PO_(4))_(3)(LGTP)is recognized as a promising solid electrolyte material for lithium ions.In this work,LGTP solid electrolyte materials were prepared under different process conditions to explore the effects of sintering temperature and holding time on relative density,phase composition,microstructure,bulk conductivity,and total conductivity.In the impedance test under frequency of 1-10^(6) Hz,the bulk conductivity of the samples increased with increasing sintering temperature,and the total conductivity first increased and then decreased.SEM results showed that the average grain size in the ceramics was controlled by the sintering temperature,which increased from(0.54±0.01)μm to(1.21±0.01)μm when the temperature changed from 750 to 950°C.The relative density of the ceramics increased and then decreased with increasing temperature as the porosity increased.The holding time had little effect on the grain size growth or sample density,but an extended holding time resulted in crack generation that served to reduce the conductivity of the solid electrolyte.
基金Project(2009AA03Z110) supported by the National High Technology Research and Development Program of ChinaProject (2011CB012902) supported by the National Basic Research Program of China
文摘The application of electric current pulse（ECP） to a solidification process refers to the immersion of electrodes into the liquid metal and the employment of thermal insulators on the upper surface of metal.In order to ascertain the effects of these two factors on the structure refinement by the ECP technique,three groups of experiments were performed with different types of electrodes or various thermal insulators.By the comparison between solidification structures under different conditions,it is followed that the electrode and the thermal insulator have an obvious influence on the grain refinement under an applied ECP,and further analysis demonstrates that the thermal conditions of the liquid surface play a vital role in the modification of solidification structure.Also,the results support the viewpoint that most of the equiaxed grains originate from the liquid surface subjected to an ECP.
基金Project(CX201108)supported by the Doctorate Foundation of Northwestern Polytechnical University,ChinaProject(51072165)supported by the National Natural Science Foundation of ChinaProjects(KP200901,SKLSP201104)supported by the Fund of State Key Laboratory of Solidification Processing in NWPU,China
文摘The effects of dwell time on the phase structure, microstructure, and electrical properties were investigated for the 0.98（K0.sNa0.5）NbO3-0.02LaFeO3 ceramics （abbreviated as 0.98KNN-0.02LF）. All the ceramics sintered for different dwell time are of pure phase and the peak intensity of the 0.98KNN-0.02LF ceramics becomes stronger with a longer dwell time. Denser microstructures with larger grain size are developed for the sample with a longer dwell time. The maximum dielectric permittivity decreases with increasing the dwell time, and the deteriorative dielectric properties are due to the increasing grain size and the domain wall motion. Ferroelectric properties results indicate that 2Pr value slightly decreases with increasing the dwell time, while the 2Ec value increases. Consequently, the 0.98KNN-0.02LF ceramic sintered at 1150 ℃ for 2 h shows optimum dielectric properties （er=2253 and tan fi〈5%） and ferroelectric properties （2Pr=34.51 gC/cm2 and 2Ec=5.07 kV/mm）.
文摘Temperature distribution and weld bead profiles of constant current and pulsed current gas tungsten arc welded aluminium alloy joints were compared. The effects of pulsed current welding on tensile properties, hardness profiles, microstructural features and residual stress distribution of aluminium alloy joints were reported. The use of pulsed current technique is found to improve the tensile properties of the weld compared with continuous current welding due to grain refinement occurring in the fusion zone.
