| With the advancement of science and technology,solid electrolyte materials have been widely developed,prepared and applied,among which the preparation methods of ceramic electrolytes are also being gradually updated.The preparation of ceramic materials by conventional pressureless sintering needs to be carried out in a high temperature environment,and at the same time,there is a large amount of energy consumption.In order to reduce the preparation cost of ceramic sintering and obtain solid electrolyte ceramic materials with excellent properties,the research on non-conventional sintering methods has attracted the attention of researchers.Flash sintering is a new field-assisted sintering technology,which is mainly a sintering process to achieve rapid densification of samples at low temperature under certain conditions.In this paper,3mol%yttria-stabilized zirconia(3YSZ)and 3YSZ-carbon nanotubes(CNTs)materials were sintered by flash sintering technology.The main research contents are as follows:(1)The influence of the electrical parameters of the flash sintering process on the microstructure and properties of the 3YSZ material.The?10 mm cylindrical 3YSZ material was prepared by flash sintering.The sintering pressure was 5 MPa;the furnace temperature was 900?;the heating rate was 5?/min;the electric field strength was100-250 V/cm;and the current density was 30-70 m A/mm~2.The phase composition and surface morphology of sintered 3YSZ materials were observed and analyzed by scanning electron microscope and X-ray diffractometer;the relative density and electrochemical properties of sintered materials were measured by densitometer and electrochemical workstation.The research results showed that the increase of the electric field strength from 100 V/cm to 250 V/cm had a little effect on the relative density and electrochemical properties of the sintered material,but the flash sintering incubation time was significantly reduced from 37 s to 3 s.When the current density was increased from 30 m A/mm~2 to 70 m A/mm~2,the relative density of 3YSZ increased from 83.7%to 92.4%;the ionic conductivity measured at 250?increased from 0.17?S/cm to 1.25?S/cm.(2)The effects of different flash sintering methods on the densification and electrochemical properties of the composites.3YSZ-5%CNTs were prepared by direct flash sintering and step-by-step flash sintering.The sintering process parameters were as follows:furnace temperature was 700?,electric field strength was 25 V/cm,and current density was 100-300 m A/mm~2.The step-by-step flash sintering was to increase the current density step by step,with a step size of 25 m A/mm~2 and an interval of 30 s.The results showed that because the direct flash sintering sample was at high current density for a longer time than the step-by-step flash sintering sample,its relative density was 94.98%higher than that of the step-by-step flash sintering sample 93.68%,and the ionic conductivity was 0.471?S/cm higher than that of the step-by-step flash sintering sample 0.125?S/cm.(3)Low-temperature sintering of 3YSZ-based doped CNTs.Under the conditions of furnace temperature of 200?,electric field strength of 60 V/cm and current density of 100-300 m A/mm~2.The composites doped with different concentrations of carbon nanotubes showed different flash sintering properties.When the CNTs concentration was 2%,the sintered sample was uniform and dense,its current density was 150m A/mm~2 and the ionic conductivity of the sintered sample was 0.11?S/cm;When the CNTs concentration was 3%,the current density was 300 m A/mm~2,and the ionic conductivity of the sintered sample can reach 0.83?S/cm;When the CNTs concentration was 4%,the ionic conductivity of the sintered sample was 0.6?S/cm,and the composite material at this CNTs concentration can be sintered at room temperature. |
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