| With the application and requirement of infrared technology,infrared window materials need to have higher properties.MgO-Y2O3composite ceramics have better mechanical properties,higher thermal shock resistance propertiesr and better optical transmittance than single-phase Y2O3ceramics.However,the traditional sintering technologies need to be completed at high temperature and high pressure,which is not conducive to the preparation of high performance MgO-Y2O3composite ceramics through fine grains.Flash sintering technology is an excellent innovative technology that has the characteristics of low sintering temperature,fast sintering speed,short holding time and the grains are finer,the properties are better.In this paper,MgO-Y2O3composite ceramics prepared by flash sintering.The effects of flash sintering process,microstructure and mechanical properties of disc-shaped MgO-Y2O3composite ceramics under different initial conditions and dog bone-shaped MgO-Y2O3composite ceramics under different current density and constant current holding time were studied.The main conclusions are as follows:（1）With the increases of electric field strength,the onset furnace temperature of flash sintering decreases.When the electric field strength is in the range of816～3720V/cm and with the decrease of furnace temperature,the increase of electric field strength is almost linear,the steady state power density is about 160m W/mm3after flash sintering.However,when the electric field strength changes from 3720V/cm to4167V/cm,the onset temperature of flash sintering changes rapidly from 1165℃to961℃.Phase change not happened during flash sintering.The overall relative density of disc-shaped MgO-Y2O3composite ceramics after flash sintering is only about 60%,and the microstructure shows obvious inhomogeneity.（2）With the increase of current density,the steady state power density increases,the relative density and Vickers hardness and average grain size first decreases and then increases in the preparation of dog bone-shaped MgO-Y2O3composite ceramics by flash sintering.When the current density is 40m A/mm2,the grain size reaches the minimum value of 0.79μm.When the current density is 60 m A/mm2,the relative density and Vickers hardness reaches the maximum of 90.70%and 7.94GPa respectively.（3）The steady state power density is maintained at about 700m W/mm3of dog bone-shaped MgO-Y2O3composite ceramics in the constant current stage of flash sintering.With the increase of constant current holding time,the average grain size first decreases and then increases,the relative density and Vickers hardness increases,the fracture toughness first increases and then decreases.When the constant current time is25s,the grain size reaches the minimum value of 0.39μm and the fracture toughness reaches the maximum value of 1.99MPa·m1/2.When the constant current time is 62s,the maximum relative density and Vickers hardness are 94.13%and 7.87GPa respectively.Currently,there is a breakthrough in the preparation of MgO-Y2O3composite ceramics by flash sintering technology,which can obtain relatively uniform in macroscopic and microscopic aspects.However,the process of MgO-Y2O3composite ceramics prepared by flash sintering technology still needs further optimization. |
