Y₂O₃-MgO Nanopowder And Nanocomposite Fabricated By Sol-Gel Method

Nanocomposites have emerged as an alternative material used in the fabrication of infrared windows/domes and cowling.However,increased mechanical strength,thermal shock resistance are required for future infrared material in harsher mechanical and thermal environment.It has been reported that the Y2O3-MgO nanocomposite has good infrared transparent in mid-IR wavelength range,and the increased mechanical strength than other infrared material.In this thesis,Sol-gel method was used to synthesize the Y2O3-MgO nanopowder,then the hot-pressing sintering was used to consolidate the nanopowder into nanocomposite.The main performance of nanopowder and nanocomposite were characterized by FT-IR,XRD,BET,TG-DTA,SEM,transmittance,relative density,etc.The optimal process of Y2O3-MgO nanopowder by Sol-gel method is as follow:the solution is place into an over preheated to 80 ? then the residual volume of gel is 50 mL,drying under 240 ? to dried gel,subsequent calcination of the dried gel at 600 ? for 10 h.The Y2O3-MgO nanopowder has fine grain,uniform composition good dispersion and specific surface area of 60 m2/g.The optimal process of Y2O3-MgO nanocomposite is as follow:the nanopowder was consolidated by the hot-pressing sintering with 1350 ? for 30 min,then postsinter annealing was conducted at 1200 ? for 6 h in air.The transmittance of Y2O3-MgO nanocomposite reaches 83%at 2-6 ?m,and the cutoff wavelength reaches 9.7 ?m,which is superior to those of spinel,AlON.In addition,the fabricated nanocomposite has fine grains,narrow grain size distribution,low porosity and increased relative density.The results indicate that the Y2O3-MgO nanocomposite has good infrared transmittance.