Preparation And Properties Of Y₂O₃-MgO Ceramic Nano/Nano Composites

Y₂O₃-MgO nanocomposite ceramic is mainly used in the infrared windows.The preparation of Y₂O₃-MgO nanocomposite powder is prepared by solid phase and sol-gel and the ceramics are prepared by normal atmosphere sintering,hot-pressing sintering and spark plasma sintering（SPS）seperately.The comprehensive performance of samples are described by scanning electron microscopy（SEM）,relative density,hardness,transmittance etc.The conclusions are as follows:Titrate the 0.25 mol/L Na2CO3 solution with 0.25 mol/L MgCl2 and then centrifugal the precipitation with stilled water and alcohol.TG-DSC curves indicate that the crystallinze water is removed at 126 ℃ and the MgCO3 decomposition at 392 ℃.The XRD curves indicate that crystal of MgO can be get at 700℃,800℃ and 90℃C,but in order to get low shrinkage rate of ceramic,we adopted 900℃ to get MgO powder.Y₂O₃-MgO nanocomposite ceramic prepared by solid-phase method is get by normal atmosphere.The optimal process is 1400℃for 2 h.The density of sample can be as 96.5%and the transmittance of it can be 24%at 6.9分m wavelength.The optimal process of preparation of Y₂O₃-MgO nanocomposite material by sol-gel are as follows:drying under a high temperature to get dry gel,and then calcined at 600 ℃ for 10 hours.The grain sizes of Y₂O₃ and MgO calculated by XRD are both 14 nm.The optimal process of sol-gel powder by SPS are as follows:at 1250℃ for 5 min.Two-step sintering are also performed.Three systems are tested:the first of two-step process is that ti is 1350℃ and t2 is 1200℃ for 24 h;the second of two-step process is that ti is 1400℃ and t2 is 1250℃ for 24 h;and the third of two-step process is that 1300℃ for 24 h.And they can contain the transmittance as high as 83%,83%,81%and they can get the relative density separately 98.3%98.5%99.7%.The optimal process of sol-gel powder by hot-pressing are as follows:dwelling press 30MPa and 1400℃ for 30 min,and then sintered for two-step sintering the ti temperature is 1400℃ and the t2 temperature is 1250℃.The sample can get the transmittance 86%at 5.5 μm wavelength.