Study On Preparation And Characterization Of MgO-Y₂O₃ Nanocomposite Ceramics

Both MgO and Y2O3 have a wide transmission window ranging from optical to middle and long infrared wavelength. MgO-Y2O3 nanocomposites have excellent mechanical, optical transmittance than that of Y2O3 polycrystalline ceramics. MgO-Y2O3 nanocomposites which, because of their excellent capabilities, are expected to use in the areas of precision electronic parts and aerospace etc.In this study there were two techniques that, which were the coprecipitation and Sol-Gel technique, have been used to produce MgO-Y2O3 nanopowder. And hot-pressed sintering was applied for producing MgO-Y2O3 composite ceramics. NH4HCO3 and H2C2O4 were chosen as precipitator, remained the condition such as temperature, pH and dropping ration unchanged during the experiments. Cane sugar has been selected as foaming agent, and acidified the solution with 10%(v/v) HNO3 to achieve a pH of 2. Those precursors were annealed at different temperature, after that observed the microstructure and the size of those powder. Basing on those powder, achieved MgO-Y2O3 composite ceramics by hot-pressed sintering, investigated the impact of temperature and holding time on sintering.The results of experiments indicated that:the precursors of sedimentation annealing upon 800℃ for 4 h, and the precursors of Sol-Gel annealing upon 400℃, could achieve MgO-Y2O3 nanopowder. As the annealing temperature elevating, the size of grain would grow up. Three different methods, which were sedimentation by NH4HCO3, H2C2O4 and Sol-Gel, obtained different grain size, and they were 20 nm,50 nm and 15 nm, respectively.The MgO-Y2O3 nanopowder sintered by hot-pressed sintering could obtain MgO-Y2O3 nanocomposite ceramics. And the higher the sintering temperature was, the more compact the ceramics would be. With the holding time prolonged, the density of ceramics were improved. The data of experiments suggest that the holding time over 90 min was appropriate. All the size of the grain of the samples throught sintering was less than 1μm.Using Sol-Gel and decomposition techniques to produce MgO-Y2O3 nanocomposites and after hot-pressed sintering obtained ceramics, which showed the property of IR transmission (2000 nm-4000 nm).