TiO_2含量对镁铝尖晶石烧结性能的影响

Effect of TiO_2 Content on Sintering of MgAl_2O_4

以分析纯氧化镁、氧化铝、氧化钛为原料,按氧化镁与氧化铝质量比28.33∶71.67配料,在合成体系中分别引入质量分数为0、0.5%、1%、2%、4%、6%、8%和10%的氧化钛,在钼丝炉中1600℃保温2 h,烧结法合成镁铝尖晶石。用X射线衍射、扫描电子显微镜和能谱对烧后试样进行分析。结果表明:引入适量的TiO_2可显著提高镁铝尖晶石的烧结性能;当TiO_2含量低于4%时,随着TiO_2的含量增加,试样的线变化率减小,显气孔率下降,体积密度增大,常温耐压强度增大。TiO_2的引入提高了镁铝尖晶石晶体空位浓度,活化了晶格,促进镁铝尖晶石的烧结。当TiO_2含量高于4%时,试样的线变化率、显气孔率和体积密度没有显著变化,常温耐压强度有所下降;尖晶石晶粒尺寸没有明显变化,且生成了一定量的Mg0.6Al0.8Ti1.6O_5,阻碍了镁铝尖晶石之间的接触,影响镁铝尖晶石烧结性能的提高。

Abstract ：The analytical pure MgO, Al2O3 and TiO2 powders as raw materials. The MgO and Al2O3 ratios is 28.33： 71.67. With different ratios of TiO2（0%, 0.5%, 1%, 2%, 4%, 6%, 8%, 10%） were added in the MgO and Al2O3 mixture, and then the mixture was sintered in molybdenum wire furnace at 1600 ℃ for 2 h. The sintered samples were analyzed by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometry, respectively. The results indicated that TiO2 can greatly improve the sintering properties of MgAl2O4. When TiO2 content is less than 4% , with increasing the content of TiO2, the MgAl2O4 linear expansivity, the cold compressive strength and the apparent porosity decreased, but the bulk density increased. With TiO2 added, the MgAl2O4 crystal vacancy concentration, sintering properties and crystal grain size increased. When TiO2 content is higher than 4% , the linear expansivity, the apparent porosity, the grain size, and the bulk density are not change significantly, but the cold compressive strength decreases, and Mg0.6Al0.8Ti1.6O5, which hindered the contact and sintering between the MgAl2O4, generated large amount.