为了在较低温度下获得致密镁铝尖晶石烧结体,以分析纯的氧化镁、氧化铝、氧化锆为原料,按n(MgO)∶n(Al2O3) =1∶1配料,在合成体系中分别引入质量分数为0、0.5％、1％和2％的ZrO2添加剂,以糊精为结合剂,经混练、成型后,置于钼丝炉中于1 600℃保温2h烧结合成镁铝尖晶石,检测了烧后试样的线变化率、体积密度和显气孔率,并采用X射线衍射仪、扫描电子显微镜和能谱仪对烧后试样进行了分析.结果表明:在1 600℃的煅烧温度下,加入ZrO2可提高合成镁铝尖晶石的烧结性能.当ZrO2加入量为1％(ω)时,合成镁铝尖晶石的烧结性能最佳;而ZrO2加入量高于1％(ω)时,较多的ZrO2弥散在尖晶石周围,发生相变,起钉扎作用,阻碍了镁铝尖晶石颗粒之间的接触,又会影响合成尖晶石的烧结性能.
To get dense sintered magnesium aluminate spinel at relatively low temperatures,analytically pure MgO,Al2O3 and ZrO2 powders were taken as raw materials in n(MgO)∶ n(Al2O3) =1∶1;ZrO2 was added as additive (0,0.5％,1％,and 2％ by mass percent,the same hereinafter) and dextrin as binder;then the mixture was mixed,shaped,and fired in a molybdenum wire furnace at 1 600 ℃ for 2 h.The linear change rate,bulk density and apparent porosity of the fired specimens were determined.The fired specimens were analyzed by X-ray diffraction,scanning electron microscopy and energy dispersive spectrometry.The resuits indicate that ZrO2 can greatly improve the sintering property of MgAl2O4 at 1 600 ℃.When the ZrO2 addition is 1 mass％,the sintering property is the best.When the ZrO2 addition is higher than 1 mass％,more ZrO2 disperses around spinel,generating phase changes that produce pinning effects,which hinders the contact between the MgAl2O4 particles and affects the sintering.
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