以分析纯MgO(粒度<5 um)和活性仅α-Al2O3微粉(粒度<5 um)为主要原料,分别添加不同量的4种稀土氧化物粉末(Y,,2O3、La2O、Nd2O3和CeO2),共混4 h后,在100 MPa下压制成φ30 mm×20 mm的试样,经110℃干燥6 h后,分别于1 100、1 200、1 300、1 400、1 500和1 650 ℃保温3 h烧成.借助DSC、XRD、SEM和能谱分析研究稀土氧化物对反应烧结合成镁铝尖晶石的影响.结果表明:(1)添加稀土氧化物降低了镁铝尖晶石'的结晶温度,促进了尖晶石的晶粒发育;(2)添加3%Nd2O3的试样经1 650℃保温3 h制备出相对密度为92%的镁铝尖晶石;(3)稀土氧化物促进镁铝尖晶石致密化的机理不同:Y2O3和Nd2O3在试样中形成复杂氧化物活化了晶格,而La2O3和CeO2在试样中主要是形成液相,从而促进了镁铝尖晶石的烧结致密化.
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