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以分析纯的MgO、活性α-Al2O3、电熔单斜锆为原料,采用淬冷法研究了Mg5+x Al2.4–x Zr1.7+0.25x O12(–0.4≤x≤0.4)的化学组成、热处理温度对合成MgO–MgAl2O4–ZrO2系三元化合物的影响,并对其合成机理进行了分析。结果表明:当温度低于1 650℃时,主要为MgAl2O4的形成及其晶粒长大过程;当温度高于1 650℃时,MgO与ZrO2向MgAl2O4扩散,反应形成了Mg4.68Al2.64Zr1.68O12;当温度为1 740℃时,Mg4.68Al2.64Zr1.68O12的合成趋于完全,其合成率达到89.5%,残留的MgAl2O4和ZrO2主要分布在Mg4.68Al2.64Zr1.68O12晶内;在合成温度为1 760℃、x=–0.2条件下,Mg4.68Al2.64Zr1.68O12的合成率最大,高达89.99%,且其晶粒发育最为完善;Mg4.68Al2.64Zr1.68O12在低温下分解成MgO、MgAl2O4和C-ZrO2共析体,实现了MgAl2O4和ZrO2的高度分散。
The chemical properties of Mg5 + x Al2.4-x Zr1.7 + 0.25x O12 (-0.4≤x≤0.4) were studied by means of quenching method using pure MgO, active α-Al2O3 and fused monoclinic zirconium as raw materials Composition and heat treatment temperature on the synthesis of MgO-MgAl2O4-ZrO2 ternary compounds, and its synthesis mechanism was analyzed. The results show that when the temperature is lower than 1 650 ℃, the formation and the grain growth of MgAl2O4 mainly occur. When the temperature is higher than 1 650 ℃, MgO and ZrO2 diffuse to MgAl2O4 and react to form Mg4.68Al2.64Zr1. 68O12. When the temperature is 1 740 ℃, the synthesis of Mg4.68Al2.64Zr1.68O12 tends to be complete and the synthesis rate reaches 89.5%. The residual MgAl2O4 and ZrO2 are mainly distributed in the crystal of Mg4.68Al2.64Zr1.68O12. Under the condition of 1 760 ℃ and x = -0.2, the synthesis rate of Mg4.68Al2.64Zr1.68O12 is the highest, reaching as high as 89.99%, and its grain growth is the most perfect. Mg4.68Al2.64Zr1.68O12 decomposes to MgO at low temperature , MgAl2O4 and C-ZrO2 eutectoid, to achieve a high degree of dispersion of MgAl2O4 and ZrO2.