【作者】 甘霖；

【导师】 柯昌明；

【作者基本信息】 武汉科技大学 ， 材料学， 2010， 硕士

【摘要】 以轻质氧化镁、工业氧化铝、α-Al2O3微粉为主要原料,系统研究了单一熔盐和复合熔盐体系中镁铝尖晶石粉体及其多孔材料合成制备以及氟化物添加剂的影响。研究结果表明:(1)熔盐体系中镁铝尖晶石的合成反应开始及终了温度与熔盐体系的熔点(或低共熔点)温度密切相关。一般而言,熔盐体系的熔点(或低共熔点)温度越低,尖晶石生成反应的开始及终了温度越低。(2)复合熔盐体系较之单一熔盐(如:KCl-LiCl较之LiCl、KCl,NaCl-KCl较之KCl、NaCl)更有利于镁铝尖晶石的合成反应;工业Al2O3较之α-Al2O3微粉更适合作为原料,用于MgAl2O4粉体的熔盐法合成制备。氟化物的引入能有效促进熔盐介质中尖晶石的形成,并能明显降低镁铝尖晶石的合成温度。(3)以工业Al2O3和轻质MgO为原料制备的尖晶石多孔块体气孔率大于相同盐料比情况下以α-Al2O3微粉和轻质MgO为原料制备的尖晶石多孔块体。NaCl-KF0.04、KCl-KF0.04、NaCl-KCl-KF0.04三种熔盐体系较有利于尖晶石多孔材料的制备。调整盐料比可以改变尖晶石多孔块体的显气孔率和体积密度,而且样品的耐压强度随显气孔率的升高明显降低,随着烧成温度的升高明显升高。但烧成温度对样品的显气孔率和体积密度无明显影响。(4)α-Al2O3微粉、轻质MgO和板状刚玉骨料原料制备的多孔刚玉-尖晶石块体显气孔率随骨料加入量的增大而减小。更多还原

【Abstract】 Molten salt synthesis of MgAl2O4 spinel powder and preparation of porous spinel material were investigated in single and compound molten salts system by using industrial alumina, activeα-Al2O3 and light calcined MgO at the temperature below 1200℃, the influence of fluorides was studied as well. The results show that:(1) The formation temperatures of magnesium aluminate spinel in molten salt media are strongly affected by the melting points temperature (or eutectic points temperature) of the molten salt systems. Generally, the lower melting (or eutectic) points temperature of the molten salt systems, the lower formation temperature of MgAl2O4 spinel.(2) Compound salts systems showed more effective than single salt systems as reaction media for synthesis of magnesium aluminate spinel (for instance: KCl-LiCl more effective than LiCl and KCl, NaCl-KCl more effective than KCl and NaCl). Industrial alumina has higher reactivity than activeα-Al2O3 as starting material for molten salt synthesis of spinel powder. The fluorides showed great accelerating effects on the formation of MgAl2O4, and may deeply decrease the reaction temperature.(3) The porosity of porous spinel materials prepared by using industrial alumina and light magnesia as raw materials in molten salt is highter than that by using activeα-Al2O3 and light magnesia as raw materials. NaCl-KF0.04, KCl-KF0.04, NaCl-KCl-KF0.04 molten salt systems are more favorable to the synthesis of porous spinel material. The ratio of salts to oxides strongly affect apparent porosity and bulk density of porous spinel material, the higher ratio of salts to oxides gives higher apparent porosity and lower bulk density, and lower crushing strength of samples. Crushing strength increased with the increase of firing temperature, but there is no evidential correlation between firing temperature and porosity or bulk density of the porous samples.(4) The porosity of porous corundum-spinel material prepared by using activeα-Al2O3, light magnesia and tabular corundum as raw materials decreased with the increase of addition amount of tabular corundum aggregations.更多还原