Effect of TiO2 on phase evolution and microstructure of MgAl2O4 spinel in different atmospheres
Effect of TiO2 on phase evolution and microstructure of MgAl2O4 spinel in different atmospheres
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DOI：
10.1016/j.ceramint.2010.09.016
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发表时间：
2011-01-01
影响因子：
5.2
通讯作者：
Golestani-Fard, F.
中科院分区：
文献类型：
--
作者：
Naghizadeh, R.;Rezaie, H. R.;Golestani-Fard, F.
研究了TiO 2在1600 ℃空气和还原条件下对镁铝尖晶石（MgAl 2 O 4）形成和显微结构的影响。在还原条件下，由于MgO的挥发，化学计量比的MgAl 2 O 4尖晶石向富铝型转变，导致烧成样品的孔隙率增加。添加石墨的MgO和Al 2 O3的混合物强化了还原条件，并加速了非化学计量比的MgAl 2 O 4的形成。对于添加MgAl 2 O 4的含TiO 2的样品，检测到镁铝钛氧化物（MgxAl 2（1-x）Ti（1+x）O 5，x = 0.2或0.3）作为次要相。在还原条件下，XRD峰位移为含TiO 2的样品比没有TiO 2的样品，由于形成的固溶体的TiO 2在MgAl 2 O 4和建立的富铝尖晶石，这对增加晶格参数具有相反的效果。在含铝土矿的样品中，鉴定出MgAl 2 O 4尖晶石、尖晶石、原钛酸镁尖晶石（Mg 2 TiO 4）和非晶相。Mg 2 TiO 4尖晶石与MgAl 2 O 4尖晶石形成完全固溶体，但由于含铝土矿样品的非均匀显微结构，Mg 2 TiO 4仍保持为单独的相。在空气烧制的含TiO 2的样品中也建立了致密的微观结构。重点讨论了铝镁碳质耐火材料在钢铁工业中的应用和设计。(C)2010 Elsevier Ltd和Techna Group S.r.l. All rights reserved.
The effect of TiO2 on the formation and microstructure of magnesium aluminate spinel (MgAl2O4) at 1600 degrees C in air and reducing conditions were investigated. Under reducing conditions, stoichiometric MgAl2O4 spinel shifted toward alumina-rich types owing to volatilization of MgO, resulting in an increase in the porosity of fired samples. Addition of graphite to mixtures of MgO and Al2O3 intensified the reducing conditions and accelerated the formation of non-stoichiometric MgAl2O4. For TiO2-containing samples on addition of MgAl2O4, magnesium aluminum titanium oxide (MgxAl2(1-x)Ti(1+x)O5,x = 0.2 or 0.3) was detected as a minor phase. Under reducing conditions, XRD peak shifts were smaller for TiO2-containing samples than for samples without TiO2 owing to the formation of a solid solution of TiO2 in MgAl2O4 and establishment of alumina-rich spinel, which have opposite effects on increasing the lattice parameter. In bauxite-containing samples, MgAl2O4 spinet, corundum, magnesium orthotitanate spinet (Mg2TiO4) and amorphous phases were identified. Mg2TiO4 spinet formed a complete solid solution with MgAl2O4 spinel but Mg2TiO4 remained as a distinct phase owing to the heterogeneous microstructure of bauxite-containing samples. Also dense microstructure established in air fired TiO2 containing samples. The results are discussed with emphasis on the application and design of alumina magnesiacarbon refractory materials, which are used in the steel industry. (C) 2010 Elsevier Ltd and Techna Group S.r.l. All rights reserved.