Influence of BaO doping on the sintered properties of magnesia-alumina
With magnesium hydroxide and alumina as raw materials,magnesium alumina spinel was synthesized by solid phase sintering.The effect of additive BaO on the sintering density of magnesia alumina spinel was stud-ied.The effects of additives on the phase composition,sintering property and microstructure of the samples were analyzed by XRD and SEM.The results show that the addition of BaO can increase the bulk density and linear shrinkage of Mg-Al spinel after sintering.At the same time,the apparent porosity can be reduced and the sintering property can be improved.With the increase of additive BaO,the granules of magnesia-alumina spinel increase first and then decrease.The linear shrinkage rate,apparent porosity and volume density of φ20 mm ×20 mm cylin-drical samples sintered at 1 600 ℃×3 h are 6.81％,54.30％and 1.65g/cm3 without adding BaO.When the amount of BaO is 0.5％,the linear shrinkage rate,apparent porosity and volume density of φ20 mm ×20 mm cylindrical samples sintered at 1 600 ℃×3 h are 6.81％,54.30％and 1.65 g/cm3 respectively.The linear shrinkage rate can reach 12.07％,the volume density can reach 1.80 g/cm3,and the apparent porosity can reduce to 47.56％.There-fore,when the additive content is 0.5％,the sintering property of MgAl2O4 is the best.
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