刚玉-尖晶石微粉的低温固相反应法制备及表征

Preparation and characterization of corundum-spinel composite powders by low temperature solid state reaction

以轻烧氧化镁和工业氧化铝为原料,引入一定量的自制复合铝盐(OKU)作为助剂,研究助剂用量、反应温度对产物物相组成的影响。结果表明:添加助剂和提高反应温度都可以促进MgO与Al2O3之间的尖晶石化反应,添加9%(质量分数)助剂的试料在1 200℃保温2 h后,MgO完全转变为尖晶石。在实验基础上在梭式窑中进行100 kg级工业生产试验,并对微粉的化学成分、物相组成、粒度分布,及其浆料的流变特性进行了表征。结果表明,制得的刚玉-尖晶石粉由质量分数分别为73%和27%的刚玉和尖晶石组成;原粉和球磨粉的粒度均呈双峰分布,中位径d50分别为9.0、1.8μm;由球磨粉制成的水性浆料为假塑性流体,具有剪切变稀现象,并且黏度随固含量的增加而增大。

Corundum-spinel composite powder were synthesized by solid state reaction at relatively low temperature using light-burned magnesia and commercial alumina as raw materials,and introducing a novel assistant agent OKU.The effect of amount of assistant agent and fired temperature on the phase composition of the powders was investigated.The laboratory research results show that,adding assistant agent and rising calcining temperature can facilitate the spinel synthesizing reaction between MgO and Al2O3.The MgO can be turned into spinel completely with 9%assistant agent and be calcined at 1200℃for 2 h.On the basis of laboratory research,an industrialized test of 100 kg grade spinel synthesizing by solid-phase reaction method with 9%assistant agent at the temperature of 1 200℃for 8 h was done.The chemical and phase composition and the particle size distribution of the products were tested.The rheological behavior of the slurry of corundum-spinel powders were also investigated.The industrialized test results indicated that,the phase composition of the powder includes spinel 27%and corundum 73%,without other phase.The medium diameter of the powder is 9.01μm,and it reduced to 1.82μm after ball milling for 4 h.The particle size distribution of the product and ball-milled powder are both bimodal distributions.The flow ability of the slurry with different solid content obeyes the law of non-Newtonian pseudo-plastic fluid.And their viscosity grows with the increasing solid content.