烧结法和烧失法制备镁质多孔原料

Preparation of porous magnesia material by sintering method and ablation method

为了制备高性能镁质保温隔热材料,以高纯镁砂为主要原料,分别采用添加Al2O3空心球(高纯镁砂与Al2O3空心球的质量比为4∶1)成球-烧结法和Mg O包覆聚苯乙烯球(高纯镁砂与聚苯乙烯球的体积比为1∶1)-烧失法制备了2种镁质球形多孔骨料;还以乙酸镁和自制的碳微球为主要原料,采用碳微球浸渍乙酸镁-烧失法制备了镁质多孔粉体材料。对3种镁质多孔材料的结构和性能进行了分析。结果表明:1)采用添加Al2O3空心球成球-烧结法制备的镁质多孔骨料为多孔球结构,球粒直径为3~5 mm,球粒内部有多个直径为200μm的氧化铝空心球形成的封闭气孔;1 550℃保温3 h后,球形多孔骨料的显气孔率为47.2%,体积密度为1.79g·cm-3,由方镁石和尖晶石组成。2)采用Mg O包覆聚苯乙烯球-烧失法制备的镁质多孔骨料为中空球结构,球粒直径约为2 mm,内孔直径为1 mm,中空球壁厚约为500μm;1 550℃保温3 h后,球形多孔骨料的显气孔率为53.5%,体积密度为1.74 g·cm-3,由方镁石组成。3)采用碳微球浸渍乙酸镁-烧失法制备的多孔材料是由表面多孔的纳米级(80~100 nm)中空氧化镁微球集聚而成的粉体,由方镁石组成。

In order to prepare high performance magnesia heat insulation materials,high purity magnesia was used as the main starting materials,two kinds of spherical porous magnesia aggregates were prepared with Al2 O3 hollow spheres sintering method（the mass ratio of high purity magnesia to Al2 O3 hollow sphere was 4∶ 1）,and Mg O coated polystyrene ball ablation method（the volume ratio of high purity magnesia to polystyrene ball was 1 ∶ 1）,respectively. Magnesium acetate and lab-made carbon microspheres were also used as the main starting materials to prepare the porous magnesia materials by impregnation magnesium acetate with carbon microspheres and ablation method. The structures and the properties of these three kinds of the magnesium porous materials were analyzed. The result shows：（1） the porous magnesia aggregate prepared by Al2 O3 hollow spheres sintering process has porous ball structure,the sphere diameter is about 3-5 mm. Within the spheres,a number of enclosed pores form from alumina hollow balls with a diameter of 200 μm. After firing at 1 550 ℃ for 3 h,the prepared spherical porous aggregate has the apparent porosity of 47. 2% and the bulk density of 1. 79 g ·cm^-3,and is composed of periclase and spinel.（2） The magnesia porous aggregate prepared by MgO coated polystyrene ball ablation method has the hollow ball structure,the sphere diameter is about 2 mm,the diameter of inner hole is 1 mm,and the wall thickness of the hollow balls is about 500 μm. After firing at 1 550 ℃ for 3 h,the prepared spherical porous aggregate has the apparent porosity of 53. 5% and the bulk density of 1. 74 g ·cm^-3,and is composed of periclase.（3） The porous material prepared by impregnation magnesium acetate with carbon microsphere and ablation method is powder made up of porous nano-scaled（80-100 nm） hollow magnesia microspheres,and is composed of periclase.