Preparation And Characterization Of Light-weight Refractory With Micropore

In this paper, gelcasting technology of lightweight refractory and drying processof gelled body were first studied. Then, lightweight mullite and mullite-anorthitecomposite were fabricated.In order to optimize gelcasting technology during preparation of silicoaluminaterefractory and to investigate the mechanism of gelcasting, industrial mullite powder,acrylamide and N-N’-methylene bis-acrylamide was used as raw material. The slurrystability, the mechanism of gelcasting and gelling time was studied to determine theslurry pH and the concentration of premixed solution. The results show that when theslurry pH was7~9and the concentration of the organic monomer in the premixsolution was5wt%, the slurry owned the suitable gelling time, gelled green body hadhigh toughness. A novel drying process was determined by studying the effect ofsurface area, the solid loading, the concentration of ethanol solution and temperatureon the drying speed. At25℃, the gelled green body was dried for300min in80vol%ethanol solution, the green body was obtained with stable shape and higher strength.Based on the above results, lightweight mullite refractory with micropore wasfabricated by means of foaming process and combustible pore-forming process. Effectof pore-process type and sintering temperature on the pore structure andmicrostructure of material were studied by mean of SEM. Porosity, pore size, bulkdensity, and compressive strength were tested and the influences of the content ofpore-forming additives, sintering temperature and the ball milling time on materialproperty were analyzed. It is shown that when foaming process was employed, thepore shape of the material was close to sphere, mullite was uniform size of the scaly.As the content of foaming agent SDBS added in from1.0wt%to2.0wt%, the materialporosity remained relatively stable, approximately50%, the pore size decreased from3.87μm to3.03μm; The starch significantly improved the porosity of the material andreduced the bulk density, when starch was added from10wt%to80wt%, the porosityof sample increased from47%to69%, the pore remained relatively stable size andwas about4.5μm, the size of mullite was uneven, individual crystals were too bulky; The ball milling time of slurry was extended from5h to20h, the size of pore reducedfrom4.5μm to0.895μm, mullite was uniform and presented short columnar or scaly.CaCO3was added into the raw materials as Ca resource to fabricatemullite-anorthite composite refractory based on preparation of light-weight mulliterefractory with micropore. The effect of sintering process parameters such astemperature, sintering aids on the sub-crystalline phase anorthite generation wereanalyzed by mean of XRD and SEM. The pore structure and mechanical propertieswere analyzed to study the rule between sub-crystalline phase anorthite and theporosity of sample. Experimental results show that: the optimum content of CaO andsintering temperature were6wt%and1400℃×5h. AlF3did not promote thegeneration of anorthite, only to improve the growth of anorthite and reduce the size ofpore. The best amount of sintering aids AlF3was5wt%, the pore diameter of samplecan be decreased to0.745μm.