Preparation of Low-cost Porous Mullite Balls from Kaolin and Alumina Using Naphthalene as Pore-former

Abstract

Low cost porous spherical mullite balls were prepared using kaolin as raw material. The spherical balls were fabricated manually with the addition of alumina to form stoichiometric mullite. Here naphthalene was used as a pore-former. The variation in porosity was achieved by changing the weight percentage (wt.%) of Naphthalene in the Al2O3-SiO2 binary system. Prepared spherical balls were heat treated at 1600oC to get the pure phase of mullite. DSC-TG curve and XRD analysis confirmed the formation of mullite phase. It was found that with an increase in the wt.% of naphthalene, bulk density decreases and apparent porosity increases whereas FESEM microstructure showed the presence of lathe type mullite structure. The maximum point load strength was also investigated to find out the mechanical stability of the porous balls.