Fluidity of a slurry of the graphite powder coated with Al2O3-based metal oxides

Graphite is widely used as a refractory material due to its many excellent properties such as high corrosion resistance and thermal shock resistance. However, because of its poor wettability by water and fluidity, it cannot be used satisfactorily in castable refractories, in which it easily segregates. The effects of Al2O3-based oxide coatings on the fluidity of the slurries of graphite powder were investigated. It is shown that the fluidity of powder coated with Al2O3-ZrO2 and Al2O3-SiO2 is similar to that of Al2O3-coated graphite powder without the dispersing agent. In the case of addition of the dispersing agent, a slurry of the graphite powder coated with Al2O3-SiO2 shows higher fluidity than that of the Al2O3-coated graphite powder. It is concluded that the fluidity of a slurry of the graphite powder depends on the fraction of free water of a slurry and the degree of dispersion of the graphite powder coated with Al2O3-based oxides. 4 refs.