The application relates to a
bauxite-based
corundum mullite hollow sphere with a gradient structure and a preparation method thereof, and belongs to the field of heat-insulating
refractory materials. The preparation method comprises the following steps: firstly, high-
alumina bauxite is beneficiated and classified and homogenized, then, according to a certain
mass percentage, III-grade high-
alumina bauxite, silica, mixed additives and an organic binder are uniformly mixed and granulated; taking spherical particles as cores, II-grade high-
alumina bauxite and I-grade high-alumina bauxite are sequentially wrapped under the rotation of a granulator to obtain a non-homogeneous spherical particle blank body with a SiO2-rich interior; and finally, the
corundum mullite hollow sphere with the gradient structure is obtained through high-temperature
calcination. The
refractory hollow sphere is designed with the gradient structure through the combined process of high-alumina bauxite classification and homogenization,
coating forming and high-temperature
calcination in-situ pore forming, the phase performance characteristics of
corundum and
mullite are fully utilized, and the
refractory hollow sphere with the low
thermal conductivity, the good
corrosion resistance, the high use temperature and the excellent
thermal shock resistance is developed.