Effects of pyrolusite and dolomite co-additives on the structure and properties of bauxite-based ceramics

The application of alumina ceramics is limited due to their expensive raw materials and high sintering temperatures. In this research, low cost bauxite-based ceramics having a strength similar to alumina ceramics were successfully prepared, using two different types of pyrolusite and dolomite co-additives. It was found that pyrolusite and dolomite as sintering aid could effectively reduce the sintering temperature. The effects of pyrolusite and dolomite on the structure and properties of the bauxite-based ceramics were researched. The results show that MnO2 plays a role of solid solution strengthening in bauxite-based ceramics. MnO2 from outside the solution, CaO and MgO were promoted the formation of a low viscosity liquid phase to fill pores during sintering. Moreover, in bauxite-based ceramics structure, most of SiO2 from all raw materials were dissolved to the liquid phase under the action of pyrolusite and dolomite to form a network structure and enhance the strength of the ceramic. The replacement of alumina ceramics in some fields of application by high-strength ceramics prepared from bauxite is important for reducing costs and saving energy. Meanwhile, it is important to broaden the application fields of bauxite-based ceramics.