Wettability and Mechanical Properties of Red Mud-Al₂O₃ Composites

In 2023, the global production of new red mud is expected to reach nearly 200 million tons, but less than 10% of it is currently being utilized in an environmentally friendly manner. To reduce the sintering temperature of alumina ceramics, a sintering aid method is used, as high-purity alumina ceramics require a solid-phase sintering temperature of over 1700 °C. The metal oxides present in red mud are necessary components for high-performance composite alumina ceramics. Composites were obtained by mixing and sintering red mud and Al₂O₃. This study focused on the mechanical properties and wettability of these composites. The results indicated that the 10% red mud-Al₂O₃ composite exhibited the highest hardness (20.12 GPa) and flexural strength (346 MPa). This is attributed to the formation of a mineral phase dominated by CaAl₁₂O₁₉, generated by the red mud during the sintering process, which filled the pores and reduced porosity. The surface energy of the red mud-Al₂O₃ composite was the highest at room temperature and high temperature, reaching 49.60 mJ·m-2 and 1164.7 mJ·m-2, respectively, indicating that it has better stability at both room and high temperatures. This study provides an important fundamental basis for the application of red mud-alumina composites to replace alumina-based composites in the field of construction materials, molten metal filters, ceramic cleavers, etc.