Tribology and mechanical performance of Al2O3/CaF2 self-lubricating ceramics prepared by gelcasting

Al 2 O 3 /CaF 2 self-lubricating ceramic materials were prepared using a low-toxicity methylacrylamide gelcasting system. The rheological properties of the Al 2 O 3 slurry were analyzed to study the effects of dispersant content, solid loading, and pH on its flowability. Optimal results were achieved with a dispersant content of 0.5 wt%, a solid loading of 54 vol%, and a pH of 9. The relative density of the resulting green body was 56 %, with a strength of 18.2 MPa. After sintering for 2 h in a vacuum furnace at 1650 °C, the material exhibited a hardness exceeding 750 HV and a bending strength above 300 MPa when the CaF 2 content was less than 10 vol%. Additionally, the tribological properties of Al 2 O 3 /CaF 2 under various conditions were investigated, revealing optimal performance at a CaF 2 content of 10 vol%. The average friction coefficient and wear rate were 0.245 and 2.96 × 10 −5  mm 3 /N⋅m, respectively, representing reductions of 48 % and 54 % compared to pure Al 2 O 3 materials. These findings demonstrate that gelcasting is an effective method for preparing self-lubricating ceramic materials, offering a new approach for fabricating complex-shaped self-lubricating ceramic components.