An advanced self-lubricating ceramic composite with the addition of core-shell structured CaF2@Al2O3 powders

Aiming to improve the performance of self-lubricating ceramic tools, an advanced self-lubricating ceramic composite was developed. Core-shell structure CaF2@Al2O3 powders were synthesized by liquid-phase non-uniform nucleation method. Al2O3/Ti(C,N)/CaF2@Al2O3 composite made by adding CaF2@Al2O3 powders exhibited notable improvements in microstructure and mechanical properties as compared with Al2O3/Ti(C,N)/CaF2 composite made by adding uncoated CaF2 powders. The core-shell coated self-lubricating ceramic tool with different content of CaF2@Al2O3 was designed and prepared by hot pressing sintering process. The results show that when the content of CaF2@Al2O3 is 10 vol%, The composite has the best mechanical properties, the flexural strength, and the fracture toughness and the hardness is 680 MPa, 6.50 MPa.m(1/2), and 17.29 GPa. Compared with the tool material with only CaF2 solid lubricant added, the above performances were increased by 8.91%, 29.48%, and 14.50% respectively. The influence of different CaF2@Al2O3 content on the physical and mechanical properties and microstructure of the tool material was analyzed.