Surface-localized-self-lubricating ZTA/CaF2 ceramics fabricated by co-sintering for enhanced tribological performance without sacrificing mechanical strength

Surface-localized-self-lubricating ZTA/CaF 2 ceramics were developed. • Textured reservoirs enabled the controlled release of CaF₂ during sliding. • A continuous fluorine-rich tribofilm was generated at the contact interface. • The optimum CaF₂ content was determined to be 10 vol%. • Friction and counterpart wear were reduced by 56.86% and 76.68%. To improve the dry tribological performance of ZTA ceramics, surface-localized self-lubricating ZTA/CaF 2 composite ceramics were fabricated by combining gel casting with an in-situ filling and co-sintering strategy. A systematic study was conducted on how slurry solid loading and CaF 2 loading influence the microstructure, mechanical properties, and tribological behavior of the resulting composites. The 54 vol% slurry exhibited favorable rheological properties and good sinterability, as indicated by the experimental results. The obtained sintered body achieved a relative density, Vickers hardness, flexural strength, and fracture toughness of 99.7%, 17.6 GPa, 583.6 MPa, and 6.48 MPa·m¹/², respectively. Compared with monolithic ZTA ceramics, the textured ceramic containing 10 vol% CaF 2 exhibited the best tribological performance among the investigated compositions, with reductions of 56.86% and 76.68% in the friction coefficient and wear rate of the Si 3 N 4 counterpart, respectively. Combined SEM, EDS, and XPS characterization indicated that the improved tribological behavior was mainly associated with the establishment of a continuous F-rich tribolayer under sliding contact. This tribofilm effectively minimized direct surface interaction between the sliding bodies and relieved localized stress buildup at the contact zone. These findings suggest that constructing textured lubricant-storage structures to achieve a synergistic balance between dynamic lubricant release and ceramic skeleton load-bearing capability provides a viable approach to improving the interface integrity and dry sliding performance of ZTA ceramics. Download: Download high-res image (239KB) Download: Download full-size image