Abstract

The degradation of wear resistance and mechanical properties caused by solid lubricants disrupting the continuity of the ceramic matrix hinders the wide application of ZrO2-matrix self-lubricating composites. Inspired by the dental crown structure, a ZrO2-graphite self-lubricating composite with a crown-like structure was successfully fabricated by embedding a dense ZrO2 ceramic layer into the middle of a ZrO2 composite with a 3D continuous structure. The surface layer imitates the superior wear resistance of enamel with the rigid matrix skeleton and ordered microstructure, whereas the middle layer mirrors the tough supporting performance of dentin. Experimental results demonstrate that the controlled graphite agglomeration and continuous ZrO2 in the surface layer not only facilitate particle migration toward the worn surface but also generate texture-like effects to capture worn debris. Concurrently, a dense friction layer formed through synergistic co-aggregation between graphite and ZrO2 effectively reduces friction and wear. Remarkably, the composite maintains a low coefficient of friction (similar to 0.28) and wear rate (similar to 5.8 & times; 10(-5) mm(3)/(N & centerdot;m)) at 600 degrees C. Furthermore, the continuous ZrO2 middle layer enhances the mechanical properties via internal and external toughening mechanisms (crack deflection and bridging, martensitic transformation) as well as a hybrid strengthening mechanism of intergranular and transgranular fracture modes. Specifically, its fracture toughness (9.2 +/- 0.3 MPa & centerdot;m(1/2)) and flexural strength (457 +/- 28 MPa) are increased by 4.7 and 2.8 times, respectively, compared with those of the 3D continuous structured ZrO2 self-lubricating composite. This provides a novel strategy for designing ceramic-matrix self-lubricating composites with superior tribological and mechanical properties.

Keywords Plus: TRIBOLOGICAL PROPERTIES，TEMPERATURE，BEHAVIOR，GRAPHITE，FRICTION，CERAMICS，TRANSFORMATION，SEAL

Published in TRIBOLOGY INTERNATIONAL，Volume220；10.1016/j.triboint.2026.111906，AUG 2026