Abstract

High-entropy dodecaboride ceramics represent a new class of ultra-high-temperature ceramics with promising mechanical strength and self-lubricating capability. However, their high-temperature tribological behavior and underlying mechanisms remain largely unexplored. In this study, single-phase (Dy0.2Ho0.2Er0.2Tm0.2Lu0.2)B-12(HEB12) ceramics were successfully synthesized by spark plasma sintering (SPS) at 1780 degrees C. Comprehensive microstructural analyses (XRD, SEM, TEM, and EBSD) confirmed a homogeneous high-entropy solid-solution structure with fine, uniformly distributed grains (similar to 3.9 mu m). The Vickers hardness of HEB12 reached 25.45 +/- 0.51 GPa at room temperature and gradually decreased to 10.38 +/- 0.20 GPa at 1200 degrees C, maintaining superior hardness across a wide temperature range. Tribological tests revealed that the friction coefficient decreased from 0.62 +/- 0.08 at room temperature to a minimum of 0.21 +/- 0.01 at 1000 degrees C, attributed to the formation of lubricious B2O3 and oxide films at elevated temperatures. Meanwhile, the wear rate remained within 10(-4) similar to 10(-6) mm(3)/N.m, demonstrating excellent wear resistance due to the synergistic effect between the tribo-oxidation film and intrinsic mechanical strength. These results reveal that HEB12 ceramics exhibit outstanding high-temperature self-lubricating and wear resistance performance, offering a viable pathway for developing next-generation tribological materials for aerospace and other extreme-environment applications.

Keywords Plus: WIDE-RANGE TEMPERATURE，SLIDING WEAR BEHAVIOR，TRIBOLOGICAL PROPERTIES，SIALON CERAMICS，DECARBURIZATION

Published in TRIBOLOGY INTERNATIONAL，Volume219；10.1016/j.triboint.2026.111836，JUL 2026