Researchers have developed a high-entropy alloy composite coating that simultaneously addresses wear and cavitation erosion in aero-engine fuel pumps, a longstanding challenge in aviation safety. The study, published in Tribology Advances, demonstrates that an Al10Cr28Co28Ni34/Ag coating fabricated via high-velocity oxygen fuel spraying achieves a friction coefficient below 0.1, wear rate approaching zero, and a cavitation erosion mass loss rate of less than 0.1 mg/h in low-viscosity aviation kerosene.
The fuel pump is critical to aero-engine performance, and its thrust bearing must endure axial loads and maintain sealing under high-speed rotation. Aviation kerosene's low viscosity prevents stable oil film formation, leading to lubrication failure, wear, and cavitation erosion that degrade fuel delivery efficiency. Existing bonded solid lubricating coatings can mitigate wear but cannot simultaneously provide cavitation erosion protection due to insufficient matrix strength, property mismatch between phases, and an inability to balance friction reduction with erosion resistance.
The new approach exploits the structural compatibility between the Al10Cr28Co28Ni34 high-entropy alloy (HEA) and silver (Ag), both of which have face-centered cubic (FCC) structures. FCC metals possess abundant slip systems that accommodate deformation under shear and impact, reducing friction and dissipating energy. The HEA, owing to its four core effects, exhibits high work-hardening capacity and strength, confining impact deformation and providing exceptional cavitation erosion resistance. Ag, a solid lubricant, forms a low-shear film to combat oil starvation. Because both phases share the FCC structure, they respond similarly to external forces, preventing cracking at phase boundaries and enabling synergistic lubrication, wear resistance, and cavitation erosion protection.
The coating also benefits from spherical particles formed in situ at the friction interface, which roll and slide to further reduce friction and wear. This mechanism, proven in the study, contributes to the near-zero wear rate and long-term cavitation erosion resistance. The findings offer a new perspective for designing protective coatings for fuel pump friction pairs, potentially extending service life and improving reliability. The research was supported by the National Science and Technology Major Project, the National Natural Science Foundation of China, the Strategic Priority Research Program of the Chinese Academy of Sciences, the Youth Innovation Promotion Association of the Chinese Academy of Sciences, and the Longyuan Youth Talent Project. The full study is available at https://doi.org/10.3724/trad-20260019.
