GNPs and h-BN@SiO₂ synergistically enhancing wide-temperature tribological performance of YSZ composites

Yttria-stabilized zirconia (YSZ) is a promising candidate for abradable seal coatings (ASC) in aero-engines, yet its inherent high coefficient of friction (COF) limits further application. This study introduced dual solid lubricant phases consisting of graphene nanoplatelets (GNPs) and silica-coated hexagonal boron nitride (h-BN@SiO₂) with different mass fractions into YSZ, and their tribological performance was systematically evaluated from room temperature to 750 °C. The composite containing 15 wt% GNPs and 5 wt% h-BN@SiO₂ exhibited low and stable COF (below 0.3) and moderate wear rates. Notably, it achieved an ultra-low COF of 0.08 at 750 °C. This outstanding performance originates from the formation of a low-shear graphene/BN interlaced lamellar structure, while tribochemically formed silicate phases and molten boron oxide further enhance the overall tribological performance of the composite. This work proposes an effective design approach for the development of high-performance YSZ-based ASC materials across a broad temperature range.