Ga-based liquid metal and ZIF-8/graphene enable adaptive lubrication coating with robust superlow friction

Interfacial chemical locking enables stable Ga incorporation into solid lubricant coatings. • Ga (stress buffer), ZIF-8 (load support), graphene (shear reduction and transfer film) synergize. • Covalent bonds (Ga O, N H, Si-O-Si) prevent agglomeration and extrusion of metal under friction. Gallium-based liquid metals exhibit fluidity and reactivity at friction interfaces, creating a lubrication mode that merges liquid-film and solid-support effects. However, their incorporation into solid lubricant coatings faces critical challenges such as poor dispersion stability, insufficient load-bearing capacity, and a tendency to be squeezed out from the contact area. In this study, we successfully constructed an interface-stabilized, densely structured inorganic-organic composite coating, designated GaZGr-K-EP, by embedding a ZIF-8 framework into liquid gallium to stabilize its morphology, introducing graphene to mitigate the sedimentation of Ga/ZIF-8, and modifying the inorganic phase with KH550 to enable interfacial chemical bonding with the epoxy resin. This inorganic-organic interfacial bonding not only prevents coating failure during friction but also, for the first time, unlocks the solid lubrication and anti-wear mechanism of liquid gallium. In this mechanism, liquid gallium dissipates contact stress through localized flow, while ZIF-8 provides rigid load-bearing support. During friction, a Ga 2 O 3 oxide film forms and is reinforced by graphene to develop a continuous transfer film, achieving an ultralow friction coefficient of 0.055 and an ultralow wear rate of 4.33 × 10 −14  m 3 /N·m. This work demonstrates that interfacial chemical locking represents a novel strategy for realizing solid lubrication with liquid metals. Download: Download high-res image (204KB) Download: Download full-size image