Bio-inspired synergistic interfacial anchoring for highly stable graphite lubricants
Graphite lubricants are critical for high-quality and high-efficiency drawing of refractory metal wires, yet inadequate dispersion stability frequently challenges their practical application. Inspired by the bio-surfactant synergic mechanism that combines different bio-surfactants to collectively reduce surface energy and friction, a binary anionic surfactant system comprising sodium dodecyl benzene sulfonate (SDBS) and sodium lignosulfonate (SL) was engineered to enhance dispersion and stability via a synergistic effect. The synergistic parameter β was calculated to be −2.34, indicating strong synergism. The resulting graphite lubricants maintained homogeneous dispersion for up to 60 days. Molecular dynamics (MD) simulations combined with density functional theory (DFT) calculations confirmed that the synergistic effects originate from steric hindrance, electrostatic repulsion, π-π stacking, and hydrogen bonding. These hierarchical secondary interactions collectively increased the interfacial formation energy at the graphite/surfactant/water tri-phase interface, thereby effectively wetting particle powders and enhancing stability. During metal wire drawing, the graphite lubricants reduced the friction coefficient between the die and metal wires to 0.06, ultimately enabling drawn tungsten wires with superior surface integrity, expanded loop diameter, and enhanced tensile strength relative to single-surfactant benchmarks. This study provides experimental and theoretical guidance to design effective graphite lubricants for high-quality drawn metal wires.