Oil-Based Fast Ultralow Friction Achieved by Semisolid Lubricant Domained by Poly-α-Olefins-Subnanowire–Stearic Acid at Steel/PTFE Interface

Abstract

Liquid lubricants can reduce the friction and wear of two relative moving surfaces. However, there are still great challenges to achieve anticreep and superlubricity of liquid lubricants at the same time. In this study, a novel semisolid lubricant (P₃₀SSA) was designed by fixing poly-α-olefins 30 (PAO30) base oil in a three-dimensional network structure constructed by subnanowires (SNW) and stearic acid (SA), avoiding the creep problem of base oil and achieving ultralow friction (0.006–0009) at steel/polytetrafluoroethylene (PTFE) interfaces in a short period (∼6 s). Compared with dry friction, the wear rate of the PTFE was reduced by 98%. Moreover, the friction coefficient remains below 0.01 after more than 150,000 cycles. The ultralow friction behavior is attributed to the increasing bearing ability caused by the three-dimensional network structure in P₃₀SSA, the reduced internal friction of P₃₀SSA generated by the shear thinning of the lubricant during the friction process, and the physisorption film formed on the surface of friction pairs. The P₃₀SSA solves the problem of liquid lubricant creeping and achieves ultralow friction on the surface of steel/PTFE. This work opens up a new direction for semisolid lubricants and provides a new idea for the study of the ultralow friction mechanism.