Design architecture of colorful Si-DLC/PLC nanostructured multilayer films for robust superlubricity at high contact stress in dry N2 atmosphere

Abstract

Diamond-like carbon (DLC) enables the design of novel lubricant structures to realize macroscale superlubricity in harsh working conditions. In this work, a series of nanostructured multilayer Si-DLC/PLC films with colorful appearances were developed to provide a lubrication state with near-zero friction and wear for responding the challenge of lubrication requirement in high-load operation environment. The results reveal the crucial role of structural parameter, namely the thickness of a bilayer period λ (i.e., 9–324 nm), in determining the construction architecture, mechanical properties and anti-friction lubricity of the multilayered films. Specifically, a bilayer period of 324 nm (total film thickness of 1.53 μm) endows the film with a superlow friction coefficient of 0.003 and a near-zero wear rate of 4.06 × 10−9 mm/Nm under a peak Hertz contact pressure of 1.76 GPa. The relationship between the load-bearing capacity, nano-clustering transformation of the sliding interface and the steady state of superlubricity is investigated in detail to clarify its high-stress adaption and robustness of the anti-friction features. The design architecture of well-tailored multicomponent and nanostructured multilayer films indeed offers an effective theoretical and technical solution to the long-term lubrication and protection of mechanical moving parts under heavy load conditions.