Enhancing anti-adhesion and wear performance at armature/rail interface through synergistic interfacial energy and lubrication effects

Abstract

During electromagnetic launch (EML) process, the adhesion of aluminum to high-strength copper-alloy rails poses a significant challenge, severely deteriorating the performance and lifetime of rails. Previous researches were primarily centered to the surface modification of copper-alloy rail with coatings. However, this process is time- and money-consuming, and raises sustainability concerns during multi-firing operations. In contrast, the modification of aluminum-a armature, featured with simplicity and economy, may offer an alternative approach for alleviating aluminum adhesion on rails. Here, we propose a novel strategy for modifying the aluminum armature surface with the combination of positive interfacial energy and lubrication effects. This is accomplished by applying a newly designed (Ti, W)N–MoS₂ coating to the aluminum armature through magnetron sputtering. Results indicate that this coating highly reduces the coefficient of friction between Cu-alloy and the coated Al-alloy from 0.56 to 0.14. The simulated EML demonstrates that the coating remarkably decreases aluminum adhesion by 97.7 %. Density functional theory (DFT) simulations reveal that the improved performance of wear between armature and rail is attributed to the synergistic effects of the formed (Ti, W)N and non-stoichiometric Mo₁₅S₁₉ phases in coating, where the former exhibits positive interfacial energy with Cu, while the later serves as a lubricator, both work together and lead to ultra-low coefficient of friction and significant reduction of Al adhesion on Cu rail.