Tribological Properties of SiO2@Cu and SiO2@MoS2 Core–Shell Microspheres as Lubricant Additives

Abstract

Herein, core-shell structural SiO 2 @Cu and SiO 2 @MoS 2 microspheres were prepared using SiO 2 as hard core, Cu and MoS 2 as shell. As lubricant additives were introduced into base oil (PAO 40), their frictionreduction and wear-resistance were investigated in detail. Comparing with onefold additive (SiO 2 , Cu and MoS 2 ), such core-shell structure additives can improve the tribological behaviors at the Hertz contact stress range of 1.26 ~ 2.72 GPa (SiO 2 @Cu reduces the friction and wear up to 32.47% and 67.86% at 2.72 GPa, respectively). Besides, the tribological properties of SiO 2 @Cu microspheres are superior to that of SiO 2 @MoS 2 (the wear volume was reduced by 48.45% at 2.72 GPa). The excellent tribological behaviors of SiO 2 @Cu microspheres can be ascribed to its structural advantage, the synergistic effect of hard SiO 2 core and Cu shell. The rolling effect of SiO 2 , easy-shearing and self-repairing of Cu shell offer a synergistic lubrication function and form a dense protection lm, thereby contributing to the optimal lubrication performance.

A comparison of wear between unidirectional and reciprocating sliding motions under different applied loads and lubricants

“…Therefore, in order to compare the quality of the lubrication film formed by PAO 40 under different lubrication conditions, the corresponding lubrication conditions should be first determined according to the λ ratio in equation (1). Where, R q is the composite roughness, and h min refers to the minimum film thickness and is evaluated by equation (2) [35][36][37].…”

A review of advances in tribology in 2020–2021

“…Oxide and metallic nanoparticles can also be used as effective lubricating additives, such as Ni nanoparticles [71], SiO 2 nanoparticles [72][73][74], CuO nanoparticles [75], oleylamine (OM)-modified CeO 2 nanoparticles [76], SiO 2 @Cu microspheres [77], ZrO 2 nanoparticles [78], carbon quantum dot (CQD) and Ni-CQD particles [79], Cu nanoparticles [80], cubic nickel nanoparticles modified with oleymine [81], some magnetic nanoparticles [82], nano-silver [83] , etc. Nanofluids formed from metal compounds also work well as lubricant additives [84][85][86][87].…”

Synthesis of ZnFe2O4@MoS2 core-shell nanocomposites with enhanced lubrication performance as lubricant additives

“…Core–shell composites have attracted widespread attention because of their unique structural advantages (Huang et al , 2019; Ren et al , 2020; Xu et al , 2018; Li et al , 2012; Lin et al , 2015; Ma et al , 2021). Hard core particles can provide better support for the soft shell, so that the shell can continuously repair deep wear marks to reduce matrix wear; at the same time, the characteristics of low shear force of soft shell can extend the rolling lubrication effect time of core particles and reduce the abrasive wear caused by core particles to the matrix; duplex composite particles form rolling elements by desorption at the friction interface, which promotes the uniformity and integrity of the transfer film and improves the self-healing ability of the transfer film (Chen et al , 2020a).…”