Cobweb-like Structural Stimuli-Responsive Composite with Oil Warehouse and Transportation System for Oil Storage and Recyclable Smart-Lubrication

Shao, Mingchao; Li, Song; Duan, Chunjian; Yang, Zenghui; Qu, Chunhui; Zhang, Yaoming; Zhang, Di; Wang, Chao; Wang, Tingmei; Wang, Qihua

doi:10.1021/acsami.8b15198

Cited by 55 publications

(33 citation statements)

References 38 publications

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“…In space, due to the limit of environment, the lubricant replenishment is difficult compared with earth conditions. It is found that the porous polyimide material impregnated with lubricants can continuously supply lubricants, , which is attributed to the porous structure that can be used to store and recycle lubricants to reduce lubricant loss. − Our recent work on the lubricant imbibition process demonstrates that the porous polyimide material indeed can recycle lubricants by the capillary effect and press in the bearing system . Thus, porous polyimide materials have been widely used as bearing retainer materials to improve lubricant supply performance in space. − To improve the performance of the lubricant supply, it is suggested to increase the pore size for storing more lubricants, and different sizes of pores were prepared by the pore-foaming agent, laser, − and forming technology. , However, it is difficult to ensure a stable supply of lubricants for a large pore.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Lubricant Outflow in Porous Polyimide Retainers of Bearings

Chen

Wang

et al. 2021

Langmuir

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The retainer of a space rolling bearing widely made of porous polyimide (PI) materials is oil-impregnated and can continuously release lubricants for lubrication. Understanding the lubricant supply mechanism in porous polyimide retainers is important to improve the lubrication performance of space bearings and therefore extends the bearing life. In this work, molecular dynamics simulations are adopted to model the lubricant outflow process from the pore of the PI material. Coarse-grained models are constructed to investigate the lubricant migration behaviors with different pore sizes and radii of rotation. At rest, a lubricant within the pore fails to outflow due to the capillary effect, which decreases with the increase of the pore size. However, for the rotating pores, if the inertial forces generated by the rotational motion exceed the capillary forces, the lubricants will begin to accumulate and some of the lubricants will flow out. Furthermore, the lubricant in the larger pore is easier to outflow due to the smaller capillary forces. This study quantifies the inertial effect and reveals that the centrifugal force is the main mechanism of lubricant outflow from the pores.

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Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations of Lubricant Outflow in Porous Polyimide Retainers of Bearings

Chen

Wang

et al. 2021

Langmuir

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“…Despite such advantages, however, the tribological properties of LISs are still poor due to the high friction coefficient of LISs, which exceeds that of conventional mineral lubricants, graphene-containing lubricants, and other lubricating materials. − There is, therefore, a need for a novel strategy to achieve superlubrication with a coefficient of friction below 0.01.…”

Section: Introductionmentioning

confidence: 99%

Green Superlubricity Enabled by Only One Water Droplet on Plant Oil-Infused Surfaces

2021

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The increase in energy loss due to friction and the use of large amounts of lubricants to improve it are major challenges we face from a global environmental perspective. Pitcher-plant-inspired liquid-infused surfaces (LISs) are emerging superrepellent surfaces against liquids. However, their coefficient of friction (CoF) against solids is higher than that of conventional lubricant surfaces. Herein, we demonstrate superlubricity with a single water droplet placed on a LIS holding oleic acid, a component of plant oil. When a water droplet is placed on the fluid layer, the CoF under reciprocating and rotating friction is 0.012 and 0.0098, respectively. A force in the direction opposite to the loading due to the Laplace pressure on the droplet and an autonomous positional movement of the water accompanied by the optimization of surface energy maintain the fluid-lubrication state and prevent direct contact between the surface and the friction material, resulting in a decrease of the dependence of the CoF on the friction velocity. The key technology here will not only present a novel strategy for preparing LISs against solids but also serve as a step toward a sustainable green strategy for friction reduction and lubrication, which would greatly reduce energy loss and environmental degradation.

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“…The tribological performance of PPMs could be affected by many factors [5][6][7][8][9][10][11], such as speed, load, oil viscosity, surface tension, pore diameter, porosity, the type and amount of additives. So far, however, researches related to PPMs have mainly focused on their preparation, the influences of internal solid and/ or oil lubricants on their tribological behaviors [12][13][14][15][16]. There are only few published papers concerning the friction mechanism.…”

Section: Introductionmentioning

confidence: 99%

Effect of Porosity on the Friction Properties of Porous Polyimide Impregnated with Poly-α-Olefin in Different Lubrication Regimes

et al. 2020

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Porous polyimide materials (PPIs) having different porosity with a constant pore size were fabricated to further understand the effect of porosity on the friction properties in the boundary lubrication, mixed lubrication and elastohydrodynamic lubrication (EHL) regime, respectively. The tribological behaviors of non-porous polyimide (PI0) immersed in poly-α-olefin oil bath and PPIs impregnated with poly-α-olefin were firstly compared, and the effects of load and porosity on the friction performances were investigated. Results show that as the speed increases, the PPIs impregnated with oil exhibit the same friction coefficient (COF) change trend as PI0 immersed in poly-α-olefin oil, which is consistent with the stribeck curve, but the COFs in whole velocity range are higher, and the EHL arrived at a higher speed. The EHL critical speed of PPIs impregnated with oil, as well as the COFs during whole lubricating regime are closely related to the load and the porosity of the material. It mainly depends on two opposite effects of porosity on the friction properties. On one hand, PPIs with higher porosity will release more oil from pores under compression to form a lubricating film, on the other hand, higher porosity will lead to higher contact pressure under the same load, and provide larger contact areas as a result of the increase in the elastic collapse area, which will aggravate the solid-solid direct rubbing and increase the COFs.

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Cobweb-like Structural Stimuli-Responsive Composite with Oil Warehouse and Transportation System for Oil Storage and Recyclable Smart-Lubrication

Cited by 55 publications

References 38 publications

Molecular Dynamics Simulations of Lubricant Outflow in Porous Polyimide Retainers of Bearings

Molecular Dynamics Simulations of Lubricant Outflow in Porous Polyimide Retainers of Bearings

Green Superlubricity Enabled by Only One Water Droplet on Plant Oil-Infused Surfaces

Effect of Porosity on the Friction Properties of Porous Polyimide Impregnated with Poly-α-Olefin in Different Lubrication Regimes

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