Water-based lubricants provide lubrication of rubbing surfaces in many technical, biological, and physiological applications. The structure hydrated ion layers adsorbed on solid that determine the lubricating properties aqueous is thought to be invariable hydration lubrication. However, we prove surface coverage dictates roughness layer its properties, especially under subnanometer confinement. We characterize different structures lubricated by trivalent electrolytes. Two superlubrication...

In this work, superlubricity between glass and Si(3)N(4) surfaces lubricated by mixtures of acid solutions glycerol has been found using a traditional tribometer. Ultralow friction coefficients 0.004 0.006 were obtained after running-in period. Related experiments indicate that the hydrogen ions in play an important role achieving superlubricity. Moreover, ultralow is also closely related to pH value concentration glycerol. According these results, possible mechanism revealed, which...

Superior wet attachment and friction performance without the need of special external or preloaded normal force, similar to tree frog's toe pad, is highly essential for biomedical engineering, wearable flexible electronics, etc. Although various pillar surfaces are proposed enhance adhesion friction, their mechanisms remain on micropillar arrays extrude interfacial liquid via an force. Here, two-level with nanocavities top discovered pads a frog, they exhibit strong boundary ≈20 times higher...

The gecko exhibits remarkably swift and reliable climbing ability on most surfaces in nature. Numerous studies have been conducted to determine the underlying mechanisms of adhesion order realise controllable gecko-inspired handling applications. This paper, reviews recent developments field dry adhesive from fabrication application. First, progress, tools source tuning contact area peeling behavior, is introduced. Then, design are comprehensively reviewed according three features adhesion,...

Thin film lubrication (TFL), a regime that fills the gap between boundary (BL) and elastohydrodynamic (EHL) regimes, was proposed 20 years ago. Since it first recorded in literature, TFL has gained substantial interest been advanced fields of theoretical experimental research. Following revelation phenomenon its central ideas, many studies have conducted. This paper attempts to systematically review major developments terms both history advances TFL. It begins with description definition...

Abstract In this work, a super-low friction coefficient of 0.003 was found between silicon nitride ball and sapphire plate lubricated by phosphoric acid solution. The wear mainly occurred in the running-in period disappeared after superlubricity achieved. effectively reduced from 0.3 to at constant speed 0.076 m/s, accompanied 12-nm-thickness film. lubrication regime indicated change boundary elastohydrodynamic period, which is also supported results versus sliding speed. addition,...

Abstract Bio-inspired reversible adhesion has significant potential in many fields requiring flexible grasping and manipulation, such as precision manufacturing, electronics, intelligent robotics. Despite extensive efforts for adhesive synthesis with a high strength at the interface, an effective strategy to actively tune capacity between strong attachment easy detachment spanning wide range of scales been lagged. Herein, we report novel soft-hard-soft sandwiched composite design achieve...

Ocean vehicles, integral to ocean engineering, require reducing operational resistance, which is crucial. This study focuses on the modification of surface melamine sponge (PDMS@SiO2) utilizing sol-gel methodology and dip coating technology, resulting in successful fabrication a resistance-reducing material characterized by superhydrophobicity exceptional impact resistance. The shows that modified has excellent superhydrophobic properties due its controlled microstructure chemical...

Frictional energy dissipation between sliding solid surfaces in aqueous media may proceed by different pathways. Using a surface force balance (SFB), we have examined systematically how such is mediated the series of hydrated cations M+ = Li+, Na+, and K+ that are trapped two atomically smooth, negatively charged, mica across ionic solutions over many orders magnitude loading. By working at local contact pressures up to ca. 30 MPa (∼300 atm), 2 higher than earlier studies, could show...

Over the past twenty years, thin film lubrication (TFL) theory has been used to characterize molecular behaviors in films thinner than 100 nm, effectively bridging gap between elastohydrodynamic and boundary lubrication. Unfortunately, date, TFL model proposed 1996 not directly proven by experimental detection. Herein, a method based on surface-enhanced Raman spectroscopy was developed show both packing orienting of liquid molecules regime. By trapping crystal structured silver surface glass...

Negative friction coefficient attributed to the water layer confined at interface is observed on microscale.

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation Jinjin Li, Liran Ma, Shaohua Zhang, Chenhui Yuhong Liu, Jianbin Luo; Investigations on the mechanism of superlubricity achieved with phosphoric acid solution by direct observation. J. Appl. Phys. 21 September 2013; 114 (11): 114901. https://doi.org/10.1063/1.4821063 Download citation file: Ris (Zotero)...

Traction stress between contact objects is ubiquitous and crucial for various physical, biological, engineering processes such as momentum transfer, tactile perception, mechanical reliability. Newly developed techniques including electronic skin or traction force microscopy enable measurement. However, measuring the three-dimensional distribution during a dynamic process remains challenging. Here, we demonstrated method based on stereo vision to measure with high spatial temporal resolution....

To reveal the film formation mechanism of oil-in-water (O/W) emulsions, thicknesses nanofilms an aqueous paraffin oil emulsion, stabilized with nonionic Tween 80 and Span surfactants, were measured in confinement between two solid surfaces, by use relative optical interference intensity (ROII) approach. Such films' found to be sensitive rolling speed. In contrast a single-phase lubricant, which as elastohydrodynamic had thickness that always increased speed when there was sufficient supply...

Abstract Humans rely on their fingers to sense and interact with external environment. Understanding the tribological behavior between finger skin object surface is crucial for various fields, including tactile perception, product appearance design, electronic research. Quantitatively describing frictional always challenging, given complex structure of finger. In this study, texture sliding direction dependence friction was quantified based explicit mathematic models. The proposed...

Abstract Superlubricity control is of great interest in both industry and scientific research, several methods have been proposed to achieve this goal. In work, ultraviolet (UV) light was introduced into titanium dioxide (TiO 2 ) silicon nitride (Si 3 N 4 tribosystems accomplish photoinduced superlubricity. The friction coefficients (COFs) between Si balls TiO plates the mixtures sulfuric acid (H SO solution glycerol were obviously reduced, system entered superlubricity region (COF <...

Photoinduced superlubricity on TiO 2 surfaces is a newfound phenomenon which draws researchers’ attention. This study provides new method to achieve (COF<0.01) with an external light field. However, photoinduced can only be realized under specific conditions. Improper running-in conditions, such as speed, load, and pH value, will lead failure even after ultraviolet illumination the surface. In this paper, different loads, speeds, or values were used in experiment of superlubricity,...