Multi-fluorous-included Counter Anions-based Ionic Copolymers:Synthesis and Enhanced Hydrophobic Adsorption Films on Copper Surface for Super Protection

Three multi-fluorous-carried anions-based ionic copolymers(ICs)including(fluorosulfonyl)imide(FSI-),(trifluorometha-nesulfonyl)imide(TFSI-)and hexafluorophosphate anions(PF6-)(IC[FSI-]),poly[1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium)bis(fluorosulfonyl)amide](IC[TFSI-]),poly{1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium)bis[(trifluoromethyl)sulfonyl]-amide}(IC[PF6-]),poly[1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium)bishexafluorophosphate]were synthesized with a simple ionic exchange method by using amphiphilic poly[1,1'-(butane-1,4-diyl)bis(3-pentyl-1H-imidazol-3-ium)bisbromide](IC[Br-])as the intermediate ionic polymer.The chemical srutrcures of the target ICs were characterized by nuclear magnetic resonance(NMR)spectroscopy and Fourier-transform infrared spectroscopy(FTIR).It is shown that the target ICs could be spontaneously adsorbed on copper surface in N,N-dimethflormamide(DMF),and the tight adsorption films were formed on metal surface.The contacting angles suggest that the formed adsorption layers of target ICs on copper surface were characterized with hydrophobic nature.Furthermore,the target ICs-copper chemistry bonding was confirmed by various means.The electrochemistry analysis showed that the target ICs adsorption layers could prevent from copper corrosion in H2SO4solution efficiently,and the maximal anticorrosion efficiency was over 95%at 0.100 g/L.In particular,the target ICs showed 85%or above anticorrosion efficiency for copper at a low concentration of 0.025 g/L,which was greater than the intermediate polymer IC[Br-].In addition,an insight of mixed chemisorption and physisorption of the target ICs on metal surface was analyzed and discussed.

Boundary lubrication by adsorption film

A complete understanding of the mechanism of boundary lubrication is a goal that scientists have been striving to achieve over the past century.Although this complicated process has been far from fully revealed,a general picture and its influencing factors have been elucidated,not only at the macroscopic scale but also at the nanoscale,which is sufficiently clear to provide effective instructions for a lubrication design in engineering and even to efficiently control the boundary lubrication properties.Herein,we provide a review on the main advances,especially the breakthroughs in uncovering the mysterious but useful process of boundary lubrication by adsorption film.Despite the existence of an enormous amount of knowledge,albeit unsystematic,acquired in this area,in the present review,an effort was made to clarify the mainline of leading perspectives and methodologies in revealing the fundamental problems inherent to boundary lubrication.The main content of this review includes the formation of boundary film,the effects of boundary film on the adhesion and friction of rough surfaces,the behavior of adsorption film in boundary lubrication,boundary lubrication at the nanoscale,and the active control of boundary lubrication,generally sequenced based on the real history of our understanding of this process over the past century,incorporated by related modern concepts and prospects.

Research on Friction Properties of Mineral Lubricants in Thin-Film-Lubricating Regime

On the basis of thin film lubrication theory, the influence of fluid film(disordered film), ordered film and adsorbed film on tribological behavior of lubricating oil in thin-film lubrication(TFL) regime was studied. The μ-L(friction coefficient versus load) curves of different oil viscosity and additive dosage were obtained by a high frequency reciprocating test rig and the adsorption capacity of additive on steel surface were measured by QCM-D. Based on the Stribeck curve and thin film lubrication theory model, some conclusions can be drawn up, namely:(1) The μ-L curves and the parameters of L0 and μ0, obtained from the high frequency reciprocating test rig with ball-disc contact, can be used to study tribological behaviors of lubricating oil under TFL conditions.(2) In comparison with the high viscosity base fluid, the lower one can enter into TFL regime under lower load and keeps a lower friction coefficient in TFL regime.(3) The polar molecules in additive formulation produce ordered adsorbed layer on steel surface to reduce friction coefficient. And in TFL regime, the molecule's polarity, layer thickness and saturation degree on steel surface probably can influence lubricant's tribological behaviors between the moving interfaces. Moreover, the further study would be focused on the competitive adsorption of different additives, the formation of dual- and/or tri-molecular adsorption layers, and other aspects.

MECHANISM OF BOUNDARY LUBRICATION UNDER POINT CONTACT

The acid number of the mixed solution of 150SN oil and oleic acid characterizes the volume content of oleic acid in the solution, based on which the adsorptive capability of oleic acid is studied on the 45 steel balls and disks. Boundary lubrication tests are carried out on a self designed ball-on-disk machine, The base oil is pure 150SN oil, and oleic acid as additive are added into the lubricant. Disks have surface roughness values （Ra） of 0.8 μn and 0.4 μn. The electrical contact resistance method is used to determine the lubrication status. Hypothesize that the molecular film is monomolecular layer in condensed state and the opposing surfaces are completely separated by molecular film. A boundary lubrication model is established according to experimental results and hypothesizes. The experimental and calculatienal results show that the adsorption of polar molecules on steel surface is the main factor to form the boundary lubrication film. Load and sliding speed contribute little to the friction coefficient of boundary lubrication. The properties of steel surface and additive for the lubricant significantly influence on the characters of boundary lubrication. The smaller the surface roughness value is, the smaller the friction coefficient of the boundary lubrication is.

Solvent-free carbon sphere nanofluids towards intelligent lubrication regulation

By simply switching the electrical circuit installed on steel/steel contact,the tribological behaviors of nanofluids(NFs)can be regulated in real time,thereby achieving the desired performance of friction reduction and wear resistance.Herein,solvent-free carbon spherical nanofluids(C-NFs)were successfully prepared for intelligent lubrication regulation.C-NFs with excellent lubrication performance can immediately reduce the coefficient of friction(COF)despite applying a weak electric potential(1.5 V).Moreover,polyethylene glycol 400(PEG400)containing 5.0 wt%C-NFs remained responsive to electrical stimulation under the intermittent voltage application with an average coefficient of friction(ACOF)reduction of 20.8%over PEG400.Such intelligent lubrication regulation of C-NFs under an external electric field(EEF)mainly depends on the orderly arranged double-electric adsorption film of ion canopy-adsorbed carbon spheres(CSs).The intermittent electrical application can continuously reinforce the adsorption film and its durability for real-time controlling the sliding interfaces.Electrical-stimulation-responsive intelligent lubricants provide a new technical support for realizing intelligent stepless control of devices.

Comparative study on boundary lubrication of Ti_(3)C_(2)T_(x) MXene and graphene oxide in water

The emerging use of two-dimensional(2D)nanomaterials as boundary lubricants in water offers numerous benefits over oil-based lubricants;whereas the friction reduction varies significantly with nanomaterial type,size,loading,morphology,etc.Graphene oxide(GO)and Ti_(3)C_(2)T_(x)MXene,a relatively new 2D material,are investigated as boundary lubricants in water in this study.The contact pair mainly includes Si3N4 balls and Si wafer.The results found(1)monodispersed GO offers better lubricity than monodispersed MXene under identical concentration and testing conditions;and(2)the mixed dispersion of GO and MXene(0.1 mg/ml:0.1 mg/ml)produced the lowest friction coefficient of~0.021,a value 4×and 10×lower than that produced by comparable mono-dispersions of GO or MXene,respectively.Wear track analysis,focused ion beam microscopy,in-situ contact observation,and atomic force microscopy(AFM)characterization suggest(1)GO nanoflakes have higher adhesion than MXene and are more easily adsorbed on the tribopairs’surfaces,and(2)GO/MXene tribofilm has a layered nanostructure constituting GO,MXene,amorphous carbon,and TiO_(2).We further hypothesized that the high lubricity of GO/MXene results from the synergy of GO’s high adhesiveness,MXene’s load support ability,and the low shear strength of both constituents.The present study highlights the key role of tribofilm stability in water-based boundary lubrication using state-of-the-art 2D nanomaterials.

Evaluation of the inhibition behavior of carbon dots on carbon steel in HCl and NaCl solutions

An eco-friendly and effective corrosion inhibitor(N-CDs)was acquired by hydrothermal method in methacrylic acid and ethyl(methyl)amine precursors.Afterwards,the weight loss and electrochemistry measurement were chosen to appraise the corrosion inhibition behavior of as-prepared N-CDs for Q235 steel in Cl-contained solutions.The change rules of EIS and Tafel data displayed that the as-prepared N-CDs revealed a high-efficiency protection for steel in all test environments.Meanwhile,the inhibition efficiency of steel reached up to 93.93%(1 M HCl)and 88.96%(3.5 wt%Na Cl)at 200 mg/L of N-CDs.Furthermore,the N-CDs could form the adsorption film on steel surface to avoid the strong attack of Cl-.By analysis,the adsorption mechanism of as-prepared N-CDs on steel surface was physicochemical interaction,which strictly complied with the Langmuir adsorption model in both solutions.