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Achieving near-infrared-light-mediated switchable friction regulation on MXene-based double network hydrogels

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Friction 2024年第1期12卷 39-51页

作者： Pengxi WU Cheng ZENG Jinglun GUO Guoqiang LIU Feng ZHOU Weimin LIU Center of Advanced lubrication and Sealing Materials State Key Laboratory of Solidification ProcessingNorthwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

MXene possesses great potential in enriching the functionalities of hydrogels due to its unique metallic conductivity,high aspect ratio,near-infrared light(NIR light)responsiveness,and wide tunability,however,the poor compatibility of MXene with hydrogels limits further applications.In this work,we report a uniformly dispersed MXene-functionalized poly-N-isopropylacrylamide(PNIPAM)/poly-2-acrylamido-2-methyl-1-propanesulfonic acid(PAMPS)double network hydrogel(M–DN hydrogel)that can achieve switchable friction regulation by using the NIR light.The dispersity of MXene in hydrogels was significantly improved by incorporating the chitosan(CS)polymer.This M–DN hydrogel showed much low coefficient of friction(COF)at 25℃ due to the presence of hydration layer on hydrogel surface.After illuminating with the NIR light,M–DN hydrogel with good photothermal effect rapidly raised the temperature to above the lower critical solution temperature(LCST),which led to an obvious increase of surface COF owing to the destruction of the hydration layer.In addition,M–DN friction control hydrogel showed good recyclability and controllability by tuning“on-off”of the NIR light.This work highlights the construction of functional MXene hydrogels for intelligent lubrication,which provides insight for interface sensing,controlled transmission,and flexible robotic arms.

关键词： MXene dispersion photothermal hydrogel near-infrared(NIR)light friction modulation

Mechanical and tribological performance of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,1)refractory high-entropy alloys

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Journal of Materials Science & Technology 2023年第25期156卷 241-253页

作者： Haozhe Li Xiaolin Li Chi Jin Qian Li Qiang Ma Ke Hua Haifeng Wang Weimin Liu state key laboratory of solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

The tribological behavior of AlCr_(0.5)NbTa_(x)Ti_(4-x)(x=0,0.5,and 1)refractory high-entropy alloys was systematically investigated from room temperature to 800℃.The relationship between the alloy composition,microstructure,mechanical properties,and tribological performance was analyzed.The results show that all three alloys have a body-centered cubic(bcc)single-phase structure.The Ta addition enhances solid solution strengthening and increases the melting point that would resist high-temperature thermal softening.As a result,high-temperature strength is enhanced considerably,the coefficients of friction(COF)and wear rates of the alloys are reduced considerably at elevated temperatures,demonstrating excellent friction-reducing and anti-wear properties,e.g.,the COF and wear rate of AlCr_(0.5) NbTaTi_(3) alloy at 800℃ are 0.34 and 4.40×10^(-7) mm^(3) N^(-1) m^(-1),respectively.The excellent wear resistance at high temperatures can be attributed to the formation of an oxide-tribo layer(Ta_(2)O_(5) and TiO_(2))with ultrafine-grained layers and good high-temperature mechanical properties.

关键词： Refractory high entropy alloys High temperature Mechanical properties Wear resistance Oxide-tribo layer

Revealing the phase-transformation path in a FeCoNiSnx eutectic high entropy alloy system by crystallographic orientation relationships

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Journal of Materials Science & Technology 2023年第25期156卷 92-106页

作者： Jianbao Zhang Dexu Cui Xin Li Yixuan He Haifeng Wang Weimin Liu state key laboratory of solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

High entropy alloys are the focus of current research.An accurate description of their phase-transformation path,however,is a challenge when their phase constituent and transformation process are complex.In this study,a FeCoNiSn x eutectic high entropy alloy(EHEA)system was investigated and a novel FeCoNiSn EHEA composed of BCC+HCP phases was reported.The transition from the hypoeutectic to the fully eutectic and then to the hypereutectic microstructure with the Sn addition was characterized by the electron backscatter diffraction(EBSD)technology,and the phase-transformation path was clari-fied by crystallographic orientation relationships.The studies reveal that the primary phase of FeCoNiSn x(x=0.2,0.4)is FCC structure,and a further Sn addition induces an obvious phase-transformation from FCC to BCC in both the primary phase and eutectic lamellar,which satisfies the Kurdjumov-Sachs(K-S)or Nishiyama-Wasserman(N-W)variant orientation relationship.The mechanical results confirm that the phase structure and microstructure transition caused by Sn addition do significantly improve the strength and hardness of FeCoNiSn x EHEAs,but have serious adverse effects on plasticity.This study would be of significance to understanding the phase-transformation process in HEAs and preparing the HEAs with aimed mechanical properties.

关键词： Eutectic high-entropy alloy Orientation relationship Phase-transformation Microstructure FeCoNiSn

Synovial fluid-inspired biomimetic lubricating microspheres:Zwitterionic polyelectrolyte brushes-grafted microgels

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Friction 2023年第6期11卷 938-948页

作者： Guoqiang LIU Yang FENG Xiaohua GAO Zhuo CHEN Nan ZHAO Feng ZHOU Weimin LIU Center of Advanced lubrication and Seal Materials State Key Laboratory of Solidification ProcessingNorthwestern Polytechnical UniversityXi’an710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

Synovial fluid is made up of various biomacromolecules,including hyaluronic acid,aggrecans,lubricins,and phosphatidylcholine lipid,which are assembled onto the surface of articular cartilage in a gel state.Among them,brush-like biomacromolecules or assemblies have a vital effect on human joint lubrication.Inspired by this,the combination of brush-like molecular structures and gel-like assembly may be an efficient approach for the synthesis of biomimetic lubricating matters.Learning from the lubrication system of human joints,poly(2-methacryloyloxyethyl phosphorylcholine)(PMPC)brushes grafted poly(N-isopropylacrylamide-co-acrylic acid)(poly(NIPAAm-co-AA))microgels,abbreviated as MBs-g-MGs,were synthesized as one kind of biomimetic lubricating additives.It is worth noting that this bionic strategy considered both molecular structure and assembled form,which enabled this hairy microgel to achieve low friction in aqueous medium.Meanwhile,the effective lubrication was still achieved when using MBs-g-MGs at high temperature,indicating that this microgel maintains a good lubricating effect over a wide range of temperature.In addition,this kind of microgel possessed good biocompatibility,which laid the foundation for potential biomedical applications.Looking beyond,these biomimetic microgels may provide an effective lubricating effect for water-based sliding interfaces,especially in biomedical systems.

关键词： biomimetic design zwitterionic polyelectrolyte brushes polymeric microgels aqueous lubrication

Tribochemical synthesis of functionalized covalent organic frameworks for anti-wear and friction reduction

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Friction 2023年第10期11卷 1804-1814页

作者： Xiaozhi ZHANG Qi LU Yaojie YAN Tingting ZHANG Shujuan LIU Meirong CAI Qian YE Feng ZHOU Weimin LIU state key laboratory of solidification Processing Center of Advanced Lubrication and Seal MaterialsSchool of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Tribochemistry can be defined as a field dealing with the chemical reactions occurring in the friction zone,capable of catalyzing mechanical and physico-chemical changes in the friction contact area,facilitating the formation of tribo-films,which is also an efficient approach to fabricate novel innovative materials.In this paper,we report the successful synthesis of the silicon oil(SO)-functionalized covalent organic frameworks(COFs)prepared via the tribochemical method when subjected to the reciprocating friction;during the friction process,the rich aldehyde-terminated COFs can bond with amino SO via the Schiff base reaction between aldehyde group and amino group to obtain the desired functionalized COFs(SO@COF-LZU1).The tribochemical reaction progress was tracked through in-situ monitoring of the friction coefficient and the operating conditions during the entire friction process.Noticeably,the friction coefficient continued to decrease until it finally stabilized as the reaction progressed,which revealed the formation of a protective tribo-film.Herein,an approximate tribochemical model was presented,wherein the reaction mechanism was investigated and analyzed by employing structural analysis techniques like magic angle spinning nuclear magnetic resonance(MAS NMR),transmission electron microscopy(TEM),and X-ray photoelectron spectroscopy(XPS).Furthermore,the tribochemical-induced SO@COF-LZU1 exhibited remarkable tribological performance with a low friction coefficient of 0.1 and 95.5%reduction in wear volume when used as additives of 500SN base oil.The prime focus of our research was on the preparation and functionalization of COF materials via tribochemical reactions,unraveling a new avenue for the rational design and preparation of functional materials.

关键词： tribochemical reaction covalent organic frameworks(COFs) silicon oil(SO)functionalization lubricant additives tribological properties

Nanoscopic tribological characteristics of a cryogenically cycled Zr-based metallic glass

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Science China(Physics,Mechanics & Astronomy) 2024年第6期67卷 113-126页

作者： Qian Jia Qiaosheng Xia Qing Zhou Yucheng Wang Yue Ren Yu Meng Haifeng Wang Feng Zhou state key laboratory of solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi key laboratory of Surface Engineering and Remanufacturing Xi’an UniversityXi’an 710065China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou 730000China

Optimized macroscopic tribological behavior can be anticipated in metallic glasses(MGs)by cryogenic cycling treatment(CCT),which is attributed to enhanced plasticity.However,the intrinsic friction mechanisms of MGs induced by cryogenic rejuvenation are still poorly understood.In the present study,nanoscopic wear tests were conducted on the Zr-based MGs surface with different CCT cycles using atomic force microscopy(AFM).After CCT treatment with 100 cycles,the MG displays the highest adhesion and ploughing frictions,but significantly improved anti-wear properties.Adhesion tests and molecular dynamics simulations disclose that the increased adhesion is attributed to the dominance of liquid-like regions in the CCT-treated MGs,and the impact of reduced hardness and weak elastic recovery results in the deteriorated ploughing friction.The enhanced plasticity effectively dissipates the strain from the AFM tip through multiple shear bands and weakens the adhesion during deformation,giving rise to excellent wear resistance.This study elucidates the promoting effect of CCT on the outstanding antiwear performance of MGs,and is helpful for the development of novel alloys.

关键词： metallic glasses cryogenic cycling treatment nanoscope wear friction mechanism

Modification of POSS and their tribological properties and resistant to space atomic oxygen irradiation as lubricant additive of multialkylated cyclopentanes

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Friction 2024年第5期12卷 884-896页

作者： Xingwei WANG Chaoyang ZHANG Chen ZHAO Yijng LIANG Ming ZHANG Wufang YANG Bo YU Qiangliang YU Meirong CAI Feng ZHOU Weimin LIU State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China Shandong laboratory of Yantai Advanced Materials and Green Manufacturing Yantai264000China

Developing functional additive resistant to space atomic oxygen(AO)irradiation through simple molecular design and chemical synthesis to enhance the lubricating performance of multialkylated cyclopentanes(MACs)oil is a significant challenge.Herein,sulfur-containing polyhedral oligomere silsesquioxane(POSS)were synthesize via a click-chemistry reaction of octavinyl polyhedral oligomeric with alkyl sulfide.The reduce-friction(RF),anti-wear(AW)properties and anti-AO irradiation of POSS-S-R as MACs base oil additives in atmospheric and simulated space environments were systematically investigated for the first time.Results demonstrate that POSS-S-R not only possesses outstanding anti-AO irradiation capacity but also effectively improves the RF and AW of MACs in atmospheric or simulated space surroundings.This improvement is due to the excellent anti-AO irradiation properties of the POSS structure itself and the high load-carrying ability of silicon-containing and sulfur-containing compounds generated by tribo-chemical reactions,which effectively separates the direct contact of the friction interface.We believe that this synthesized POSS-S-R is a promising additive for space lubricants.

关键词： POSS additive reduce-friction anti-wear multialkylated cyclopentanes(MACs) resistant atomic irradiation

Nature-inspired Polysaccharide-based Aerogel for Oil–water Separation

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Journal of Bionic Engineering 2023年第5期20卷 1956-1966页

作者： Ye Fu Shulun Ai Zhiguang Guo Weimin Liu Ministry of Education key laboratory for the Green Preparation and Application of Functional Materials Hubei UniversityWuhan430062China State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of SciencesLanzhou730000China

Oily wastewater pollution is an urgent problem to be solved.Complicated preparation process,toxic hydrophobic modifiers and poor mechanical properties limit the application of polysaccharide-based aerogel in oil–water separation.Inspired by the Strider’s Leg structure in nature,an eco-friendly and reusable polysaccharide-based composite aerogel was prepared by hydrophobic modification with zein for efficient oil–water separation.The introduction of hydrophobic zein into aerogel by simple immersion method without the use of toxic modifiers can build micro/nanostructures similar to the villi on a water strider’s leg to increase the surface roughness and the hydrophobicity.And three degradable,non-toxic and economical polysaccharides including chitosan,carboxylated cellulose nanofibers and starch were used to construct aerogel skeleton,endowing aerogel with porous structures and good mechanical properties.The resulting composite aerogel(ZOMA)showed low density(0.11 g/cm^(3)),good oil absorption capacity(9 g/g),high flux oil–water separation(5595 L m^(−2)h^(−1))and excellent oil–water separation performance(99.8%).And ZOMA still had good tensile strength and elasticity after 50 compression cycles.After 10 cycles of absorption and desorption,ZOMA aerogel remained still more than 90%of its initial absorption capacity.This study provides new insight for the design of environmentally friendly and efficient adsorbents for oil–water separation.

关键词： Polysaccharide based aerogel Zein Hydrophobic modification Oil-water separation

Tribological Behavior of Al CoCrFeNi(Ti_(0.5))High Entropy Alloys under Oil and MACs lubrication

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Journal of Materials Science & Technology 2016年第5期32卷 470-476页

作者： Yuan Yu Jun Wang Jinshan Li Jun Yang Hongchao Kou Weimin Liu state key laboratory of solidification Processing Northwestern Polytechnical University State Key Laboratory of Solid Lubrication Lanzhou Institute of Chemical PhysicsChinese Academy of Sciences

The tribological properties of AICoCrFeNi and AICoCrFeNiTi0.5 high entropy alloys under gear oil and multiply alkylated cyclopentanes （MACs） lubrication condition have been studied. The equiaxed crystal structure of AICoCrFeNi alloy is obtained after heat-treatment. The AlCoCrFeNiTi0.5 alloy keeps dendrite structure. Under the gear oil with good lubrication action, AlCoCrFeNiTi0.5 alloy preserves better tribological properties than AICoCrFeNi alloy. The delamination and crack behaviors tend to occur in the grain boundary of AICoCrFeNi alloy and along the interdendrite region of AICoCrFeNiTi0.5 alloy. Under the MACs with relatively poor lubrication action, the applied load slightly influences the wear behavior of AICoCrFeNi alloy, but seriously impacts the wear mechanism of AlCoCrFeNiTi0.5 alloy. Compared with AlCoCrFeNi alloy, AlCoCrFeNiTi0.5 alloy keeps better wear-resistance at low applied load of 100 N, but preserves less wearresistance at high applied load of 200 N.

关键词： High entropy alloy Oil lubrication Tribological properties Microstructure Delamination