Early knee osteoarthritis(KOA)is characterized by progressive degeneration of the articular cartilage,synovial inflammation,and excessive accumulation of reactive oxygen species(ROS).At present,intra-articular injecti...Early knee osteoarthritis(KOA)is characterized by progressive degeneration of the articular cartilage,synovial inflammation,and excessive accumulation of reactive oxygen species(ROS).At present,intra-articular injection of hyaluronic acid(HA)is widely used to alleviate symptoms;however,its lubrication persistence,antioxidant,and anti-inflammatory abilities are limited,and it is difficult to effectively delay the early process of cartilage degeneration.Based on this,hyaluronic acid-g-lipoic acid(HA-LA)was synthesized by esterification reaction,and HA-LA microspheres were prepared by a reversed-phase emulsion method,which was combined with a macromolecular HA-LA solution to form injectable hydrogels.The objective of this study was to evaluate the efficacy of an injectable hydrogel based on hyaluronic acid-g-lipoic acid microspheres(HA-LA MS)for the treatment of KOA and to verify its injectability,lubricity,reactive oxygen species(ROS)scavenging ability,and anti-inflammatory effects.The results show that the HA-LA MS hydrogel has excellent shear thinning characteristics and continuous injectability,and its microsphere structure significantly reduces the interfacial friction coefficient through the rolling effect.In vitro experiments have shown that the hydrogel can efficiently scavenge ROS,reduce the expression of inflammatory factors,and is non-cytotoxic.The HA-LA MS injectable hydrogel has excellent lubricity,ROS scavenging ability,and anti-inflammatory effects in vivo,which can effectively delay the degeneration of early KOA cartilage,and its efficacy is significantly better than that of traditional hyaluronic acid,making it a promising intra-articular injection preparation.展开更多
The development of substitutable meniscus implants that can effectively protect articular cartilage remains a great challenge.Herein,a polyurethane with chemical crosslinking and sulfobetaine extenders containing hydr...The development of substitutable meniscus implants that can effectively protect articular cartilage remains a great challenge.Herein,a polyurethane with chemical crosslinking and sulfobetaine extenders containing hydrophobic chains(PU-CL-hSB)is developed,which could improve comprehensive properties and long-term stability simultaneously.By regulating the mole ratio of functional groups,PU-CL-hSB with appropriate mechanical properties,excellent tribological properties,and good fatigue resistance is used to prepare substitutable meniscus implant by hot-pressing.Due to the synergistic effect of functional groups,PU-CL-hSB meniscus implant presents comparable or even superior properties to native meniscus.It withstands a maximum force of 26.08 N versus 25.14 N for native meniscus,an energy dissipation from 45.93 to 39.17 N mm compared to 28.83 to 19.11 N mm for native meniscus over 300 cycles,and a friction coefficient from 0.08 to 0.19 compared to 0.11 to 0.26 for native meniscus.This PU-CL-hSB meniscus implant is further implanted into live rabbit knee joints for 8 and 25 weeks by a new approach,and in vivo data indicate that PU-CL-hSB meniscus implant not only protects articular cartilage from severe damage without eliciting inflammatory responses,but also can maintain normal physiological activities in the native state.Our findings present a substitutable meniscus implant that could be applied in vivo and propose evaluation methodologies for meniscus implants.展开更多
Floating ring bearings are widely used in high-speed turbomachinery such as turbochargers and turbogenerators.Research-ers have recently explored various surface texturing strategies on the inner surface of floating r...Floating ring bearings are widely used in high-speed turbomachinery such as turbochargers and turbogenerators.Research-ers have recently explored various surface texturing strategies on the inner surface of floating rings to enhance bearing performance.In this study,the herring patterns are textured on the inner surface of the floating ring.This pattern is inspired by the secondary flight feathers of the Indian pigeon,which aid the bird in reducing viscous drag during flight.The result-ing Herringbone Textured Floating Ring Bearing(HTFRB)is investigated for its potential application in locomotive turbo-chargers.The HTFRB is numerically modeled using the Reynolds equation to evaluate the bearing's pressure distribution and static characteristics,including load-carrying capacity,power loss,and side leakage.Dynamic characteristics are determined by solving the zeroth-and first-order perturbed Reynolds equation.A Sobol sensitivity analysis is conducted to quantify the influence of groove parameters-helix angle,groove depth,groove width ratio,and number of grooves-on bearing performance metrics.An artificial intelligence-based optimization framework,integrating artificial neural networks and adaptive neuro-fuzzy inference systems,is developed to maximize load carrying capacity while minimiz-ing power loss,side leakage,and friction coefficient.The optimized texture parameters obtained from this framework are employed to validate the ANN model and evaluate the static and dynamic characteristics of the HTFRB.The dynamic coefficients of the HTFRB are further employed to evaluate the stability and robustness of the turbocharger rotor-HTFRB system.This study underscores the potential of combining bio-inspired texture design with numerical modeling and AI-based optimization to develop high-performance HTFRB.展开更多
The development of gradient lubrication materials is critical for numerous biomedical applications,particularly in magnifying mechanical properties and service longevity.Herein,we present an innovative approach to fab...The development of gradient lubrication materials is critical for numerous biomedical applications,particularly in magnifying mechanical properties and service longevity.Herein,we present an innovative approach to fabricate biomimetic gradient lubrication hydrogel through the synergistic integration of three-dimensional(3D)printed metal-organic frameworks(MOFs)nanoparticle network hydrogel skeletons with bioinspired lubrication design.Specifically,robust hydrogel skeletons were engineered through single or multi-material 3D printing,followed by the in situ growth of MOFs nanoparticles within this hydrogel network to create a reinforced,load-bearing architecture.Subsequently,biomimetic lubrication capability was enabled by mechanically coupling another lubricating hydrogel within 3D-printed MOFs nanoparticle network hydrogel skeleton.The superficial layer is highly lubricious to ensure low coefficient of friction(~0.1141)and wear resistance(40,000 cycles),while the deeper layer is stiffer to afford the obligatory mechanical support(fracture strength~2.50 MPa).Furthermore,the gradient architecture stiffness of the hydrogel can be modulated by manipulating the spatial distribution of MOFs within the 3D-printed hydrogel skeleton.As a proof-of-concept,biomimetic gradient hydrogel meniscus structures with C-and O-shaped configurations were constructed by leveraging multi-material 3D printing,demonstrating exceptional lubrication performance.This innovative biomimetic design opens new avenues for creating implantable biomedical gradient lubricating materials with reinforced mechanical and lubrication performance.展开更多
Magnetorheological(MR)bearings,with their field-controllable rheological properties,offer new possibilities for control of rotor instabilities.However,their nonlinear dynamic behaviors and the underlying physical mech...Magnetorheological(MR)bearings,with their field-controllable rheological properties,offer new possibilities for control of rotor instabilities.However,their nonlinear dynamic behaviors and the underlying physical mechanisms governing these instabilities remain insufficiently understood.This work develops a coupled MR bearingrotor system model,where the oil film force is derived from a novel bilinear constitutive equation to capture the field-sensitive shear behaviors of MR fluids.Complex nonlinear dynamic behaviors including period doubling,quasi-period,and chaos are revealed,which emerge from the interaction between oil film vortex dynamics and magnetic excitation.The critical instability mechanism is identified from the evolution of intrinsic dynamic characteristics of MR bearings.When the whirl speed within the oil film reaches approximately half of the rotor speed,the damping force balances the destabilizing force,thereby defining a critical threshold beyond which the system transitions to instability.This threshold can be effectively tuned by adjusting the excitation current,which modifies the yield stress of MR fluids and consequently regulates the damping force.As a result,the nonlinear vibrations of oil whirl and whip can be suppressed,and the system stability can be significantly enhanced.These findings provide both theoretical insight and practical guidance for the design and control of MR bearing supported rotor systems.展开更多
The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ...The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ oxygen-passivated WS_(2) lubricating film(W–S–Ti–O composite film) was deposited to withstand AO irradiation. The structural and tribological evolution of the film was examined after a six-month space exposure experiment conducted outside the Chinese Space Station. The results show that in situ oxygen passivation of sulfur vacancies in the WS_(2) film promoted the formation of a dominant WS_(x)O_(y) phase within the W–S–Ti–O composite film. This phase effectively suppressed excessive WO_(3) formation during prolonged AO exposure while maintaining a low friction coefficient. After space exposure, the film exhibited a low friction coefficient and a wear life exceeding 4.5 × 10^(5) cycles. This performance is attributed to two main factors:(1) the presence of friction-induced spherical WO_(3) nanoparticles(approximately 11 nm) embedded in the transfer film, which promoted a transition from pure sliding to a mixed rolling–sliding regime;and(2) the retention of oriented WS_(2)(002) crystalline layers in the tribofilm, which mitigated the plowing effect of nanoparticles and prevented a significant increase in the wear rate.展开更多
Minimum quantity lubrication(MQL),as a new sustainable and eco-friendly alternative cooling/lubrication technology that addresses the limitations of dry and wet machining,utilizes a small amount of lubricant or coolan...Minimum quantity lubrication(MQL),as a new sustainable and eco-friendly alternative cooling/lubrication technology that addresses the limitations of dry and wet machining,utilizes a small amount of lubricant or coolant to reduce friction,tool wear,and heat during cutting processes.MQL technique has witnessed significant developments in recent years,such as combining MQL with other sustainable techniques to achieve optimum results,using biodegradable lubricants,and innovations in nozzle designs and delivery methods.This review presents an in-depth analysis of machining characteristics(e.g.,cutting forces,temperature,tool wear,chip morphology and surface integrity,etc.)and sustainability characteristics(e.g.,energy consumption,carbon emissions,processing time,machining cost,etc.)of conventional MQL and hybrid MQL techniques like cryogenic MQL,Ranque-Hilsch vortex tube MQL,nanofluids MQL,hybrid nanofluid MQL and ultrasonic vibration assisted MQL in machining of aeronautical materials.Subsequently,the latest research and developments are analyzed and summarized in the field of MQL,and provide a detailed comparison between each technique,considering advantages,challenges,and limitations in practical implementation.In addition,this review serves as a valuable source for researchers and engineers to optimize machining processes while minimizing environmental impact and operational costs.Ultimately,the potential future aspects of MQL for research and industrial execution are discussed.展开更多
Diamond coatings possess numerous excellent properties,making them desirable materials for high-performance surface applications.However,without a revolutionary surface modification method,the surface roughness and fr...Diamond coatings possess numerous excellent properties,making them desirable materials for high-performance surface applications.However,without a revolutionary surface modification method,the surface roughness and friction behavior of diamond coatings can impede their ability to meet the demanding requirements of advanced engineering surfaces.This study proposed the thermal stress control at coating interfaces and demonstrated a novel process of precise graphenization on conventional diamond coatings surface through laser induction and mechanical cleavage,without causing damage to the metal substrate.Through experiments and simulations,the influence mechanism of surface graphitization and interfacial thermal stress was elucidated,ultimately enabling rapid conversion of the diamond coating surface to graphene while controlling the coating’s thickness and roughness.Compared to the original diamond coatings,the obtained surfaces exhibited a 63%-72%reduction in friction coefficients,all of which were below 0.1,with a minimum of 0.06,and a 59%-67%decrease in specific wear rates.Moreover,adhesive wear in the friction counterpart was significantly inhibited,resulting in a reduction in wear by 49%-83%.This demonstrated a significant improvement in lubrication and inhibition of mechanochemical wear properties.This study provides an effective and cost-efficient avenue to overcome the application bottleneck of engineered diamond surfaces,with the potential to significantly enhance the performance and expand the application range of diamond-coated components.展开更多
Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological b...Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological behavior of AZ91D magnesium alloy rubbed against GCr15 steel was studied under lubricating oil with surface-modified MSH nanotubes as additives.The effects of the concentration,applied load,and reciprocating frequency on the friction and wear of the AZ91D alloy were studied using an SRV-4 sliding wear tester.Results show a decrease of 18.7–68.5%in friction coefficient,and a reduction of 19.4–54.3%in wear volume of magnesium alloy can be achieved by applying the synthetic serpentine additive under different conditions.A suspension containing 0.3 wt.%MSH was most efficient in reducing wear and friction.High frequency and medium load were more conducive to improving the tribological properties of magnesium alloys.A series of beneficial physical and chemical processes occurring at the AZ91D alloy/steel interface can be used to explain friction and wear reduction based on the characterization of the morphology,chemical composition,chemical state,microstructure,and nanomechanical properties of the worn surface.The synthetic MSH,with serpentine structure and nanotube morphology,possesses excellent adsorbability,high chemical activity,and good self-lubrication and catalytic activity.Therefore,physical polishing,tribochemical reactions,and physicalchemical depositions can occur easily on the sliding contacts.A dense tribolayer with a complex composition and composite structure was formed on the worn surface.Its high hardness,good toughness and plasticity,and prominent lubricity resulted in the improvement of friction and wear,making the synthetic MSH a promising efficient oil additive for magnesium alloys under boundary and mixed lubrication.展开更多
During high-speed rotation,the surface of aeronautic spiral bevel gears will generate significant pressure and viscous forces,which will cause a certain amount of windage power loss and reduce the efficiency of the tr...During high-speed rotation,the surface of aeronautic spiral bevel gears will generate significant pressure and viscous forces,which will cause a certain amount of windage power loss and reduce the efficiency of the transmission system.Based on the computational fluid dynamics,this paper analyzes the windage power loss of a single spiral bevel gear and a spiral bevel gear pair under oil injection lubrication.In addition,the shroud is used to suppress gear windage loss,and the clearance size and opening angle of the designed shroud are optimized.Finally,by comparing and analyzing the experimental results,the following conclusions were obtained:(1)For a single gear,the speed is the most important factor affecting windage loss,followed by the hand of spiral,and rotation direction;(2)For gear pairs,under oil injection lubrication,the input speed has the greatest impact on windage power loss,followed by the influence of oil injection port speed,temperature and oil injection port pressure;(3)Installing a shroud is an effective method to reduce windage power loss;(4)In the pure air phase,the smaller the clearance between the shroud and the gear surface,and the smaller the radial direction between the shroud and the shaft,the better the effect of reducing windage;(5)In the two-phase flow of oil and gas,it is necessary to design oil drainage holes on the shroud to ensure the smooth discharge of lubricating oil and improve the drag reduction effect.展开更多
The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(ar...The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(aramid nanofibers)–MoS_(2)composite films with nacre-like layered structure here are fabricated after the introduction of MoS_(2)into binary MXene/ANF composite system.The introduction of MoS_(2)fulfills an impressive“kill three birds with one stone”improvement effect:lubrication toughening mechanical performance,reduction in secondary reflection pollution of electromagnetic wave,and improvement in the performance of photothermal conversion.After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 50:50),the strain to failure and tensile strength increase from 22.1±1.7%and 105.7±6.4 MPa and to 25.8±0.7%and 167.3±9.1 MPa,respectively.The toughness elevates from 13.0±4.1 to 26.3±0.8 MJ m^(−3)(~102.3%)simultaneously.And the reflection shielding effectiveness(SE_(R))of MXene/ANF(mass ratio of 50:50)decreases~10.8%.EMI shielding effectiveness(EMI SE)elevates to 41.0 dB(8.2–12.4 GHz);After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 60:40),the strain to failure increases from 18.3±1.9%to 28.1±0.7%(~53.5%),the SE_(R)decreases~22.2%,and the corresponding EMI SE is 43.9 dB.The MoS_(2)also leads to a more efficient photothermal conversion performance(~45 to~55℃).Additionally,MXene/ANF–MoS_(2)composite films exhibit excellent electric heating performance,quick temperature elevation(15 s),excellent cycle stability(2,2.5,and 3 V),and long-term stability(2520 s).Combining with excellent mechanical performance with high MXene content,electric heating performance,and photothermal conversion performance,EMI shielding ternary MXene/ANF–MoS_(2)composite films could be applied in many industrial areas.This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.展开更多
Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubri...Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.展开更多
The use of Minimum Quantity Lubrication(MQL)with bio-lubricants has been extensively studied in aerospace sustainable manufacturing.Enhanced MQL technologies have been proposed to reduce tool wear and improve workpiec...The use of Minimum Quantity Lubrication(MQL)with bio-lubricants has been extensively studied in aerospace sustainable manufacturing.Enhanced MQL technologies have been proposed to reduce tool wear and improve workpiece surface integrity by increasing lubricant activity.However,the relationship between enhancement behavior,physicochemical properties of biolubricants,and processability remains unclear,presenting challenges for MQL technologies,particularly with difficult-to-machine materials.To address this gap,this paper provides an in-depth mechanism analysis and a comprehensive quantitative evaluation of the machinability of enhanced MQL technologies,considering chemistry,molecular dynamics,fluid dynamics,tribology,and heat transfer.Firstly,the cooling and lubrication enhancement mechanisms of nano-lubricants were systematically summarized.focusing on molecular structure.physical properties,and preparation processes.Secondly,the atomization enhancement mechanism of Electrostatic Minimum Quantity Lubrication(EMQL)was analyzed.revealing a 49%reduction in PM2.5 concentration during the atomization process compared to conventional MQL.Thirdly,the transport and infiltration enhancement mechanisms of bio-lubricants in cutting and grinding zones were summarized,incorporating electromagnetic fields and ultrasound-assisted processes.Finally,for cutting and grinding applications involving difficult-to-machine materials in aerospace,the optimized machinability of enhanced MQL technologies was concluded,showing a 50.1%increase in lubricant heat transfer coefficient and a 31.6%decrease in grinding temperature compared to standard MQL.This paper aims to help scientists understand the effective mechanisms,formulate process specifications,and identify future development trends in this technology.展开更多
As the manufacturing industry shifts toward environmentally sustainable practices,grinding—a high-precision pro-cessing method—is commonly used to ensure final workpiece dimensions and surface quality.The greening o...As the manufacturing industry shifts toward environmentally sustainable practices,grinding—a high-precision pro-cessing method—is commonly used to ensure final workpiece dimensions and surface quality.The greening of grind-ing processes has emerged as an important challenge for both academia and industry.Numerous studies proposing different methods for sustainable grinding have increased rapidly;however,the technical mechanisms and develop-ment trends remain unclear.This paper applies bibliometric methods to analyze relevant articles published on WOS from 2008 to 2023.Results show that China has the highest number of publications(45.38%),with research institu-tions primarily located in China,India,and Brazil.Among publishing journals,70%are classified as Q2 or above.Addi-tionally,popular authors and influential articles in this field are identified.Keyword frequency and hotspot literature analysis reveal that research focuses primarily on minimal quantity lubrication(MQL)grinding,especially using biolubricants and nanoparticles to improve grinding performance.This article reviews the mechanisms and effects of biolubricants and nanoparticles in MQL.It further examines how multi-energy field applications enhance MQL by influencing droplet atomization,wettability,and machining performance.A low-temperature field improves the heat exchange capacity of MQL droplets,while an electrostatic field enhances droplet contact angles and disper-sion.Ultrasonic energy enhances the atomization of biolubricants,and magnetic fields facilitate nanoparticle penetra-tion into the grinding zone,reducing grinding forces.Additionally,innovations in grinding wheel structures and solid lubrication grinding can reduce grinding temperatures and forces.This paper presents a comprehensive review of eco-friendly grinding development hotspots,providing technical support and theoretical guidance for academia and industry.展开更多
Using different external stimuli to control interfacial friction, rather than just pursuing low friction, is a highly attractive research regime due to its economic and scientific importance. One option to achieve suc...Using different external stimuli to control interfacial friction, rather than just pursuing low friction, is a highly attractive research regime due to its economic and scientific importance. One option to achieve such a goal is to use external stimuli that modulate the energy dissipation pathways. In particular, electric stimuli such as surface potential has gained remarkable interest for two reasons: Electrotunable friction has the potential for real-time, in situ manipulation of friction, and external electric stimuli is relatively easy to apply and to remove for reversible change. In this review, we explore the emerging research area of electrotunable friction mainly under the boundary lubrication situation, when the contacting surfaces are separated by a molecularly thin layer, reviewing typical achievements from experiments using electrochemical atomic force microscopy and modified surface force balances, as well as molecular dynamics simulations. Additionally, we explore the theoretical and practical challenges that may need to be tackled in the future.展开更多
Synthetic materials decorated with hydrogel coatings can accommodate the requirements of biological tissues for biocompatibility,lubricity,and flexibility.Nevertheless,these features may be subject to deterioration un...Synthetic materials decorated with hydrogel coatings can accommodate the requirements of biological tissues for biocompatibility,lubricity,and flexibility.Nevertheless,these features may be subject to deterioration under long-term severe friction conditions.Inspired by Ambystoma mexicanum,a regenerative hydrogel coating to circumventing existing notions of wear resistance is presented,which can maintain a long-term lubricated and soft surface through the utilization of increment substances under abiotic mechanisms.The term regenerative refers to a process of directional differentiation without the use of external raw materials,whereby a hydrophobic plastic(PDHEA)is transformed into a hydrophilic hydrogel(PHEA)coating in response to external stimulation.Such a regenerative hydrogel coating can not only be repaired after local wear and reborn after full wear,but also be adjusted with the thickness and mechanical properties according to specific engineering requirements during differentiation.Furthermore,the regenerative hydrogel coating is applied for the surgery of artificial cartilage,with potential clinical applications such as long-acting protection of bone tissue.展开更多
Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines.In this study,VAlN/Ag multi-layer coatings with excellent interfacial matchi...Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines.In this study,VAlN/Ag multi-layer coatings with excellent interfacial matching were fabricated using a hybrid magnetron sputtering technique.The type and energy of discharge plasmas were analyzed to comprehend their effects on depositing coatings.The coatings exhibit self-adaptive lubrication properties during the designed consecutive friction with stepwise heating from 25℃to 650℃.The microstructure evolution during early friction facilitates sufficient tribo-chemical reaction at 650℃,leading to the formation of a distinctive"ball-on-rail"structure that significantly reduces friction coefficient.Based on the first-principles calculations,it was found that the bond energy of Ag-O is lower than that of V-O in both AgVO_(3)and Ag_(3)VO_(4),which promotes slipping along the(110)crystal plane and contributes to exceptional tribological properties.The fatigue wear failure mechanism of hard coatings under the thermal-force coupling effects has been elucidated,alongside an exploration of consecutive tribology mechanism at atomic scales over a wide temperature range.展开更多
With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components ope...With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components operating in high-temperature environments within the aerospace sector.However,typical high-temperature coatings currently face challenges in effectively integrating excellent oxidation resistance,wear resistance,and lubrication properties in high-temperature settings.Studies have demonstrated the significant potential of Transition Metal Dichalcogenides(TMDCs)as lubricant additives in high-temperature lubrication,attributable to their distinctive crystal structures.Thus,this review concentrates on the compositional design of individual MX_(2)-type(M=W,Mo,Nb,Ta;X=S,Se)TMDCs(molybdenum disulfide(MoS_(2)),tungsten disulfide(WS2),niobium diselenide(NbSe_(2)),molybdenum diselenide(MoSe_(2)),tungsten diselenide(WSe_(2)))and their composites,including inorganic oxygen-containing sulfides,and explores the utilization of TMDCs in self-lubricating coatings.Furthermore,conventional preparation methods(mechanical exfoliation,liquid-phase ultrasonic exfoliation,chemical vapour deposition)for synthesizing TMDCs are outlined.Finally,an analysis of the lubrication mechanism of MX_(2)-type TMDCs is provided,along with future directions for enhancing the high-temperature lubrication performance of composite coatings.展开更多
The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment.We used a castor oil a...The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment.We used a castor oil and electrospun cellulose acetate propionate(CAp)as raw materials.We hypothesized that the acetyl and propionyl groups could provide an adequate chemical compatibility with the castor oil and that the electrospun nanostructures could enable improved physical stability by creating a variety of morphologies allowing the tailoring of the rheological and tribological properties of the resulting greases.The experimental results show that the use of electrospun CAp nanostructures can indeed yield physically stable formulations,even when used at low concentrations(3 wt%).The resulting dispersions went through structural transitions due to changes in the thickener morphologies and/or concentration,as shown by oscillatory rheology,oil holding capacity,tackiness,and lubrication performance in metal–metal contact.We found that the formulations,containing smooth or porous CAp nanofibers,at 5 wt%as a thickener,possess suitable rheological and tribological properties with a performance comparable to that of traditional lithium lubricating greases.展开更多
Endotracheal intubation-related complications are common in clinical,and there are currently no effective strategies to address these matters.Inspired by the biological characteristics of human airway mucus(HAM),an ar...Endotracheal intubation-related complications are common in clinical,and there are currently no effective strategies to address these matters.Inspired by the biological characteristics of human airway mucus(HAM),an artificial airway mucus(ARM)coating is straightforwardly constructed by combining carboxymethyl chitosan with methyl cellulose.The ARM coating exhibited excellent lubricity(coefficient of friction(Co F)=0.05)and hydrophilicity(water contact angle(WCA)=21.3°),and was capable of coating both the internal and external surfaces of the endotracheal tube(ETT).In vitro experiments demonstrated that the ARM coating not only showed good broad-spectrum antibacterial activity,but also significantly reduced nonspecific protein adhesion.Through an in vivo intubation cynomolgus monkey model,ARM-coated ETT potently mitigated airway injury and inflammation,and was highly potential to prevent bacterial infection and catheter blockage.This work offers a promising avenue for the development of airway-friendly invasive devices.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.82272472 and 52373146)。
文摘Early knee osteoarthritis(KOA)is characterized by progressive degeneration of the articular cartilage,synovial inflammation,and excessive accumulation of reactive oxygen species(ROS).At present,intra-articular injection of hyaluronic acid(HA)is widely used to alleviate symptoms;however,its lubrication persistence,antioxidant,and anti-inflammatory abilities are limited,and it is difficult to effectively delay the early process of cartilage degeneration.Based on this,hyaluronic acid-g-lipoic acid(HA-LA)was synthesized by esterification reaction,and HA-LA microspheres were prepared by a reversed-phase emulsion method,which was combined with a macromolecular HA-LA solution to form injectable hydrogels.The objective of this study was to evaluate the efficacy of an injectable hydrogel based on hyaluronic acid-g-lipoic acid microspheres(HA-LA MS)for the treatment of KOA and to verify its injectability,lubricity,reactive oxygen species(ROS)scavenging ability,and anti-inflammatory effects.The results show that the HA-LA MS hydrogel has excellent shear thinning characteristics and continuous injectability,and its microsphere structure significantly reduces the interfacial friction coefficient through the rolling effect.In vitro experiments have shown that the hydrogel can efficiently scavenge ROS,reduce the expression of inflammatory factors,and is non-cytotoxic.The HA-LA MS injectable hydrogel has excellent lubricity,ROS scavenging ability,and anti-inflammatory effects in vivo,which can effectively delay the degeneration of early KOA cartilage,and its efficacy is significantly better than that of traditional hyaluronic acid,making it a promising intra-articular injection preparation.
基金supported by the Special Project for High-tech Industrialization of Science and Technology Cooperation between Jilin Province and Chinese Academy of Sciences(2023SYHZ0042)。
文摘The development of substitutable meniscus implants that can effectively protect articular cartilage remains a great challenge.Herein,a polyurethane with chemical crosslinking and sulfobetaine extenders containing hydrophobic chains(PU-CL-hSB)is developed,which could improve comprehensive properties and long-term stability simultaneously.By regulating the mole ratio of functional groups,PU-CL-hSB with appropriate mechanical properties,excellent tribological properties,and good fatigue resistance is used to prepare substitutable meniscus implant by hot-pressing.Due to the synergistic effect of functional groups,PU-CL-hSB meniscus implant presents comparable or even superior properties to native meniscus.It withstands a maximum force of 26.08 N versus 25.14 N for native meniscus,an energy dissipation from 45.93 to 39.17 N mm compared to 28.83 to 19.11 N mm for native meniscus over 300 cycles,and a friction coefficient from 0.08 to 0.19 compared to 0.11 to 0.26 for native meniscus.This PU-CL-hSB meniscus implant is further implanted into live rabbit knee joints for 8 and 25 weeks by a new approach,and in vivo data indicate that PU-CL-hSB meniscus implant not only protects articular cartilage from severe damage without eliciting inflammatory responses,but also can maintain normal physiological activities in the native state.Our findings present a substitutable meniscus implant that could be applied in vivo and propose evaluation methodologies for meniscus implants.
文摘Floating ring bearings are widely used in high-speed turbomachinery such as turbochargers and turbogenerators.Research-ers have recently explored various surface texturing strategies on the inner surface of floating rings to enhance bearing performance.In this study,the herring patterns are textured on the inner surface of the floating ring.This pattern is inspired by the secondary flight feathers of the Indian pigeon,which aid the bird in reducing viscous drag during flight.The result-ing Herringbone Textured Floating Ring Bearing(HTFRB)is investigated for its potential application in locomotive turbo-chargers.The HTFRB is numerically modeled using the Reynolds equation to evaluate the bearing's pressure distribution and static characteristics,including load-carrying capacity,power loss,and side leakage.Dynamic characteristics are determined by solving the zeroth-and first-order perturbed Reynolds equation.A Sobol sensitivity analysis is conducted to quantify the influence of groove parameters-helix angle,groove depth,groove width ratio,and number of grooves-on bearing performance metrics.An artificial intelligence-based optimization framework,integrating artificial neural networks and adaptive neuro-fuzzy inference systems,is developed to maximize load carrying capacity while minimiz-ing power loss,side leakage,and friction coefficient.The optimized texture parameters obtained from this framework are employed to validate the ANN model and evaluate the static and dynamic characteristics of the HTFRB.The dynamic coefficients of the HTFRB are further employed to evaluate the stability and robustness of the turbocharger rotor-HTFRB system.This study underscores the potential of combining bio-inspired texture design with numerical modeling and AI-based optimization to develop high-performance HTFRB.
基金support from the National Key Research and Development Program of China(2022YFB4600101)the National Natural Science Foundation of China(52505231 and 52175201)+5 种基金the Key R&D Program of Shandong Province(2024CXPT035)the Research Program of Science and Technology Department of Gansu Province(24JRRA059,24JRRA044 and 24ZDGA014)the Science Fund of Shandong Laboratory of Advanced Materials and Green Manufacturing at Yantai(AMGM2024F12)the Innovation and Entrepreneurship Team Prject of YEDA(2021TD007)the Special Supporting Project for Provincial Leading Talents of Yantai,the Major Program(ZYFZFX-2)the Fundamental Research Special Zone Project of the Lanzhou Institute of Chemical Physics,CAS,the Special Research Assistant Project of the Chinese Academy of Sciences,and the Taishan Scholars Program.
文摘The development of gradient lubrication materials is critical for numerous biomedical applications,particularly in magnifying mechanical properties and service longevity.Herein,we present an innovative approach to fabricate biomimetic gradient lubrication hydrogel through the synergistic integration of three-dimensional(3D)printed metal-organic frameworks(MOFs)nanoparticle network hydrogel skeletons with bioinspired lubrication design.Specifically,robust hydrogel skeletons were engineered through single or multi-material 3D printing,followed by the in situ growth of MOFs nanoparticles within this hydrogel network to create a reinforced,load-bearing architecture.Subsequently,biomimetic lubrication capability was enabled by mechanically coupling another lubricating hydrogel within 3D-printed MOFs nanoparticle network hydrogel skeleton.The superficial layer is highly lubricious to ensure low coefficient of friction(~0.1141)and wear resistance(40,000 cycles),while the deeper layer is stiffer to afford the obligatory mechanical support(fracture strength~2.50 MPa).Furthermore,the gradient architecture stiffness of the hydrogel can be modulated by manipulating the spatial distribution of MOFs within the 3D-printed hydrogel skeleton.As a proof-of-concept,biomimetic gradient hydrogel meniscus structures with C-and O-shaped configurations were constructed by leveraging multi-material 3D printing,demonstrating exceptional lubrication performance.This innovative biomimetic design opens new avenues for creating implantable biomedical gradient lubricating materials with reinforced mechanical and lubrication performance.
基金Project supported by the National Natural Science Foundation of China(Nos.52575093 and 12202229)the China Postdoctoral Science Foundation(No.2025M771368)the Fundamental Research Funds for the Central Universities of China(Nos.buctrc202405 and JD2522)。
文摘Magnetorheological(MR)bearings,with their field-controllable rheological properties,offer new possibilities for control of rotor instabilities.However,their nonlinear dynamic behaviors and the underlying physical mechanisms governing these instabilities remain insufficiently understood.This work develops a coupled MR bearingrotor system model,where the oil film force is derived from a novel bilinear constitutive equation to capture the field-sensitive shear behaviors of MR fluids.Complex nonlinear dynamic behaviors including period doubling,quasi-period,and chaos are revealed,which emerge from the interaction between oil film vortex dynamics and magnetic excitation.The critical instability mechanism is identified from the evolution of intrinsic dynamic characteristics of MR bearings.When the whirl speed within the oil film reaches approximately half of the rotor speed,the damping force balances the destabilizing force,thereby defining a critical threshold beyond which the system transitions to instability.This threshold can be effectively tuned by adjusting the excitation current,which modifies the yield stress of MR fluids and consequently regulates the damping force.As a result,the nonlinear vibrations of oil whirl and whip can be suppressed,and the system stability can be significantly enhanced.These findings provide both theoretical insight and practical guidance for the design and control of MR bearing supported rotor systems.
基金financially supported by the Space Utilization System of China Manned Space Engineering (Grant No.KJZ-YY-WCL05)。
文摘The space environment, particularly highly reactive atomic oxygen(AO), often causes performance degradation and accelerated wear of solid-lubricating materials used in aerospace applications. In this study, an in situ oxygen-passivated WS_(2) lubricating film(W–S–Ti–O composite film) was deposited to withstand AO irradiation. The structural and tribological evolution of the film was examined after a six-month space exposure experiment conducted outside the Chinese Space Station. The results show that in situ oxygen passivation of sulfur vacancies in the WS_(2) film promoted the formation of a dominant WS_(x)O_(y) phase within the W–S–Ti–O composite film. This phase effectively suppressed excessive WO_(3) formation during prolonged AO exposure while maintaining a low friction coefficient. After space exposure, the film exhibited a low friction coefficient and a wear life exceeding 4.5 × 10^(5) cycles. This performance is attributed to two main factors:(1) the presence of friction-induced spherical WO_(3) nanoparticles(approximately 11 nm) embedded in the transfer film, which promoted a transition from pure sliding to a mixed rolling–sliding regime;and(2) the retention of oriented WS_(2)(002) crystalline layers in the tribofilm, which mitigated the plowing effect of nanoparticles and prevented a significant increase in the wear rate.
基金financially supported by the National Natural Science Foundation of China(Nos.92160301,92060203,52175415,and 52205475)the Science Center for Gas Turbine Project(Nos.P2022-AB-IV-002-001 and P2023-B-IV-003-001)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20210295)the Superior Postdoctoral Project of Jiangsu Province(No.2022ZB215)the National Key Laboratory of Science and Technology on Helicopter Transmission in NUAA(No.HTL-A-22G12).
文摘Minimum quantity lubrication(MQL),as a new sustainable and eco-friendly alternative cooling/lubrication technology that addresses the limitations of dry and wet machining,utilizes a small amount of lubricant or coolant to reduce friction,tool wear,and heat during cutting processes.MQL technique has witnessed significant developments in recent years,such as combining MQL with other sustainable techniques to achieve optimum results,using biodegradable lubricants,and innovations in nozzle designs and delivery methods.This review presents an in-depth analysis of machining characteristics(e.g.,cutting forces,temperature,tool wear,chip morphology and surface integrity,etc.)and sustainability characteristics(e.g.,energy consumption,carbon emissions,processing time,machining cost,etc.)of conventional MQL and hybrid MQL techniques like cryogenic MQL,Ranque-Hilsch vortex tube MQL,nanofluids MQL,hybrid nanofluid MQL and ultrasonic vibration assisted MQL in machining of aeronautical materials.Subsequently,the latest research and developments are analyzed and summarized in the field of MQL,and provide a detailed comparison between each technique,considering advantages,challenges,and limitations in practical implementation.In addition,this review serves as a valuable source for researchers and engineers to optimize machining processes while minimizing environmental impact and operational costs.Ultimately,the potential future aspects of MQL for research and industrial execution are discussed.
基金support from the National Natural Science Foundation of China(NSFC)[No.52475464,52475463]National Natural Science Foundation of Jiangsu Province(No.BK20231442)+4 种基金the Fundamental Research Funds for the Central Universities(No.NS2024032)the International Joint Laboratory of Sustainable Manufacturing,Ministry of Education and the Fundamental Research Funds for the Central Universities(No.NG2024007)China Scholarship Council(No.202206830048)the Foundation of the Graduate Innovation Center,Nanjing University of Aeronautics and Astronautics(No.kfjj20200510)Funding for Outstanding Doctoral Dissertation in NUAA(No.BCXJ23-09)。
文摘Diamond coatings possess numerous excellent properties,making them desirable materials for high-performance surface applications.However,without a revolutionary surface modification method,the surface roughness and friction behavior of diamond coatings can impede their ability to meet the demanding requirements of advanced engineering surfaces.This study proposed the thermal stress control at coating interfaces and demonstrated a novel process of precise graphenization on conventional diamond coatings surface through laser induction and mechanical cleavage,without causing damage to the metal substrate.Through experiments and simulations,the influence mechanism of surface graphitization and interfacial thermal stress was elucidated,ultimately enabling rapid conversion of the diamond coating surface to graphene while controlling the coating’s thickness and roughness.Compared to the original diamond coatings,the obtained surfaces exhibited a 63%-72%reduction in friction coefficients,all of which were below 0.1,with a minimum of 0.06,and a 59%-67%decrease in specific wear rates.Moreover,adhesive wear in the friction counterpart was significantly inhibited,resulting in a reduction in wear by 49%-83%.This demonstrated a significant improvement in lubrication and inhibition of mechanochemical wear properties.This study provides an effective and cost-efficient avenue to overcome the application bottleneck of engineered diamond surfaces,with the potential to significantly enhance the performance and expand the application range of diamond-coated components.
基金support from the National Natural Science Foundation of China(grant number 52075544)Innovation Funds of Jihua Laboratory(X220971UZ230)+1 种基金Basic and Applied Basic Research Foundation of Guangdong Province(2022A1515110649)Funds from Research Platforms of Guangdong Higher Education Institutes(2022ZDJS038).
文摘Efficient lubrication of magnesium alloys is a highly challenging topic in the field of tribology.In this study,magnesium silicate hydroxide(MSH)nanotubes with serpentine structures were synthesized.The tribological behavior of AZ91D magnesium alloy rubbed against GCr15 steel was studied under lubricating oil with surface-modified MSH nanotubes as additives.The effects of the concentration,applied load,and reciprocating frequency on the friction and wear of the AZ91D alloy were studied using an SRV-4 sliding wear tester.Results show a decrease of 18.7–68.5%in friction coefficient,and a reduction of 19.4–54.3%in wear volume of magnesium alloy can be achieved by applying the synthetic serpentine additive under different conditions.A suspension containing 0.3 wt.%MSH was most efficient in reducing wear and friction.High frequency and medium load were more conducive to improving the tribological properties of magnesium alloys.A series of beneficial physical and chemical processes occurring at the AZ91D alloy/steel interface can be used to explain friction and wear reduction based on the characterization of the morphology,chemical composition,chemical state,microstructure,and nanomechanical properties of the worn surface.The synthetic MSH,with serpentine structure and nanotube morphology,possesses excellent adsorbability,high chemical activity,and good self-lubrication and catalytic activity.Therefore,physical polishing,tribochemical reactions,and physicalchemical depositions can occur easily on the sliding contacts.A dense tribolayer with a complex composition and composite structure was formed on the worn surface.Its high hardness,good toughness and plasticity,and prominent lubricity resulted in the improvement of friction and wear,making the synthetic MSH a promising efficient oil additive for magnesium alloys under boundary and mixed lubrication.
基金Supported by National Natural Science Foundation of China(Grant Nos.51175422,61973011)Shaanxi Provincial Natural Science Basic Research Plan of China(Grant No.2022JM-195)+1 种基金Fundamental Research Funds for the Central Universities of Chinathe Research Start-up Funds of Hangzhou International Innovation Institute of Beihang University(Grant No.2024KQ036)。
文摘During high-speed rotation,the surface of aeronautic spiral bevel gears will generate significant pressure and viscous forces,which will cause a certain amount of windage power loss and reduce the efficiency of the transmission system.Based on the computational fluid dynamics,this paper analyzes the windage power loss of a single spiral bevel gear and a spiral bevel gear pair under oil injection lubrication.In addition,the shroud is used to suppress gear windage loss,and the clearance size and opening angle of the designed shroud are optimized.Finally,by comparing and analyzing the experimental results,the following conclusions were obtained:(1)For a single gear,the speed is the most important factor affecting windage loss,followed by the hand of spiral,and rotation direction;(2)For gear pairs,under oil injection lubrication,the input speed has the greatest impact on windage power loss,followed by the influence of oil injection port speed,temperature and oil injection port pressure;(3)Installing a shroud is an effective method to reduce windage power loss;(4)In the pure air phase,the smaller the clearance between the shroud and the gear surface,and the smaller the radial direction between the shroud and the shaft,the better the effect of reducing windage;(5)In the two-phase flow of oil and gas,it is necessary to design oil drainage holes on the shroud to ensure the smooth discharge of lubricating oil and improve the drag reduction effect.
基金supported by the Talent Fund of Beijing Jiaotong University(No,2023XKRC015)the National Natural Science Foundation of China(Nos.52172081,52073010 and 52373259).
文摘The design and fabrication of high toughness electromagnetic interference(EMI)shielding composite films with diminished reflection are an imperative task to solve electromagnetic pollution problem.Ternary MXene/ANF(aramid nanofibers)–MoS_(2)composite films with nacre-like layered structure here are fabricated after the introduction of MoS_(2)into binary MXene/ANF composite system.The introduction of MoS_(2)fulfills an impressive“kill three birds with one stone”improvement effect:lubrication toughening mechanical performance,reduction in secondary reflection pollution of electromagnetic wave,and improvement in the performance of photothermal conversion.After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 50:50),the strain to failure and tensile strength increase from 22.1±1.7%and 105.7±6.4 MPa and to 25.8±0.7%and 167.3±9.1 MPa,respectively.The toughness elevates from 13.0±4.1 to 26.3±0.8 MJ m^(−3)(~102.3%)simultaneously.And the reflection shielding effectiveness(SE_(R))of MXene/ANF(mass ratio of 50:50)decreases~10.8%.EMI shielding effectiveness(EMI SE)elevates to 41.0 dB(8.2–12.4 GHz);After the introduction of MoS_(2)into binary MXene/ANF(mass ratio of 60:40),the strain to failure increases from 18.3±1.9%to 28.1±0.7%(~53.5%),the SE_(R)decreases~22.2%,and the corresponding EMI SE is 43.9 dB.The MoS_(2)also leads to a more efficient photothermal conversion performance(~45 to~55℃).Additionally,MXene/ANF–MoS_(2)composite films exhibit excellent electric heating performance,quick temperature elevation(15 s),excellent cycle stability(2,2.5,and 3 V),and long-term stability(2520 s).Combining with excellent mechanical performance with high MXene content,electric heating performance,and photothermal conversion performance,EMI shielding ternary MXene/ANF–MoS_(2)composite films could be applied in many industrial areas.This work broadens how to achieve a balance between mechanical properties and versatility of composites in the case of high-function fillers.
文摘Increasing environmental concerns about limiting harmful emissions has necessitated sulfur-and phosphorus-free green lubricant additives.Although boron-containing compounds have been widely investigated as green lubricant additives,their macromolecular analogs have been rarely considered yet to develop environmentally friendly lubricant additives.In this work,a series of boron-containing copolymers have been synthesized by free-radical copolymerization of stearyl methacrylate and isopropenyl boronic acid pinacol ester with different feeding ratios(S_(n)-r-B_(m),n=1,m=1/3,1,2,3,5,9).The resulting copolymers of S_(n)-r-B_(m)(n=1,m=1/3,1,2,3,5)are readily dispersed in the PAO-10 base oil and form micelle-like aggregates with hydrodynamic diameters ranging from 9.7 to 52 nm.SRV-IV oscillating reciprocating tribological tests on ball-on-flat steel pairs show that compared with the base oil of PAO-10,the friction coefficients and wear volumes of the base oil solutions of S_(n)-r-B_(m)decrease considerably up to 62%and 97%,respectively.Moreover,the base oil solution of S_(1)-r-B_(1)exhibits an excellent load-bearing capacity of(850±100)N.These superior lubricating properties are due to the formation of protective tribofilms comprising S_(n)-r-B_(m),boron oxide,and iron oxide compounds on the lubricated steel surface.Therefore,the boron-containing copolymers can be regarded as a novel class of environmentally friendly lubricating oil macroadditives for efficient friction and wear reduction without sulfur and phosphorus elements.
基金supported by the following organizations:the Special Fund of Taishan Scholars Project(No.tsqn202211179)the National Natural Science Foundation of China(No.52105457)+2 种基金Young Talent of Lifting engineering for Science and Technology in Shandong,China(No.SDAST2021qt12)the National Natural Science Foundation of China(No.52375447)China Postdoctoral Science Foundation Funded Project(No.2023M732826).
文摘The use of Minimum Quantity Lubrication(MQL)with bio-lubricants has been extensively studied in aerospace sustainable manufacturing.Enhanced MQL technologies have been proposed to reduce tool wear and improve workpiece surface integrity by increasing lubricant activity.However,the relationship between enhancement behavior,physicochemical properties of biolubricants,and processability remains unclear,presenting challenges for MQL technologies,particularly with difficult-to-machine materials.To address this gap,this paper provides an in-depth mechanism analysis and a comprehensive quantitative evaluation of the machinability of enhanced MQL technologies,considering chemistry,molecular dynamics,fluid dynamics,tribology,and heat transfer.Firstly,the cooling and lubrication enhancement mechanisms of nano-lubricants were systematically summarized.focusing on molecular structure.physical properties,and preparation processes.Secondly,the atomization enhancement mechanism of Electrostatic Minimum Quantity Lubrication(EMQL)was analyzed.revealing a 49%reduction in PM2.5 concentration during the atomization process compared to conventional MQL.Thirdly,the transport and infiltration enhancement mechanisms of bio-lubricants in cutting and grinding zones were summarized,incorporating electromagnetic fields and ultrasound-assisted processes.Finally,for cutting and grinding applications involving difficult-to-machine materials in aerospace,the optimized machinability of enhanced MQL technologies was concluded,showing a 50.1%increase in lubricant heat transfer coefficient and a 31.6%decrease in grinding temperature compared to standard MQL.This paper aims to help scientists understand the effective mechanisms,formulate process specifications,and identify future development trends in this technology.
基金Supported by National Natural Science Foundation of China(Grant Nos.52375447,52305477 and 52105457)Shandong Provincial Natural Science Foundation(Grant Nos.ZR2023QE057,ZR2024QE100 and ZR2024ME255)+2 种基金Qingdao Municipal Science and Technology Planning Park Cultivation Plan(Grant No.23-1-5-yqpy-17-qy)Shandong Provincial Science and Technology SMEs Innovation Capacity Improvement Project(Grant No.2022TSGC1115)the Special Fund of Taishan Scholars。
文摘As the manufacturing industry shifts toward environmentally sustainable practices,grinding—a high-precision pro-cessing method—is commonly used to ensure final workpiece dimensions and surface quality.The greening of grind-ing processes has emerged as an important challenge for both academia and industry.Numerous studies proposing different methods for sustainable grinding have increased rapidly;however,the technical mechanisms and develop-ment trends remain unclear.This paper applies bibliometric methods to analyze relevant articles published on WOS from 2008 to 2023.Results show that China has the highest number of publications(45.38%),with research institu-tions primarily located in China,India,and Brazil.Among publishing journals,70%are classified as Q2 or above.Addi-tionally,popular authors and influential articles in this field are identified.Keyword frequency and hotspot literature analysis reveal that research focuses primarily on minimal quantity lubrication(MQL)grinding,especially using biolubricants and nanoparticles to improve grinding performance.This article reviews the mechanisms and effects of biolubricants and nanoparticles in MQL.It further examines how multi-energy field applications enhance MQL by influencing droplet atomization,wettability,and machining performance.A low-temperature field improves the heat exchange capacity of MQL droplets,while an electrostatic field enhances droplet contact angles and disper-sion.Ultrasonic energy enhances the atomization of biolubricants,and magnetic fields facilitate nanoparticle penetra-tion into the grinding zone,reducing grinding forces.Additionally,innovations in grinding wheel structures and solid lubrication grinding can reduce grinding temperatures and forces.This paper presents a comprehensive review of eco-friendly grinding development hotspots,providing technical support and theoretical guidance for academia and industry.
基金supported by Beijing Natural Science Foundation (No. L244035)Science Fund Program for Distinguished Young Scholars (Overseas, Nos. KZ37114301, KZ37125801)the support from Israel Science Foundation-National Natural Science Foundation of China joint research program (No. 3618/21)。
文摘Using different external stimuli to control interfacial friction, rather than just pursuing low friction, is a highly attractive research regime due to its economic and scientific importance. One option to achieve such a goal is to use external stimuli that modulate the energy dissipation pathways. In particular, electric stimuli such as surface potential has gained remarkable interest for two reasons: Electrotunable friction has the potential for real-time, in situ manipulation of friction, and external electric stimuli is relatively easy to apply and to remove for reversible change. In this review, we explore the emerging research area of electrotunable friction mainly under the boundary lubrication situation, when the contacting surfaces are separated by a molecularly thin layer, reviewing typical achievements from experiments using electrochemical atomic force microscopy and modified surface force balances, as well as molecular dynamics simulations. Additionally, we explore the theoretical and practical challenges that may need to be tackled in the future.
基金supported by the National Natural Science Foundation of China(22335008)The authors thank Mr.Zhenhao Wang and Dr.Yingchao Ma for photography.Antong Ma and Zhaoxiang Yang contribute equally to this work.
文摘Synthetic materials decorated with hydrogel coatings can accommodate the requirements of biological tissues for biocompatibility,lubricity,and flexibility.Nevertheless,these features may be subject to deterioration under long-term severe friction conditions.Inspired by Ambystoma mexicanum,a regenerative hydrogel coating to circumventing existing notions of wear resistance is presented,which can maintain a long-term lubricated and soft surface through the utilization of increment substances under abiotic mechanisms.The term regenerative refers to a process of directional differentiation without the use of external raw materials,whereby a hydrophobic plastic(PDHEA)is transformed into a hydrophilic hydrogel(PHEA)coating in response to external stimulation.Such a regenerative hydrogel coating can not only be repaired after local wear and reborn after full wear,but also be adjusted with the thickness and mechanical properties according to specific engineering requirements during differentiation.Furthermore,the regenerative hydrogel coating is applied for the surgery of artificial cartilage,with potential clinical applications such as long-acting protection of bone tissue.
基金supported by the National Natural Science Foundation of China(No.52025014)Natural Science Foundation of Zhejiang Province(No.LQ23E010002)+1 种基金Natural Science Foundation of Ningbo(No.2023QL049)Major Special Project of Ningbo(No.2023Z022).
文摘Solid lubricating coatings play a crucial role in preventing friction and wear failure of the hot-end sliding components in aviation engines.In this study,VAlN/Ag multi-layer coatings with excellent interfacial matching were fabricated using a hybrid magnetron sputtering technique.The type and energy of discharge plasmas were analyzed to comprehend their effects on depositing coatings.The coatings exhibit self-adaptive lubrication properties during the designed consecutive friction with stepwise heating from 25℃to 650℃.The microstructure evolution during early friction facilitates sufficient tribo-chemical reaction at 650℃,leading to the formation of a distinctive"ball-on-rail"structure that significantly reduces friction coefficient.Based on the first-principles calculations,it was found that the bond energy of Ag-O is lower than that of V-O in both AgVO_(3)and Ag_(3)VO_(4),which promotes slipping along the(110)crystal plane and contributes to exceptional tribological properties.The fatigue wear failure mechanism of hard coatings under the thermal-force coupling effects has been elucidated,alongside an exploration of consecutive tribology mechanism at atomic scales over a wide temperature range.
文摘With the rapid advancement of science and technology,along with an increasing global focus on space exploration,there is a growing concern for addressing friction and wear issues in surface coatings for components operating in high-temperature environments within the aerospace sector.However,typical high-temperature coatings currently face challenges in effectively integrating excellent oxidation resistance,wear resistance,and lubrication properties in high-temperature settings.Studies have demonstrated the significant potential of Transition Metal Dichalcogenides(TMDCs)as lubricant additives in high-temperature lubrication,attributable to their distinctive crystal structures.Thus,this review concentrates on the compositional design of individual MX_(2)-type(M=W,Mo,Nb,Ta;X=S,Se)TMDCs(molybdenum disulfide(MoS_(2)),tungsten disulfide(WS2),niobium diselenide(NbSe_(2)),molybdenum diselenide(MoSe_(2)),tungsten diselenide(WSe_(2)))and their composites,including inorganic oxygen-containing sulfides,and explores the utilization of TMDCs in self-lubricating coatings.Furthermore,conventional preparation methods(mechanical exfoliation,liquid-phase ultrasonic exfoliation,chemical vapour deposition)for synthesizing TMDCs are outlined.Finally,an analysis of the lubrication mechanism of MX_(2)-type TMDCs is provided,along with future directions for enhancing the high-temperature lubrication performance of composite coatings.
基金sponsored by MCIN/AEI/10.13039/501100011033“ERDF A way of making Europe”(grant PID2021-125637OB-I00)FEDER/Junta de Andalucía Programmes(grants PY20_00751 and UHU202029).
文摘The aim of this work is to find an alternative lubricating grease formulation that can be produced from renewable and biodegradable sources with minimal risks to human health and the environment.We used a castor oil and electrospun cellulose acetate propionate(CAp)as raw materials.We hypothesized that the acetyl and propionyl groups could provide an adequate chemical compatibility with the castor oil and that the electrospun nanostructures could enable improved physical stability by creating a variety of morphologies allowing the tailoring of the rheological and tribological properties of the resulting greases.The experimental results show that the use of electrospun CAp nanostructures can indeed yield physically stable formulations,even when used at low concentrations(3 wt%).The resulting dispersions went through structural transitions due to changes in the thickener morphologies and/or concentration,as shown by oscillatory rheology,oil holding capacity,tackiness,and lubrication performance in metal–metal contact.We found that the formulations,containing smooth or porous CAp nanofibers,at 5 wt%as a thickener,possess suitable rheological and tribological properties with a performance comparable to that of traditional lithium lubricating greases.
基金supported by the National Natural Science Foundation of China(Nos.52203046 and 82171219)Sichuan Science and Technology Program(No.2023NSFSC1944)+3 种基金West China Nursing Discipline Development Special Fund ProjectSichuan University(No.HXHL21007)the China Postdoctoral Science Foundation(No.2023M742483)the National Natural Science Foundation of Guangdong(No.2024A1515012881)。
文摘Endotracheal intubation-related complications are common in clinical,and there are currently no effective strategies to address these matters.Inspired by the biological characteristics of human airway mucus(HAM),an artificial airway mucus(ARM)coating is straightforwardly constructed by combining carboxymethyl chitosan with methyl cellulose.The ARM coating exhibited excellent lubricity(coefficient of friction(Co F)=0.05)and hydrophilicity(water contact angle(WCA)=21.3°),and was capable of coating both the internal and external surfaces of the endotracheal tube(ETT).In vitro experiments demonstrated that the ARM coating not only showed good broad-spectrum antibacterial activity,but also significantly reduced nonspecific protein adhesion.Through an in vivo intubation cynomolgus monkey model,ARM-coated ETT potently mitigated airway injury and inflammation,and was highly potential to prevent bacterial infection and catheter blockage.This work offers a promising avenue for the development of airway-friendly invasive devices.
