Metal cutting fluids(MCFs)under flood conditions do not meet the urgent needs of reducing carbon emission.Biolubricant-based minimum quantity lubrication(MQL)is an effective alternative to flood lubrication.However,pn...Metal cutting fluids(MCFs)under flood conditions do not meet the urgent needs of reducing carbon emission.Biolubricant-based minimum quantity lubrication(MQL)is an effective alternative to flood lubrication.However,pneumatic atomization MQL has poor atomization properties,which is detrimental to occupational health.Therefore,electrostatic atomization MQL requires preliminary exploratory studies.However,systematic reviews are lacking in terms of capturing the current research status and development direction of this technology.This study aims to provide a comprehensive review and critical assessment of the existing understanding of electrostatic atomization MQL.This research can be used by scientists to gain insights into the action mechanism,theoretical basis,machining performance,and development direction of this technology.First,the critical equipment,eco-friendly atomization media(biolubricants),and empowering mechanisms of electrostatic atomization MQL are presented.Second,the advanced lubrication and heat transfer mechanisms of biolubricants are revealed by quantitatively comparing MQL with MCF-based wet machining.Third,the distinctive wetting and infiltration mechanisms of electrostatic atomization MQL,combined with its unique empowering mechanism and atomization method,are compared with those of pneumatic atomization MQL.Previous experiments have shown that electrostatic atomization MQL can reduce tool wear by 42.4%in metal cutting and improve the machined surface Ra by 47%compared with pneumatic atomization MQL.Finally,future development directions,including the improvement of the coordination parameters and equipment integration aspects,are proposed.展开更多
In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied ...In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied voltages and flow rates.The results showed that to obtain stable cone-jet mode spraying and hence gain better monodispersity of droplets,electrical conductivity,viscosity and surface tension of the liquid are important controlling factors.The stable cone-jet mode could be easily established for liquids having shear viscosities in the range from 80 to 1 400 mPa·s and surface tensions below 65 mN·m-1.In contrast,methylcellulose aqueous solutions with shear viscosities ranging from 10 to 540 mPa·s and moderate surface tensions(50~56 mN·m-1)generated more complicated spraying modes.However,fine TiO2 powder(a few micrometers in size)could be prepared using the EA method from its precursor solutions.展开更多
The nickel-based high-temperature alloy GH4169 is the material of choice for manufacturing critical components in aeroengines,and electrostatic atomization minimum quantity lubrication(EMQL)milling represents a fundam...The nickel-based high-temperature alloy GH4169 is the material of choice for manufacturing critical components in aeroengines,and electrostatic atomization minimum quantity lubrication(EMQL)milling represents a fundamental machining process for GH4169.However,the effects of electric field parameters,jet parameters,nozzle position,and milling parameters on milling performance remain unclear,which constrains the broad application of EMQL in aerospace manufacturing.This study evaluated the milling performance of EMQL on nickel-based alloys using soybean oil as the lubrication medium.Results revealed that compared with conventional pneumatic atomization MQL milling,EMQL reduced the milling force by 15.2%-15.9%,lowered the surface roughness by 30.9%-54.2%,decreased the average roughness spacing by 47.4%-58.3%,and decreased the coefficient of friction and the specific energy of cutting by 55%and 19.6%,respectively.Subsequent optimization experiments using orthogonal arrays demonstrated that air pressure most significantly affected the milling force and specific energy of cutting,with a contribution rate of 22%,whereas voltage had the greatest effect on workpiece surface roughness,contributing 36.71%.Considering the workpiece surface morphology and the potential impact of droplet drift on environmental and health safety,the optimal parameter combination identified were a flow rate of 80 mL/h,an air pressure of 0.1 MPa,a voltage of 30 kV,a nozzle incidence angle of 35°,an elevation angle of 30°,and a target distance of 40 mm.This research aimed to provide technical insights for improving the surface integrity of aerospace materials that are difficult to machine during cutting operations.展开更多
Minimum quantity lubrication(MQL)is a relatively efficient and clean alternative to flooding workpiece machining.Electrostatic atomization has the merits of small droplet diameter,high uniformity of droplet size,and s...Minimum quantity lubrication(MQL)is a relatively efficient and clean alternative to flooding workpiece machining.Electrostatic atomization has the merits of small droplet diameter,high uniformity of droplet size,and strong coating,hence its superiority to pneumatic atomization.However,as the current research hotspot,the influence of jet parameters and electrical parameters on the average diameter of droplets is not clear.First,by observing the shape of the liquid film at the nozzle outlet,the influence law of air pressure and voltage on liquid film thickness(h)and transverse and longitudinal fluctuations are determined.Then,the mathematical model of charged droplet volume average diameter(VAD)is constructed based on three dimensions of the liquid film,namely its thickness,transverse wavelength(λ_(h)),and longitudinal wavelength(λ_(z)).The model results under different working conditions are obtained by numerical simulation.Comparisons of the model results with the experimental VAD of the droplet confirm the error of the mathematical model to be less than 10%.The droplet diameter distribution span value Rosin–Rammler distribution span(R.S)and percentage concentrations of PM10(particle size of less than 10μm)/PM2.5(particle size of less than 2.5μm)under different working conditions are further analyzed.The results show that electrostatic atomization not only reduces the diameter distribution span of atomized droplets but also significantly inhibits the formation of PM10 and PM2.5 fine-suspension droplets.When the air pressure is 0.3 MPa,and the voltage is 40 kV,the percentage concentrations of PM10 and PM2.5 can be reduced by 80.72%and 92.05%,respectively,compared with that under the pure pneumatic atomization condition at 0.3 MPa.展开更多
The duration of a bound electron tunneling through the barrier formed by atomic potential and electrostatic field is calculated by the Bohmian trajectories scheme. The time of the tunneling ionization decreases with t...The duration of a bound electron tunneling through the barrier formed by atomic potential and electrostatic field is calculated by the Bohmian trajectories scheme. The time of the tunneling ionization decreases with the increase of the amplitude of the electrostatic field. By using the information about the position, velocity and force of the Bohmian trajectories, the dynamical process of tunneling through the barrier is investigated.展开更多
The properties of nanoparticles are often different from those of larger grains of the same solid material because of their very large specific surface area. This enables many novel applications, but properties such a...The properties of nanoparticles are often different from those of larger grains of the same solid material because of their very large specific surface area. This enables many novel applications, but properties such as agglomeration can also hinder their potential use. By creating nanostructured particles one can take optimum benefit from the desired properties while minimizing the adverse effects. We aim at developing high-precision routes for scalable production of nanostructured particles. Two gas-phase synthesis routes are explored. The first one - covering nanoparticles with a continuous layer - is carried out using atomic layer deposition in a fluidized bed. Through fluidization, the full surface area of the nanoparticles becomes available. With this process, particles can be coated with an ultra-thin film of constant and well-tunable thickness. For the second route - attaching nanoparticles to larger particles - a novel approach using electrostatic forces is demonstrated. The micron-sized particles are charged with one polarity using tribocharging. Using electrospraying, a spray of charged nanoparticles with opposite polarity is generated. Their charge prevents agglomeration, while it enhances efficient deposition at the surface of the host particle. While the proposed processes offer good potential for scale-up, further work is needed to realize large-scale processes.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51975305,51905289,52105457 and 52105264)National key Research and Development plan(2020YFB2010500)+2 种基金Key projects of Shandong Natural Science Foundation of China(Grant Nos.ZR2020KE027,ZR2020ME158 and ZR2021QE116)Major Science and technology innovation engineering projects of Shandong Province(Grant No.2019JZZY020111)Source Innovation Project of Qingdao West Coast New Area(Grant Nos.2020-97 and 2020-98).
文摘Metal cutting fluids(MCFs)under flood conditions do not meet the urgent needs of reducing carbon emission.Biolubricant-based minimum quantity lubrication(MQL)is an effective alternative to flood lubrication.However,pneumatic atomization MQL has poor atomization properties,which is detrimental to occupational health.Therefore,electrostatic atomization MQL requires preliminary exploratory studies.However,systematic reviews are lacking in terms of capturing the current research status and development direction of this technology.This study aims to provide a comprehensive review and critical assessment of the existing understanding of electrostatic atomization MQL.This research can be used by scientists to gain insights into the action mechanism,theoretical basis,machining performance,and development direction of this technology.First,the critical equipment,eco-friendly atomization media(biolubricants),and empowering mechanisms of electrostatic atomization MQL are presented.Second,the advanced lubrication and heat transfer mechanisms of biolubricants are revealed by quantitatively comparing MQL with MCF-based wet machining.Third,the distinctive wetting and infiltration mechanisms of electrostatic atomization MQL,combined with its unique empowering mechanism and atomization method,are compared with those of pneumatic atomization MQL.Previous experiments have shown that electrostatic atomization MQL can reduce tool wear by 42.4%in metal cutting and improve the machined surface Ra by 47%compared with pneumatic atomization MQL.Finally,future development directions,including the improvement of the coordination parameters and equipment integration aspects,are proposed.
文摘In the present study,electrostatic atomization(EA)behavior of several test liquids having much higher viscosities(1 400 mPa·s)than have previously been studied was investigated by spraying at a series of applied voltages and flow rates.The results showed that to obtain stable cone-jet mode spraying and hence gain better monodispersity of droplets,electrical conductivity,viscosity and surface tension of the liquid are important controlling factors.The stable cone-jet mode could be easily established for liquids having shear viscosities in the range from 80 to 1 400 mPa·s and surface tensions below 65 mN·m-1.In contrast,methylcellulose aqueous solutions with shear viscosities ranging from 10 to 540 mPa·s and moderate surface tensions(50~56 mN·m-1)generated more complicated spraying modes.However,fine TiO2 powder(a few micrometers in size)could be prepared using the EA method from its precursor solutions.
基金financially supported by the National Natural Science Foundation of China(Grant No.52205481)the Support Plan for Outstanding Youth Innovation Team in Universities of Shandong Province,China(Grant No.2023KJ114)the Qingdao Science and Technology Planning Park Cultivation Plan,China(Grant No.23-1-5-yqpy-17-qy).
文摘The nickel-based high-temperature alloy GH4169 is the material of choice for manufacturing critical components in aeroengines,and electrostatic atomization minimum quantity lubrication(EMQL)milling represents a fundamental machining process for GH4169.However,the effects of electric field parameters,jet parameters,nozzle position,and milling parameters on milling performance remain unclear,which constrains the broad application of EMQL in aerospace manufacturing.This study evaluated the milling performance of EMQL on nickel-based alloys using soybean oil as the lubrication medium.Results revealed that compared with conventional pneumatic atomization MQL milling,EMQL reduced the milling force by 15.2%-15.9%,lowered the surface roughness by 30.9%-54.2%,decreased the average roughness spacing by 47.4%-58.3%,and decreased the coefficient of friction and the specific energy of cutting by 55%and 19.6%,respectively.Subsequent optimization experiments using orthogonal arrays demonstrated that air pressure most significantly affected the milling force and specific energy of cutting,with a contribution rate of 22%,whereas voltage had the greatest effect on workpiece surface roughness,contributing 36.71%.Considering the workpiece surface morphology and the potential impact of droplet drift on environmental and health safety,the optimal parameter combination identified were a flow rate of 80 mL/h,an air pressure of 0.1 MPa,a voltage of 30 kV,a nozzle incidence angle of 35°,an elevation angle of 30°,and a target distance of 40 mm.This research aimed to provide technical insights for improving the surface integrity of aerospace materials that are difficult to machine during cutting operations.
基金This research was financially supported by the National Natural Science Foundation of China(Grant Nos.52105457 and 51975305)the National Key R&D Program of China(Grant No.2020YFB2010500)+1 种基金Major Science and Technology Innovation Engineering Projects of Shandong Province(Grant No.2019JZZY020111)General project of Liaoning Provincial Department of Education(Grant No.LJKMZ20220971).
文摘Minimum quantity lubrication(MQL)is a relatively efficient and clean alternative to flooding workpiece machining.Electrostatic atomization has the merits of small droplet diameter,high uniformity of droplet size,and strong coating,hence its superiority to pneumatic atomization.However,as the current research hotspot,the influence of jet parameters and electrical parameters on the average diameter of droplets is not clear.First,by observing the shape of the liquid film at the nozzle outlet,the influence law of air pressure and voltage on liquid film thickness(h)and transverse and longitudinal fluctuations are determined.Then,the mathematical model of charged droplet volume average diameter(VAD)is constructed based on three dimensions of the liquid film,namely its thickness,transverse wavelength(λ_(h)),and longitudinal wavelength(λ_(z)).The model results under different working conditions are obtained by numerical simulation.Comparisons of the model results with the experimental VAD of the droplet confirm the error of the mathematical model to be less than 10%.The droplet diameter distribution span value Rosin–Rammler distribution span(R.S)and percentage concentrations of PM10(particle size of less than 10μm)/PM2.5(particle size of less than 2.5μm)under different working conditions are further analyzed.The results show that electrostatic atomization not only reduces the diameter distribution span of atomized droplets but also significantly inhibits the formation of PM10 and PM2.5 fine-suspension droplets.When the air pressure is 0.3 MPa,and the voltage is 40 kV,the percentage concentrations of PM10 and PM2.5 can be reduced by 80.72%and 92.05%,respectively,compared with that under the pure pneumatic atomization condition at 0.3 MPa.
基金Supported by the National Basic Research Program of China under Grant No 2013CB922200the National Natural Science Foundation of China under Grant Nos 11274141,11304116,11274001 and 11247024the Jilin Provincial Research Foundation for Basic Research under Grant No 20140101168JC
文摘The duration of a bound electron tunneling through the barrier formed by atomic potential and electrostatic field is calculated by the Bohmian trajectories scheme. The time of the tunneling ionization decreases with the increase of the amplitude of the electrostatic field. By using the information about the position, velocity and force of the Bohmian trajectories, the dynamical process of tunneling through the barrier is investigated.
文摘The properties of nanoparticles are often different from those of larger grains of the same solid material because of their very large specific surface area. This enables many novel applications, but properties such as agglomeration can also hinder their potential use. By creating nanostructured particles one can take optimum benefit from the desired properties while minimizing the adverse effects. We aim at developing high-precision routes for scalable production of nanostructured particles. Two gas-phase synthesis routes are explored. The first one - covering nanoparticles with a continuous layer - is carried out using atomic layer deposition in a fluidized bed. Through fluidization, the full surface area of the nanoparticles becomes available. With this process, particles can be coated with an ultra-thin film of constant and well-tunable thickness. For the second route - attaching nanoparticles to larger particles - a novel approach using electrostatic forces is demonstrated. The micron-sized particles are charged with one polarity using tribocharging. Using electrospraying, a spray of charged nanoparticles with opposite polarity is generated. Their charge prevents agglomeration, while it enhances efficient deposition at the surface of the host particle. While the proposed processes offer good potential for scale-up, further work is needed to realize large-scale processes.
