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
The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusio...The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.展开更多
The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can caus...The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can cause changes in cutting force/heat,resulting in affecting gear machining precision.Therefore,this paper studies the effect of different process parameters on gear machining precision.A multi-objective optimization model is established for the relationship between process parameters and tooth surface deviations,tooth profile deviations,and tooth lead deviations through the cutting speed,feed rate,and cutting depth of the worm wheel gear grinding machine.The response surface method(RSM)is used for experimental design,and the corresponding experimental results and optimal process parameters are obtained.Subsequently,gray relational analysis-principal component analysis(GRA-PCA),particle swarm optimization(PSO),and genetic algorithm-particle swarm optimization(GA-PSO)methods are used to analyze the experimental results and obtain different optimal process parameters.The results show that optimal process parameters obtained by the GRA-PCA,PSO,and GA-PSO methods improve the gear machining precision.Moreover,the gear machining precision obtained by GA-PSO is superior to other methods.展开更多
Microgrinding is widely used in clinical bone surgery,but saline spray cooling faces technical challenges such as low wettability at the microgrinding tool–bone interface,easy clogging of the microgrinding tools,and ...Microgrinding is widely used in clinical bone surgery,but saline spray cooling faces technical challenges such as low wettability at the microgrinding tool–bone interface,easy clogging of the microgrinding tools,and high grinding temperatures.These issues can lead to bone necrosis,irreversible thermal damage to nerves,or even surgical failure.Inspired by the water-trapping and directional transportation abilities of desert beetles,this study proposes a biomimetic desert beetle microgrinding tool.The flow-field distribution directly influences the convective heat transfer of the cooling medium in the grinding zone,which in turn affects the grinding temperature.To address this,a mathematical model of the two-phase flow field at the biomimetic microgrinding tool–bone interface is developed.The results indicate an average error of 14.74%between the calculated and experimentally obtained airflow field velocities.Next,a biomimetic desert beetle microgrinding tool is prepared.Experiments with physiological saline spray cooling were conducted on fresh bovine femur bone,which has mechanical properties similar to human bone.Results show that,compared with conventional microgrinding tools,the biomimetic tools reduced bone surface temperature by 21.7%,13.2%,5.8%,20.3%,and 25.8%at particle sizes of 150#,200#,240#,270#,and 300#,respectively.The surface morphology of the biomimetic microgrinding tools after grinding is observed and analyzed,revealing a maximum clogging area reduction of 23.0%,which is 6.1%,6.0%,10.0%,15.6%,and 9.5%less than that observed with conventional tools.Finally,this study unveils the dynamic mechanism of cooling medium transfer in the flow field at the biomimetic microgrinding tool–bone interface.This research provides theoretical guidance and technical support for clinical bone resection surgery.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
During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wh...During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wheels,and the wheelsets will seriously affect the stability of the grinding force.In this paper,the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory,which is embedded as a submodel into the dynamic model of the multi-rigid buggy.The interaction among the frame,the grinding wheels and the wheelsets is analysed by setting the convex irregularity on the rail.The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions.The results show that when the grinding buggy passes the convex irregularity,the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels.The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame,less affecting the wheelset.For the long wave corrugation of the subway,the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation.The research results provide an important reference for the setting of the grinding pattern.展开更多
Micro-grinding has been widely used in aerospace and other industry.However,the small diameter of the micro-grinding tool has limited its machining performance and efficiency.In order to solve the above problems,micro...Micro-grinding has been widely used in aerospace and other industry.However,the small diameter of the micro-grinding tool has limited its machining performance and efficiency.In order to solve the above problems,micro-structure has been applied on the micro-grinding tool.A morphology modeling has been established in this study to characterize the surface of microstructured micro-grinding tool,and the grinding performance of micro-structured micro-grinding tool has been analyzed through undeformed chip thickness,abrasive edge width,and effective distance between abrasives.Then deviation analysis,path optimization and parameter optimization of microchannel array precision grinding have been finished to improve processing quality and efficiency,and the deflection angle has the most obvious effects on the rectangular slot depth,micro-structured micro-grinding tool could reduce 10%surface roughness and 20%grinding force compared to original micro-grinding tool.Finally,the microchannel array has been machined with a size deviation of 2μm and surface roughness of 0.2μm.展开更多
SiC-reinforced aluminum matrix(SiCp/Al)composite is widely utilized in the aerospace,automotive,and electronics industries due to the combination of ceramic hardness and metal toughness.However,the significant dispari...SiC-reinforced aluminum matrix(SiCp/Al)composite is widely utilized in the aerospace,automotive,and electronics industries due to the combination of ceramic hardness and metal toughness.However,the significant disparity in properties between SiC particles and the aluminum matrix results in severe tool wear and diminished surface quality during conventional machining.This study proposes an environmentally friendly and clean dry electrical discharge assisted grinding process as an efficient and low-damage machining method for SiCp/Al.An experimental platform was set up to study the impact of grinding and discharge process parameters on surface quality.The study compared the chip formation mechanism and surface quality between dry electrical discharge assisted grinding and conventional grinding,revealing relationships between surface roughness,grinding force,grinding temperature,and related parameters.The results indicate that the proposed grinding method leads to smaller chip sizes,lower grinding forces and temperatures,and an average reduction of 19.2%in surface roughness compared to conventional grinding.The axial,tangential,and normal grinding forces were reduced by roughly 10.5%,37.8%,and 23.0%,respectively.The optimized process parameters were determined to be N=2500 r/min,vf=30 mm/min,a=10μm,E=15 V,f=5000 Hz,dc=80%,resulting in a surface roughness of 0.161μm.展开更多
Gear flank modification is essential to reduce the noise generated in the gear meshing process,improve the gear transmission performance,and reduce the meshing impact.Aiming at the problem of solving the additional mo...Gear flank modification is essential to reduce the noise generated in the gear meshing process,improve the gear transmission performance,and reduce the meshing impact.Aiming at the problem of solving the additional motions of each axis in the higher-order topology modification technique and how to accurately add the different movements expressed in the form of higher-order polynomials to the corresponding motion axes of the machine tool,a flexible higher-order gear topology modification technique based on an electronic gearbox is proposed.Firstly,a two-parameter topology gear surface equation and a grinding model of wheel grinding gears are established,and the axial feed and tangential feed are expressed in a fifth-order polynomial formula.Secondly,the polynomial coefficients are solved according to the characteristics of the point contact when grinding gears.Finally,an improved electronic gearbox model is constructed by combining the polynomial interpolation function to achieve gear topology modification.The validity and feasibility of the modification method based on the electronic gearbox are verified by experimental examples,which is of great significance for the machining of modification gears based on the continuous generative grinding method of the worm grinding wheel.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
The effects of calcination temperature and mechanical ball milling on the physicochemical properties of electrolytic manganese residue(EMR),mineral phase transition,pozzolanic activity,and pore structure were studied....The effects of calcination temperature and mechanical ball milling on the physicochemical properties of electrolytic manganese residue(EMR),mineral phase transition,pozzolanic activity,and pore structure were studied.The experimental results show that the strength activity index(SAI)of 20%EMR mixed mortar at 28 days is 90.54%,95.40%,and 90.73%,respectively,after pretreatment with EMR at 800℃calcined for 3,5,and 8 min.This is mainly attributed to the high temperature decomposition of gypsum dihydrate to form activated calcium oxide.In addition,high temperature and mechanical force destroys the Si-O chemical bond and promotes the formation of calcium silicate gel structure.Due to the existence of a large number of gypsum phases in EMR mixed mortar,a large number of ettringite,C-S-H,aluminosilicate,C-A-S-H,and AFm are formed,which strongly verifies the volcanic activity of EMR.The leaching test shows that high temperature calcination has a significant effect on the stabilization of NH_(3)-N.However,the curing effect of Mn^(2+)is significant only in the calcination at 1000℃,but both Mn^(2+)and NH_(3)-N in the calcined EMR are higher than the emission standard.The encapsulation effect of EMR composite mortar provided by hydration products,and the buffering capacity of the Si-Al system for solidification of heavy metals and strong alkalis are conducive to the stability of Mn^(2+)and NH_(3)-N.After the EMR mixed mortar is aged for 3 days,Mn and NH_(3)-N are completely lower than the emission standard.In general,the EMR mixed mortar can meet the requirements for green building use.展开更多
In ball milling,the process parameters are decisive in influencing the quality and performance of the final ball-milled product,and crucial but often neglected is the ratio of the grinding balls in terms of their size...In ball milling,the process parameters are decisive in influencing the quality and performance of the final ball-milled product,and crucial but often neglected is the ratio of the grinding balls in terms of their size.Here,for a given number of large grinding balls,the ratio of large to small ones is set to 1:2,1:3,1:4,and 1:5 by altering the number of small ones,and how this affects the morphology,structure,and electrochemical properties of ball-milled graphene nanosheets is investigated.The results show that changing the ball ratio causes distinct changes in the morphology,structure,and properties of the graphene nanosheets.Increasing the number of small(6 mm)grinding balls decreases the nanosheet grain size monotonically;meanwhile,the crystal plane spacing,defect density,and specific surface area increase and then decrease,but the graphitization degree decreases and then increases.Ball-milled samples are then used as anodes for lithium-ion batteries,and both the specific capacity and rate capability exhibit the same trend of increase and then decrease.The ball ratio of 1:3 gives the best electrochemical performance,i.e.,a reversible specific capacity of 262.09 mA·h/g at a current density of 100 mA/g,and even after 2000 cycles at 2000 mA/g,the reversible specific capacity is 87.4%of the optimal value.展开更多
The mechanochemical synthesis of polycarboxylate superplasticizers(PCEs)was achieved using a planetary ball mill at ambient temperature.The effects of ball milling parameters,including speed,time,and stop method,on PC...The mechanochemical synthesis of polycarboxylate superplasticizers(PCEs)was achieved using a planetary ball mill at ambient temperature.The effects of ball milling parameters,including speed,time,and stop method,on PCE performance,molecular weight,and distribution were investigated to optimize conditions.The experimental results suggest that ball milling impacts PCE molecular weight and distribution,striking a balance between polymerization and mechanical degradation during synthesis.The optimal parameters were found to be 400 rpm,120 minutes total time,and 30 minutes milling plus 3 minutes rest cycles.Under these conditions,the PCE exhibits excellent dispersibility with a cement paste fluidity of 260 mm.The mechanochemical approach eliminates heating requirements,and also reduces the reaction time from 300 to 120 minutes compared to traditional aqueous synthesis.The optimized PCE demonstrates an increased density of long-side chains,leading to enhanced early strength,heightens adsorption,and diminished zeta potential in cement systems.These characteristics are comparable to traditionally synthesized PCEs.Moreover,at higher dosages,further augmentation of PCE adsorption and increased cement paste fluidity were noted here.展开更多
The use of recycled concrete and oyster shells as partial cement and aggregate replacements is ongoing research to solve this multifaceted problem of concrete waste in the construction industry as well as waste from o...The use of recycled concrete and oyster shells as partial cement and aggregate replacements is ongoing research to solve this multifaceted problem of concrete waste in the construction industry as well as waste from oyster shell farming. However, there is a lack of evidence on the possibility of producing a fully recycled composite consisting of recycled concrete and oyster shell without the need for new cement and natural aggregates. In this study, recycled concrete powder (RCP) and oyster shell were used to produce a green composite. Separate ground and combined ground (separate ground and co-ground) RCP and oyster shells are used to determine the effects of grinding approaches on the mechanical and chemical properties of the composite. The composite samples were molded via press molding by applying 30 MPa of pressure for 10 minutes. The results revealed that the composite prepared via the combined ground approach presented the highest flexural strength compared to the separate ground and unground samples. The FTIR and XRD characterization results revealed no chemical or phase alterations in the raw materials or the resulting composites before and after grinding. SEM analysis revealed that combined grinding reduced the particles’ size and improved the dispersion of the mixture, thereby increasing the strength.展开更多
Extracting lithium from coal measures can alleviate the shortage of strategic metal resources.However,the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and en...Extracting lithium from coal measures can alleviate the shortage of strategic metal resources.However,the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and entrainment behavior are the challenges that constrain the extraction efficiency of lithium from coal series.This study focuses on improving the separation efficiency between lithium-contain-ing minerals and other minerals and the release behavior of lithium in the liquid phase.First,the feasibility of extracting lithium from car-rier minerals is confirmed based on the occurrence state and the process mineralogy characterized by Bgrimm process mineralogy analyz-ing system(BPMA)and time of flight secondary ion mass spectrometry(TOF-SIMS).The optimal selective grinding behavior is achieved within 15 min,allowing Li carrier minerals,including chlorite,kaolinite,and halloysite,to deliver the best dispersion effect with other minerals.Thus,the enriched lithium carrier minerals have been preenriched through screening.The leaching efficiency of Li has reached 97.43%under 1 mol/L hydrochloric acid,15 g/L pulp density,70℃,and 20 min.Leaching kinetics studies indicate that the de-crease in apparent energy validates the impact of grinding on metal leaching,aligning with the rate-controlling step of a chemical reaction.The process proposed in this study achieves the coordinated control of size and components in coal gangue and actualizes the effective se-lective enrichment of lithium through its low energy consumption and environmentally friendly nature.展开更多
Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a c...Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province,southwest China,was used as the research object.The content,modes of occurrence,and extraction(acid leaching after pretreatment of selective grinding,tailings discarding,and alkali roasting)of REY from the sample were analyzed.The result shows that the content of REY(1038.26μg/g)in pyrite and quartz is low but mainly enriched in kaolinite.Under the following conditions of a filling ratio of 40%(grinding media steel ball)and grinding time of 8 min,selective grinding pretreatment is applied to achieve 176.95μg/g(yield 24.08%)and 1104.93μg/g(yield 75.92%)of REY in+2 mm and-2 mm fractions,respectively.Thus,the-2 mm coal gangue fraction is selected,used as the feed,and roasted and leached with HCl.When Na_(2)CO_(3)and NaCl are separately used as roasting activators,the REY leaching ratios are 91.41%and 68.88%,respectively,under the optimum conditions.The contents of REY in the final leachate are 1010.02 and 761.08μg/g when Na_(2)CO_(3)and NaCl are used,respectively.The two REY contents are relatively higher than the impurity ions in the leachate,which facilitates further REY separation.The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue,which promotes leachate penetration and improves reaction efficiency.In addition,roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts,thus releasing REY into the solution.The appropriate roasting temperature transforms the activator into a molten state.Thus,the reaction between coal gangue and activator is a solid-liquid reaction rather than a solid-solid reaction,which improves the efficiency of the chemical reaction.展开更多
Sulfuric acid slag,a common byproduct with high iron content,poses challenges due to its high levels of harmful impurities and is often discarded as solid waste,leading to significant environmental and water pollution...Sulfuric acid slag,a common byproduct with high iron content,poses challenges due to its high levels of harmful impurities and is often discarded as solid waste,leading to significant environmental and water pollution.To address this issue and improve resource utilization,the preparation process of oxidized pellets from sulfuric acid slag was studied,exploring suitable pelletizing systems and thermal parameters.Additionally,the removal of harmful elements and the consolidation mechanism were established during the oxidation roasting process.The findings revealed that sulfuric acid slag along with specific processing conditions,such as using two high-pressure grinding rolls and adding 1.25 wt.%bentonite,resulted in the production of qualified green pellets with desirable physical properties.Through a thermal treatment process involving preheating and roasting,the desulfurization rate of the pellets reached 95.55%and the removal efficiency of arsenic achieved 27.11%.Hematite recrystallizes,shrinks,and forms a reticulated structure with Fe2O3 recrystallization as the backbone,resulting in higher consolidation strength.展开更多
The machining precision of blades is critical to the service performance of aero engines.The Leading Edge(LE) of high-pressure compressor blades poses a challenge for precision machining due to its thin size, high deg...The machining precision of blades is critical to the service performance of aero engines.The Leading Edge(LE) of high-pressure compressor blades poses a challenge for precision machining due to its thin size, high degree of bending, and significant change of curvature. Aimed at optimizing the machining error, this paper presents a framework that integrates toolpath planning and process parameter regulation. Firstly, an Iterative Subdivision Algorithm(ISA) for clamped Bspline curve is proposed, based on which toolpath planning method towards the LE is developed.Secondly, the removal effect of Cutter Contact(CC) point on the sampling points is investigated in the calculation of grinding dwell time by traversing in u-v space. A global material removal model is constructed for the solution. Thirdly, the previous two steps are interconnected based on the Improved Whale Optimization Algorithm(IWOA), and the optimal parameter combination is searched using the Root Mean Square Error(RMSE) of the machining error as the objective function. Based on this, the off-line programming and robotic grinding experiments are carried out. The experimental results show that the proposed method with error optimization can achieve 0.0143 mm mean value and 0.0160 mm standard deviations of LE surface error, which is an improvement of32.5% and 33.9%, respectively, compared with previous method.展开更多
Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials,including single-crystal silicon,silicon carbide,and gallium arsenide.Surface roughness and sub...Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials,including single-crystal silicon,silicon carbide,and gallium arsenide.Surface roughness and subsurface damage depth(SDD)are crucial indicators for evaluating the surface quality of these materials after grinding.Existing prediction models lack general applicability and do not accurately account for the complex material behavior under grinding conditions.This paper introduces novel models for predicting both surface roughness and SDD in hard and brittle semiconductor materials.The surface roughness model uniquely incorporates the material’s elastic recovery properties,revealing the significant impact of these properties on prediction accuracy.The SDD model is distinguished by its analysis of the interactions between abrasive grits and the workpiece,as well as the mechanisms governing stress-induced damage evolution.The surface roughness model and SDD model both establish a stable relationship with the grit depth of cut(GDC).Additionally,we have developed an analytical relationship between the GDC and grinding process parameters.This,in turn,enables the establishment of an analytical framework for predicting surface roughness and SDD based on grinding process parameters,which cannot be achieved by previous models.The models were validated through systematic experiments on three different semiconductor materials,demonstrating excellent agreement with experimental data,with prediction errors of 6.3%for surface roughness and6.9%for SDD.Additionally,this study identifies variations in elastic recovery and material plasticity as critical factors influencing surface roughness and SDD across different materials.These findings significantly advance the accuracy of predictive models and broaden their applicability for grinding hard and brittle semiconductor materials.展开更多
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)+3 种基金the Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology(No.JSKL2223K01)the Natural Science Foundation of Jiangsu Province(No.BK20210295)the Superior Postdoctoral Project of Jiangsu Province(No.2022ZB215)the Henan Science and Technology Public Relations Project(No.212102210445).
文摘The undeformed chip thickness and grinding force are key parameters for revealing the material removal mechanism in the grinding process.However,they are difficult to be well expressed due to the ununiformed protrusion height and random position distribution of abrasive grains on the abrasive wheel surface.This study investigated the distribution of undeformed chip thickness and grinding force considering the non-uniform characteristics of abrasive wheel in the grinding of K4002 nickel-based superalloy.First,a novel grinding force model was established through a kinematic-geometric analysis and a grain-workpiece contact analysis.Then,a series of grinding experiments were conducted for verifying the model.The results indicate that the distribution of undeformed chip thickness is highly consistent with the Gaussian distribution formula.The increase in the grinding depth mainly leads to an increase in the average value of Gaussian distribution.On the contrary,the increase in the workpiece infeed speed or the decrease in the grinding speed mainly increases the standard deviation of Gaussian distribution.The average and maximum errors of the grinding force model are 4.9%and 14.6%respectively,indicating that the model is of high predication accuracy.
基金Projects(U22B2084,52275483,52075142)supported by the National Natural Science Foundation of ChinaProject(2023ZY01050)supported by the Ministry of Industry and Information Technology High Quality Development,China。
文摘The gears of new energy vehicles are required to withstand higher rotational speeds and greater loads,which puts forward higher precision essentials for gear manufacturing.However,machining process parameters can cause changes in cutting force/heat,resulting in affecting gear machining precision.Therefore,this paper studies the effect of different process parameters on gear machining precision.A multi-objective optimization model is established for the relationship between process parameters and tooth surface deviations,tooth profile deviations,and tooth lead deviations through the cutting speed,feed rate,and cutting depth of the worm wheel gear grinding machine.The response surface method(RSM)is used for experimental design,and the corresponding experimental results and optimal process parameters are obtained.Subsequently,gray relational analysis-principal component analysis(GRA-PCA),particle swarm optimization(PSO),and genetic algorithm-particle swarm optimization(GA-PSO)methods are used to analyze the experimental results and obtain different optimal process parameters.The results show that optimal process parameters obtained by the GRA-PCA,PSO,and GA-PSO methods improve the gear machining precision.Moreover,the gear machining precision obtained by GA-PSO is superior to other methods.
基金Supported by National Natural Science Foundation of China(Grant Nos.52205481,52305477)Outstanding Youth Innovation Team in Universities of Shandong Province(Grant No.2023KJ114)+2 种基金Qingdao Science and Technology Planning Park Cultivation Plan(Grant No.23-1-5-yqpy-17-qy)Young Talent of Lifting engineering for Science and Technology in Shandong(Grant No.SDAST2024QTA043)Key Lab of Industrial Fluid Energy Conservation and Pollution Control(Ministry of Education)(Grant No.CK-2024-0033)。
文摘Microgrinding is widely used in clinical bone surgery,but saline spray cooling faces technical challenges such as low wettability at the microgrinding tool–bone interface,easy clogging of the microgrinding tools,and high grinding temperatures.These issues can lead to bone necrosis,irreversible thermal damage to nerves,or even surgical failure.Inspired by the water-trapping and directional transportation abilities of desert beetles,this study proposes a biomimetic desert beetle microgrinding tool.The flow-field distribution directly influences the convective heat transfer of the cooling medium in the grinding zone,which in turn affects the grinding temperature.To address this,a mathematical model of the two-phase flow field at the biomimetic microgrinding tool–bone interface is developed.The results indicate an average error of 14.74%between the calculated and experimentally obtained airflow field velocities.Next,a biomimetic desert beetle microgrinding tool is prepared.Experiments with physiological saline spray cooling were conducted on fresh bovine femur bone,which has mechanical properties similar to human bone.Results show that,compared with conventional microgrinding tools,the biomimetic tools reduced bone surface temperature by 21.7%,13.2%,5.8%,20.3%,and 25.8%at particle sizes of 150#,200#,240#,270#,and 300#,respectively.The surface morphology of the biomimetic microgrinding tools after grinding is observed and analyzed,revealing a maximum clogging area reduction of 23.0%,which is 6.1%,6.0%,10.0%,15.6%,and 9.5%less than that observed with conventional tools.Finally,this study unveils the dynamic mechanism of cooling medium transfer in the flow field at the biomimetic microgrinding tool–bone interface.This research provides theoretical guidance and technical support for clinical bone resection surgery.
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 National Natural Science Foundation of China(Grant No.52475137)Sichuan Provincial Science and Technology Program(Grant No.2024YFHZ0280)Sichuan Provincial Nature and Science Foundation Innovation Research Group Project(Grant No.2023NSFSC1975).
文摘During the grinding train operation process,the grinding force between the grinding wheel and the rail is critical in ensuring the grinding quality and efficiency.The coupling vibration among the frame,the grinding wheels,and the wheelsets will seriously affect the stability of the grinding force.In this paper,the coupled mechanical model of the grinding wheel/rail is established based on the contact mechanics theory,which is embedded as a submodel into the dynamic model of the multi-rigid buggy.The interaction among the frame,the grinding wheels and the wheelsets is analysed by setting the convex irregularity on the rail.The grinding effect is evaluated in combination with the subway’s long wave corrugation grinding conditions.The results show that when the grinding buggy passes the convex irregularity,the vibration excited by the wheelset system has a significant impact on the dynamic behavior of the grinding wheels.The vibration of the grinding wheel is mainly transmitted between the grinding wheel and the frame,less affecting the wheelset.For the long wave corrugation of the subway,the grinding effect of the grinding wheel has a certain correlation with the phase angle of the wheelset through the corrugation.The research results provide an important reference for the setting of the grinding pattern.
基金co-supported by the Enterprise Innovation and Development Joint Program of the National Natural Science Foundation of China(No.U20B2032)Open Project Funding of State Key Laboratory for High Performance Tools(GXNGJSKL-2024-08)+1 种基金Open Foundation of the State Key Laboratory of Intelligent Manufacturing Equipment and Technology(IMETKF2023005)Introduced Innovative Scientific Research Team Project of Zhongshan(the tenth batch)(CXTD2023008)。
文摘Micro-grinding has been widely used in aerospace and other industry.However,the small diameter of the micro-grinding tool has limited its machining performance and efficiency.In order to solve the above problems,micro-structure has been applied on the micro-grinding tool.A morphology modeling has been established in this study to characterize the surface of microstructured micro-grinding tool,and the grinding performance of micro-structured micro-grinding tool has been analyzed through undeformed chip thickness,abrasive edge width,and effective distance between abrasives.Then deviation analysis,path optimization and parameter optimization of microchannel array precision grinding have been finished to improve processing quality and efficiency,and the deflection angle has the most obvious effects on the rectangular slot depth,micro-structured micro-grinding tool could reduce 10%surface roughness and 20%grinding force compared to original micro-grinding tool.Finally,the microchannel array has been machined with a size deviation of 2μm and surface roughness of 0.2μm.
基金Supported by National Natural Science Foundation of China(Grant Nos.52475480,51805334)Guangdong Basic and Applied Basic Research Foundation(Grant Nos.2023A1515030249,2023A1515110059)Shenzhen Science and Technology Program(Grant No.GJHZ20220913144212023).
文摘SiC-reinforced aluminum matrix(SiCp/Al)composite is widely utilized in the aerospace,automotive,and electronics industries due to the combination of ceramic hardness and metal toughness.However,the significant disparity in properties between SiC particles and the aluminum matrix results in severe tool wear and diminished surface quality during conventional machining.This study proposes an environmentally friendly and clean dry electrical discharge assisted grinding process as an efficient and low-damage machining method for SiCp/Al.An experimental platform was set up to study the impact of grinding and discharge process parameters on surface quality.The study compared the chip formation mechanism and surface quality between dry electrical discharge assisted grinding and conventional grinding,revealing relationships between surface roughness,grinding force,grinding temperature,and related parameters.The results indicate that the proposed grinding method leads to smaller chip sizes,lower grinding forces and temperatures,and an average reduction of 19.2%in surface roughness compared to conventional grinding.The axial,tangential,and normal grinding forces were reduced by roughly 10.5%,37.8%,and 23.0%,respectively.The optimized process parameters were determined to be N=2500 r/min,vf=30 mm/min,a=10μm,E=15 V,f=5000 Hz,dc=80%,resulting in a surface roughness of 0.161μm.
基金Projects(52275483,52075142,U22B2084)supported by the National Natural Science Foundation of ChinaProject(JZ2023HGPA0292)supported by the Fundamental Research Funds for the Central Universities of China。
文摘Gear flank modification is essential to reduce the noise generated in the gear meshing process,improve the gear transmission performance,and reduce the meshing impact.Aiming at the problem of solving the additional motions of each axis in the higher-order topology modification technique and how to accurately add the different movements expressed in the form of higher-order polynomials to the corresponding motion axes of the machine tool,a flexible higher-order gear topology modification technique based on an electronic gearbox is proposed.Firstly,a two-parameter topology gear surface equation and a grinding model of wheel grinding gears are established,and the axial feed and tangential feed are expressed in a fifth-order polynomial formula.Secondly,the polynomial coefficients are solved according to the characteristics of the point contact when grinding gears.Finally,an improved electronic gearbox model is constructed by combining the polynomial interpolation function to achieve gear topology modification.The validity and feasibility of the modification method based on the electronic gearbox are verified by experimental examples,which is of great significance for the machining of modification gears based on the continuous generative grinding method of the worm grinding wheel.
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Funded by the National Natural Science Foundation of China(No.52178216)the Gansu Provincial Science and Technology Programme(No.23JRRA813)。
文摘The effects of calcination temperature and mechanical ball milling on the physicochemical properties of electrolytic manganese residue(EMR),mineral phase transition,pozzolanic activity,and pore structure were studied.The experimental results show that the strength activity index(SAI)of 20%EMR mixed mortar at 28 days is 90.54%,95.40%,and 90.73%,respectively,after pretreatment with EMR at 800℃calcined for 3,5,and 8 min.This is mainly attributed to the high temperature decomposition of gypsum dihydrate to form activated calcium oxide.In addition,high temperature and mechanical force destroys the Si-O chemical bond and promotes the formation of calcium silicate gel structure.Due to the existence of a large number of gypsum phases in EMR mixed mortar,a large number of ettringite,C-S-H,aluminosilicate,C-A-S-H,and AFm are formed,which strongly verifies the volcanic activity of EMR.The leaching test shows that high temperature calcination has a significant effect on the stabilization of NH_(3)-N.However,the curing effect of Mn^(2+)is significant only in the calcination at 1000℃,but both Mn^(2+)and NH_(3)-N in the calcined EMR are higher than the emission standard.The encapsulation effect of EMR composite mortar provided by hydration products,and the buffering capacity of the Si-Al system for solidification of heavy metals and strong alkalis are conducive to the stability of Mn^(2+)and NH_(3)-N.After the EMR mixed mortar is aged for 3 days,Mn and NH_(3)-N are completely lower than the emission standard.In general,the EMR mixed mortar can meet the requirements for green building use.
基金supported financially by the National Natural Science Foundation of China(Grant No.12275047).
文摘In ball milling,the process parameters are decisive in influencing the quality and performance of the final ball-milled product,and crucial but often neglected is the ratio of the grinding balls in terms of their size.Here,for a given number of large grinding balls,the ratio of large to small ones is set to 1:2,1:3,1:4,and 1:5 by altering the number of small ones,and how this affects the morphology,structure,and electrochemical properties of ball-milled graphene nanosheets is investigated.The results show that changing the ball ratio causes distinct changes in the morphology,structure,and properties of the graphene nanosheets.Increasing the number of small(6 mm)grinding balls decreases the nanosheet grain size monotonically;meanwhile,the crystal plane spacing,defect density,and specific surface area increase and then decrease,but the graphitization degree decreases and then increases.Ball-milled samples are then used as anodes for lithium-ion batteries,and both the specific capacity and rate capability exhibit the same trend of increase and then decrease.The ball ratio of 1:3 gives the best electrochemical performance,i.e.,a reversible specific capacity of 262.09 mA·h/g at a current density of 100 mA/g,and even after 2000 cycles at 2000 mA/g,the reversible specific capacity is 87.4%of the optimal value.
基金Funded by the National Natural Science Foundation of China(Nos.U1905216 and 52108208)the Henan Provincial Science and Technology Research Project(No.212102310559)。
文摘The mechanochemical synthesis of polycarboxylate superplasticizers(PCEs)was achieved using a planetary ball mill at ambient temperature.The effects of ball milling parameters,including speed,time,and stop method,on PCE performance,molecular weight,and distribution were investigated to optimize conditions.The experimental results suggest that ball milling impacts PCE molecular weight and distribution,striking a balance between polymerization and mechanical degradation during synthesis.The optimal parameters were found to be 400 rpm,120 minutes total time,and 30 minutes milling plus 3 minutes rest cycles.Under these conditions,the PCE exhibits excellent dispersibility with a cement paste fluidity of 260 mm.The mechanochemical approach eliminates heating requirements,and also reduces the reaction time from 300 to 120 minutes compared to traditional aqueous synthesis.The optimized PCE demonstrates an increased density of long-side chains,leading to enhanced early strength,heightens adsorption,and diminished zeta potential in cement systems.These characteristics are comparable to traditionally synthesized PCEs.Moreover,at higher dosages,further augmentation of PCE adsorption and increased cement paste fluidity were noted here.
文摘The use of recycled concrete and oyster shells as partial cement and aggregate replacements is ongoing research to solve this multifaceted problem of concrete waste in the construction industry as well as waste from oyster shell farming. However, there is a lack of evidence on the possibility of producing a fully recycled composite consisting of recycled concrete and oyster shell without the need for new cement and natural aggregates. In this study, recycled concrete powder (RCP) and oyster shell were used to produce a green composite. Separate ground and combined ground (separate ground and co-ground) RCP and oyster shells are used to determine the effects of grinding approaches on the mechanical and chemical properties of the composite. The composite samples were molded via press molding by applying 30 MPa of pressure for 10 minutes. The results revealed that the composite prepared via the combined ground approach presented the highest flexural strength compared to the separate ground and unground samples. The FTIR and XRD characterization results revealed no chemical or phase alterations in the raw materials or the resulting composites before and after grinding. SEM analysis revealed that combined grinding reduced the particles’ size and improved the dispersion of the mixture, thereby increasing the strength.
基金supported by the National Key R&D Program of China(No.2023YFC2907701)This work was also supported by the Fundamental Research Program of Shanxi Province,China(No.202103021223045)+4 种基金the Shanxi Scholarship Council of China(No.2022-062)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi,China(No.2021L064)This study was also funded by Open Foundation of State Key Laboratory of Mineral Processing(No.BGRIMM-KJSKL-2025-26)This work was supported by the National Natural Science Foundation of China(No.52104260)This work was supported by Young Elite Scientists Sponsorship Program by CAST(No.2022QNRC001).
文摘Extracting lithium from coal measures can alleviate the shortage of strategic metal resources.However,the lattice substitution characteristics of lithium in carrier minerals and its extremely fine intercalation and entrainment behavior are the challenges that constrain the extraction efficiency of lithium from coal series.This study focuses on improving the separation efficiency between lithium-contain-ing minerals and other minerals and the release behavior of lithium in the liquid phase.First,the feasibility of extracting lithium from car-rier minerals is confirmed based on the occurrence state and the process mineralogy characterized by Bgrimm process mineralogy analyz-ing system(BPMA)and time of flight secondary ion mass spectrometry(TOF-SIMS).The optimal selective grinding behavior is achieved within 15 min,allowing Li carrier minerals,including chlorite,kaolinite,and halloysite,to deliver the best dispersion effect with other minerals.Thus,the enriched lithium carrier minerals have been preenriched through screening.The leaching efficiency of Li has reached 97.43%under 1 mol/L hydrochloric acid,15 g/L pulp density,70℃,and 20 min.Leaching kinetics studies indicate that the de-crease in apparent energy validates the impact of grinding on metal leaching,aligning with the rate-controlling step of a chemical reaction.The process proposed in this study achieves the coordinated control of size and components in coal gangue and actualizes the effective se-lective enrichment of lithium through its low energy consumption and environmentally friendly nature.
基金Project supported by the National Natural Science Foundation of China(51964009)。
文摘Co-associated rare earth elements(lanthanide and yttrium,REY)in coal and its by-products have been considered important potential nontraditional rare earth sources.In this study,a coal gangue sample collected from a coal processing plant in Jinsha County of Guizhou Province,southwest China,was used as the research object.The content,modes of occurrence,and extraction(acid leaching after pretreatment of selective grinding,tailings discarding,and alkali roasting)of REY from the sample were analyzed.The result shows that the content of REY(1038.26μg/g)in pyrite and quartz is low but mainly enriched in kaolinite.Under the following conditions of a filling ratio of 40%(grinding media steel ball)and grinding time of 8 min,selective grinding pretreatment is applied to achieve 176.95μg/g(yield 24.08%)and 1104.93μg/g(yield 75.92%)of REY in+2 mm and-2 mm fractions,respectively.Thus,the-2 mm coal gangue fraction is selected,used as the feed,and roasted and leached with HCl.When Na_(2)CO_(3)and NaCl are separately used as roasting activators,the REY leaching ratios are 91.41%and 68.88%,respectively,under the optimum conditions.The contents of REY in the final leachate are 1010.02 and 761.08μg/g when Na_(2)CO_(3)and NaCl are used,respectively.The two REY contents are relatively higher than the impurity ions in the leachate,which facilitates further REY separation.The mechanism study reveals that high-temperature roasting increases the pore size and the total pore area of the gangue,which promotes leachate penetration and improves reaction efficiency.In addition,roasting facilitates the reaction between the sodium salt activator and kaolinite and other aluminosilicate minerals in the coal gangue to generate soluble salts,thus releasing REY into the solution.The appropriate roasting temperature transforms the activator into a molten state.Thus,the reaction between coal gangue and activator is a solid-liquid reaction rather than a solid-solid reaction,which improves the efficiency of the chemical reaction.
基金financially supported by the Fundamental Research Funds for the Central Universities of Central South University(2023ZZTS0506).
文摘Sulfuric acid slag,a common byproduct with high iron content,poses challenges due to its high levels of harmful impurities and is often discarded as solid waste,leading to significant environmental and water pollution.To address this issue and improve resource utilization,the preparation process of oxidized pellets from sulfuric acid slag was studied,exploring suitable pelletizing systems and thermal parameters.Additionally,the removal of harmful elements and the consolidation mechanism were established during the oxidation roasting process.The findings revealed that sulfuric acid slag along with specific processing conditions,such as using two high-pressure grinding rolls and adding 1.25 wt.%bentonite,resulted in the production of qualified green pellets with desirable physical properties.Through a thermal treatment process involving preheating and roasting,the desulfurization rate of the pellets reached 95.55%and the removal efficiency of arsenic achieved 27.11%.Hematite recrystallizes,shrinks,and forms a reticulated structure with Fe2O3 recrystallization as the backbone,resulting in higher consolidation strength.
基金supported by the National Natural Science Foundation of China (No. 52075059)Graduate Scientific Research and Innovation Foundation of Chongqing (No. CYB23021)the Innovation Fund of Aero Engine Corporation of China (No. ZZCX-2022-019)。
文摘The machining precision of blades is critical to the service performance of aero engines.The Leading Edge(LE) of high-pressure compressor blades poses a challenge for precision machining due to its thin size, high degree of bending, and significant change of curvature. Aimed at optimizing the machining error, this paper presents a framework that integrates toolpath planning and process parameter regulation. Firstly, an Iterative Subdivision Algorithm(ISA) for clamped Bspline curve is proposed, based on which toolpath planning method towards the LE is developed.Secondly, the removal effect of Cutter Contact(CC) point on the sampling points is investigated in the calculation of grinding dwell time by traversing in u-v space. A global material removal model is constructed for the solution. Thirdly, the previous two steps are interconnected based on the Improved Whale Optimization Algorithm(IWOA), and the optimal parameter combination is searched using the Root Mean Square Error(RMSE) of the machining error as the objective function. Based on this, the off-line programming and robotic grinding experiments are carried out. The experimental results show that the proposed method with error optimization can achieve 0.0143 mm mean value and 0.0160 mm standard deviations of LE surface error, which is an improvement of32.5% and 33.9%, respectively, compared with previous method.
基金supported by the National Key Research and Development Program of China(2022YFB3605902)the National Natural Science Foundation of China(52375411,52293402)。
文摘Workpiece rotational grinding is widely used in the ultra-precision machining of hard and brittle semiconductor materials,including single-crystal silicon,silicon carbide,and gallium arsenide.Surface roughness and subsurface damage depth(SDD)are crucial indicators for evaluating the surface quality of these materials after grinding.Existing prediction models lack general applicability and do not accurately account for the complex material behavior under grinding conditions.This paper introduces novel models for predicting both surface roughness and SDD in hard and brittle semiconductor materials.The surface roughness model uniquely incorporates the material’s elastic recovery properties,revealing the significant impact of these properties on prediction accuracy.The SDD model is distinguished by its analysis of the interactions between abrasive grits and the workpiece,as well as the mechanisms governing stress-induced damage evolution.The surface roughness model and SDD model both establish a stable relationship with the grit depth of cut(GDC).Additionally,we have developed an analytical relationship between the GDC and grinding process parameters.This,in turn,enables the establishment of an analytical framework for predicting surface roughness and SDD based on grinding process parameters,which cannot be achieved by previous models.The models were validated through systematic experiments on three different semiconductor materials,demonstrating excellent agreement with experimental data,with prediction errors of 6.3%for surface roughness and6.9%for SDD.Additionally,this study identifies variations in elastic recovery and material plasticity as critical factors influencing surface roughness and SDD across different materials.These findings significantly advance the accuracy of predictive models and broaden their applicability for grinding hard and brittle semiconductor materials.
