To promote early rapid osteogenesis and prevent late implant-related infection,it is critical to develop ef-fective and reliable surface treatment technologies for enhancing both osteogenic and antibacterial prop-erti...To promote early rapid osteogenesis and prevent late implant-related infection,it is critical to develop ef-fective and reliable surface treatment technologies for enhancing both osteogenic and antibacterial prop-erties of titanium alloy implants.Reduced graphene oxide(rGO)is considered a promising modification candidate.However,whether rGO retains its osteogenic and antibacterial functions after being applied to modify titanium alloy surfaces depends on the surface treatment technology employed.In this study,rGO was integrated onto the surface of Ti-35Nb-2Ta-3Zr(TNTZ)alloy through friction stir processing(FSP),yielding a consolidated TNTZ/F-rGO composite.The incorporation of rGO not only significantly im-proved the microhardness and hydrophilicity of the material,but also exhibited positive biological effects in vitro experiments:it effectively promoted the proliferation,osteogenic differentiation,alkaline phos-phatase(ALP)production and extracellular matrix mineralization of BMSCs.Furthermore,TNTZ/F-rGO ex-hibited potent antibacterial activity via surface-contact mechanisms.In summary,the rGO-modified in-tegrated titanium alloy has excellent osteogenic properties and high-efficiency antibacterial ability.This study provides new insights and strategies for the design of graphene-based biomaterials and implant surface modification technologies.展开更多
Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work...Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work, a method was established for identifying the extrusion process window considering temperature control using response surface methodology. Firstly, the response surface models, which correlate temperature rise and peak temperature to key extrusion parameters, have been developed by orthogonal regression based on finite element calculated data. Secondly, the coupled effects of the key extrusion parameters on the temperature rise and peak temperature have been disclosed based on the regression models. Lastly, suitable extrusion processing windows, which are described by contour map of peak temperature in the space of extrusion speed and initial billet temperature, have been established for different extrusion ratios. Using the identified process window, a suitable combination of the key extrusion parameters can be determined conveniently and quickly.展开更多
Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing （FRSP）. Severe strain was imposed into the surface layer and strain gradient wa...Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing （FRSP）. Severe strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique On the surface of the sheets, ultra-fine grains were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during recrystallization were also studied by electron back-scattered diffraction （EBSD） technique after being annealed at selected temperatures and time. The results indicated that the preferred orientations resulting from FRSP and annealing in the surface layer were formed during rolling and its recrystallization textures were reduced by FRSP. In addition, the texture evolved stably without change in main components during the annealing.展开更多
The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensil...The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensile stress to compressive stress,decreasing the surface roughness and increasing the ratio of the β-Li phase.The USRPed LZ91 sample(3 passes)showed superior corrosion resistance,with the corrosion current density changing from 57.11 to 24.70μA cm^(-2),and the polarization resistance increasing from 576.3 to 1146.1Ωcm^(2).According to the corrosion procedure evaluations,in situ observation revealed that the LZ91 alloy initially experiences pitting,which subsequently develops into cracking.The substantial area coverage of the β-Li phase facilitates the formation of a protective film on the surface,effectively delaying localized corrosion.展开更多
Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative cont...Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.展开更多
[Objectives] To optimize the crystallization process of ceftriaxone sodium using response surface methodology (RSM) for enhancing both the crystallization rate and the quality of the final product. [Methods] Four key ...[Objectives] To optimize the crystallization process of ceftriaxone sodium using response surface methodology (RSM) for enhancing both the crystallization rate and the quality of the final product. [Methods] Four key factors, including crystallization temperature, stirring speed, solvent drop rate, and seed crystal content, were employed as independent variables, while the crystallization rate served as the response variable. The Box-Behnken response surface method was utilized for the optimization design. [Results] The optimal parameters for the crystallization process, determined through optimization, were as follows: a temperature of 10.6 ℃, a stirring rate of 150 rpm, a solvent drop rate of 1.50 mL/min, and a seed crystal content of 0.12 g. Validation tests conducted under these conditions yielded an average crystallization rate of 94.38% for the refined product. [Conclusions] The crystallization efficiency of ceftriaxone sodium is markedly enhanced, thereby offering substantial support for its industrial production and clinical application.展开更多
Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, sa...Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, samples of bionic non-smooth surfaces of stainless steel 0Crl 8Ni9 were manufactured in the form of reseau structure by laser multiple processing. The mechanical properties (including microhardness, residual stress, surface roughness) and microstructure of the samples treated by laser multiple processing were compared with those of the samples without LSP The results show that the mechanical properties of these samples by laser multiple processing were clearly improved in comparison with those of the samples without LSP The mechanisms underlying the improved surface microhardness and surface residual stress were analyzed, and the relations between hardness, comnressive residual stress and roughness were also presented.展开更多
This study investigates the effects of the ultrasonic surface rolling process(USRP)on the surface microstructure,texture,and wear behavior of commercial AZ31 magnesium alloy sheet.The application of USRP induces a dep...This study investigates the effects of the ultrasonic surface rolling process(USRP)on the surface microstructure,texture,and wear behavior of commercial AZ31 magnesium alloy sheet.The application of USRP induces a depth-dependent gradient microstructure characterized by a gradual transition from fine-grained surface layers to coarser-grained regions.Severe plastic deformation at the surface significantly enhances surface microhardness,with values increasing from 63.8 HV in the untreated specimen to 132.9 HV after USRP-4 passes.The thickness of the plastic deformation layer exhibits process-dependent behavior,growing from 200μm(two passes)to 250μm(four passes).Wear test results indicate that the wear resistance of the material is significantly enhanced after USRP treatment.This improvement is primarily attributed to the combined effects of the following factors:surface grain refinement,the role of dislocation-induced twinning,increased hardness,the formation of nanoscale secondary phases,introduction of residual compressive stresses,weakened surface texture,and reduced surface roughness.Notably,both friction coefficients and wear volumes show a direct dependence on the number of rolling passes.This study systematically elucidates the underlying mechanisms linking USRP-induced microstructural evolution to enhanced wear performance,providing critical insights for optimizing surface engineering strategies in magnesium alloys.展开更多
Inconel 718 superalloy has extensive applications in a variety of industries such as the moulding,aerospace and medical due to its excellent mechanical features such as poor thermal conductivity,high strength at high ...Inconel 718 superalloy has extensive applications in a variety of industries such as the moulding,aerospace and medical due to its excellent mechanical features such as poor thermal conductivity,high strength at high temperatures and corrosion resistance.However,it is very difficult to process by traditional machining and finishing methods.Abrasive based finishing process is one of non-traditional finishing method applied to complex surfaces.Shot peening process is one of the surface treatment processes mostly applied to improve the surface strength.The superior advantages of these two processes are combined into one process.This newly developed and patented process is called as GOV process.In this study,the effects of GOV process parameters(number of cycles,steel ball size,media concentration)on the surface quality of Inconel 718 already pre-processed by wire electric discharge machining are investigated.The performance parameters are identified as surface roughness,material removal and white layer thickness.Surface finishing with the GOV process improves the surface roughness,Ra value by decreasing from 2.63μm to 0.46μm by removing micro-level chips up to 10.7 mg which is supported by SEM images.White layer formed due to nature of EDM process is completely removed from specimen surface.展开更多
The Zoige Basin,located in the eastern region of the Tibetan Plateau of China,is characterized by its climate sensitivity and complex surface environment.It is vital to understand the response of the surface processes...The Zoige Basin,located in the eastern region of the Tibetan Plateau of China,is characterized by its climate sensitivity and complex surface environment.It is vital to understand the response of the surface processes to environmental changes in the Zoige Basin since the last deglaciation,as well as the response of environmental changes and surface processes on the Tibetan Plateau relate to global changes.In August 2020,a field investigation was conducted in the Zoige Basin.A complete set of stratigraphic profile from the high platform at the front of the glacial-diluvial fan in the Maqu reach of the western basin was selected as the research subject.Optically stimulated luminescence(OSL)dating samples and sedimentary samples were collected from key layers and brought back to the laboratory for experimental analysis,and the surface processes and environment changes since the last deglaciation in the Zoige Basin were investigated through particle size analysis and OSL dating.The results showed that during the last glacial period before 14.5 kyr,a substantial glacial-alluvial fan composed of sand and gravel layers was formed by flash flood processes triggered by glacial meltwater and heavy precipitation.In the Bølling-Allerød warm period of 14.5–11.7 kyr,a warm and humid climate prevailed,with the formation of silty bog environments in the shallow depressions at the glacial-alluvial fan's forefront and the development of gray-green bog soil deposits.However,during the Younger Dryas period,an abrupt climate deterioration occurred,with the upper section of the gray-green bog soil layer in the shallow depression to experience folding and deformation due to surface freeze-thaw actions.During the early Holocene period from 11.7 kyr to 8.5 kyr,the climate was relatively dry,resulting in prevalent aeolian sand activitities.Coarse silt accumulated in the shallow depression,and sedimentary facies alternating between aeolian sand and bog soil deposits developed owing to strong wind patterns on the plateau surface.In the warm and humid period from 8.5 kyr to 3.1 kyr,increased weathering and pedogenesis enhanced clay content in sediments,which developed into the paleosol.In the late Holocene,starting from 3.1 kyr,the climate became relatively dry once more,with aeolian sand activity prevalent.The coarse silt that accumulated during the late Holocene transformed into subalpine meadow black soil because of rising temperature and humidity levels.These findings indicated that the developmental process of the high platform in the Maqu reach of the Zoige Basin,which was significant for understanding the environmental changes and surface processes in the source region of the Yellow River since the last deglaciation.展开更多
To solve the problems of deformation,micro-cracks,and residual tensile stress in laser cladding coatings,the technique of laser cladding with Fe-based memory alloy can be considered.However,the process of in-situ synt...To solve the problems of deformation,micro-cracks,and residual tensile stress in laser cladding coatings,the technique of laser cladding with Fe-based memory alloy can be considered.However,the process of in-situ synthesis of Fe-based memory alloy coatings is extremely complex.At present,there is no clear guidance scheme for its preparation process,which limits its promotion and application to some extent.Therefore,in this study,response surface methodology(RSM)was used to model the response surface between the target values and the cladding process parameters.The NSGA-2 algorithm was employed to optimize the process parameters.The results indicate that the composite optimization method consisting of RSM and the NSGA-2 algorithm can establish a more accurate model,with an error of less than 4.5%between the predicted and actual values.Based on this established model,the optimal scheme for process parameters corresponding to different target results can be rapidly obtained.The prepared coating exhibits a uniform structure,with no defects such as pores,cracks,and deformation.The surface roughness and microhardness of the coating are enhanced,the shaping quality of the coating is effectively improved,and the electrochemical corrosion performance of the coating in 3.5%NaCl solution is obviously better than that of the substrate,providing an important guide for engineering applications.展开更多
The present study was designed to optimize the processing of Fructus Arctii by response surface methodology （RSM）. Based on single factor studies, a three-variable, three-level Box-Behnken design （BBD） was used to...The present study was designed to optimize the processing of Fructus Arctii by response surface methodology （RSM）. Based on single factor studies, a three-variable, three-level Box-Behnken design （BBD） was used to monitor the effects of independent variables, including processing temperature and time, on the dependent variables. Response surfaces and contour plots of the contents of total lignans, chlorogenic acid, arctiin, and aretigenin were obtained through ultraviolet and visible （UV-Vis） monitoring and high performance liquid chromatography （HPLC）. Fructus Arctii should be processed under heating in a pot at 311℃, medicine at 119℃ for 123s with flipping frequently. The experimental values under the optimized processing technology were consistent with the predicted values. In conclusion, RSM is an effective method to optimize the processing of traditional Chinese medicine （TCM）.展开更多
A new surface inspection system for cold rolled strips based on image processing is introduced. The system is equipped withtwo different illumination structures and CCD matrix cameras. The structure and image processi...A new surface inspection system for cold rolled strips based on image processing is introduced. The system is equipped withtwo different illumination structures and CCD matrix cameras. The structure and image processing of the inspection system are described. Some efficient algorithms for image processing and classification are presented. The system is tested with strip samples fromcold rolling plants. The results show that the system can detect and recognize six common defects of cold rolled strips successfully.展开更多
This monograph presents an overview of friction stir processing(FSP)of surface metal-matrix composites(MMCs)using the AZ91 magnesium alloy.The reported results in relation to various reinforcing particles,including si...This monograph presents an overview of friction stir processing(FSP)of surface metal-matrix composites(MMCs)using the AZ91 magnesium alloy.The reported results in relation to various reinforcing particles,including silicon carbide(SiC),alumina(Al_(2)O_(3)),quartz(SiO_(2)),boron carbide(B_(4)C),titanium carbide(TiC),carbon fiber,hydroxyapatite(HA),in-situ formed phases,and hybrid reinforcements are summarized.AZ91 composite fabricating methods based on FSP are explained,including groove filling(grooving),drilled hole filling,sandwich method,stir casting followed by FSP,and formation of in-situ particles.The effects of introducing second-phase particles and FSP process parameters(e.g.,tool rotation rate,traverse speed,and the number of passes)on the microstructural modification,grain refinement,homogeneity in the distribution of particles,inhibition of grain growth,mechanical properties,strength–ductility trade-off,wear/tribological behavior,and corrosion resistance are discussed.Finally,useful suggestions for future work are proposed,including focusing on the superplasticity and superplastic forming,metal additive manufacturing processes based on friction stir engineering(such as additive friction stir deposition),direct FSP,stationary shoulder FSP,correlation of the dynamic recrystallization(DRX)grain size with the Zener–Hollomon parameter similar to hot deformation studies,process parameters(such as the particle volume fraction and external cooling),and common reinforcing phases such as zirconia(ZrO_(2))and carbon nanotubes(CNTs).展开更多
Surface metal matrix composites(MMCs)are a group of modern engineered materials where the surface of the material is modified by dispersing secondary phase in the form of particles or fibers and the core of the materi...Surface metal matrix composites(MMCs)are a group of modern engineered materials where the surface of the material is modified by dispersing secondary phase in the form of particles or fibers and the core of the material experience no change in chemical composition and structure.The potential applications of the surface MMCs can be found in automotive,aerospace,biomedical and power industries.Recently,friction stir processing(FSP)technique has been gaining wide popularity in producing surface composites in solid state itself.Magnesium and its alloys being difficult to process metals also have been successfully processed by FSP to fabricate surface MMCs.The aim of the present paper is to provide a comprehensive summary of state-of-the-art in fabricating magnesium based composites by FSP.Influence of the secondary phase particles and grain refinement resulted from FSP on the properties of these composites is also discussed.展开更多
Rising concerns about climate change drive the demand for lightweight components.Magnesium(Mg)alloys are highly valued for their low weight,making them increasingly important in various industries.Researchers focusing...Rising concerns about climate change drive the demand for lightweight components.Magnesium(Mg)alloys are highly valued for their low weight,making them increasingly important in various industries.Researchers focusing on enhancing the characteristics of Mg alloys and developing their Metal Matrix Composites(MMCs)have gained significant attention worldwide over the past decade,driven by the global shift towards lightweight materials.Friction Stir Processing(FSP)has emerged as a promising technique to enhance the properties of Mg alloys and produce Mg-MMCs.Initially,FSP adapted to refine grain size from the micro to the nano level and accelerated the development of MMCs due to its solid-state nature and the synergistic effects of microstructure refinement and reinforcement,improving strength,hardness,ductility,wear resistance,corrosion resistance,and fatigue strength.However,producing defect-free and sound FSPed Mg and Mg-MMCs requires addressing several variables and their interdependencies,which opens up a broad range of practical applications.Despite existing reviews on individual FSP of Mg,its alloys,and MMCs,an attempt has been made to analyze the latest research on these three aspects collectively to enhance the understanding,application,and effectiveness of FSP for Mg and its derivatives.This review article discusses the literature,classifies the importance of Mg alloys,provides a historical background,and explores developments and potential applications of FSPed Mg alloys.It focuses on novel fabrication methods,reinforcement strategies,machine and tool design parameters,material characterization,and integration with other methods for enhanced properties.The influence of process parameters and the emergence of defects are examined,along with specific applications in mono and hybrid composites and their microstructure evolution.The study identifies promising reinforcement materials and highlights research gaps in FSP for Mg alloys and MMCs production.It concludes with significant recommendations for further exploration,reflecting ongoing advancements in this field.展开更多
Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium...Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium alloy.In this technique,the workpiece is vibrated normal to the processing direction.The results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the microstructure.The results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were developed.The elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.展开更多
An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The ...An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The tool rotational speed was varied from 800 to 1200 r/min in step of 200 r/min. The traverse speed, axial force, groove width and tool pin profile were kept constant. Optical microscopy and scanning electron microscopy were used to study the microstructure of the fabricated surface composites. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The results indicate that the tool rotational speed significantly influences the area of the surface composite and the distribution of B4C particles. Higher rotational speed exhibits homogenous distribution of B4C particles, while lower rotational speed causes poor distribution of B4C particles in the surface composite. The effects of tool rotational speed on the grain size, microhardness, wear rate, worn surface and wear debris were reported.展开更多
Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communicati...Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communications systems.Meanwhile,it has been recently admitted that implementing artificial intelligence(AI)into RIS communications will extensively benefit the reconfiguration capacity and enhance the robustness to complicated transmission environments.Besides the conventional model-driven approaches,AI can also deal with the existing signal processing problems in a data-driven manner via digging the inherent characteristic from the real data.Hence,AI is particularly suitable for the signal processing problems over RIS networks under unideal scenarios like modeling mismatching,insufficient resource,hardware impairment,as well as dynamical transmissions.As one of the earliest survey papers,we will introduce the merging of AI and RIS,called AIRIS,over various signal processing topics,including environmental sensing,channel acquisition,beamforming design,and resource scheduling,etc.We will also discuss the challenges of AIRIS and present some interesting future directions.展开更多
A new method of collision-free path plan integrated in virtual processing is developed to improve the efficiency of laser surface hardening on dies. The path plan is based on the premise of no collision and the optimi...A new method of collision-free path plan integrated in virtual processing is developed to improve the efficiency of laser surface hardening on dies. The path plan is based on the premise of no collision and the optimization object is the shortest path. The optimization model of collision-free path is built from traveling salesman problem （TSP）. Collision-free path between two machining points is calculated in configuration space （C-Space）. Ant colony optimization （ACO） algorithm is applied to TSP of all the machining points to find the shortest path, which is simulated in virtual environment set up by IGRIP software. Virtual machining time, no-collision report, etc, are put out atter the simulation. An example on autobody die is processed in the virtual platform, the simulation results display that ACO has perfect optimization effect, and the method of virtual processing with integration of collision-free optimal path is practical.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52272283,52311530772,and 52274387)the Science and Technology Commission of Shanghai Municipality(No.22S31902900)+4 种基金the Shanghai Medical Key Specialty(No.2024ZDXK0048)the Medical Key Subject of Xuhui District(No.SHXHZDXK202302)the National Key Research and Development Program of China(No.2024YFE0109000)the Medical-Engineering Cross Foundation of Shanghai Jiao Tong University(No.YG2024LC04)the Institute-level Research Project of Xuhui District Dental Center(No.SHXYF202212).
文摘To promote early rapid osteogenesis and prevent late implant-related infection,it is critical to develop ef-fective and reliable surface treatment technologies for enhancing both osteogenic and antibacterial prop-erties of titanium alloy implants.Reduced graphene oxide(rGO)is considered a promising modification candidate.However,whether rGO retains its osteogenic and antibacterial functions after being applied to modify titanium alloy surfaces depends on the surface treatment technology employed.In this study,rGO was integrated onto the surface of Ti-35Nb-2Ta-3Zr(TNTZ)alloy through friction stir processing(FSP),yielding a consolidated TNTZ/F-rGO composite.The incorporation of rGO not only significantly im-proved the microhardness and hydrophilicity of the material,but also exhibited positive biological effects in vitro experiments:it effectively promoted the proliferation,osteogenic differentiation,alkaline phos-phatase(ALP)production and extracellular matrix mineralization of BMSCs.Furthermore,TNTZ/F-rGO ex-hibited potent antibacterial activity via surface-contact mechanisms.In summary,the rGO-modified in-tegrated titanium alloy has excellent osteogenic properties and high-efficiency antibacterial ability.This study provides new insights and strategies for the design of graphene-based biomaterials and implant surface modification technologies.
基金Project(2009ZX04005-031-11)supported by the Major National Science and Technology Special Project of ChinaProject(318968)supported by the Marie Curie International Research Staff Exchange Scheme(IRSES,Mat Pro Future)within the 7th EC Framework Program(FP7)Project(B08040)supported by the 111 Plan,China
文摘Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work, a method was established for identifying the extrusion process window considering temperature control using response surface methodology. Firstly, the response surface models, which correlate temperature rise and peak temperature to key extrusion parameters, have been developed by orthogonal regression based on finite element calculated data. Secondly, the coupled effects of the key extrusion parameters on the temperature rise and peak temperature have been disclosed based on the regression models. Lastly, suitable extrusion processing windows, which are described by contour map of peak temperature in the space of extrusion speed and initial billet temperature, have been established for different extrusion ratios. Using the identified process window, a suitable combination of the key extrusion parameters can be determined conveniently and quickly.
基金support in part by Grant-in-aid for Scientific Research from the Japan Society for Promotion of Science under Contract No. 16560605
文摘Commercial purity and high purity titanium sheets were initially strained by a new technique, named as friction roll surface processing （FRSP）. Severe strain was imposed into the surface layer and strain gradient was formed through the thickness of the sheet. The microstructure and texture in as-strained state were investigated by optical microscopy and X-ray diffraction technique On the surface of the sheets, ultra-fine grains were found to have a sharp texture with a preferred orientation strongly related to the FRSP direction. The evolution of microstructure and crystallographic texture of FRSPed samples during recrystallization were also studied by electron back-scattered diffraction （EBSD） technique after being annealed at selected temperatures and time. The results indicated that the preferred orientations resulting from FRSP and annealing in the surface layer were formed during rolling and its recrystallization textures were reduced by FRSP. In addition, the texture evolved stably without change in main components during the annealing.
基金financially supported by the National Natural Science Foundation of China(No.52271091)the National Key Research and Development Program of China(No.2021YFB3701100)the Natural Science Foundation Project of Ningxia Province(No.2023AAC03324).
文摘The Mg-9Li-1Zn(LZ91)alloy was subjected to an ultrasonic surface rolling process(USRP)with varying passes for the purpose of modifying its surface state.The USRP transformed surface residual stress from initial tensile stress to compressive stress,decreasing the surface roughness and increasing the ratio of the β-Li phase.The USRPed LZ91 sample(3 passes)showed superior corrosion resistance,with the corrosion current density changing from 57.11 to 24.70μA cm^(-2),and the polarization resistance increasing from 576.3 to 1146.1Ωcm^(2).According to the corrosion procedure evaluations,in situ observation revealed that the LZ91 alloy initially experiences pitting,which subsequently develops into cracking.The substantial area coverage of the β-Li phase facilitates the formation of a protective film on the surface,effectively delaying localized corrosion.
基金financially supported by the National Science Foundation of China(No.41920104010)the China Postdoctoral Science Foundation(No.2024M762767)+3 种基金the Fundamental Research Funds for the Central University,CHD(No.300102264104)by the Postdoctoral Fellowship Program of CPSF(No.GZC20241444)supported by Fondazione Cariplo and Fondazione CDP(No.2022-1546_001)by the Italian Ministry of Education,MUR(Project Dipartimenti di Eccellenza,TECLA,Department of Earth and Environmental Sciences,University of Milano-Bicocca)。
文摘Mantle plumes and surface erosion and sediment deposition affect the modes of continental lithospheric rupturing in extensional tectonic settings,modulating the evolution of rifting margins.However,their relative contributions to the overall evolution of rifting margins and possible roles in the formation of microcontinent are still elusive.Here,we use coupled geodynamic and surface processes numerical modeling to assess the extent to which surface processes may determine the formation of microcontinent during lithospheric stretching in presence or absence of a mantle plume underneath.Our modeling results indicate that fast extension rates and hillslope(i.e.,diffusion)erosion promote ridge jump events and therefore the formation of microcontinents.On the contrary,efficient fluvial erosion and far-reaching sediment transport(i.e.,stream power erosion)inhibits ridge jump events and the formation of microcontinents.The ridge jump event and overall evolution in our numerical models is consistent with the shift from the Mascarene Ridge to the Carlsberg Ridge that determined the formation of the Seychelles microcontinent.We therefore speculate that hillslope erosion,rather than fluvial erosion,was predominant during the formation of the Seychelles,a possible indication of overall dry local climate conditions.
基金Supported by Central Guided Local Science and Technology Development Funds(ZY20230102)Guilin Scientific Research and Technology Development Programme Project(2023010301-1,20220104-4)+1 种基金Guangxi Science and Technology Programme Project(GK AB24010263)Guangxi Innovation Driving Development Special Funds Project(GK AA22096020).
文摘[Objectives] To optimize the crystallization process of ceftriaxone sodium using response surface methodology (RSM) for enhancing both the crystallization rate and the quality of the final product. [Methods] Four key factors, including crystallization temperature, stirring speed, solvent drop rate, and seed crystal content, were employed as independent variables, while the crystallization rate served as the response variable. The Box-Behnken response surface method was utilized for the optimization design. [Results] The optimal parameters for the crystallization process, determined through optimization, were as follows: a temperature of 10.6 ℃, a stirring rate of 150 rpm, a solvent drop rate of 1.50 mL/min, and a seed crystal content of 0.12 g. Validation tests conducted under these conditions yielded an average crystallization rate of 94.38% for the refined product. [Conclusions] The crystallization efficiency of ceftriaxone sodium is markedly enhanced, thereby offering substantial support for its industrial production and clinical application.
基金supported by the National Natural Science Foundation of China (Grant No.50705038,50735001 and 10804037)the Foundation of Jiangsu Province (Grant No.06-D-023,BK2007512 and BG2007033)+2 种基金The 8th Student Research Train Program of Jiangsu University (Grant No.08A172)the Innovation Program of Graduated Student of Jiangsu Province (Grant No.XM2006-45)the Open Foundation of Jiangsu Key Laboratory of Advanced Numerical Control Technology (Grant No.KXJ07126)
文摘Laser multiple processing, i.e. laser surface texturing and then Laser Shock Processing (LSP), is a new surface processing technology for the preparation of bionic non-smooth surfaces. Based on engineering bionics, samples of bionic non-smooth surfaces of stainless steel 0Crl 8Ni9 were manufactured in the form of reseau structure by laser multiple processing. The mechanical properties (including microhardness, residual stress, surface roughness) and microstructure of the samples treated by laser multiple processing were compared with those of the samples without LSP The results show that the mechanical properties of these samples by laser multiple processing were clearly improved in comparison with those of the samples without LSP The mechanisms underlying the improved surface microhardness and surface residual stress were analyzed, and the relations between hardness, comnressive residual stress and roughness were also presented.
基金supported by the National Natural Science Foundation of China(Nos.52271107 and 52301164)Natural Science Foundation of Shandong Province(No.ZR2021ME241)supported by Young Talent of Lifting engineering for Science and Technology in Shandong,China(SDAST2025 QTA034).
文摘This study investigates the effects of the ultrasonic surface rolling process(USRP)on the surface microstructure,texture,and wear behavior of commercial AZ31 magnesium alloy sheet.The application of USRP induces a depth-dependent gradient microstructure characterized by a gradual transition from fine-grained surface layers to coarser-grained regions.Severe plastic deformation at the surface significantly enhances surface microhardness,with values increasing from 63.8 HV in the untreated specimen to 132.9 HV after USRP-4 passes.The thickness of the plastic deformation layer exhibits process-dependent behavior,growing from 200μm(two passes)to 250μm(four passes).Wear test results indicate that the wear resistance of the material is significantly enhanced after USRP treatment.This improvement is primarily attributed to the combined effects of the following factors:surface grain refinement,the role of dislocation-induced twinning,increased hardness,the formation of nanoscale secondary phases,introduction of residual compressive stresses,weakened surface texture,and reduced surface roughness.Notably,both friction coefficients and wear volumes show a direct dependence on the number of rolling passes.This study systematically elucidates the underlying mechanisms linking USRP-induced microstructural evolution to enhanced wear performance,providing critical insights for optimizing surface engineering strategies in magnesium alloys.
文摘Inconel 718 superalloy has extensive applications in a variety of industries such as the moulding,aerospace and medical due to its excellent mechanical features such as poor thermal conductivity,high strength at high temperatures and corrosion resistance.However,it is very difficult to process by traditional machining and finishing methods.Abrasive based finishing process is one of non-traditional finishing method applied to complex surfaces.Shot peening process is one of the surface treatment processes mostly applied to improve the surface strength.The superior advantages of these two processes are combined into one process.This newly developed and patented process is called as GOV process.In this study,the effects of GOV process parameters(number of cycles,steel ball size,media concentration)on the surface quality of Inconel 718 already pre-processed by wire electric discharge machining are investigated.The performance parameters are identified as surface roughness,material removal and white layer thickness.Surface finishing with the GOV process improves the surface roughness,Ra value by decreasing from 2.63μm to 0.46μm by removing micro-level chips up to 10.7 mg which is supported by SEM images.White layer formed due to nature of EDM process is completely removed from specimen surface.
基金Under the auspices of the National Natural Science Foundation of China(No.41971116,42271046,42277449)Fundamental Research Funds for the Central Universities(No.2020TS102)。
文摘The Zoige Basin,located in the eastern region of the Tibetan Plateau of China,is characterized by its climate sensitivity and complex surface environment.It is vital to understand the response of the surface processes to environmental changes in the Zoige Basin since the last deglaciation,as well as the response of environmental changes and surface processes on the Tibetan Plateau relate to global changes.In August 2020,a field investigation was conducted in the Zoige Basin.A complete set of stratigraphic profile from the high platform at the front of the glacial-diluvial fan in the Maqu reach of the western basin was selected as the research subject.Optically stimulated luminescence(OSL)dating samples and sedimentary samples were collected from key layers and brought back to the laboratory for experimental analysis,and the surface processes and environment changes since the last deglaciation in the Zoige Basin were investigated through particle size analysis and OSL dating.The results showed that during the last glacial period before 14.5 kyr,a substantial glacial-alluvial fan composed of sand and gravel layers was formed by flash flood processes triggered by glacial meltwater and heavy precipitation.In the Bølling-Allerød warm period of 14.5–11.7 kyr,a warm and humid climate prevailed,with the formation of silty bog environments in the shallow depressions at the glacial-alluvial fan's forefront and the development of gray-green bog soil deposits.However,during the Younger Dryas period,an abrupt climate deterioration occurred,with the upper section of the gray-green bog soil layer in the shallow depression to experience folding and deformation due to surface freeze-thaw actions.During the early Holocene period from 11.7 kyr to 8.5 kyr,the climate was relatively dry,resulting in prevalent aeolian sand activitities.Coarse silt accumulated in the shallow depression,and sedimentary facies alternating between aeolian sand and bog soil deposits developed owing to strong wind patterns on the plateau surface.In the warm and humid period from 8.5 kyr to 3.1 kyr,increased weathering and pedogenesis enhanced clay content in sediments,which developed into the paleosol.In the late Holocene,starting from 3.1 kyr,the climate became relatively dry once more,with aeolian sand activity prevalent.The coarse silt that accumulated during the late Holocene transformed into subalpine meadow black soil because of rising temperature and humidity levels.These findings indicated that the developmental process of the high platform in the Maqu reach of the Zoige Basin,which was significant for understanding the environmental changes and surface processes in the source region of the Yellow River since the last deglaciation.
基金financial supports from the National Natural Science Foundation of China-Youth Project(51801076)the Provincial Colleges and Universities Natural Science Research Project of Jiangsu Province(18KJB430009)+1 种基金the Postdoctoral Research Support Project of Jiangsu Province(1601055C)the Senior Talents Research Startup of Jiangsu University(14JDG126)。
文摘To solve the problems of deformation,micro-cracks,and residual tensile stress in laser cladding coatings,the technique of laser cladding with Fe-based memory alloy can be considered.However,the process of in-situ synthesis of Fe-based memory alloy coatings is extremely complex.At present,there is no clear guidance scheme for its preparation process,which limits its promotion and application to some extent.Therefore,in this study,response surface methodology(RSM)was used to model the response surface between the target values and the cladding process parameters.The NSGA-2 algorithm was employed to optimize the process parameters.The results indicate that the composite optimization method consisting of RSM and the NSGA-2 algorithm can establish a more accurate model,with an error of less than 4.5%between the predicted and actual values.Based on this established model,the optimal scheme for process parameters corresponding to different target results can be rapidly obtained.The prepared coating exhibits a uniform structure,with no defects such as pores,cracks,and deformation.The surface roughness and microhardness of the coating are enhanced,the shaping quality of the coating is effectively improved,and the electrochemical corrosion performance of the coating in 3.5%NaCl solution is obviously better than that of the substrate,providing an important guide for engineering applications.
基金financially supported by the Natural Science Foundation of Jiangsu Province(BK2011135)Found Project for Transformation of Scientific and Technological Achievements of Jiangsu Province(No.BZ2011053)+1 种基金Open Project of National First Class Key Discipline for Science of Chinese Materia Medica,Nanjing University of Chinese Medicine(No.2011ZYX2-013)Scientific Innovation Research of University Graduate of Jiangsu Province(CXZZ130626)
文摘The present study was designed to optimize the processing of Fructus Arctii by response surface methodology （RSM）. Based on single factor studies, a three-variable, three-level Box-Behnken design （BBD） was used to monitor the effects of independent variables, including processing temperature and time, on the dependent variables. Response surfaces and contour plots of the contents of total lignans, chlorogenic acid, arctiin, and aretigenin were obtained through ultraviolet and visible （UV-Vis） monitoring and high performance liquid chromatography （HPLC）. Fructus Arctii should be processed under heating in a pot at 311℃, medicine at 119℃ for 123s with flipping frequently. The experimental values under the optimized processing technology were consistent with the predicted values. In conclusion, RSM is an effective method to optimize the processing of traditional Chinese medicine （TCM）.
文摘A new surface inspection system for cold rolled strips based on image processing is introduced. The system is equipped withtwo different illumination structures and CCD matrix cameras. The structure and image processing of the inspection system are described. Some efficient algorithms for image processing and classification are presented. The system is tested with strip samples fromcold rolling plants. The results show that the system can detect and recognize six common defects of cold rolled strips successfully.
文摘This monograph presents an overview of friction stir processing(FSP)of surface metal-matrix composites(MMCs)using the AZ91 magnesium alloy.The reported results in relation to various reinforcing particles,including silicon carbide(SiC),alumina(Al_(2)O_(3)),quartz(SiO_(2)),boron carbide(B_(4)C),titanium carbide(TiC),carbon fiber,hydroxyapatite(HA),in-situ formed phases,and hybrid reinforcements are summarized.AZ91 composite fabricating methods based on FSP are explained,including groove filling(grooving),drilled hole filling,sandwich method,stir casting followed by FSP,and formation of in-situ particles.The effects of introducing second-phase particles and FSP process parameters(e.g.,tool rotation rate,traverse speed,and the number of passes)on the microstructural modification,grain refinement,homogeneity in the distribution of particles,inhibition of grain growth,mechanical properties,strength–ductility trade-off,wear/tribological behavior,and corrosion resistance are discussed.Finally,useful suggestions for future work are proposed,including focusing on the superplasticity and superplastic forming,metal additive manufacturing processes based on friction stir engineering(such as additive friction stir deposition),direct FSP,stationary shoulder FSP,correlation of the dynamic recrystallization(DRX)grain size with the Zener–Hollomon parameter similar to hot deformation studies,process parameters(such as the particle volume fraction and external cooling),and common reinforcing phases such as zirconia(ZrO_(2))and carbon nanotubes(CNTs).
文摘Surface metal matrix composites(MMCs)are a group of modern engineered materials where the surface of the material is modified by dispersing secondary phase in the form of particles or fibers and the core of the material experience no change in chemical composition and structure.The potential applications of the surface MMCs can be found in automotive,aerospace,biomedical and power industries.Recently,friction stir processing(FSP)technique has been gaining wide popularity in producing surface composites in solid state itself.Magnesium and its alloys being difficult to process metals also have been successfully processed by FSP to fabricate surface MMCs.The aim of the present paper is to provide a comprehensive summary of state-of-the-art in fabricating magnesium based composites by FSP.Influence of the secondary phase particles and grain refinement resulted from FSP on the properties of these composites is also discussed.
文摘Rising concerns about climate change drive the demand for lightweight components.Magnesium(Mg)alloys are highly valued for their low weight,making them increasingly important in various industries.Researchers focusing on enhancing the characteristics of Mg alloys and developing their Metal Matrix Composites(MMCs)have gained significant attention worldwide over the past decade,driven by the global shift towards lightweight materials.Friction Stir Processing(FSP)has emerged as a promising technique to enhance the properties of Mg alloys and produce Mg-MMCs.Initially,FSP adapted to refine grain size from the micro to the nano level and accelerated the development of MMCs due to its solid-state nature and the synergistic effects of microstructure refinement and reinforcement,improving strength,hardness,ductility,wear resistance,corrosion resistance,and fatigue strength.However,producing defect-free and sound FSPed Mg and Mg-MMCs requires addressing several variables and their interdependencies,which opens up a broad range of practical applications.Despite existing reviews on individual FSP of Mg,its alloys,and MMCs,an attempt has been made to analyze the latest research on these three aspects collectively to enhance the understanding,application,and effectiveness of FSP for Mg and its derivatives.This review article discusses the literature,classifies the importance of Mg alloys,provides a historical background,and explores developments and potential applications of FSPed Mg alloys.It focuses on novel fabrication methods,reinforcement strategies,machine and tool design parameters,material characterization,and integration with other methods for enhanced properties.The influence of process parameters and the emergence of defects are examined,along with specific applications in mono and hybrid composites and their microstructure evolution.The study identifies promising reinforcement materials and highlights research gaps in FSP for Mg alloys and MMCs production.It concludes with significant recommendations for further exploration,reflecting ongoing advancements in this field.
基金the Amirkabir University of Technology(AUT)Sharif University of Technologythe National Elites Foundation of Iran for their support during this research。
文摘Friction stir processing(FSP)can be used to improve surface composites.In this study,a modified method of FSP called friction stir vibration processing(FSVP)was applied to develop a surface composite on AZ91 magnesium alloy.In this technique,the workpiece is vibrated normal to the processing direction.The results illustrated that compared with the FSP method,the FSVP caused a better homogeneous distribution of SiC particles in the microstructure.The results also showed that matrix grains of friction stir vibration processed(FSV-processed)samples((26.43±2.00)μm)were finer than those of friction stir processed(FS-processed)specimens((39.43±2.00)μm).The results indicated that the ultimate tensile strength(UTS)of FSV-processed specimens(361.82 MPa)was higher than that of FS-processed specimens(324.97 MPa).The higher plastic strain in the material during FSVP,due to workpiece vibration,resulted in higher dynamic recrystallization,and consequently,finer grains were developed.The elongation and formability index of the FSV-processed specimen(16.88%and 6107.52 MPa·%,respectively)were higher than those of the FS-processed sample(15.24%and 4952.54 MPa·%,respectively).Moreover,the effects of FSVP were also found to intensify as the vibration frequency increased.
文摘An attempt was made to synthesize Cu/B4C surface composite using friction stir processing（FSP） and to analyze the influence of tool rotational speed on microstructure and sliding wear behavior of the composite. The tool rotational speed was varied from 800 to 1200 r/min in step of 200 r/min. The traverse speed, axial force, groove width and tool pin profile were kept constant. Optical microscopy and scanning electron microscopy were used to study the microstructure of the fabricated surface composites. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The results indicate that the tool rotational speed significantly influences the area of the surface composite and the distribution of B4C particles. Higher rotational speed exhibits homogenous distribution of B4C particles, while lower rotational speed causes poor distribution of B4C particles in the surface composite. The effects of tool rotational speed on the grain size, microhardness, wear rate, worn surface and wear debris were reported.
基金This work was supported in part by National Key Research and Development Program of China under Grant 2017YFB1010002in part by National Natural Science Foundation of China under Grant 61871455,61831013.
文摘Reconfigurable intelligent surface(RIS)is an emerging meta-surface that can provide additional communications links through reflecting the signals,and has been recognized as a strong candidate of 6G mobile communications systems.Meanwhile,it has been recently admitted that implementing artificial intelligence(AI)into RIS communications will extensively benefit the reconfiguration capacity and enhance the robustness to complicated transmission environments.Besides the conventional model-driven approaches,AI can also deal with the existing signal processing problems in a data-driven manner via digging the inherent characteristic from the real data.Hence,AI is particularly suitable for the signal processing problems over RIS networks under unideal scenarios like modeling mismatching,insufficient resource,hardware impairment,as well as dynamical transmissions.As one of the earliest survey papers,we will introduce the merging of AI and RIS,called AIRIS,over various signal processing topics,including environmental sensing,channel acquisition,beamforming design,and resource scheduling,etc.We will also discuss the challenges of AIRIS and present some interesting future directions.
基金This project is supported by Great Device Development Project of Chinese Academy of Sciences, China(No.[1997]167)Knowledge Innovation Great Project of Chinese Academy of Sciences, China, in 2000-2003(No. KGCX1-11).
文摘A new method of collision-free path plan integrated in virtual processing is developed to improve the efficiency of laser surface hardening on dies. The path plan is based on the premise of no collision and the optimization object is the shortest path. The optimization model of collision-free path is built from traveling salesman problem （TSP）. Collision-free path between two machining points is calculated in configuration space （C-Space）. Ant colony optimization （ACO） algorithm is applied to TSP of all the machining points to find the shortest path, which is simulated in virtual environment set up by IGRIP software. Virtual machining time, no-collision report, etc, are put out atter the simulation. An example on autobody die is processed in the virtual platform, the simulation results display that ACO has perfect optimization effect, and the method of virtual processing with integration of collision-free optimal path is practical.
