High-moisture extrusion technology should be considered one of the best choices for producing plant-based meat substitutes with the rich fibrous structure offered by real animal meat products.Unfortunately,the extrusi...High-moisture extrusion technology should be considered one of the best choices for producing plant-based meat substitutes with the rich fibrous structure offered by real animal meat products.Unfortunately,the extrusion process has been seen as a“black box”with limited information about what occurs inside,causing serious obstacles in developing meat substitutes.This study designed a high-moisture extrusion process and developed 10 new plant-based meat substitutes comparable to the fibrous structure of real animal meat.The study used the Feature-Augmented Principal Component Analysis(FA-PCA)method to visualize and understand the whole extrusion process in three ways systematically and accurately.It established six sets of mathematical models of the high-moisture extrusion process based on 8000 pieces of data,including five types of parameters.The FA-PCA method improved the R^(2) values significantly compared with the PCA method.The Way 3 was the best to predict product quality(Z),demonstrating that the gradually molecular conformational changes(Y^(n'))were critical in controlling the final quality of the plant-based meat substitutes.Moreover,the first visualization platform software for the high-moisture extrusion process has been established to clearly show the“black box”by combining the virtual simulation technology.Through the software,some practice work such as equipment installation,parameter adjustment,equipment disassembly,and data prediction can be easily achieved.展开更多
To fully utilize the in-situ resources on the moon to facilitate the establishment of a lunar habitat is significant to realize the long-term residence of mankind on the moon and the deep space exploration in the futu...To fully utilize the in-situ resources on the moon to facilitate the establishment of a lunar habitat is significant to realize the long-term residence of mankind on the moon and the deep space exploration in the future.Thus,intensive research works have been conducted to develop types of 3D printing approach to adapt to the extreme environment and utilize the lunar regolith for in-situ construction.However,the in-situ 3D printing using raw lunar regolith consumes extremely high energy and time.In this work,we proposed a cost-effective melting extrusion system for lunar regolith-based composite printing,and engineering thermoplastic powders are employed as a bonding agent for lunar regolith composite.The high-performance nylon and lunar regolith are uniformly pre-mixed in powder form with different weight fractions.The high-pressure extrusion system is helpful to enhance the interface affinity of polymer binders with lunar regolith as well as maximize the loading ratio of in-situ resources of lunar regolith.Mechanical properties such as tensile strength,elastic modulus,and Poisson’s ratio of the printed specimens were evaluated systematically.Especially,the impact performance was emphasized to improve the resistance of the meteorite impact on the moon.The maximum tensile strength and impact toughness reach 36.2 MPa and 5.15 kJ/m2,respectively.Highpressure melt extrusion for lunar regolith composite can increase the effective loading fraction up to 80 wt.% and relatively easily adapt to extreme conditions for in-situ manufacturing.展开更多
The samples obtained by Finite Element Method (FEM) simulation for section extrusion process have been trained on BP Neural Networks. The mapping relationsbetween die's geometrical parameters and energetic paramet...The samples obtained by Finite Element Method (FEM) simulation for section extrusion process have been trained on BP Neural Networks. The mapping relationsbetween die's geometrical parameters and energetic parameters, such as stress and strain generated in the die are established. The extrusion process model and its expert system are also determined. The excellent expansibility this system possesses provides a new prospect for the future development of expert system for section extrusion dies.展开更多
BACKGROUND Intra-gastric migration of the distal ventriculoperitoneal shunt(VPS)catheter clinically presenting with or without trans-oral extrusion is one of the rare complications of VPS catheter insertion.AIM To ide...BACKGROUND Intra-gastric migration of the distal ventriculoperitoneal shunt(VPS)catheter clinically presenting with or without trans-oral extrusion is one of the rare complications of VPS catheter insertion.AIM To identify the demographics,clinical presentation,clinical findings,and results of surgical therapy offered for the treatment of intra-gastric migration of the distal VPS catheter,clinically presented with or without trans-oral extrusion.METHODS An online search was performed for the extraction/retrieval of the published/available literature pertaining to the above-mentioned VPS complication.Manuscripts were searched from PubMed,PMC(PubMed Central),ResearchGate,and Google Scholar databases using various terminology relating to the VPS complications.The first case of migration of a VPS catheter into the stomach was reported in the year 1980,and the data were retrieved from 1980 to December 2022.Cases were categorized into two groups;Group A:Cases who had migration of the distal VPS catheter into the stomach and clinically presented with trans-oral extrusion of the same,and Group B:Cases who had migration of the distal VPS catheter into the stomach,but presented without trans-oral extrusion.RESULTS A total of n=46 cases(n=27;58.69%male,and n=19;41.3%females)were recruited for the systematic review.Group A included n=32,and Group B n=14 cases.Congenital hydrocephalus was the indication for the primary VPS insertion for approximately half of the(n=22)cases.Approximately sixty percent(n=27)of them were children≤5 years of age at the time of the diagnosis of the complication mentioned above.In seventy-two percent(n=33)cases,this complication was detected within 24 mo after the VPS insertion/last shunt revision.Clinical diagnosis was evident for the entire group A cases.Various diagnostic modalities were used to confirm the diagnosis for Group B cases.Various surgical procedures were offered for the management of the complication in n=43 cases of both Groups.In two instances,intra-gastric migration of the distal VPS catheter was detected during the autopsy.This review documented four deaths.CONCLUSION Intra-gastric migration of the peritoneal end of a VPS catheter is one of the rare complications of VPS catheter implantation done for the treatment of hydrocephalus across all age groups.It was more frequently reported in children,although also reported in adults and older people.A very high degree of clinical suspicion is required for the diagnosis of a case of an intra-gastric migration of the distal VPS catheter clinically presenting without transoral extrusion.展开更多
Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusi...Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.展开更多
To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (...To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (MEM)process has been developed successfully. And the key issues to develop such a system are discussed. Based on theactual forming experiment, it is concluded that the MEM600-l works reliably and the forming efficiency is muchhigher than its parallel equipments.展开更多
Solvent evaporation method for preparation of nanomatrix has the disadvantages,such as residual organic solvent,environmental pollution,explosion-proofing and so on.To overcome these shortcomings,a series of fenofibra...Solvent evaporation method for preparation of nanomatrix has the disadvantages,such as residual organic solvent,environmental pollution,explosion-proofing and so on.To overcome these shortcomings,a series of fenofibrate nanomatrix drug delivery system(NDDS)consisting of nano-porous silica Sylysia■350(S350)and pH sensitive material Eudragit■L100-55(EL100-55)were prepared using hot-melt extrusion(HME),and their in vitro dissolution and in vivo bioavailability were compared.Finally,the formulation with the highest in vivo bioavailability was selected as the optimized formulation for DSC and PXRD characterization.The results showed that the optimized NDDS showed a higher bioavailability than the reference formulation,although there was crystalline form drug remaining in NDDS.The relative bioavailability of the optimized formulation was 157.1%compared with the commercial product Lipanthyl■.In addition,the relative bioavailability of the optimized formulation was 124.8%in comparison with the formulation prepared by solvent evaporation method,showing that the NDDS prepared by the HME method was effective in improving the bioavailability of fenofibrate.In conclusion,HME was a promising method to prepare NDDS.展开更多
Extrusion is a common process technique used to fabricate porous materials such as catalysts and membranes. The performance and efficiency of such materials are governed by porosity and pore distribution. The spatial ...Extrusion is a common process technique used to fabricate porous materials such as catalysts and membranes. The performance and efficiency of such materials are governed by porosity and pore distribution. The spatial variation of porosity within the catalyst structure can be linked to process variables in the extrusion processes such as extrusion velocity. A change in extrusion velocity can lead to a change in extrusion pressure. The extrusion pressure effect is a combination of die entry deformation and frictional die land shear. In this work, the effect of extrusion velocity on the spatial variation of porosity in a titania-binder extrudate has been studied. Capillary rheometer analysis was done to investigate the effect of extrusion velocity. A segmentation approach was developed to study the spatial variation of porosity at the die wall (sheared region) compared to the unsheared (center) region of the extrudate. The results show that the extrusion pressure effect increases as the velocity increases. The extrusion conditions affect the spatial variation of porosity.展开更多
To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,t...To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,thereby improving both microstructure uniformity and mechanical properties of sintered bodies.The results indicate that WIP reduces defects in MEX greens,thus decreasing the dimensions and numbers of defects,modifying shapes of pores within sintered bodies,while preserving surface quality and shape characteristics.Compared with WC-9Co prepared via MEX followed by debinding and sintering(DS),the hardness of WC-9Co prepared using MEX-WIP-DS does not change significantly,ranging HV_(30)1494-1508,the transverse rupture strength increases by up to 49.3%,reaching 2998-3514 MPa,and the fracture toughness remains high,ranging 14.8-17.0 MPa·m^(1/2).The mechanical properties surpass comparable cemented carbides fabricated through other AM methods and are comparable to those produced by powder metallurgy.The integration of green WIP into MEX-DS broadens the MEX processing window,and improves the overall mechanical properties of MEX AM WC-Co cemented carbides.展开更多
The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods w...The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods were investigated at different extrusion temperatures and shear stresses.The experimental results show that the proportion of dynamic recrystallization(DRX)and texture for Al and Mg alloys are controlled by the combination of temperature and shear stress.The texture type of the Al alloys exhibits slight variations at different temperatures.With the increase of temperature,the DRX behavior of Mg alloy shifts from discontinuous DRX(DDRX),continuous DRX(CDRX),and twin-induced DRX(TDRX)dominant to CDRX,the dislocation density in Mg alloy grains decreases significantly,and the average value of Schmid factor(SF)of the basalslip system increases.In particular,partial grains exhibit a distinct dominant slip system at 390℃.The hardness and thickness of the bonding layer,as well as the yield strength and elongation of the Mg alloy,reach their maximum at 360℃as a result of the intricate influence of the combined temperature and shear stress.展开更多
The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are asso...The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are associated with the specific microstructure known as the Mille-Feuille(MF)structure that can occur in this alloy as well after proper heat treatment.This study systematically compares the traditional ingot metallurgy method with the Bridgman method(slow cooling),coupled with diverse heat treatments and extrusion process.Microscopic analyses reveal variations in the presence of LPSO phases,MF structure,and especially grain size,leading to divergent mechanical and corrosion properties.The Bridgman approach surprisingly stands out,ensuring superior mechanical properties due to kink and texture strengthening.展开更多
Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered ext...Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered extrusion(SE)process was used to form the curved profile of AZ31 magnesium alloy in this paper.The study investigates the mapping relationship between the curvature,microstructure,and mechanical properties of the formed profiles by using different eccentricities of the die.Scanning electron microscopy(SEM)and electron backscatter diffraction techniques are employed to examine the effects of different eccentricity values(e)on grain morphology,recrystallization mechanisms,texture,and Schmid factors of the products.The results demonstrate that the staggered extrusion method promotes the deep refinement of grain size in the extruded products,with an average grain size of only 15%of the original billet,reaching 12.28μm.The tensile strength and elongation of the curved profiles after extrusion under the eccentricity value of 10 mm,20 mm and 30 mm are significantly higher than those of the billet,with the tensile strength is increased to 250,270,235 MPa,and the engineering strain elongation increased to 10.5%,12.1%,15.9%.This indicates that staggered extrusion enables curvature control of the profiles while improving their strength.展开更多
Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with...Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.展开更多
Prefabricated twinning represents an effective strategy for optimizing the microstructure of extruded forming components and facilitating changes in texture.The study examines the incorporation of[10-12]twins into an ...Prefabricated twinning represents an effective strategy for optimizing the microstructure of extruded forming components and facilitating changes in texture.The study examines the incorporation of[10-12]twins into an AZ31 magnesium alloy billet via cold pre-upsetting deformation before alternating forward extrusion(CUAFE).The experimental results indicate that the initial presence of[10-12]twins is advantageous for the development of[10-10]and[11-20]texture components during the extrusion process.In addition,different DRX mechanisms have different influences on the evolution of basal texture.The CDRX grains tend to preferentially select the[11-20]texture orientation,weakening the[10-10]texture and enhancing the[11-20]texture.However,most DDRX grains deviate significantly from the orientation of their surrounding original grain and do not have a preferred orientation.This is reflected in the mechanical properties of the CUAFE part.The tensile strength is 323.5 MPa,while the elongation is as high as 20.1%.展开更多
This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on t...This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.展开更多
Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional e...Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional extrusion at low temperature,which breaks through the stereotypical"fewer RE,lower strength"wisdom.The microstructure of the alloy and mechanical properties were examined with op-tical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Instron testing machine.This alloy exhibits a high tensile yield strength of 410 MPa and a favorable elongation of 7.8%,outperforming the majority of traditional high-strength Mg-Gd-Y(-Zn)-Zr extrusion alloys with high RE additions,at least 12 wt%.The high yield strength of the alloy is closely associated with the synergistic effect of submicron recrystallized grains and highly-textural hot-worked grains containing numerous dynamic precipitates and residual dislocations,rather than the widely-considered age-hardening in those heavy RE containing Mg alloys.This work provides an important reference for the development of high-performance extruded Mg alloys with low RE solutes.展开更多
The utilization of lunar regolith for construction on the lunar surface presents a critical challenge in-situ resource utilization.This study proposes a lunar regolith manufacturing method that uses a high-performance...The utilization of lunar regolith for construction on the lunar surface presents a critical challenge in-situ resource utilization.This study proposes a lunar regolith manufacturing method that uses a high-performance resin binder characterized by a high regolith content and strong forming capabilities.A combined resin material with both thermosetting and photosetting properties was developed and mixed with lunar regolith to create a slurry.This slurry can be directly molded or additively extruded into green bodies with specific structures.These green bodies can self-cure under the high temperatures and ultraviolet radiation experienced during the lunar day,reducing energy consumption and fulfilling the requirements of lunar construction.The material-forming processes and effects of various additive types and concentrations,regolith mass ratios,and processing parameters on the properties of the slurry and the formed specimens were thoroughly investigated.The mechanical performance and microstructure of the fabricated samples were analyzed.The lunar regolith mass ratio reached 90 wt%(approximately 79 vol%),with the highest compressive strengths exceeding 60 MPa for cast specimens and 30 MPa for printed samples.This technology shows significant potential for enabling in-situ lunar regolith-based construction in future lunar missions.展开更多
The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical micro...The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter diffraction.The results show that extrusion produces a typical basal fiber texture and streamlines of second phases.All samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the strength.After being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other samples.This hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.展开更多
In the current study the wear behavior of the ZK60/SiC composites reinforced by particles and whiskers in both as-cast and extruded conditions was examined.Furthermore,the wear behavior of the extruded samples along t...In the current study the wear behavior of the ZK60/SiC composites reinforced by particles and whiskers in both as-cast and extruded conditions was examined.Furthermore,the wear behavior of the extruded samples along the extrusion direction and perpendicular to the extrusion direction was studied.The wear tests were performed at temperatures of 100,200,and 300℃under loads of 10,20,and 30 N.The results showed that the whisker-reinforced sample(5.8×10^(–4)g/[N.m])had higher wear resistance than the particle-reinforced sample(1.3×10^(–3)g/[N.m]).The lowest wear rate was observed for the extruded sample in the extrusion direction(3.53×10^(–4)g/[N.m]).It was also found that the wear rate increased by∼20%with increasing temperature,but in the ZK60/SiC_(w)sample,dynamic precipitation increased the wear resistance.The coefficient of friction was also found to increase with rising temperature,showing an increase of approximately 12.5%at a 10 N load and 20%at a 30 N load.Examination of the worn surfaces by scanning electron microscopy showed that the as-cast ZK60 alloy at 100℃had the oxidative-abrasive as the dominant mechanism.It was found that by extruding the sample,the strength of the sample increased and the mechanism changed to adhesive wear.In the ZK60/SiC_(p)composite,the viscoplastic wear mechanism was dominant.Although in the extruded sample the dominant mechanism changed to plastic deformation.As temperature increases,the viscoplastic wear mechanism became dominant again.In the as-cast ZK60/SiC_(w)composite,the abrasive wear mechanism changed to delamination with increasing temperature.By extruding the sample,the dominant mechanism changed to adhesive wear.Finally,dynamic precipitation induced by temperature caused an increase in the wear resistance.展开更多
Solid propellants are essential energy sources for rockets and other aerospace vehicles,and improvements in their performance have significant implications for the aerospace industry.The application of additive manufa...Solid propellants are essential energy sources for rockets and other aerospace vehicles,and improvements in their performance have significant implications for the aerospace industry.The application of additive manufacturing(AM)in the production of solid propellants promises a substantial leap in the design and fabrication of solid propellant grains.This review summarizes recent research on AM techniques for solid propellant manufacturing,evaluates current applications,and explores development trends.This review highlights that AM technology for solid propellants offers unparalleled advantages in terms of propellant design flexibility and functional gradient loading compared with traditional processes.This study presents a new perspective for the future manufacturing of intelligent and controllable solid propulsion systems.展开更多
基金supported by the National Natural Science Foundation of China(31901608)the National Key Research and Development Plan of China(2021YFC2101402)the Science and Technology Innovation Project of Chinese Academy of Agricultural Sciences(CAAS-ASTIP-2022-IFST)。
文摘High-moisture extrusion technology should be considered one of the best choices for producing plant-based meat substitutes with the rich fibrous structure offered by real animal meat products.Unfortunately,the extrusion process has been seen as a“black box”with limited information about what occurs inside,causing serious obstacles in developing meat substitutes.This study designed a high-moisture extrusion process and developed 10 new plant-based meat substitutes comparable to the fibrous structure of real animal meat.The study used the Feature-Augmented Principal Component Analysis(FA-PCA)method to visualize and understand the whole extrusion process in three ways systematically and accurately.It established six sets of mathematical models of the high-moisture extrusion process based on 8000 pieces of data,including five types of parameters.The FA-PCA method improved the R^(2) values significantly compared with the PCA method.The Way 3 was the best to predict product quality(Z),demonstrating that the gradually molecular conformational changes(Y^(n'))were critical in controlling the final quality of the plant-based meat substitutes.Moreover,the first visualization platform software for the high-moisture extrusion process has been established to clearly show the“black box”by combining the virtual simulation technology.Through the software,some practice work such as equipment installation,parameter adjustment,equipment disassembly,and data prediction can be easily achieved.
基金supported by the National Key R&D Program of China(Grant No.2017YFB1102800)the National Natural Science Foundation of China for Excellent Young Scholars(Grant No.11722219)+1 种基金the National Natural Science Foundation of China(Grant No.51905439)the Emerging(Interdisciplinary)Cultivation Project of Northwestern Polytechnical University,China(Grant Nos.19SH030403,20SH030201,and 21SH030601).
文摘To fully utilize the in-situ resources on the moon to facilitate the establishment of a lunar habitat is significant to realize the long-term residence of mankind on the moon and the deep space exploration in the future.Thus,intensive research works have been conducted to develop types of 3D printing approach to adapt to the extreme environment and utilize the lunar regolith for in-situ construction.However,the in-situ 3D printing using raw lunar regolith consumes extremely high energy and time.In this work,we proposed a cost-effective melting extrusion system for lunar regolith-based composite printing,and engineering thermoplastic powders are employed as a bonding agent for lunar regolith composite.The high-performance nylon and lunar regolith are uniformly pre-mixed in powder form with different weight fractions.The high-pressure extrusion system is helpful to enhance the interface affinity of polymer binders with lunar regolith as well as maximize the loading ratio of in-situ resources of lunar regolith.Mechanical properties such as tensile strength,elastic modulus,and Poisson’s ratio of the printed specimens were evaluated systematically.Especially,the impact performance was emphasized to improve the resistance of the meteorite impact on the moon.The maximum tensile strength and impact toughness reach 36.2 MPa and 5.15 kJ/m2,respectively.Highpressure melt extrusion for lunar regolith composite can increase the effective loading fraction up to 80 wt.% and relatively easily adapt to extreme conditions for in-situ manufacturing.
文摘The samples obtained by Finite Element Method (FEM) simulation for section extrusion process have been trained on BP Neural Networks. The mapping relationsbetween die's geometrical parameters and energetic parameters, such as stress and strain generated in the die are established. The extrusion process model and its expert system are also determined. The excellent expansibility this system possesses provides a new prospect for the future development of expert system for section extrusion dies.
文摘BACKGROUND Intra-gastric migration of the distal ventriculoperitoneal shunt(VPS)catheter clinically presenting with or without trans-oral extrusion is one of the rare complications of VPS catheter insertion.AIM To identify the demographics,clinical presentation,clinical findings,and results of surgical therapy offered for the treatment of intra-gastric migration of the distal VPS catheter,clinically presented with or without trans-oral extrusion.METHODS An online search was performed for the extraction/retrieval of the published/available literature pertaining to the above-mentioned VPS complication.Manuscripts were searched from PubMed,PMC(PubMed Central),ResearchGate,and Google Scholar databases using various terminology relating to the VPS complications.The first case of migration of a VPS catheter into the stomach was reported in the year 1980,and the data were retrieved from 1980 to December 2022.Cases were categorized into two groups;Group A:Cases who had migration of the distal VPS catheter into the stomach and clinically presented with trans-oral extrusion of the same,and Group B:Cases who had migration of the distal VPS catheter into the stomach,but presented without trans-oral extrusion.RESULTS A total of n=46 cases(n=27;58.69%male,and n=19;41.3%females)were recruited for the systematic review.Group A included n=32,and Group B n=14 cases.Congenital hydrocephalus was the indication for the primary VPS insertion for approximately half of the(n=22)cases.Approximately sixty percent(n=27)of them were children≤5 years of age at the time of the diagnosis of the complication mentioned above.In seventy-two percent(n=33)cases,this complication was detected within 24 mo after the VPS insertion/last shunt revision.Clinical diagnosis was evident for the entire group A cases.Various diagnostic modalities were used to confirm the diagnosis for Group B cases.Various surgical procedures were offered for the management of the complication in n=43 cases of both Groups.In two instances,intra-gastric migration of the distal VPS catheter was detected during the autopsy.This review documented four deaths.CONCLUSION Intra-gastric migration of the peritoneal end of a VPS catheter is one of the rare complications of VPS catheter implantation done for the treatment of hydrocephalus across all age groups.It was more frequently reported in children,although also reported in adults and older people.A very high degree of clinical suspicion is required for the diagnosis of a case of an intra-gastric migration of the distal VPS catheter clinically presenting without transoral extrusion.
基金supported by the National Science and Technology Major Project,China(No.2019-VI-0004-0118)the National Natural Science Foundation of China(No.51771152)the National Key R&D Program of China(No.2018YFB1106800)。
文摘Microstructure,texture,and mechanical properties of the extruded Mg-2.49Nd-1.82Gd-0.2Zn-0.2Zr alloy were investigated at different extrusion temperatures(260 and 320℃),extrusion ratios(10:1,15:1,and 30:1),and extrusion speeds(3 and 6 mm/s).The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy,and the second phase showed streamline distribution along the extrusion direction(ED).With extrusion temperature increased from 260 to 320℃,the microstructure,texture,and mechanical properties of alloys changed slightly.The dynamic recrystallization(DRX)degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1,and the strength gradually decreased but elongation(EL)increased.With the extrusion speed increased from 3 to 6 mm/s,the grain sizes and DRX degree increased significantly,and the samples presented the typical<2111>-<1123>rare-earth(RE)textures.The alloy extruded at 260℃ with extrusion ratio of 10:1 and extrusion speed of 3 mm/s showed the tensile yield strength(TYS)of 213 MPa and EL of 30.6%.After quantitatively analyzing the contribution of strengthening mechanisms,it was found that the grain boundary strengthening and dislocation strengthening played major roles among strengthening contributions.These results provide some guidelines for enlarging the industrial application of extruded Mg-RE alloy.
基金The author would like to acknowledge the support by the National Natural Science Foundation of China (Grant No. 50105006)and the support by the 985 Foundation of Tsinghua University,Beijing, China.
文摘To develop large-scale RP systems used to producing functional parts and large-sized models has become an urgentcall now. In this paper, a large-scale RP system, MEM600-l, based on the melted extrusion manufacturing (MEM)process has been developed successfully. And the key issues to develop such a system are discussed. Based on theactual forming experiment, it is concluded that the MEM600-l works reliably and the forming efficiency is muchhigher than its parallel equipments.
基金National Basic Research Program of China(Grant No.2015CB932100)
文摘Solvent evaporation method for preparation of nanomatrix has the disadvantages,such as residual organic solvent,environmental pollution,explosion-proofing and so on.To overcome these shortcomings,a series of fenofibrate nanomatrix drug delivery system(NDDS)consisting of nano-porous silica Sylysia■350(S350)and pH sensitive material Eudragit■L100-55(EL100-55)were prepared using hot-melt extrusion(HME),and their in vitro dissolution and in vivo bioavailability were compared.Finally,the formulation with the highest in vivo bioavailability was selected as the optimized formulation for DSC and PXRD characterization.The results showed that the optimized NDDS showed a higher bioavailability than the reference formulation,although there was crystalline form drug remaining in NDDS.The relative bioavailability of the optimized formulation was 157.1%compared with the commercial product Lipanthyl■.In addition,the relative bioavailability of the optimized formulation was 124.8%in comparison with the formulation prepared by solvent evaporation method,showing that the NDDS prepared by the HME method was effective in improving the bioavailability of fenofibrate.In conclusion,HME was a promising method to prepare NDDS.
文摘Extrusion is a common process technique used to fabricate porous materials such as catalysts and membranes. The performance and efficiency of such materials are governed by porosity and pore distribution. The spatial variation of porosity within the catalyst structure can be linked to process variables in the extrusion processes such as extrusion velocity. A change in extrusion velocity can lead to a change in extrusion pressure. The extrusion pressure effect is a combination of die entry deformation and frictional die land shear. In this work, the effect of extrusion velocity on the spatial variation of porosity in a titania-binder extrudate has been studied. Capillary rheometer analysis was done to investigate the effect of extrusion velocity. A segmentation approach was developed to study the spatial variation of porosity at the die wall (sheared region) compared to the unsheared (center) region of the extrudate. The results show that the extrusion pressure effect increases as the velocity increases. The extrusion conditions affect the spatial variation of porosity.
基金supported by the Key Project of Chinese Academy of Engineering(No.2019-XZ-11)the General Project of Chinese Academy of Engineering(No.2023-XY-18)+1 种基金the Open Fund of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials of China(No.HKDNM201907)the Independent Project of State Key Laboratory of Powder Metallurgy,China。
文摘To tackle the common issue of green defects in material extrusion(MEX)additive manufacturing(AM)cemented carbides,warm isostatic pressing(WIP)was introduced to eliminate defects of MEX WC-9Co cemented carbide greens,thereby improving both microstructure uniformity and mechanical properties of sintered bodies.The results indicate that WIP reduces defects in MEX greens,thus decreasing the dimensions and numbers of defects,modifying shapes of pores within sintered bodies,while preserving surface quality and shape characteristics.Compared with WC-9Co prepared via MEX followed by debinding and sintering(DS),the hardness of WC-9Co prepared using MEX-WIP-DS does not change significantly,ranging HV_(30)1494-1508,the transverse rupture strength increases by up to 49.3%,reaching 2998-3514 MPa,and the fracture toughness remains high,ranging 14.8-17.0 MPa·m^(1/2).The mechanical properties surpass comparable cemented carbides fabricated through other AM methods and are comparable to those produced by powder metallurgy.The integration of green WIP into MEX-DS broadens the MEX processing window,and improves the overall mechanical properties of MEX AM WC-Co cemented carbides.
基金supported by the general project of the National Natural Science Foundation of China(No.52071042)Chongqing Natural Science Foundation Project,China(Nos.CSTB2023NSCQ-MSX0079,cstc2021ycjh-bgzxm0148)Graduate Student Innovation Program of Chongqing University of Technology,China(No.gzlcx20232008).
文摘The Mg−Al composite rods of aluminum core-reinforced magnesium alloy were prepared by the extrusion−shear(ES)process,and the microstructure,deformation mechanism,and mechanical properties of the Mg−Al composite rods were investigated at different extrusion temperatures and shear stresses.The experimental results show that the proportion of dynamic recrystallization(DRX)and texture for Al and Mg alloys are controlled by the combination of temperature and shear stress.The texture type of the Al alloys exhibits slight variations at different temperatures.With the increase of temperature,the DRX behavior of Mg alloy shifts from discontinuous DRX(DDRX),continuous DRX(CDRX),and twin-induced DRX(TDRX)dominant to CDRX,the dislocation density in Mg alloy grains decreases significantly,and the average value of Schmid factor(SF)of the basalslip system increases.In particular,partial grains exhibit a distinct dominant slip system at 390℃.The hardness and thickness of the bonding layer,as well as the yield strength and elongation of the Mg alloy,reach their maximum at 360℃as a result of the intricate influence of the combined temperature and shear stress.
基金supported by Japan Society for the Promotion of Science(KAKENHI Grant-in-Aid for Scientific Research,18H05475,18H05476 and JP20H00312)MRC International Collaborative Research Grant+4 种基金The authors would like to thank the Czech Science Foundation(Project No.22-22248S)specific university research(A1_FCHT_2024_007)for financial supportsupported by the Ministry of Education,Youth,and Sports of the Czech Republic.Project No.CZ.02.01.01/00/22_008/0004591co-funded by the European UnionCzechNanoLab project LM2023051 funded by MEYS CR is gratefully acknowledged for the financial support of the measurements/sample fabrication at LNSM Research Infrastructure。
文摘The Mg-Y-Zn magnesium alloy system is known for the presence of Long-Period Stacking Ordered(LPSO)phases that improves strength and ductility with minimal amounts of alloying elements.Even better improvements are associated with the specific microstructure known as the Mille-Feuille(MF)structure that can occur in this alloy as well after proper heat treatment.This study systematically compares the traditional ingot metallurgy method with the Bridgman method(slow cooling),coupled with diverse heat treatments and extrusion process.Microscopic analyses reveal variations in the presence of LPSO phases,MF structure,and especially grain size,leading to divergent mechanical and corrosion properties.The Bridgman approach surprisingly stands out,ensuring superior mechanical properties due to kink and texture strengthening.
基金Project(JQ2022E004)supported by the Natural Science Foundation of Heilongjiang Province,China。
文摘Traditional manufacturing processes for lightweight curved profiles are often associated with lengthy procedures,high costs,low efficiency,and high energy consumption.In order to solve this problem,a new staggered extrusion(SE)process was used to form the curved profile of AZ31 magnesium alloy in this paper.The study investigates the mapping relationship between the curvature,microstructure,and mechanical properties of the formed profiles by using different eccentricities of the die.Scanning electron microscopy(SEM)and electron backscatter diffraction techniques are employed to examine the effects of different eccentricity values(e)on grain morphology,recrystallization mechanisms,texture,and Schmid factors of the products.The results demonstrate that the staggered extrusion method promotes the deep refinement of grain size in the extruded products,with an average grain size of only 15%of the original billet,reaching 12.28μm.The tensile strength and elongation of the curved profiles after extrusion under the eccentricity value of 10 mm,20 mm and 30 mm are significantly higher than those of the billet,with the tensile strength is increased to 250,270,235 MPa,and the engineering strain elongation increased to 10.5%,12.1%,15.9%.This indicates that staggered extrusion enables curvature control of the profiles while improving their strength.
基金financially supported by the National Natural Science Foundation of China (No. 52062029)the Key Science and Technology Project of Gansu Province (No. 18YF1GA064)the Natural Science Foundation of Gansu Provence (No. 25JRRA094)。
文摘Investment casting shell moulds are widely applied to cast alloys, but how to efficiently form a hierarchical porous structure inside the wall is an innovation and challenge. In this research, porous shell moulds with three infill patterns(rectilinear, grid, and honeycomb) were prepared using bauxite slurry and slurry extrusionbased additive manufacturing technology, and the effects of infill patterns on the properties were evaluated. The hierarchical pores inside the wall are composed of the macropores formed by infills and the micropores among bauxite particles. Different infill patterns result in changes in distribution and shape of pores, thereby affecting the properties of the shell moulds. The honeycomb pattern has more comprehensive advantages compared to the other two infill patterns. The samples prepared with the honeycomb pattern exhibit the highest bending strength(11.62 MPa) and porosity(41.6%), as well as good heat-transfer ability, with an average shrinkage rate within 2.0%. This work provides an attractive feasibility for fabricating shell moulds with hierarchical porous walls.
基金supported by the National Natural Science Foundation of China(No.52475341).
文摘Prefabricated twinning represents an effective strategy for optimizing the microstructure of extruded forming components and facilitating changes in texture.The study examines the incorporation of[10-12]twins into an AZ31 magnesium alloy billet via cold pre-upsetting deformation before alternating forward extrusion(CUAFE).The experimental results indicate that the initial presence of[10-12]twins is advantageous for the development of[10-10]and[11-20]texture components during the extrusion process.In addition,different DRX mechanisms have different influences on the evolution of basal texture.The CDRX grains tend to preferentially select the[11-20]texture orientation,weakening the[10-10]texture and enhancing the[11-20]texture.However,most DDRX grains deviate significantly from the orientation of their surrounding original grain and do not have a preferred orientation.This is reflected in the mechanical properties of the CUAFE part.The tensile strength is 323.5 MPa,while the elongation is as high as 20.1%.
基金supported by National Natural Science Foundation of China(Grant No.52205344,51925401)Postdoctoral Research Foundation of China(Grant No.2023M732398)+1 种基金National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact(Grant No.WDZC2023-1)Key Research and Development Program of Shandong Province(Grant No.2023CXPT066).
文摘This work managed the extrusion strain path by designing various extrusion die cavities,successfully realizing the texture modification for the ZK60 magnesium alloy.The mechanisms involving the texture dependence on the extrusion die cavity as well as their effects on the mechanical properties were emphatically investigated.Results showed that dynamic recrystallization refined the grain size and improved the microstructure homogeneity in the three extrusion specimens,but did not produce too large microstructure differences.By comparison,significant texture differences developed owing to the various extrusion die cavities,which here were mainly reflected in the strong or weak texture components for the c-axes//TD and the c-axes//ND.Such texture differences started from the deformation texture instead of the recrystallization texture whose roles only consisted in dispersing the texture component and reducing the texture intensity.The results from the finite element analysis and the visco-plastic self-consistent model indicated that,in order to accommodate the different strain components induced by the extrusion die cavities,slip systems or tension twinning were activated differently,and this was the critical reason causing the above texture differences.One modified Hall-Petch relationship was adopted to analyze the conjoint effects of grain refinement and texture variation on the yield stress.Additionally,the quantitative results about deformation mechanism activation fractions demonstrated that the texture variations influenced the competition relationships between the twinning induced deformation and the slip dominant deformation,and the former generally produced the lower yield stress and the increasing stage of strain hardening rate,while the latter produced the higher yield stress and the continuous decline of strain hardening rate.
基金supported by National Natural Science Foundation of China(52201111,52201137,52275389)Taiyuan University of Science and Technology Scientific Research Initial Funding(20232102)+1 种基金Reward funds for excellent doctor of work in coming to Shanxi(No.20242068)Special fund for Scienceand Technology Innovation Teamsof ShanxiProvince.
文摘Obtaining high strength in low-RE-alloyed Mg alloys(RE<6 wt%)remains a huge challenge so far.In this work,we fabricated a novel high-strength and low-RE-alloyed Mg-3Yb-0.6Zn-0.4Zr(wt%)alloy using the conventional extrusion at low temperature,which breaks through the stereotypical"fewer RE,lower strength"wisdom.The microstructure of the alloy and mechanical properties were examined with op-tical microscopy(OM),X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and Instron testing machine.This alloy exhibits a high tensile yield strength of 410 MPa and a favorable elongation of 7.8%,outperforming the majority of traditional high-strength Mg-Gd-Y(-Zn)-Zr extrusion alloys with high RE additions,at least 12 wt%.The high yield strength of the alloy is closely associated with the synergistic effect of submicron recrystallized grains and highly-textural hot-worked grains containing numerous dynamic precipitates and residual dislocations,rather than the widely-considered age-hardening in those heavy RE containing Mg alloys.This work provides an important reference for the development of high-performance extruded Mg alloys with low RE solutes.
基金supported by International Partnership Program of the Chinese Academy of Sciences(Grant No.310GJH2024010GC)National Natural Science Foundation of China(Grant No.52005479)the China Building Materials Federation(Grant No.2023JBGS0401)。
文摘The utilization of lunar regolith for construction on the lunar surface presents a critical challenge in-situ resource utilization.This study proposes a lunar regolith manufacturing method that uses a high-performance resin binder characterized by a high regolith content and strong forming capabilities.A combined resin material with both thermosetting and photosetting properties was developed and mixed with lunar regolith to create a slurry.This slurry can be directly molded or additively extruded into green bodies with specific structures.These green bodies can self-cure under the high temperatures and ultraviolet radiation experienced during the lunar day,reducing energy consumption and fulfilling the requirements of lunar construction.The material-forming processes and effects of various additive types and concentrations,regolith mass ratios,and processing parameters on the properties of the slurry and the formed specimens were thoroughly investigated.The mechanical performance and microstructure of the fabricated samples were analyzed.The lunar regolith mass ratio reached 90 wt%(approximately 79 vol%),with the highest compressive strengths exceeding 60 MPa for cast specimens and 30 MPa for printed samples.This technology shows significant potential for enabling in-situ lunar regolith-based construction in future lunar missions.
基金supported by the National Natural Science Foundation of China(No.51904036)the Hunan Provincial Key Research and Development Program,China(No.2023GK2049)+2 种基金Changsha Municipal Natural Science Foundation,China(Nos.kq2402016,kq2402014)the Postgraduate Scientific Research Innovation Project of Hunan Province,China(No.CX20240772)the Sichuan Science and Technology Program,China(No.2024NSFSC0151)。
文摘The microstructure and mechanical properties of Mg−4.5Al−2.5Zn−0.3Mn−0.2Ca(wt.%,designated as AZ42)alloys in extruded(at extrusion ratios of 28,20 and 11.5)and peak-aged states were investigated,by using optical microscopy,scanning electron microscopy,energy dispersive spectrometry and electron backscatter diffraction.The results show that extrusion produces a typical basal fiber texture and streamlines of second phases.All samples exhibit the lowest Schmid factor of basal slip(SFb)and the superior tensile yield strength(TYS)along extrusion direction(ED).The sample with extrusion ratio of 20 exhibits the largest average grain size,but the smallest SFb which compensates for the disadvantage of grain coarsening and maintains the strength.After being peak-aged at 175℃for 48 h,the sample with the extrusion ratio of 20 shows the optimal TYS along all the directions,compared to the other samples.This hopes to provide useful information for optimizing the deformation parameters of the AZ42 alloys.
文摘In the current study the wear behavior of the ZK60/SiC composites reinforced by particles and whiskers in both as-cast and extruded conditions was examined.Furthermore,the wear behavior of the extruded samples along the extrusion direction and perpendicular to the extrusion direction was studied.The wear tests were performed at temperatures of 100,200,and 300℃under loads of 10,20,and 30 N.The results showed that the whisker-reinforced sample(5.8×10^(–4)g/[N.m])had higher wear resistance than the particle-reinforced sample(1.3×10^(–3)g/[N.m]).The lowest wear rate was observed for the extruded sample in the extrusion direction(3.53×10^(–4)g/[N.m]).It was also found that the wear rate increased by∼20%with increasing temperature,but in the ZK60/SiC_(w)sample,dynamic precipitation increased the wear resistance.The coefficient of friction was also found to increase with rising temperature,showing an increase of approximately 12.5%at a 10 N load and 20%at a 30 N load.Examination of the worn surfaces by scanning electron microscopy showed that the as-cast ZK60 alloy at 100℃had the oxidative-abrasive as the dominant mechanism.It was found that by extruding the sample,the strength of the sample increased and the mechanism changed to adhesive wear.In the ZK60/SiC_(p)composite,the viscoplastic wear mechanism was dominant.Although in the extruded sample the dominant mechanism changed to plastic deformation.As temperature increases,the viscoplastic wear mechanism became dominant again.In the as-cast ZK60/SiC_(w)composite,the abrasive wear mechanism changed to delamination with increasing temperature.By extruding the sample,the dominant mechanism changed to adhesive wear.Finally,dynamic precipitation induced by temperature caused an increase in the wear resistance.
基金supported by National Key Research and Development Program of China(Grant.No.2022YFB4603102)Insight Action(Grant.No.AA5F41D0).
文摘Solid propellants are essential energy sources for rockets and other aerospace vehicles,and improvements in their performance have significant implications for the aerospace industry.The application of additive manufacturing(AM)in the production of solid propellants promises a substantial leap in the design and fabrication of solid propellant grains.This review summarizes recent research on AM techniques for solid propellant manufacturing,evaluates current applications,and explores development trends.This review highlights that AM technology for solid propellants offers unparalleled advantages in terms of propellant design flexibility and functional gradient loading compared with traditional processes.This study presents a new perspective for the future manufacturing of intelligent and controllable solid propulsion systems.
