Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prep...Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prepared under different HIP temperatures (880–1000℃), and the microstructural evolution and mechanical properties were systematically investigated. The results demonstrated that the HIPed alloys were predominantly composed of more than 80 vol.% α phase and a small amount of β phase, and their phase compositions were basically unaffected by the HIP temperatures. Under the typical single-temperature-maintained HIP (STM-HIP) regime, the microstructure of alloy significantly coarsened as the HIP temperature increased, and the alloy strength exhibited an obvious linear negative correlation with the HIP temperature. On the basis of Hall–Petch relation, the prediction model of grain size was established, and the mathematical equation between HIP temperature and grain size (d=M(T_(HIP-N)^(-2))) was deduced. Furthermore, a possible evolution mechanism of microstructure was proposed, which could be divided into the decomposition of initial α′ martensite for as-received powder, formation of the globular α grains in prior particle boundaries (PPBs) region, and precipitation of the platelet α grains in non-PPBs region. For these alloys prepared by the dual-temperature-maintained HIP (DTM-HIP) regime, although their tensile properties were comparable to that of alloy prepared by STM-HIP regime with same high-temperature holding stage, higher proportion of globular α grains occurred due to more recrystallization nucleation during the low-temperature holding stage, which probably provided a solution for improving the dynamic service performance of HIPed alloys.展开更多
The microstructure,micro-hardness,and tensile properties of interface between hot isostatic pressing densified low alloy steel and Inconel 690 cladding were investigated during the aging process at 600℃.The results s...The microstructure,micro-hardness,and tensile properties of interface between hot isostatic pressing densified low alloy steel and Inconel 690 cladding were investigated during the aging process at 600℃.The results show that the interface region can be divided into four zones from base metal to deposited metal:carbon-depleted zone(CDZ),partial melting zone(PMZ),planar growth zone(PGZ),and brownish feature zone(BFZ).Dimensions of these zones do not significantly change during aging.However,type I carbides noticeably increase in size in the PMZ,and precipitates clearly occur in the PGZ.The main reason for their growth and occurrence is continuous carbon migration.The highest micro-hardness appears in the PGZ and BFZ regions,which is related to carbon accumulation and precipitates in these regions.Tensile failure occurs on the base metal side due to the high strength mismatch between these two materials.The CDZ,composed of only ferrite,has lower strength and fractures at the boundary between CDZ and base metal.The ultimate tensile strength decreases by only 50 MPa after aging for 1500 h,and the interface region maintains high strength without significant deformation.展开更多
To enhance the mechanical properties of Mo alloys prepared through laser powder bed fusion(LPBF),a hot isostatic pressing(HIP)treatment was used.Results show that following HIP treatment,the porosity decreases from 0....To enhance the mechanical properties of Mo alloys prepared through laser powder bed fusion(LPBF),a hot isostatic pressing(HIP)treatment was used.Results show that following HIP treatment,the porosity decreases from 0.27%to 0.22%,enabling the elements Mo and Ti to diffuse fully and to distribute more uniformly,and to forming a substantial number of low-angle grain boundaries.The tensile strength soars from 286±32 MPa to 598±22 MPa,while the elongation increases from 0.08%±0.02%to 0.18%±0.02%,without notable alterations in grain morphology during the tensile deformation.HIP treatment eliminates the molten pool boundaries,which are the primary source for premature failure in LPBFed Mo alloys.Consequently,HIP treatment emerges as a novel and effective approach for strengthening the mechanical properties of LPBFed Mo alloys,offering a fresh perspective on producing high-performance Mo-based alloys.展开更多
In this study,the interaction between deformation and precipitates during multiple equal channel angular pressing(ECAP)deformations and inter-pass aging combination and its effect on the mechanical properties of 7050 ...In this study,the interaction between deformation and precipitates during multiple equal channel angular pressing(ECAP)deformations and inter-pass aging combination and its effect on the mechanical properties of 7050 aluminum alloy are studied.The result show that ECAP induces numerous substructures and dislocations,effectively promoting the precipitation of theηʹphase exhibiting a bimodal structure during inter-pass aging.Following inter-pass aging and subsequent ECAP,the decrease in grain size(4.8μm)is together with the increase in dislocation density(1.24×10^(15) m^(−2))due to the pinning effect of the precipitated phase.Simultaneously,the dislocation motion causes the second phase particles to become even finer and more diffuse.The synergistic effects of precipitation strengthening,fine grain strengthening,and dislocation strengthening collectively enhance the high strength of aluminum alloys,with ultimate tensile strength and yield strength reaching approximately 610 and 565 MPa,respectively.Meanwhile,ductility remains largely unchanged,primarily due to coordinated grain boundary sliding and the uniform and fine dispersion of second phase particles.展开更多
Pure titanium fabricated by powder metallurgy generally encounters problems including low relative density and low strength,which limits its application performance.This work proposed a multi-step pressing(MSP)techniq...Pure titanium fabricated by powder metallurgy generally encounters problems including low relative density and low strength,which limits its application performance.This work proposed a multi-step pressing(MSP)technique for developing highstrength pure titanium.The MSP processes of spherical Ti powders of 15–53μm,53–105μm,and 75–180μm were systematically investigated through multi-particle fnite element method(MPFEM)compared with conventional one-step pressing(OSP)technique.The relative density,phase constitution,microstructure,and compressive mechanical properties of the sintered bulk pure titanium were characterized.Simulation results demonstrate that the MSP technique signifcantly increases the relative density of green compacts by 3.2%,3.3%,and 5.2%,respectively,compared with OSP technique.Experimental results indicate the relative density of the sintered specimens prepared by MSP spherical powders increases by 5.4%,4.5%,and 4.5%,respectively,compared to OSP,and the yield strength improves by 16%,13%,and 18%.For the sintered specimens prepared by MSP irregular powder of 15–53μm,the relative density increases by 6.0%and the yield strength increases by 15%.The enhancement of relative density and yield strength is mainly because the MSP technique mitigates stress concentration between powder particles.Compared to spherical powder,irregular powder exhibits stronger mechanical interlocking owing to the greater propensity for displacement and deformation,which facilitates mutual wedging and interlocking,resulting in superior strength performance.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
Objective:To explore the effects of acupoint catgut embedding combined with auricular point pressing with beans on symptom management self-efficacy and quality of life in patients with nonalcoholic steatohepatitis(NAS...Objective:To explore the effects of acupoint catgut embedding combined with auricular point pressing with beans on symptom management self-efficacy and quality of life in patients with nonalcoholic steatohepatitis(NASH)of liver depression and spleen deficiency type.Methods:Sixty patients with NASH of liver depression and spleen deficiency type admitted to our hospital from January 2021 to December 2023 were selected and divided into an acupoint catgut embedding group(n=30)and a combined group(n=30)using the envelope lottery method.The acupoint catgut embedding group received acupoint catgut embedding intervention,while the combined group received auricular point pressing with beans on the basis of the acupoint catgut embedding group.The two groups were compared in terms of TCM syndrome scores,symptom management self-efficacy[Chronic Disease Self-Efficacy Scale(CDSES)],and quality of life[Chronic Liver Disease Questionnaire(CLDQ)].Results:After intervention,the combined group had lower TCM syndrome scores for both primary and secondary symptoms compared to the acupoint catgut embedding group(P<0.05).The combined group also had higher scores in all dimensions and total score of the CDSES compared to the acupoint catgut embedding group(P<0.05).Similarly,the combined group had higher scores in all dimensions and total score of the CLDQ compared to the acupoint catgut embedding group(P<0.05).Conclusion:Acupoint catgut embedding combined with auricular point pressing with beans can effectively improve TCM symptoms,enhance symptom management self-efficacy,and improve quality of life in patients with NASH of liver depression and spleen deficiency type.展开更多
In this study,we developed an in-situ hot-pressing sintering(HPS)device that can be coupled to a lab-oratory X-ray microscope,offering laboratory-available observation of the morphology evolution.With the help of this...In this study,we developed an in-situ hot-pressing sintering(HPS)device that can be coupled to a lab-oratory X-ray microscope,offering laboratory-available observation of the morphology evolution.With the help of this device,in-situ three-dimensional(3D)visualizations of the microstructural evolution of 7055 aluminum alloys during the HPS process were conducted.The 3D results revealed that the twodimensional(2D)methods usually underestimated sintering neck width and exhibited significant standard deviation in statistical analysis.Benefiting from the precise microstructure characterization of the insitu 3D methods,the diffusion activation energy for the sintering of 7055 alloys was calculated,and the quantitative relationship between the sintering temperature and the sintering process was constructed.Moreover,it was experimentally found an accelerative effect of satellite particles on the sintering process,and its mechanisms were discussed.The satellite particles enhanced the curvature near the sintering neck and thus increased the sintering driving stress,promoting the densification process.These findings provide new insights for optimizing sintering processes.展开更多
Laser powder bed fusion(LPBF)technology offers a promising solution to the fabricability challenges of titanium alloys;however,it introduces defects such as porosity and cracking.Here,we evaluated the effectiveness of...Laser powder bed fusion(LPBF)technology offers a promising solution to the fabricability challenges of titanium alloys;however,it introduces defects such as porosity and cracking.Here,we evaluated the effectiveness of hot isostatic pressing(HIP)in eliminating defects and enhancing the overall properties of LPBF Ti-6Al-4V alloy.Our findings indicated that LPBF Ti-6Al-4V alloy after HIP established better corrosion resistance and ductility.These improvements could be related to the decomposition ofαʹphase and the elimination of internal defects within alloy matrix.Furthermore,the application prospect of LPBF Ti-6Al-4V alloy in spent fuel reprocessing environment was expounded.展开更多
In order to solve the problems of traditional long sintering time and relatively low density of synthesized Al_(4)SiC_(4),Al_(4)SiC_(4) was prepared via hot pressing sintering using aluminum powder,silicon carbide pow...In order to solve the problems of traditional long sintering time and relatively low density of synthesized Al_(4)SiC_(4),Al_(4)SiC_(4) was prepared via hot pressing sintering using aluminum powder,silicon carbide powder,flake graphite,and pretreated synthetic Al_(4)C_(3) as raw materials.The phase composition of the Al_(4)C_(3) specimen,which was prepared by pretreating aluminum powder and flake graphite at different temperatures,was investigated.The effects of the heat treatment temperature and duration on the phase composition,microstructure,physical properties,and oxidation resistance of the Al_(4)SiC_(4) specimen were also explored.The results show that under the condition of firing at 1650℃ for 3 h,the Al_(4)SiC_(4) specimen exhibits an apparent porosity of 13.1%,a bulk density of 2.88 g·cm^(-3),a cold compressive strength as high as 63.23 MPa,and a mass loss rate of 1.2%.The preparation of relatively-high-density Al_(4)SiC_(4) ceramics by hot pressing sintering has potential industrial application prospects.展开更多
To investigate the effect of microstructure evolution on corrosion behavior and strengthening mechanism of Mg-1Zn-1Ca(wt.%)alloys,as-cast Mg-1Zn-1Ca alloys were performed by equal channel angular pressing(ECAP)with 1 ...To investigate the effect of microstructure evolution on corrosion behavior and strengthening mechanism of Mg-1Zn-1Ca(wt.%)alloys,as-cast Mg-1Zn-1Ca alloys were performed by equal channel angular pressing(ECAP)with 1 and 4 passes.The corrosion behavior and mechanical properties of alloys were investigated by optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),electrochemical tests,immersion tests and tensile tests.The results showed that mechanical properties improved after ECAP 1 pass;however,the corrosion resistance deteriorated due to high-density dislocations and fragmented secondary phases by ECAP.In contrast,synchronous improvement in the mechanical properties and corrosion resistance was achieved though grain refinement after ECAP 4 passes;fine grains led to a significant improvement in the yield strength,ultimate tensile strength,elongation,and corrosion rate of 103 MPa,223 MPa,30.5%,and 1.5843 mm/a,respectively.The enhanced corrosion resistance was attributed to the formation of dense corrosion product films by finer grains and the barrier effect by high-density grain boundaries.These results indicated that Mg-1Zn-1Ca alloy has a promising potential for application in biomedical materials.展开更多
In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and proper...In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and properties of the alloy were investigated in detail.The results showed that the samples deformed by the combination of cryogenic equal channel angular pressing(ECAP)and rolling had good comprehensive properties after aging at 400℃.The tensile strength of the peak-aged and over-aged samples was 1120 MPa and 940 MPa,with their corresponding electrical conductivity of 14.7%IACS and 22.1%IACS,respectively.ECAP and cryogenic rolling introduced high density dislocations,leading to the inhibition of the softening effects and refinement of the grains.After a long time aging at 400℃,the alloy exhibited ultra-high strength with obvious increasing electrical conductivity.The high strength was attributed to the synergistic effect of work hardening,grain refinement strengthening and precipitation strengthening.The precipitation of a large amount of Ti atoms from the matrix led to the high electrical conductivity of the over-aged sample.展开更多
Hot isostatic pressing(HIP)is usually applied to reduce the defects including cracks and pores in the materials prepared by laser powder bed fusion(LPBF).In the present research,in order to improve the relative densit...Hot isostatic pressing(HIP)is usually applied to reduce the defects including cracks and pores in the materials prepared by laser powder bed fusion(LPBF).In the present research,in order to improve the relative density and mechanical property,HIP was employed on the LPBF-processed Al-Cr-Fe-Ni-V high-entropy alloy(HEA)with microcracks and pores.The microstructure evolution and property improvement induced by HIP were investigated.In the LPBF-processed HEA,the microcracks were caused by residual stress and element segregation,and these microcracks as well as the pores reduced significantly after HIP treatments.Remarkably,HIP temperature has a more critical effect on the microcrack closure than the holding time,thus,microcracks and pores still existed after HIP-1 treatment(1273 K,8 h),while HIP-2 treatment(1473 K,4 h)could close the microcracks significantly.The crack closure was attributed to the interfacial diffusion of the alloying element under high temperature accompanied by high pressure,and the degree of element diffusion at both interfaces of the cracks determined the bonding strength after crack closure.Higher temperatures at high pressure induced more adequate element diffusion and higher bonding strength.The above high temperature and high pressure also induced the growth of the L1_(2) phase and the precipitation of the B2 phase in HEA.Consequently,the tensile strength and elonga-tion of the LPBF-processed HEA after HIP-2 treatment were simultaneously enhanced(80.7%and 222.5%higher than that of LPBF-processed HEA,respectively).This could be attributed to the combined effect of microcrack/pore closure and precipitation strengthening.The strengthening effect of the B2 phase and L1_(2) phase accounted for 53%(dislocation by-pass mechanism)and 47%(dislocation shearing mechanism)of the total precipitation strengthening,respectively.展开更多
The functional properties of BaTiO_(3)ceramics,produced by using the same pressing/sintering strategy from nanopowders with two distinct morphologies(cuboidal/equiaxed nanoparticles)and similar particle sizes,are comp...The functional properties of BaTiO_(3)ceramics,produced by using the same pressing/sintering strategy from nanopowders with two distinct morphologies(cuboidal/equiaxed nanoparticles)and similar particle sizes,are comparatively investigated.The sintered ceramics exhibit similar nanoscale structures,with faceted crystalline grains and crystalline inclusions,clean grain boundaries and well-defined 90°lamellar domains extending in some entire grains or finer nanodomains inside grain regions.The differences in the functional behavior originating from the different nanopowder morphology are described in terms of the nanoparticle assembly during the pressing step.The numerically simulated green body densification indicated a more efficient assembly resulting in higher density for the cubic particles(0.90 vs.0.84 relative density)and a more homogeneous pore distribution in the spherical-derived ones.As a result of the higher density after sintering,the functional properties are enhanced in cuboid-originated ceramics.For comparison,the ceramic produced from cubic nanoparticles sintered at T_(1)/T_(2)=1250/800℃shows higher permittivity(room temperature value of∼2100-cubic vs.∼1700-rounded),enhanced ferroelectric characteristics(cubic:P_(s)=8.57μC cm^(-2),P_(r)=0.95μC cm^(-2),and E_(c)=2.3 kV cm^(-1),with respect to P_(s)=6.06μC cm^(-2),P_(r)=0.4μC cm^(-2),and E_(c)=1.4 kV cm^(-1),for spherical-derived ones,measured at E_(max)=29.3 kV cm^(-1))and a stronger dc-field dependence of their permittivity of∼12%(cubic)vs.only∼2%(spherical),for a dc-applied field in the range of-15 kV cm^(-1)<Edc<15 kV cm^(-1).In contrast,the spherical particles-derived ceramics contain fewer defects and have a more homogeneous and finer porosity distribution in the ceramic volume and consequently,they are more stable and sustain larger field applications in comparison with the cubic-derived counterparts.展开更多
The combination of electrospinning and hot pressing,namely the electrospinning-hot pressing technique(EHPT),is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage ...The combination of electrospinning and hot pressing,namely the electrospinning-hot pressing technique(EHPT),is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage performance.The emerging composite membrane prepared by EHPT,which exhibits the advantages of large surface area,controllable morphology,and compact structure,has attracted immense attention.In this paper,the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT are systematically discussed.Moreover,the state-of-the-art applications of composite membranes in these two fields are introduced.In particular,in the field of thermal energy storage,EHPT-prepared membranes have longitudinal and transverse nanofibers,which generate unique thermal conductivity pathways;also,these nanofibers offer enough space for the filling of functional materials.Moreover,EHPT-prepared membranes are beneficial in thermal management systems,building energy conservation,and electrical energy storage,e.g.,improving the electrochemical properties of the separators as well as their mechanical and thermal stability.The application of electrospinning-hot pressing membranes on capacitors,lithium-ion batteries(LIBs),fuel cells,sodium-ion batteries(SIBs),and hydrogen bromine flow batteries(HBFBs)still requires examination.In the future,EHPT is expected to make the field more exciting through its own technological breakthroughs or be combined with other technologies to produce intelligent materials.展开更多
The Mg-7Gd-4Y-2Zn-0.5Zr alloy chips were successfully recycled through isothermal sintering and equal channel angular pressing(ECAP).The mechanical properties and microstructure evolution of samples during the recycli...The Mg-7Gd-4Y-2Zn-0.5Zr alloy chips were successfully recycled through isothermal sintering and equal channel angular pressing(ECAP).The mechanical properties and microstructure evolution of samples during the recycling process were studied in detail.The eutectic phases in the as-cast alloy transform into long period-stacking ordered(LPSO)phases after homogenization,which can improve the plasticity of the material.After isothermal sintering,the density of the sample is lower than that of the homogenized sample,and oxide films are formed adjacent to the bonding interface of the metal chips.Hence,the plasticity of the sintered sample is poor.Dense samples are fabricated after ECAP.Although the grains are not refined compared to the sintered sample,the microstructure becomes more uniform due to recrystallization.Fiber interdendritic LPSO phase and kinked 14H-LPSO phase are formed in the alloy due to the shear deformation during the ECAP process,which improves the strength and plasticity of the sample significantly.Furthermore,the basal texture is weakened due to the Bc route of the ECAP process,which can increase the Schmid factor of the basal slip system and improve the elongation of the sample.After 2 ECAP passes,the fully densified recycled billet shows superior mechanical properties with an ultimate tensile strength of 307.1 MPa and elongation of 11.1%.展开更多
Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded to...Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.展开更多
Ti-25Ta alloy samples were fabricated by selective laser melting,and the relative density,microstructure,microhardness and tensile properties of the as-built and hot isostatic pressing(HIP)-prepared samples were chara...Ti-25Ta alloy samples were fabricated by selective laser melting,and the relative density,microstructure,microhardness and tensile properties of the as-built and hot isostatic pressing(HIP)-prepared samples were characterized.Results show that the track width and penetration depth are increased with the increase in laser power,and the surface morphology is improved.The maximum relative density improves from 95.31%to 98.01%after HIP process.Moreover,the microstructure is refined into the lath martensite and cellular grains with the increase in input power.After densification treatment,the subgrain coalescence occurs and high angle grain boundaries are formed.In addition,HIP process stabilizes the microhardness and enhances the tensile strength and elongation.展开更多
Molasses can serve as a natural adhesive for plywood and particleboard.However,several disadvantages remain,including lower dimensional stability and low bonding strength compared to other adhesives.Therefore,modifica...Molasses can serve as a natural adhesive for plywood and particleboard.However,several disadvantages remain,including lower dimensional stability and low bonding strength compared to other adhesives.Therefore,modifications are needed to use molasses as an adhesive for plywood.This research aims to improve bio-based molasses(MO)adhesive for plywood using citric acid(CA)adhesive.In addition,this research aims to analyze the effect of adding citric acid and to investigate the optimum hot-pressing temperature to produce the best quality plywood.In the first stage,the molasses and citric acid were combined in a ratio of 100:0,75:25,50:50,25:75,0:100 w/w%.Then,the second stage focuses on analyzing the influences of pressing temperature based on an optimum first stage.The research demonstrated that the addition of CA altered the gelation time,solid content,viscosity,and pH of the molasses adhesives.In addition,the thermal properties of molasses adhesives were changed after mixing with citric acid.These phenomena indicate changes in characteristics,such as the curing of adhesive.Overall,the characteristics of plywood showed a steady improvement as the CA ratio increased but revealed a significant decline for the 25:75 MO-CA ratio.By raising the pressing temperature from 180℃ to 200℃,the quality of plywood was effectively improved.The plywood that was bonded using adhesives with a 50:50 MO-CA ratio exhibited superior mechanical properties and improved dimensional stability compared to the plywood bonded solely with MO.Furthermore,the optimal mechanical and physical properties resulted in plywood bonded with a 50:50 MO-CA ratio when subjected to a pressing temperature of 200℃.The Thermal and FTIR measurements revealed that CA established ester bonds with both the MO and wood veneers.In conclusion,the mechanical characteristics of plywood were improved,while maintaining its excellent dimensional stability.展开更多
(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the...(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.展开更多
基金support from CAS Project for Young Scientists in Basic Research(YSBR-025)and the Technology Innovation(RCJJ-145-24-39)R.P.Guo acknowledges the financial support from the National Natural Science Foundation of China(No.52401104)+1 种基金the Fundamental Research Program of Shanxi Province(No.202203021221072)the China Postdoctoral Science Foundation(No.2024M753298).
文摘Hot isostatic pressing (HIP) temperature has a significant impact on the service performance of powder metallurgy titanium alloys. In this study, a high-temperature titanium alloy, Ti-6.5Al-3.5Mo-1.5Zr-0.3Si, was prepared under different HIP temperatures (880–1000℃), and the microstructural evolution and mechanical properties were systematically investigated. The results demonstrated that the HIPed alloys were predominantly composed of more than 80 vol.% α phase and a small amount of β phase, and their phase compositions were basically unaffected by the HIP temperatures. Under the typical single-temperature-maintained HIP (STM-HIP) regime, the microstructure of alloy significantly coarsened as the HIP temperature increased, and the alloy strength exhibited an obvious linear negative correlation with the HIP temperature. On the basis of Hall–Petch relation, the prediction model of grain size was established, and the mathematical equation between HIP temperature and grain size (d=M(T_(HIP-N)^(-2))) was deduced. Furthermore, a possible evolution mechanism of microstructure was proposed, which could be divided into the decomposition of initial α′ martensite for as-received powder, formation of the globular α grains in prior particle boundaries (PPBs) region, and precipitation of the platelet α grains in non-PPBs region. For these alloys prepared by the dual-temperature-maintained HIP (DTM-HIP) regime, although their tensile properties were comparable to that of alloy prepared by STM-HIP regime with same high-temperature holding stage, higher proportion of globular α grains occurred due to more recrystallization nucleation during the low-temperature holding stage, which probably provided a solution for improving the dynamic service performance of HIPed alloys.
基金Major Scientific and Technological Project of Gansu(22ZD6GA008)Excellent Doctorate Project of Gansu(23JRRA806)National Natural Science Foundation of China(52175325,51961024,52071170)。
文摘The microstructure,micro-hardness,and tensile properties of interface between hot isostatic pressing densified low alloy steel and Inconel 690 cladding were investigated during the aging process at 600℃.The results show that the interface region can be divided into four zones from base metal to deposited metal:carbon-depleted zone(CDZ),partial melting zone(PMZ),planar growth zone(PGZ),and brownish feature zone(BFZ).Dimensions of these zones do not significantly change during aging.However,type I carbides noticeably increase in size in the PMZ,and precipitates clearly occur in the PGZ.The main reason for their growth and occurrence is continuous carbon migration.The highest micro-hardness appears in the PGZ and BFZ regions,which is related to carbon accumulation and precipitates in these regions.Tensile failure occurs on the base metal side due to the high strength mismatch between these two materials.The CDZ,composed of only ferrite,has lower strength and fractures at the boundary between CDZ and base metal.The ultimate tensile strength decreases by only 50 MPa after aging for 1500 h,and the interface region maintains high strength without significant deformation.
基金National Natural Science Foundation of China(52105385)Stable Support Plan Program of Shenzhen Natural Science Fund(20220810132537001)+2 种基金Guangdong Basic and Applied Basic Research Foundation(2022A1515010781)Joint Fund of Henan Province Science and Technology R&D Program(225200810002)Fundamental Research Funds of Henan Academy of Sciences(240621041)。
文摘To enhance the mechanical properties of Mo alloys prepared through laser powder bed fusion(LPBF),a hot isostatic pressing(HIP)treatment was used.Results show that following HIP treatment,the porosity decreases from 0.27%to 0.22%,enabling the elements Mo and Ti to diffuse fully and to distribute more uniformly,and to forming a substantial number of low-angle grain boundaries.The tensile strength soars from 286±32 MPa to 598±22 MPa,while the elongation increases from 0.08%±0.02%to 0.18%±0.02%,without notable alterations in grain morphology during the tensile deformation.HIP treatment eliminates the molten pool boundaries,which are the primary source for premature failure in LPBFed Mo alloys.Consequently,HIP treatment emerges as a novel and effective approach for strengthening the mechanical properties of LPBFed Mo alloys,offering a fresh perspective on producing high-performance Mo-based alloys.
基金Project(52275350)supported by the National Natural Science Foundation of ChinaProject(0301006)supported by the International Cooperative Scientific Research Platform of SUES,China。
文摘In this study,the interaction between deformation and precipitates during multiple equal channel angular pressing(ECAP)deformations and inter-pass aging combination and its effect on the mechanical properties of 7050 aluminum alloy are studied.The result show that ECAP induces numerous substructures and dislocations,effectively promoting the precipitation of theηʹphase exhibiting a bimodal structure during inter-pass aging.Following inter-pass aging and subsequent ECAP,the decrease in grain size(4.8μm)is together with the increase in dislocation density(1.24×10^(15) m^(−2))due to the pinning effect of the precipitated phase.Simultaneously,the dislocation motion causes the second phase particles to become even finer and more diffuse.The synergistic effects of precipitation strengthening,fine grain strengthening,and dislocation strengthening collectively enhance the high strength of aluminum alloys,with ultimate tensile strength and yield strength reaching approximately 610 and 565 MPa,respectively.Meanwhile,ductility remains largely unchanged,primarily due to coordinated grain boundary sliding and the uniform and fine dispersion of second phase particles.
基金supports from the National Natural Science Foundation of China(No.52404382)the Key Research and Development Project of Shaanxi Province(No.2023-YBGY-090).
文摘Pure titanium fabricated by powder metallurgy generally encounters problems including low relative density and low strength,which limits its application performance.This work proposed a multi-step pressing(MSP)technique for developing highstrength pure titanium.The MSP processes of spherical Ti powders of 15–53μm,53–105μm,and 75–180μm were systematically investigated through multi-particle fnite element method(MPFEM)compared with conventional one-step pressing(OSP)technique.The relative density,phase constitution,microstructure,and compressive mechanical properties of the sintered bulk pure titanium were characterized.Simulation results demonstrate that the MSP technique signifcantly increases the relative density of green compacts by 3.2%,3.3%,and 5.2%,respectively,compared with OSP technique.Experimental results indicate the relative density of the sintered specimens prepared by MSP spherical powders increases by 5.4%,4.5%,and 4.5%,respectively,compared to OSP,and the yield strength improves by 16%,13%,and 18%.For the sintered specimens prepared by MSP irregular powder of 15–53μm,the relative density increases by 6.0%and the yield strength increases by 15%.The enhancement of relative density and yield strength is mainly because the MSP technique mitigates stress concentration between powder particles.Compared to spherical powder,irregular powder exhibits stronger mechanical interlocking owing to the greater propensity for displacement and deformation,which facilitates mutual wedging and interlocking,resulting in superior strength performance.
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.
文摘Objective:To explore the effects of acupoint catgut embedding combined with auricular point pressing with beans on symptom management self-efficacy and quality of life in patients with nonalcoholic steatohepatitis(NASH)of liver depression and spleen deficiency type.Methods:Sixty patients with NASH of liver depression and spleen deficiency type admitted to our hospital from January 2021 to December 2023 were selected and divided into an acupoint catgut embedding group(n=30)and a combined group(n=30)using the envelope lottery method.The acupoint catgut embedding group received acupoint catgut embedding intervention,while the combined group received auricular point pressing with beans on the basis of the acupoint catgut embedding group.The two groups were compared in terms of TCM syndrome scores,symptom management self-efficacy[Chronic Disease Self-Efficacy Scale(CDSES)],and quality of life[Chronic Liver Disease Questionnaire(CLDQ)].Results:After intervention,the combined group had lower TCM syndrome scores for both primary and secondary symptoms compared to the acupoint catgut embedding group(P<0.05).The combined group also had higher scores in all dimensions and total score of the CDSES compared to the acupoint catgut embedding group(P<0.05).Similarly,the combined group had higher scores in all dimensions and total score of the CLDQ compared to the acupoint catgut embedding group(P<0.05).Conclusion:Acupoint catgut embedding combined with auricular point pressing with beans can effectively improve TCM symptoms,enhance symptom management self-efficacy,and improve quality of life in patients with NASH of liver depression and spleen deficiency type.
基金supported by the National Key Research&Development Plan(No.2021YFA1600702)the National Natural Science Foundation of China(Nos.92263201,52301155,and 52001161).
文摘In this study,we developed an in-situ hot-pressing sintering(HPS)device that can be coupled to a lab-oratory X-ray microscope,offering laboratory-available observation of the morphology evolution.With the help of this device,in-situ three-dimensional(3D)visualizations of the microstructural evolution of 7055 aluminum alloys during the HPS process were conducted.The 3D results revealed that the twodimensional(2D)methods usually underestimated sintering neck width and exhibited significant standard deviation in statistical analysis.Benefiting from the precise microstructure characterization of the insitu 3D methods,the diffusion activation energy for the sintering of 7055 alloys was calculated,and the quantitative relationship between the sintering temperature and the sintering process was constructed.Moreover,it was experimentally found an accelerative effect of satellite particles on the sintering process,and its mechanisms were discussed.The satellite particles enhanced the curvature near the sintering neck and thus increased the sintering driving stress,promoting the densification process.These findings provide new insights for optimizing sintering processes.
基金supported by the National Natural Science Foundation of China(Nos.52101105,52373321)the IMR Innovation Fund(2023-PY03)the LingChuang Research Project of China National Nuclear Corporation(CNNC-LCKY-202274).
文摘Laser powder bed fusion(LPBF)technology offers a promising solution to the fabricability challenges of titanium alloys;however,it introduces defects such as porosity and cracking.Here,we evaluated the effectiveness of hot isostatic pressing(HIP)in eliminating defects and enhancing the overall properties of LPBF Ti-6Al-4V alloy.Our findings indicated that LPBF Ti-6Al-4V alloy after HIP established better corrosion resistance and ductility.These improvements could be related to the decomposition ofαʹphase and the elimination of internal defects within alloy matrix.Furthermore,the application prospect of LPBF Ti-6Al-4V alloy in spent fuel reprocessing environment was expounded.
文摘In order to solve the problems of traditional long sintering time and relatively low density of synthesized Al_(4)SiC_(4),Al_(4)SiC_(4) was prepared via hot pressing sintering using aluminum powder,silicon carbide powder,flake graphite,and pretreated synthetic Al_(4)C_(3) as raw materials.The phase composition of the Al_(4)C_(3) specimen,which was prepared by pretreating aluminum powder and flake graphite at different temperatures,was investigated.The effects of the heat treatment temperature and duration on the phase composition,microstructure,physical properties,and oxidation resistance of the Al_(4)SiC_(4) specimen were also explored.The results show that under the condition of firing at 1650℃ for 3 h,the Al_(4)SiC_(4) specimen exhibits an apparent porosity of 13.1%,a bulk density of 2.88 g·cm^(-3),a cold compressive strength as high as 63.23 MPa,and a mass loss rate of 1.2%.The preparation of relatively-high-density Al_(4)SiC_(4) ceramics by hot pressing sintering has potential industrial application prospects.
基金financially supported by the National Natural Science Foundation of China(No.52374395)the Natural Science Foundation of Shanxi Province,China(Nos.20210302123135,202303021221143)+5 种基金the Scientific and Technological Achievements Transformation Guidance Special Project of Shanxi Province,China(Nos.202104021301022,202204021301009)the Central Government Guided Local Science and Technology Development Projects,China(No.YDZJSX20231B003)the Ministry of Science and Higher Education of the Russian Federation for financial support under the Megagrant(No.075-15-2022-1133)the National Research Foundation(NRF)grant funded by the Ministry of Science and ICT of Korea through the Research Institute of Advanced Materials(No.2015R1A2A1A01006795)the China Postdoctoral Science Foundation(No.2022M710541)the Research Project supported by Shanxi Scholarship Council of China(No.2022-038)。
文摘To investigate the effect of microstructure evolution on corrosion behavior and strengthening mechanism of Mg-1Zn-1Ca(wt.%)alloys,as-cast Mg-1Zn-1Ca alloys were performed by equal channel angular pressing(ECAP)with 1 and 4 passes.The corrosion behavior and mechanical properties of alloys were investigated by optical microscopy(OM),scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),electrochemical tests,immersion tests and tensile tests.The results showed that mechanical properties improved after ECAP 1 pass;however,the corrosion resistance deteriorated due to high-density dislocations and fragmented secondary phases by ECAP.In contrast,synchronous improvement in the mechanical properties and corrosion resistance was achieved though grain refinement after ECAP 4 passes;fine grains led to a significant improvement in the yield strength,ultimate tensile strength,elongation,and corrosion rate of 103 MPa,223 MPa,30.5%,and 1.5843 mm/a,respectively.The enhanced corrosion resistance was attributed to the formation of dense corrosion product films by finer grains and the barrier effect by high-density grain boundaries.These results indicated that Mg-1Zn-1Ca alloy has a promising potential for application in biomedical materials.
基金Project(U2202255)supported by the National Natural Science Foundation of ChinaProject(2024JJ2076)supported by the Hunan Provincial Natural Science Foundation of ChinaProject(2023Z092)supported by the Key Technology Research Program of Ningbo,China。
文摘In this paper,equal channel angular pressing and thermomechanical treatment was employed to improve the strength and electrical conductivity of an aging strengthened Cu-Ti-Cr-Mg alloy,and the microstructure and properties of the alloy were investigated in detail.The results showed that the samples deformed by the combination of cryogenic equal channel angular pressing(ECAP)and rolling had good comprehensive properties after aging at 400℃.The tensile strength of the peak-aged and over-aged samples was 1120 MPa and 940 MPa,with their corresponding electrical conductivity of 14.7%IACS and 22.1%IACS,respectively.ECAP and cryogenic rolling introduced high density dislocations,leading to the inhibition of the softening effects and refinement of the grains.After a long time aging at 400℃,the alloy exhibited ultra-high strength with obvious increasing electrical conductivity.The high strength was attributed to the synergistic effect of work hardening,grain refinement strengthening and precipitation strengthening.The precipitation of a large amount of Ti atoms from the matrix led to the high electrical conductivity of the over-aged sample.
基金National Natural Science Foundation of China(Grant Nos.51901004,52001025,and 52171060)State Key Laboratory of Powder Metallurgy,Central South University,Changsha,China.
文摘Hot isostatic pressing(HIP)is usually applied to reduce the defects including cracks and pores in the materials prepared by laser powder bed fusion(LPBF).In the present research,in order to improve the relative density and mechanical property,HIP was employed on the LPBF-processed Al-Cr-Fe-Ni-V high-entropy alloy(HEA)with microcracks and pores.The microstructure evolution and property improvement induced by HIP were investigated.In the LPBF-processed HEA,the microcracks were caused by residual stress and element segregation,and these microcracks as well as the pores reduced significantly after HIP treatments.Remarkably,HIP temperature has a more critical effect on the microcrack closure than the holding time,thus,microcracks and pores still existed after HIP-1 treatment(1273 K,8 h),while HIP-2 treatment(1473 K,4 h)could close the microcracks significantly.The crack closure was attributed to the interfacial diffusion of the alloying element under high temperature accompanied by high pressure,and the degree of element diffusion at both interfaces of the cracks determined the bonding strength after crack closure.Higher temperatures at high pressure induced more adequate element diffusion and higher bonding strength.The above high temperature and high pressure also induced the growth of the L1_(2) phase and the precipitation of the B2 phase in HEA.Consequently,the tensile strength and elonga-tion of the LPBF-processed HEA after HIP-2 treatment were simultaneously enhanced(80.7%and 222.5%higher than that of LPBF-processed HEA,respectively).This could be attributed to the combined effect of microcrack/pore closure and precipitation strengthening.The strengthening effect of the B2 phase and L1_(2) phase accounted for 53%(dislocation by-pass mechanism)and 47%(dislocation shearing mechanism)of the total precipitation strengthening,respectively.
基金supported by the Romanian Ministry of Education and Research,CNCS-UEFISCDI Research Grant No.PN-Ⅲ-P1-1.1-PD-2021-0531.
文摘The functional properties of BaTiO_(3)ceramics,produced by using the same pressing/sintering strategy from nanopowders with two distinct morphologies(cuboidal/equiaxed nanoparticles)and similar particle sizes,are comparatively investigated.The sintered ceramics exhibit similar nanoscale structures,with faceted crystalline grains and crystalline inclusions,clean grain boundaries and well-defined 90°lamellar domains extending in some entire grains or finer nanodomains inside grain regions.The differences in the functional behavior originating from the different nanopowder morphology are described in terms of the nanoparticle assembly during the pressing step.The numerically simulated green body densification indicated a more efficient assembly resulting in higher density for the cubic particles(0.90 vs.0.84 relative density)and a more homogeneous pore distribution in the spherical-derived ones.As a result of the higher density after sintering,the functional properties are enhanced in cuboid-originated ceramics.For comparison,the ceramic produced from cubic nanoparticles sintered at T_(1)/T_(2)=1250/800℃shows higher permittivity(room temperature value of∼2100-cubic vs.∼1700-rounded),enhanced ferroelectric characteristics(cubic:P_(s)=8.57μC cm^(-2),P_(r)=0.95μC cm^(-2),and E_(c)=2.3 kV cm^(-1),with respect to P_(s)=6.06μC cm^(-2),P_(r)=0.4μC cm^(-2),and E_(c)=1.4 kV cm^(-1),for spherical-derived ones,measured at E_(max)=29.3 kV cm^(-1))and a stronger dc-field dependence of their permittivity of∼12%(cubic)vs.only∼2%(spherical),for a dc-applied field in the range of-15 kV cm^(-1)<Edc<15 kV cm^(-1).In contrast,the spherical particles-derived ceramics contain fewer defects and have a more homogeneous and finer porosity distribution in the ceramic volume and consequently,they are more stable and sustain larger field applications in comparison with the cubic-derived counterparts.
基金supported by the National Natural Science Foundation of China(No.52274252)the Key Science and Technology Project of Changsha City,China(No.kq2102005)+1 种基金the Special Fund for the Construction of Innovative Province in Hunan Province,China(Nos.2020RC3038 and 2022WK4004)the Changsha City Fund for Distinguished and Innovative Young Scholars,China(No.kq1802007).
文摘The combination of electrospinning and hot pressing,namely the electrospinning-hot pressing technique(EHPT),is an efficient and convenient method for preparing nanofibrous composite materials with good energy storage performance.The emerging composite membrane prepared by EHPT,which exhibits the advantages of large surface area,controllable morphology,and compact structure,has attracted immense attention.In this paper,the conduction mechanism of composite membranes in thermal and electrical energy storage and the performance enhancement method based on the fabrication process of EHPT are systematically discussed.Moreover,the state-of-the-art applications of composite membranes in these two fields are introduced.In particular,in the field of thermal energy storage,EHPT-prepared membranes have longitudinal and transverse nanofibers,which generate unique thermal conductivity pathways;also,these nanofibers offer enough space for the filling of functional materials.Moreover,EHPT-prepared membranes are beneficial in thermal management systems,building energy conservation,and electrical energy storage,e.g.,improving the electrochemical properties of the separators as well as their mechanical and thermal stability.The application of electrospinning-hot pressing membranes on capacitors,lithium-ion batteries(LIBs),fuel cells,sodium-ion batteries(SIBs),and hydrogen bromine flow batteries(HBFBs)still requires examination.In the future,EHPT is expected to make the field more exciting through its own technological breakthroughs or be combined with other technologies to produce intelligent materials.
基金supported by the fund of the National Natural Science Foundation of China(51875127,52275322).
文摘The Mg-7Gd-4Y-2Zn-0.5Zr alloy chips were successfully recycled through isothermal sintering and equal channel angular pressing(ECAP).The mechanical properties and microstructure evolution of samples during the recycling process were studied in detail.The eutectic phases in the as-cast alloy transform into long period-stacking ordered(LPSO)phases after homogenization,which can improve the plasticity of the material.After isothermal sintering,the density of the sample is lower than that of the homogenized sample,and oxide films are formed adjacent to the bonding interface of the metal chips.Hence,the plasticity of the sintered sample is poor.Dense samples are fabricated after ECAP.Although the grains are not refined compared to the sintered sample,the microstructure becomes more uniform due to recrystallization.Fiber interdendritic LPSO phase and kinked 14H-LPSO phase are formed in the alloy due to the shear deformation during the ECAP process,which improves the strength and plasticity of the sample significantly.Furthermore,the basal texture is weakened due to the Bc route of the ECAP process,which can increase the Schmid factor of the basal slip system and improve the elongation of the sample.After 2 ECAP passes,the fully densified recycled billet shows superior mechanical properties with an ultimate tensile strength of 307.1 MPa and elongation of 11.1%.
基金funding from the NATO Agency Science for Peace and Security (#G5787)Ballistic investigations were co-financed by Military University of Technology in Warsaw under research project UGB 829/2023/WATSeparate works made in G.V.Kurdyumov Institute for Metal Physics of N.A.S.of Ukraine were partially financially supported by N.A.S.of Ukraine within the frames of project#III09-18。
文摘Metal matrix composites tiles based on Ti-6Al-4V(Ti64)alloy,reinforced with 10,20,and 40(vol%)of either TiC or TiB particles were made using press-and-sinter blended elemental powder metallurgy(BEPM)and then bonded together into 3-layer laminated plates using hot isostatic pressing(HIP).The laminates were ballistically tested and demonstrated superior performance.The microstructure and properties of the laminates were analyzed to determine the effect of the BEPM and HIP processing on the ballistic properties of the layered plates.The effect of porosity in sintered composites on further diffusion bonding of the plates during HIP is analyzed to understand the bonding features at the interfaces between different adjacent layers in the laminate.Exceptional ballistic performance of fabricated structures was explained by a significant reduction in the residual porosity of the BEPM products by their additional processing using HIP,which provides an unprecedented increase in the hardness of the layered composites.It is argued that the combination of the used two technologies,BEPM and HIP is principally complimentary for the materials in question with the abilities to solve the essential problems of each used individually.
基金Key Realm R&D Program of Guangdong Province(2018B090904004)Supported by State Key Laboratory of Advanced Metals and Materials(2022-Z16)+3 种基金Key Research Program of Guangzhou(202206040001)International Science and Technology Cooperation Program of Guangdong Province(2022A0505050025)Guangdong Academy of Science Project of Science and Technology Development(2020GDASYL-20200504001,2022GDASZH-2022010107,2022GDASZH-2022010109)National Key Research and Development Project(2022YFC2406000)。
文摘Ti-25Ta alloy samples were fabricated by selective laser melting,and the relative density,microstructure,microhardness and tensile properties of the as-built and hot isostatic pressing(HIP)-prepared samples were characterized.Results show that the track width and penetration depth are increased with the increase in laser power,and the surface morphology is improved.The maximum relative density improves from 95.31%to 98.01%after HIP process.Moreover,the microstructure is refined into the lath martensite and cellular grains with the increase in input power.After densification treatment,the subgrain coalescence occurs and high angle grain boundaries are formed.In addition,HIP process stabilizes the microhardness and enhances the tensile strength and elongation.
基金funded by Riset dan Inovasi untuk Indonesia Maju(RIIM)National Riset and Innovation Agency(Grant Numbers:4/IV/KS/05/2023 and 13955/IT3/PT.01.03/P/B/2023)Research Program by Research Organization of Nanotechnology and Materials,National Research and Innovation Agency(Grant Number 20/III.10/HK/2024).
文摘Molasses can serve as a natural adhesive for plywood and particleboard.However,several disadvantages remain,including lower dimensional stability and low bonding strength compared to other adhesives.Therefore,modifications are needed to use molasses as an adhesive for plywood.This research aims to improve bio-based molasses(MO)adhesive for plywood using citric acid(CA)adhesive.In addition,this research aims to analyze the effect of adding citric acid and to investigate the optimum hot-pressing temperature to produce the best quality plywood.In the first stage,the molasses and citric acid were combined in a ratio of 100:0,75:25,50:50,25:75,0:100 w/w%.Then,the second stage focuses on analyzing the influences of pressing temperature based on an optimum first stage.The research demonstrated that the addition of CA altered the gelation time,solid content,viscosity,and pH of the molasses adhesives.In addition,the thermal properties of molasses adhesives were changed after mixing with citric acid.These phenomena indicate changes in characteristics,such as the curing of adhesive.Overall,the characteristics of plywood showed a steady improvement as the CA ratio increased but revealed a significant decline for the 25:75 MO-CA ratio.By raising the pressing temperature from 180℃ to 200℃,the quality of plywood was effectively improved.The plywood that was bonded using adhesives with a 50:50 MO-CA ratio exhibited superior mechanical properties and improved dimensional stability compared to the plywood bonded solely with MO.Furthermore,the optimal mechanical and physical properties resulted in plywood bonded with a 50:50 MO-CA ratio when subjected to a pressing temperature of 200℃.The Thermal and FTIR measurements revealed that CA established ester bonds with both the MO and wood veneers.In conclusion,the mechanical characteristics of plywood were improved,while maintaining its excellent dimensional stability.
文摘(Gd,Lu)_(2)O_(3)∶Eu scintillation ceramics have promising applications in the high-energy X-ray imaging.Eu0.1Gd0.6Lu1.3O3 nano-powders with pure phase were prepared from the precursor calcined at 1050℃for 4 h by the co-precipitation method.Using the synthesized nano-powders as initial material,Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics were fabri-cated by vacuum pre-sintering at different temperatures for 2 h and hot isostatic pressing(HIP)at 1750℃for 3 h in ar-gon.The influence of pre-sintering temperature on the microstructure,optical and luminescence properties was investi-gated.The Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics pre-sintered at 1625℃for 2 h combined with HIP post-treatment show the high-est in-line transmittance of 75.2%at 611 nm.The photoluminescence(PL)and X-ray excited luminescence(XEL)spectra of the Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)transparent ceramics demonstrate a strong red emission peak at 611 nm due to the^(5)D_(0)→^(7)F_(2) transition of Eu^(3+).The PL,PLE and XEL intensities of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics show a trend of first ascending and then descending with the increase of pre-sintering temperature.The thermally stimulated lumines-cence(TSL)curve of the HIP post-treated Eu_(0.1)Gd_(0.6)Lu_(1.3)O_(3)ceramics presents one high peak at 178 K and two peaks with lower intensities at 253 K and 320 K.The peak at 320 K may be related to oxygen vacancies,and the lumines-cence peak at 178 K is related to defects caused by the valence state changes of Eu^(3+)ions.
