Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties...Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties were investigated.The results showed that the cold arc process reduced splashing at the moment of liquid bridge breakage and effectively shortened the droplet transfer period.The microstructures of the deposited samples exhibited layered characteristics with alternating distributions of coarse and fine grains.During layer-by-layer deposition,the β-phase precipitated and grew preferentially along grain boundaries,while the fineη-Al_(8)Mn_(5)phase was dispersed in the α-Mg matrix.The mechanical properties of the CA-WAAM deposited sample showed isotropic characteristics.The ultimate tensile strength and elongation in the building direction(BD)were 282.7 MPa and 14.2%,respectively.The microhardness values of the deposited parts were relatively uniform,with an average value of HV 69.6.展开更多
This study demonstrates the successful fabrication of solid-state bilayers using LiFePO_(4)(LFP)cathodes and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)-based Composite Solid Electrolytes(CSEs)via Cold Sintering Proces...This study demonstrates the successful fabrication of solid-state bilayers using LiFePO_(4)(LFP)cathodes and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)-based Composite Solid Electrolytes(CSEs)via Cold Sintering Process(CSP).By optimizing the sintering pressure,it is achieved an intimate contact between the cathode and the solid electrolyte,leading to an enhanced electrochemical performance.Bilayers cold sintered at 300 MPa and a low-sintering temperature of 150℃exhibit high ionic conductivities(0.5 mS cm^(-1))and stable specific capacities at room temperature(160.1 mAh g^(-1)LFP at C/10 and 75.8 mAh g^(-1)_(LFP)at 1 C).Moreover,an operando electrochemical impedance spectroscopy(EIS)technique is employed to identify limiting factors of the bilayer kinetics and to anticipate the overall electrochemical behavior.Results suggest that capacity fading can occur in samples prepared with high sintering pressures due to a volume reduction in the LFP crystalline cell.This work demonstrates the potential of CSP to produce straightforward high-performance bilayers and introduces a valuable non-destructive instrument for understanding and avoiding degradation in solid-state lithium-based batteries.展开更多
Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly l...Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.展开更多
Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy.The novel hole cold expansion technique introduced in th...Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy.The novel hole cold expansion technique introduced in this work involves the laser texturing process(LTP)followed by the Hertz contact rotary expansion process(HCREP),where the cylindrical sleeve is the critical component connecting the abovementioned two processes.The purpose of LTP is to obtain the most optimized strengthened cylindrical sleeve surface,preparing for the following HCREP.Hereafter,the HCREP acts on the nickel-based hole components by the rotary extruding movements of the strengthened sleeve and conical mandrel tools.As compared to the as-received GH4169 material,the surface integrity characterization for the strengthened hole shows that a plastic deformation layer with finer grains,higher micro-hardness,deeper compressive residual stress(CRS)distribution and lower surface roughness is formed at the hole wall.In addition,transmission electron microscope(TEM)observations reveal the microstructure evolution mechanism in the strengthened hole.Grain refinement near the hole wall is regarded as the fundamental reason for improving the surface integrity,where the aggregated dislocations and recombined dislocation walls can be clearly observed.展开更多
Uncontrolled residual stresses have significant effects on the service time and defects of the spun parts.Nowadays,X-Ray Diffraction(XRD)method has been widely used in the residual stress measurement of industry produ...Uncontrolled residual stresses have significant effects on the service time and defects of the spun parts.Nowadays,X-Ray Diffraction(XRD)method has been widely used in the residual stress measurement of industry products with different forming processes.The calculated residual stress is usually obtained from the data fitting slope of strain and angle with Ordinary Least Squares(OLS)method.But this fitting method is not always suitable for the big fluctuant data.In this paper,the Weighted Least Square(WLS)method is used for the data fitting and compared with the OLS method.The nickel-based superalloy GH3030 and iron-based superalloy GH1140 are applied in the multi-pass cold spinning experiments.The residual stress distributions of normal,potential crack and wrinkle workpieces are discussed with the grain structure.The results show that WLS method has better goodness of fit compared with OLS method.The residual stress distributions have special relationship with potential crack,wrinkle workpiece and grain structure.展开更多
Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bond...Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process （CWSP） is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination （AIB3CID3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity） is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.展开更多
Building energy consumption accounts for nearly 40% of global energy consumption, HVAC （Heating, Ventilating, and Air Conditioning） systems are the major building energy consumers, and as one type of HVAC systems, t...Building energy consumption accounts for nearly 40% of global energy consumption, HVAC （Heating, Ventilating, and Air Conditioning） systems are the major building energy consumers, and as one type of HVAC systems, the heat pump air conditioning system, which is more energy-efficient compared to the traditional air conditioning system, is being more widely used to save energy. However, in northern China, extreme climatic conditions increase the cooling and heating load of the heat pump air conditioning system and accelerate the aging of the equipment, and the sensor may detect drifted parameters owing to climate change. This non-linear drifted parameter increases the false alarm rate of the fault detection and the need for unnecessary troubleshooting. In order to overcome the impact of the device aging and the drifted parameter, a Kalman filter and SPC （statistical process control） fault detection method are introduced in this paper. In this method, the model parameter and its standard variance can he estimated by Kalman filter based on the gray model and the real-time data of the air conditioning system. Further, by using SPC to construct the dynamic control limits, false alarm rate is reduced. And this paper mainly focuses on the cold machine failure in the component failure and its soft fault detection. This approach has been tested on a simulation model of the ＂Sino-German Energy Conservation Demonstration Center＂ building heat pump air-conditioning system in Shenyang, China, and the results show that the Kalman filter and SPC fault detection method is simple and highly efficient with a low false alarm rate, and it can deal with the difficulties caused by the extreme environment and the non-linear influence of the parameters, and what＇s more, it provides a good foundation for dynamic fault diagnosis and fault prediction analysis.展开更多
[Objectives]This study was conducted to investigate the effect of compound fresh-keeping liquid on the browning and quality of fresh-cut yam during the cold chain process.[Methods]Under the simulated cold chain condit...[Objectives]This study was conducted to investigate the effect of compound fresh-keeping liquid on the browning and quality of fresh-cut yam during the cold chain process.[Methods]Under the simulated cold chain condition of 4℃,a uniform design(U6*(64))experiment was carried out to optimize the compound preservative formula,and a better compound preservative formula was obtained using the regression equation.[Results]The compound preservative formula was:AA 0.25%,CA 0.5%,Nisin 0.09%,GSH 0.15%.The compound fresh-keeping liquid effectively delayed the browning of fresh-cut yam and the accumulation of MDA,maintained the content of TSS,inhibited the activity of PAL and delayed the appearance of the maximum activity of POD and POD.[Conclusions]This study provides technical support for the actual extension of the shelf life of fresh-cut yam.展开更多
For plastic deformed parts, the dimensional accuracy is significantly affected by residual stresses and so does the performance in service. Therefore, the rolling process of GH4169 alloy sheet at room temperature was ...For plastic deformed parts, the dimensional accuracy is significantly affected by residual stresses and so does the performance in service. Therefore, the rolling process of GH4169 alloy sheet at room temperature was investigated by finite element method. The effects of rolling reduction, friction coefficient, rolling velocity and initial stress on the longitudinal residual stress distribution over the thickness of GH4169 alloy sheet were analyzed. The results show that the values of longitudinal residual stress can be slightly reduced by increasing the rolling reduction and velocity. The longitudinal residual stress over the thickness distributes as ‘‘V＇＇ type or weak ‘‘W＇＇ type. The initial stress mainly has an effect on the longitudinal stress in the backward slip area. But the friction coefficient has remarkable influence on longitudinal residual stress. With the friction coefficient increasing from 0.1 to 0.5, the value of longitudinal residual stress on the sheet surface is reduced by 282 MPa. Simultaneously, the tensile stress turns into compressive stress with a strong‘‘W＇＇ type distribution.展开更多
Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples ...Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples at a relatively low temperature(170℃)using the cold sintering process(CSP)with AgNO_(3)solution as a transient liquid agent.The effect of AgNO_(3)addition during CSP on the micro-structure and TE properties was investigated.The results from phase,composition and microstructure analyses showed that the introduc-tion of AgNO_(3)solution induced the formation of Ag nano-precipitates within the Ag_(2)Se matrix.Although the nano-precipitates do not af-fect the phase and crystal structure of orthorhombicβ-Ag_(2)Se,they suppressed crystal growth,leading to reduced crystallite sizes.The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density.Consequently,these effects contributed to sig-nificantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorpor-ated.This resulted in an improved average power factor from~1540μW·m^(−1)·K^(−2)for pure Ag_(2)Se to~1670μW·m^(−1)·K^(−2)for Ag_(2)Se with additional Ag precipitates.However,excessive Ag addition had a detrimental effect on the power factor.Furthermore,thermal conductiv-ity was effectively suppressed in Ag_(2)Se fabricated using AgNO_(3)-assisted CSP,attributed to enhanced phonon scattering at crystal inter-faces,pores,and Ag nano-precipitates.The highest figure-of-merit(zT)of 0.92 at 300 K was achieved for the Ag_(2)Se with 0.5wt%Ag dur-ing CSP fabrication,equivalent to>20%improvement compared to the controlled Ag_(2)Se without extra Ag solution.Thus,the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag_(2)Se and enhance its TE performance at room temperature.展开更多
Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit ...Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit thermo-plasticity, which can facilitate the release of huge amount of stresses generated during preheating or in operation. On the contrary, pitch bonded MgO-C bricks, show better pyro-plasticity due to formation of an anisotropic and graphitized coke structure during carbonization of pitch. Hence, pitch bonded bricks show a superior structural spalling resistance in comparison to resin-bonded bricks. One of the drawbacks of pitch-bonded bricks is that the manufacturing requires a hot mixing process and hot pressing facility. This paper describes how a combination of above two processes was optimized to make a MgO-C brick via cold process. These bricks exhibit a low Modulus of Elasticity and thereby facilitate release of stresses during operation. Normal coal tar pitch is considered as an environmental hazard due to the presence of polyaromatic hydrocarbons like benzopyrene B [ a ] P. So, a special binder with a low B[ a ] P was selected, which is eco-friendly in nature. Such bricks were made in our plant in China and supplied to an integrated steel plant in Europe for their ladle. The bricks supplied have given encouraging life.展开更多
The cold box plus process it discussed in principle When the proper heating to the corebox is given (65℃±2℃). the binder lever can be saved, also the core strength and surface hardnessare imtroved, the moisture...The cold box plus process it discussed in principle When the proper heating to the corebox is given (65℃±2℃). the binder lever can be saved, also the core strength and surface hardnessare imtroved, the moisture-sensitvity is reduced. The mechanism of the cold box plus process isthat the proper heat increases the activity of resin function groups and promotes the crosslinking re-action The result of a scanning electron microscope analysis shows that the core surface strength isimproved by heat展开更多
The characteristics of summertime raindrop size distribution(DSD) and associated relations in the semi-arid region over the Inner Mongolian Plateau(IMP) were investigated,utilizing five-year continuous observations by...The characteristics of summertime raindrop size distribution(DSD) and associated relations in the semi-arid region over the Inner Mongolian Plateau(IMP) were investigated,utilizing five-year continuous observations by a PARSIVEL2disdrometer in East Ujimqin County(EUC),China.It is found that only 7.94% of the 15 664 one-min precipitation samples meet classification criteria as convective rain(CR),but its contribution to the total rainfall amount is 63.87%.Notably,40.72% of the rainfall comes from large-sized raindrops(D> 3 mm),despite the fact that large-sized raindrops account for only 1.73% of the CR total number concentration.Further results show that the mean value of mass-weighted mean diameters(Dm) is larger(2.43 mm) and generalized intercepts(lgN_(W)) is lower(3.19) in CR,aligning with a "continentallike" cluster,which is mainly influenced by the joint impact of in-cloud ice-based processes and the below-cloud environmental background.Also,the empirical relationships of shape-slope(μ-Λ),radar reflectivity-rain rate(Z-R),and rainfall kinetic energy(KE_(time)-Rand KE_(time)-Z) are localized.To quantitatively analyze the impact of DSD parameters on kinetic energy estimation,power-law KE_(time)-R and KE_(time)-Z relationships are derived based on the normalized gamma distribution.N_(W)takes precedence over μ in affecting variabilities of multiplicative coefficients,especially for KE_(time)-R relationship where the multiplicative coefficient is proportional to N_(W)^(-0.287).It should be noted that although the proportion of CR occurring throughout the summer is small,raindrops with lower N_(W) and larger Dmwill generate higher KE_(time),which will bring a higher potential risk of soil erosion in semi-arid regions over IMP.展开更多
The cold sintering process(CSP)is a green and innovative method of material densification at low temperatures(<350°C).The traditional CSP entails the addition of liquid phases as a solvent to achieve material ...The cold sintering process(CSP)is a green and innovative method of material densification at low temperatures(<350°C).The traditional CSP entails the addition of liquid phases as a solvent to achieve material densification through the dissolution-precipitation mechanism.However,it is difficult to realize for materials with low solubility.To address this challenge,a universal cold sintering method without the addition of liquid phases has been proposed in this work.The addition of a special polyester-polymer assisted the densification of insoluble ceramics,and hydroxyapatite(HA)and Al_(2)O_(3)were successfully sintered below 100°C,achieving 95-100%densities in a short time(5-20 min).This achievement can be attributed to the low glass transition temperature and the abundance of active sites(C=O)of the polyester-polymer.The denser ceramics exhibited enhanced mechanical properties,with the compression strength of polymer-assisted CSP HA increasing by 147.3%compared to the nanoparticles.Additionally,serving as an advanced bone substitute material,HA underwent quantitative analysis using the CCK-8 method and assessed the impact of polymer presence on cell proliferation and cytotoxicity.Meanwhile,a tight bonding between the polymer and ceramic materials was achieved during CSP,providing a generalized method for designing multifunctional ceramic-polymer.展开更多
A high voltage gradient(V_(g))of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices.However,improving V_(g) of ZnObased varistor ceramics through conventi...A high voltage gradient(V_(g))of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices.However,improving V_(g) of ZnObased varistor ceramics through conventional high-temperature sintering process remains a significant challenge.Here,we present a strategy to fabricate ultrahigh voltage-gradient ZnO-based varistor ceramics by combining cold sintering process/spark plasma sintering(CSP–SPS)with post-annealing process.Employing CSP–SPS,the ZnO-based varistor ceramics were initially densified at 300℃ and subsequently annealed at a low temperature of 700–900℃.CSP–SPS technique combined with a low annealing temperature enables the production of ZnO-based varistor ceramics with fine and homogeneous microstructures,while suppressing the volatilization of Bi-rich phases at grain boundaries.This approach achieves the ultrahigh V_(g) of~1832.71 V/mm,high nonlinear coefficient(α)of~106.69,and low leakage current density(J_(L))of less than 0.2μA/cm^(2).This work shows that the integration of CSP–SPS and post-annealing provides a promising way to design ZnO-based varistor ceramics with ultrahigh V_(g).展开更多
Cold-sintered ceramics typically exhibit inferior mechanical properties compared to high-temperature sintered counterparts.We demonstrate that introducing large internal stress through highly concentrated nanodiamonds...Cold-sintered ceramics typically exhibit inferior mechanical properties compared to high-temperature sintered counterparts.We demonstrate that introducing large internal stress through highly concentrated nanodiamonds(NDs)significantly enhances cold-sintered a-quartz composites to structural ceramic levels.At 500 MPa cold-sintering pressure,uniformly dispersed NDs generate 1.2 GPa local prestress via Young's modulus difference,while pressure-modulated internal stress is evidenced by dielectric property changes.The optimized composite achieves fracture toughness of(3.65±0.21)MPa·m^(1/2)(180%increase)and Vickers hardness of 10.6 GPa(80%increase),matching some hightemperature-sintered ceramics.Toughening arises from prestress-driven crack deflection and crack tip bridging,while hardness enhancement stems from NDs'rigid constraint and high-pressure-induced dislocations in silica matrix.Compressive strength increases by 90%and fatigue life exceeds 1000 cycles,attributed to internal stress-strengthened grain boundaries and improved toughness.This work presents a transformative strategy for developing damage-resistant ceramics,meriting further exploration of scalability and engineering applications.展开更多
Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to...Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat.However,achieving adequate thermal conductivity(k)in ceramics sintered at low temperatures is challenging.In this study,we employed the cold sintering process(CSP)to fabricate Li_(2)MoO_(4)-x%Al_(2)O_(3)(0≤x≤80,in volume)ceramics under 200 MPa pressure at 150℃.The Li_(2)MoO_(4)-40%Al_(2)O_(3)composite exhibited significantly enhanced k of 5.4 W·m^(-1)·K^(-1),an 80%increase compared to pure Li_(2)MoO_(4)ceramic with k of 3 W·m^(-1)·K^(-1).At 40%Al_(2)O_(3)content,the Li_(2)MoO_(4)eAl_(2)O_(3)ceramic demonstrated notable microwave properties(ε~6.67,Q×f~17,846 GHz,tf~^(-1)05×10^(-6)℃^(-1)).Additionally,simulation of a microstrip patch antenna for 5 GHz applications using Li_(2)MoO_(4)-20%Al_(2)O_(3)ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance,with radiation efficiency exceeding 99%and low return loss(S_(11)<-30 dB)at both 4.9 GHz and 28.0 GHz center frequencies.These findings underscore the suitability of Li_(2)MoO_(4)eAl_(2)O_(3)ceramics for microwave dielectric substrate.展开更多
Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susc...Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susceptibility to degradation and failure when exposed to ambient environment significantly hampers their widespread applications.Herein,we reported an effective strategy to encapsulate CsPbBr_(3)nanocrystals into robust KBr matrix via cold sintering process at 120℃.The well prepared translucent CsPbBr_(3)@KBr ceramic displays a narrow green photoluminescence(with a fullwidth at half-maximum of~22 nm)and an quantum yield of 73.6%with remarkable thermal stability.By incorporating red emitting K_(2)SiF_(4):Mn^(4+)phosphor into the KBr matrix,the color gamut of the constructed white LED improves to 118%of the National Television System Committee(NTSC)standard,suggesting that the thermally robust and narrow-band green emitter holds significant promise for widecolor-gamut liquid crystal displays.展开更多
The cold sintering process(CSP)is an advanced low-temperature sintering technology whose effectiveness is closely related to the selection of transient liquid phases(TLPs).While water serves as an ideal TLP for water-...The cold sintering process(CSP)is an advanced low-temperature sintering technology whose effectiveness is closely related to the selection of transient liquid phases(TLPs).While water serves as an ideal TLP for water-soluble ceramics,most water-insoluble materials necessitate acids,bases,or specialized solvents instead.This limitation has severely restricted the application of CSP,as many water-insoluble ceramics cannot be densified due to the lack of suitable TLPs.This study demonstrates a breakthrough approach that exploits nanoscale effects to enable water to act as an effective TLP for the densification of water-insoluble Li_(2)TiO_(3)ceramics.A comparison of nano(19.71 nm)and microscale Li_(2)TiO_(3)powders under identical sintering conditions revealed that despite the exceptionally low aqueous solubility of Li_(2)TiO_(3),the nanopowders achieved 94.33%relative density at only 300°C and 700 MPa,whereas the micropowders attained only 78%density.Further analysis revealed a distinctive densification mechanism that integrates dislocation-mediated plastic deformation with localized dissolution phenomena at nanoparticle interfaces.Compared with conventional sintering(1000°C),the resulting nanoceramics exhibited superior Vickers hardness(905 HV)and enhanced electrical conductivity while maintaining a refined nanoscale grain structure(26.42 nm).This study established an effective strategy for the cold sintering of water-insoluble ceramics with layered structures using water as a TLP,significantly expanding the applicability of CSP technology and offering new pathways for the energy-efficient fabrication of advanced functional ceramics.展开更多
A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperatur...A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperature 300℃ under uniaxial pressure in the presence of small amount o f transient liquid.The fabricated composite achieved as high as 98.65% of the theoretical density.The NaCl-Al2O3 composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750℃-850℃ together with a holding period o f 24h at 850℃.X-ray diffraction measurements indicated congruent solubility o f the alumina in chloride salt,excellent compatibility o f NaCl with Al2O3,and chemical stability at high temperature.Structural analysis by scanning electron microscope also showed limited grain growth,high density,uniform NaCl distribution and clear faceted composite structure without inter-diffusion.The latent heat storage density o f 252.5J/g was obtained from simultaneous thermal analysis.Fracture strength test showed high sintered strength around 5 GPa after 50 min.The composite was found to have fair mass losses due to volatilization.Overall,cold sintering process has the potential to be an efficient,safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.展开更多
基金supported by the National Natural Science Foundation of China(No.51805265)the Fundamental Research Funds for the Central Universities,China(No.30922010921).
文摘Thin walls of an AZ91 magnesium alloy with fine equiaxed grains were fabricated via cold arc-based wire arc additive manufacturing(CA-WAAM),and the droplet transfer behaviours,microstructures,and mechanical properties were investigated.The results showed that the cold arc process reduced splashing at the moment of liquid bridge breakage and effectively shortened the droplet transfer period.The microstructures of the deposited samples exhibited layered characteristics with alternating distributions of coarse and fine grains.During layer-by-layer deposition,the β-phase precipitated and grew preferentially along grain boundaries,while the fineη-Al_(8)Mn_(5)phase was dispersed in the α-Mg matrix.The mechanical properties of the CA-WAAM deposited sample showed isotropic characteristics.The ultimate tensile strength and elongation in the building direction(BD)were 282.7 MPa and 14.2%,respectively.The microhardness values of the deposited parts were relatively uniform,with an average value of HV 69.6.
基金support from Generalitat Valenciana under Pla Complementari“Programa de Materials Avanc¸ats”,2022(grant number MFA/2022/030)Ministerio de Ciencia,Innovaci´on y Universidades(Spain)(grant number MCIN/AEI/10.13039/501100011033)+1 种基金support from UJI(UJI-2023-16 and GACUJIMC/2023/08)Generalitat Valenciana through FPI Fellowship Program(grant numbers ACIF/2020/294 and CIACIF/2021/050).
文摘This study demonstrates the successful fabrication of solid-state bilayers using LiFePO_(4)(LFP)cathodes and Li_(1.3)Al_(0.3)Ti_(1.7)(PO_(4))_(3)(LATP)-based Composite Solid Electrolytes(CSEs)via Cold Sintering Process(CSP).By optimizing the sintering pressure,it is achieved an intimate contact between the cathode and the solid electrolyte,leading to an enhanced electrochemical performance.Bilayers cold sintered at 300 MPa and a low-sintering temperature of 150℃exhibit high ionic conductivities(0.5 mS cm^(-1))and stable specific capacities at room temperature(160.1 mAh g^(-1)LFP at C/10 and 75.8 mAh g^(-1)_(LFP)at 1 C).Moreover,an operando electrochemical impedance spectroscopy(EIS)technique is employed to identify limiting factors of the bilayer kinetics and to anticipate the overall electrochemical behavior.Results suggest that capacity fading can occur in samples prepared with high sintering pressures due to a volume reduction in the LFP crystalline cell.This work demonstrates the potential of CSP to produce straightforward high-performance bilayers and introduces a valuable non-destructive instrument for understanding and avoiding degradation in solid-state lithium-based batteries.
文摘Potential engineering applications of magnesium(Mg)and Mg-based alloys,as the lightest structural metal,have made them a popular subject of study.However,the inferior corrosion and wear characteristics significantly limit their application range.It is widely recognized that surface treatment is the most commonly utilized technique for remarkably improving a substrate’s surface characteristics.Numerous methods have been introduced for the surface treatment of Mg and Mg-based alloys to improve their corrosion behavior and tribological performance.Among these,thermal spray(TS)technology provides several methods for deposition of various functional metallic,ceramic,cermet,or other coatings tailored to particular conditions.Recent researches have shown the tremendous potential for thermal spray coated Mg alloys for biomedical and industrial applications.In this context,the cold spray(CS)method,as a comparatively new TS coating technique,can generate the coating layer using kinetic energy rather than combined thermal and kinetic energies,like the high-velocity oxy-fuel(HVOF)spray method.Moreover,the CS process,as a revolutionary method,is able to repair and refurbish with a faster turnaround time;it also provides solutions that do not require dealing with the thermal stresses that are part of the other repair processes,such as welding or other TS processes using a high-temperature flame.In this review paper,the recently designed coatings that are specifically applied to Mg alloys(primarily for industrial applications)employing various coating processes are reviewed.Because of the increased utilization of CS technology for both 3D printed(additively manufactured)coatings and repair of structurally critical components,the most recent CS methods for the surface treatment,repair,and refurbishment of Mg alloys as well as their benefits and restrictions are then discussed and reviewed in detail.Lastly,the prospects of this field of study are briefly discussed,along with a summary of the presented work.
基金sponsored by the National Key Research and Development Program of China(2018YFC1902404)the National Natural Science Foundation of China(51725503,51705155)Innovation Program of Shanghai Municipal Education Commission(2019-01-07-00-02-E00068)。
文摘Preferred surface integrity around the hole wall is one of the key parameters to ensure the optimized performance of hole components for nickel-based superalloy.The novel hole cold expansion technique introduced in this work involves the laser texturing process(LTP)followed by the Hertz contact rotary expansion process(HCREP),where the cylindrical sleeve is the critical component connecting the abovementioned two processes.The purpose of LTP is to obtain the most optimized strengthened cylindrical sleeve surface,preparing for the following HCREP.Hereafter,the HCREP acts on the nickel-based hole components by the rotary extruding movements of the strengthened sleeve and conical mandrel tools.As compared to the as-received GH4169 material,the surface integrity characterization for the strengthened hole shows that a plastic deformation layer with finer grains,higher micro-hardness,deeper compressive residual stress(CRS)distribution and lower surface roughness is formed at the hole wall.In addition,transmission electron microscope(TEM)observations reveal the microstructure evolution mechanism in the strengthened hole.Grain refinement near the hole wall is regarded as the fundamental reason for improving the surface integrity,where the aggregated dislocations and recombined dislocation walls can be clearly observed.
基金supported by the Zhejiang Provincial Natural Science Foundation,China(No.LZ17E050001)the National Natural Science Foundation of China(No.51975301 and No.52075359)。
文摘Uncontrolled residual stresses have significant effects on the service time and defects of the spun parts.Nowadays,X-Ray Diffraction(XRD)method has been widely used in the residual stress measurement of industry products with different forming processes.The calculated residual stress is usually obtained from the data fitting slope of strain and angle with Ordinary Least Squares(OLS)method.But this fitting method is not always suitable for the big fluctuant data.In this paper,the Weighted Least Square(WLS)method is used for the data fitting and compared with the OLS method.The nickel-based superalloy GH3030 and iron-based superalloy GH1140 are applied in the multi-pass cold spinning experiments.The residual stress distributions of normal,potential crack and wrinkle workpieces are discussed with the grain structure.The results show that WLS method has better goodness of fit compared with OLS method.The residual stress distributions have special relationship with potential crack,wrinkle workpiece and grain structure.
基金Supported by National Natural Science Foundation of China(Grant Nos.51175186,51675185)Guangdong Provincial Natural Science Foundation of China(Grant No.S2013020012757)EU project PIIF-GA-2012-332304(Grant No.ESR332304)
文摘Sealing quality strongly affects heat pipe performance, but few studies focus on the process of heat pipe sealing. Cold welding sealing technology based on a stamping process is applied for heat pipe sealing. The bonding mechanism of the cold welding sealing process （CWSP） is investigated and compared with the experimental results obtained from the bonding interface analysis. An orthogonal experiment is conducted to observe the effects of various parameters, including the sealing gap, sealing length, sealing diameter, and sealing velocity on bonding strength. A method with the utilization of saturated vapor pressure inside a copper tube is proposed to evaluate bonding strength. A corresponding finite element model is developed to investigate the effects of sealing gap and sealing velocity on plastic deformation during the cold welding process. Effects of various parameters on the bonding strength are determined and it is found that the sealing gap is the most critical factor and that the sealing velocity contributes the least effect. The best parameter combination （AIB3CID3, with a 0.5 mm sealing gap, 6 mm sealing length, 3.8 mm sealing diameter, and 50 mm/s sealing velocity） is derived within the experimental parameters. Plastic deformation results derived from the finite element model are consistent with those from the experiment. The instruction for the CWSP of heat pipes and the design of sealing dies of heat pipes are provided.
基金Supported by the National Natural Science Foundation Committee of China(61503259)China Postdoctoral Science Foundation Funded Project(2017M611261)+1 种基金Chinese Scholarship Council(201608210107)Hanyu Plan of Shenyang Jianzhu University(XKHY2-64)
文摘Building energy consumption accounts for nearly 40% of global energy consumption, HVAC （Heating, Ventilating, and Air Conditioning） systems are the major building energy consumers, and as one type of HVAC systems, the heat pump air conditioning system, which is more energy-efficient compared to the traditional air conditioning system, is being more widely used to save energy. However, in northern China, extreme climatic conditions increase the cooling and heating load of the heat pump air conditioning system and accelerate the aging of the equipment, and the sensor may detect drifted parameters owing to climate change. This non-linear drifted parameter increases the false alarm rate of the fault detection and the need for unnecessary troubleshooting. In order to overcome the impact of the device aging and the drifted parameter, a Kalman filter and SPC （statistical process control） fault detection method are introduced in this paper. In this method, the model parameter and its standard variance can he estimated by Kalman filter based on the gray model and the real-time data of the air conditioning system. Further, by using SPC to construct the dynamic control limits, false alarm rate is reduced. And this paper mainly focuses on the cold machine failure in the component failure and its soft fault detection. This approach has been tested on a simulation model of the ＂Sino-German Energy Conservation Demonstration Center＂ building heat pump air-conditioning system in Shenyang, China, and the results show that the Kalman filter and SPC fault detection method is simple and highly efficient with a low false alarm rate, and it can deal with the difficulties caused by the extreme environment and the non-linear influence of the parameters, and what＇s more, it provides a good foundation for dynamic fault diagnosis and fault prediction analysis.
基金Natural Science Foundation of Guangxi(2017GXNSFAA198082)Guangxi Aquatic Vegetable Fresh-keeping and Processing Engineering Research Center Project(GXSSSCBXYJGZX1912)。
文摘[Objectives]This study was conducted to investigate the effect of compound fresh-keeping liquid on the browning and quality of fresh-cut yam during the cold chain process.[Methods]Under the simulated cold chain condition of 4℃,a uniform design(U6*(64))experiment was carried out to optimize the compound preservative formula,and a better compound preservative formula was obtained using the regression equation.[Results]The compound preservative formula was:AA 0.25%,CA 0.5%,Nisin 0.09%,GSH 0.15%.The compound fresh-keeping liquid effectively delayed the browning of fresh-cut yam and the accumulation of MDA,maintained the content of TSS,inhibited the activity of PAL and delayed the appearance of the maximum activity of POD and POD.[Conclusions]This study provides technical support for the actual extension of the shelf life of fresh-cut yam.
基金supported by the fund of Special Inventive Fund of Science and Technology in Shenyang under the Contract Number F15-172-6-00the State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, under the Contract Number SKLAB02014001
文摘For plastic deformed parts, the dimensional accuracy is significantly affected by residual stresses and so does the performance in service. Therefore, the rolling process of GH4169 alloy sheet at room temperature was investigated by finite element method. The effects of rolling reduction, friction coefficient, rolling velocity and initial stress on the longitudinal residual stress distribution over the thickness of GH4169 alloy sheet were analyzed. The results show that the values of longitudinal residual stress can be slightly reduced by increasing the rolling reduction and velocity. The longitudinal residual stress over the thickness distributes as ‘‘V＇＇ type or weak ‘‘W＇＇ type. The initial stress mainly has an effect on the longitudinal stress in the backward slip area. But the friction coefficient has remarkable influence on longitudinal residual stress. With the friction coefficient increasing from 0.1 to 0.5, the value of longitudinal residual stress on the sheet surface is reduced by 282 MPa. Simultaneously, the tensile stress turns into compressive stress with a strong‘‘W＇＇ type distribution.
基金supported by the National Research Council of Thailand(NRCT)(Nos.N42A650237 and N41A661163)the National Science,Research and Innovation Fund(NSRF)via the Fundamental Fund of Khon Kaen Universitythe NSRF via the Program Management Unit for Human Resources&Institutional Development,Research and Innovation(No.B37G660011).
文摘Silver selenide(Ag_(2)Se)stands out as a promising thermoelectric(TE)material,particularly for applications near room temper-atures.This research presents a novel approach for the fabrication of bulk Ag_(2)Se samples at a relatively low temperature(170℃)using the cold sintering process(CSP)with AgNO_(3)solution as a transient liquid agent.The effect of AgNO_(3)addition during CSP on the micro-structure and TE properties was investigated.The results from phase,composition and microstructure analyses showed that the introduc-tion of AgNO_(3)solution induced the formation of Ag nano-precipitates within the Ag_(2)Se matrix.Although the nano-precipitates do not af-fect the phase and crystal structure of orthorhombicβ-Ag_(2)Se,they suppressed crystal growth,leading to reduced crystallite sizes.The samples containing Ag nano-precipitates also exhibited high porosity and low bulk density.Consequently,these effects contributed to sig-nificantly enhanced electrical conductivity and a slight decrease in the Seebeck coefficient when small Ag concentrations were incorpor-ated.This resulted in an improved average power factor from~1540μW·m^(−1)·K^(−2)for pure Ag_(2)Se to~1670μW·m^(−1)·K^(−2)for Ag_(2)Se with additional Ag precipitates.However,excessive Ag addition had a detrimental effect on the power factor.Furthermore,thermal conductiv-ity was effectively suppressed in Ag_(2)Se fabricated using AgNO_(3)-assisted CSP,attributed to enhanced phonon scattering at crystal inter-faces,pores,and Ag nano-precipitates.The highest figure-of-merit(zT)of 0.92 at 300 K was achieved for the Ag_(2)Se with 0.5wt%Ag dur-ing CSP fabrication,equivalent to>20%improvement compared to the controlled Ag_(2)Se without extra Ag solution.Thus,the process outlined in this study presents an effective strategy to tailor the microstructure of bulk Ag_(2)Se and enhance its TE performance at room temperature.
文摘Conventional resin bonded MgO-C bricks, which are manufactured via cold mixing process, harden and attain brittleness during carbonization of resin due to the formation of isotropic glassy carbon. They do not exhibit thermo-plasticity, which can facilitate the release of huge amount of stresses generated during preheating or in operation. On the contrary, pitch bonded MgO-C bricks, show better pyro-plasticity due to formation of an anisotropic and graphitized coke structure during carbonization of pitch. Hence, pitch bonded bricks show a superior structural spalling resistance in comparison to resin-bonded bricks. One of the drawbacks of pitch-bonded bricks is that the manufacturing requires a hot mixing process and hot pressing facility. This paper describes how a combination of above two processes was optimized to make a MgO-C brick via cold process. These bricks exhibit a low Modulus of Elasticity and thereby facilitate release of stresses during operation. Normal coal tar pitch is considered as an environmental hazard due to the presence of polyaromatic hydrocarbons like benzopyrene B [ a ] P. So, a special binder with a low B[ a ] P was selected, which is eco-friendly in nature. Such bricks were made in our plant in China and supplied to an integrated steel plant in Europe for their ladle. The bricks supplied have given encouraging life.
文摘The cold box plus process it discussed in principle When the proper heating to the corebox is given (65℃±2℃). the binder lever can be saved, also the core strength and surface hardnessare imtroved, the moisture-sensitvity is reduced. The mechanism of the cold box plus process isthat the proper heat increases the activity of resin function groups and promotes the crosslinking re-action The result of a scanning electron microscope analysis shows that the core surface strength isimproved by heat
基金supported by the National Natural Science Foundation of China(Grant Nos.42325503,42075063,42075066,and 42021004)the Hubei Provincial Natural Science Foundation and the Meteorological Innovation and Development Project of China(Grant No.2023AFD096)the Beijige Foundation of NJIAS(Grant No.BJG202304).
文摘The characteristics of summertime raindrop size distribution(DSD) and associated relations in the semi-arid region over the Inner Mongolian Plateau(IMP) were investigated,utilizing five-year continuous observations by a PARSIVEL2disdrometer in East Ujimqin County(EUC),China.It is found that only 7.94% of the 15 664 one-min precipitation samples meet classification criteria as convective rain(CR),but its contribution to the total rainfall amount is 63.87%.Notably,40.72% of the rainfall comes from large-sized raindrops(D> 3 mm),despite the fact that large-sized raindrops account for only 1.73% of the CR total number concentration.Further results show that the mean value of mass-weighted mean diameters(Dm) is larger(2.43 mm) and generalized intercepts(lgN_(W)) is lower(3.19) in CR,aligning with a "continentallike" cluster,which is mainly influenced by the joint impact of in-cloud ice-based processes and the below-cloud environmental background.Also,the empirical relationships of shape-slope(μ-Λ),radar reflectivity-rain rate(Z-R),and rainfall kinetic energy(KE_(time)-Rand KE_(time)-Z) are localized.To quantitatively analyze the impact of DSD parameters on kinetic energy estimation,power-law KE_(time)-R and KE_(time)-Z relationships are derived based on the normalized gamma distribution.N_(W)takes precedence over μ in affecting variabilities of multiplicative coefficients,especially for KE_(time)-R relationship where the multiplicative coefficient is proportional to N_(W)^(-0.287).It should be noted that although the proportion of CR occurring throughout the summer is small,raindrops with lower N_(W) and larger Dmwill generate higher KE_(time),which will bring a higher potential risk of soil erosion in semi-arid regions over IMP.
基金supported by the Jilin Provincial Natural Science Foundation(No.20240101118JC)the funds of Medical+X cross innovation team granted by medical department of Jilin University(No.2022JBGS07)+1 种基金the Jilin Province Science and Technology development project(No.20210101437JC)the WU JIEPING Medical Foundation(No.320.6750.2023-3-20 to TGM)。
文摘The cold sintering process(CSP)is a green and innovative method of material densification at low temperatures(<350°C).The traditional CSP entails the addition of liquid phases as a solvent to achieve material densification through the dissolution-precipitation mechanism.However,it is difficult to realize for materials with low solubility.To address this challenge,a universal cold sintering method without the addition of liquid phases has been proposed in this work.The addition of a special polyester-polymer assisted the densification of insoluble ceramics,and hydroxyapatite(HA)and Al_(2)O_(3)were successfully sintered below 100°C,achieving 95-100%densities in a short time(5-20 min).This achievement can be attributed to the low glass transition temperature and the abundance of active sites(C=O)of the polyester-polymer.The denser ceramics exhibited enhanced mechanical properties,with the compression strength of polymer-assisted CSP HA increasing by 147.3%compared to the nanoparticles.Additionally,serving as an advanced bone substitute material,HA underwent quantitative analysis using the CCK-8 method and assessed the impact of polymer presence on cell proliferation and cytotoxicity.Meanwhile,a tight bonding between the polymer and ceramic materials was achieved during CSP,providing a generalized method for designing multifunctional ceramic-polymer.
基金supported by the Joint Funds of the National Natural Science Foundation of China(No.U23B20115)the Fok Ying-Tong Education Foundation,China(No.171050)。
文摘A high voltage gradient(V_(g))of ZnO-based varistor ceramics is critical for realizing miniaturized and lightweight overvoltage protection devices.However,improving V_(g) of ZnObased varistor ceramics through conventional high-temperature sintering process remains a significant challenge.Here,we present a strategy to fabricate ultrahigh voltage-gradient ZnO-based varistor ceramics by combining cold sintering process/spark plasma sintering(CSP–SPS)with post-annealing process.Employing CSP–SPS,the ZnO-based varistor ceramics were initially densified at 300℃ and subsequently annealed at a low temperature of 700–900℃.CSP–SPS technique combined with a low annealing temperature enables the production of ZnO-based varistor ceramics with fine and homogeneous microstructures,while suppressing the volatilization of Bi-rich phases at grain boundaries.This approach achieves the ultrahigh V_(g) of~1832.71 V/mm,high nonlinear coefficient(α)of~106.69,and low leakage current density(J_(L))of less than 0.2μA/cm^(2).This work shows that the integration of CSP–SPS and post-annealing provides a promising way to design ZnO-based varistor ceramics with ultrahigh V_(g).
基金supported by the National Natural Science Foundation of China(No.52472066,No.52350443 and No.52302061)“Dawn”Program of Shanghai Education Commission(No.24SG32)the Natural Science Foundation of Shanghai(No.21ZR1400300).
文摘Cold-sintered ceramics typically exhibit inferior mechanical properties compared to high-temperature sintered counterparts.We demonstrate that introducing large internal stress through highly concentrated nanodiamonds(NDs)significantly enhances cold-sintered a-quartz composites to structural ceramic levels.At 500 MPa cold-sintering pressure,uniformly dispersed NDs generate 1.2 GPa local prestress via Young's modulus difference,while pressure-modulated internal stress is evidenced by dielectric property changes.The optimized composite achieves fracture toughness of(3.65±0.21)MPa·m^(1/2)(180%increase)and Vickers hardness of 10.6 GPa(80%increase),matching some hightemperature-sintered ceramics.Toughening arises from prestress-driven crack deflection and crack tip bridging,while hardness enhancement stems from NDs'rigid constraint and high-pressure-induced dislocations in silica matrix.Compressive strength increases by 90%and fatigue life exceeds 1000 cycles,attributed to internal stress-strengthened grain boundaries and improved toughness.This work presents a transformative strategy for developing damage-resistant ceramics,meriting further exploration of scalability and engineering applications.
基金supported by National Natural Science Foundation of China(No.52361165625)Shenzhen Science and Technology Program,Guangdong Province,China(Nos.KQTD20180411143514543,JCYJ20220818100613029,and JSGGZD20220822095603006)We acknowledge the support of Project 2019CX01C079 of Guangdong Province。
文摘Dielectric ceramics are essential components in communication systems that operate within the microwave frequency range.In high-density packages,dielectric substrates ceramics must possess high thermal conductivity to efficiently dissipate heat.However,achieving adequate thermal conductivity(k)in ceramics sintered at low temperatures is challenging.In this study,we employed the cold sintering process(CSP)to fabricate Li_(2)MoO_(4)-x%Al_(2)O_(3)(0≤x≤80,in volume)ceramics under 200 MPa pressure at 150℃.The Li_(2)MoO_(4)-40%Al_(2)O_(3)composite exhibited significantly enhanced k of 5.4 W·m^(-1)·K^(-1),an 80%increase compared to pure Li_(2)MoO_(4)ceramic with k of 3 W·m^(-1)·K^(-1).At 40%Al_(2)O_(3)content,the Li_(2)MoO_(4)eAl_(2)O_(3)ceramic demonstrated notable microwave properties(ε~6.67,Q×f~17,846 GHz,tf~^(-1)05×10^(-6)℃^(-1)).Additionally,simulation of a microstrip patch antenna for 5 GHz applications using Li_(2)MoO_(4)-20%Al_(2)O_(3)ceramic as dielectric substrate via Finite Element Simulation software showed excellent performance,with radiation efficiency exceeding 99%and low return loss(S_(11)<-30 dB)at both 4.9 GHz and 28.0 GHz center frequencies.These findings underscore the suitability of Li_(2)MoO_(4)eAl_(2)O_(3)ceramics for microwave dielectric substrate.
基金supported by the National Natural Science Foundation of China(No.52350443 and No.52122203)the Natural Science Foundation of Shanghai(No.21ZR1400300).
文摘Thanks to their tunable luminescence,narrow emission range,and superior color fidelity,perovskite quantum dots(PeQDs)are widely considered as promising materials for next-generation backlight displays.However,the susceptibility to degradation and failure when exposed to ambient environment significantly hampers their widespread applications.Herein,we reported an effective strategy to encapsulate CsPbBr_(3)nanocrystals into robust KBr matrix via cold sintering process at 120℃.The well prepared translucent CsPbBr_(3)@KBr ceramic displays a narrow green photoluminescence(with a fullwidth at half-maximum of~22 nm)and an quantum yield of 73.6%with remarkable thermal stability.By incorporating red emitting K_(2)SiF_(4):Mn^(4+)phosphor into the KBr matrix,the color gamut of the constructed white LED improves to 118%of the National Television System Committee(NTSC)standard,suggesting that the thermally robust and narrow-band green emitter holds significant promise for widecolor-gamut liquid crystal displays.
基金supported by the Natural Science Foundation of Sichuan Province of China(No.2023NSFSC5889).
文摘The cold sintering process(CSP)is an advanced low-temperature sintering technology whose effectiveness is closely related to the selection of transient liquid phases(TLPs).While water serves as an ideal TLP for water-soluble ceramics,most water-insoluble materials necessitate acids,bases,or specialized solvents instead.This limitation has severely restricted the application of CSP,as many water-insoluble ceramics cannot be densified due to the lack of suitable TLPs.This study demonstrates a breakthrough approach that exploits nanoscale effects to enable water to act as an effective TLP for the densification of water-insoluble Li_(2)TiO_(3)ceramics.A comparison of nano(19.71 nm)and microscale Li_(2)TiO_(3)powders under identical sintering conditions revealed that despite the exceptionally low aqueous solubility of Li_(2)TiO_(3),the nanopowders achieved 94.33%relative density at only 300°C and 700 MPa,whereas the micropowders attained only 78%density.Further analysis revealed a distinctive densification mechanism that integrates dislocation-mediated plastic deformation with localized dissolution phenomena at nanoparticle interfaces.Compared with conventional sintering(1000°C),the resulting nanoceramics exhibited superior Vickers hardness(905 HV)and enhanced electrical conductivity while maintaining a refined nanoscale grain structure(26.42 nm).This study established an effective strategy for the cold sintering of water-insoluble ceramics with layered structures using water as a TLP,significantly expanding the applicability of CSP technology and offering new pathways for the energy-efficient fabrication of advanced functional ceramics.
文摘A form stable NaCl-Al2O3(50-50 wt-%)composite material for high temperature thermal energy storage was fabricated by cold sintering process,a process recently applied to the densification of ceramics at low temperature 300℃ under uniaxial pressure in the presence of small amount o f transient liquid.The fabricated composite achieved as high as 98.65% of the theoretical density.The NaCl-Al2O3 composite also retained the chloride salt without leakage after 30 heating-cooling cycles between 750℃-850℃ together with a holding period o f 24h at 850℃.X-ray diffraction measurements indicated congruent solubility o f the alumina in chloride salt,excellent compatibility o f NaCl with Al2O3,and chemical stability at high temperature.Structural analysis by scanning electron microscope also showed limited grain growth,high density,uniform NaCl distribution and clear faceted composite structure without inter-diffusion.The latent heat storage density o f 252.5J/g was obtained from simultaneous thermal analysis.Fracture strength test showed high sintered strength around 5 GPa after 50 min.The composite was found to have fair mass losses due to volatilization.Overall,cold sintering process has the potential to be an efficient,safe and cost-effective strategy for the fabrication of high temperature thermal energy storage materials.
