To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretre...To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.展开更多
The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical pr...The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical properties,can significantly enhance the oxidation resistance of Mg alloys.Based on our previous study,we conclude that REs such as Gd,Y,and Ce enhance the oxidation resistance of Mg-RE alloys.This article comprehensively reviews recent research progress on high-temperature oxidation behavior and the potential mechanism in Mg-RE alloys.Based on the thermodynamic and kinetic analyses,the evolution of the complex oxide system formed during the high-temperature oxidation of Mg-RE alloys is first summarized.The diffusion behavior and concentration control mechanisms of REs during the oxidation process and how these mechanisms affect the sustained growth of the oxide film and antioxidant properties were elucidated.Moreover,the different structures of the oxide films were classified,and their properties were discussed.Finally,this paper introduces the applications of commonly used REs in Mg alloys and frontier research on their oxidation mechanisms.Based on the above review,we propose that future research perspectives can be explored in terms of expanding the experimental temperature range for oxidation tests,optimizing the chemical composition by adding trace REs to study their synergistic mechanism,revealing the underlying oxidation mechanism through advanced in situ microscopic characterization methods,and investigating the mechanical properties of oxide films using diverse approaches.展开更多
TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing Ti...TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.展开更多
In this study,the design,analysis,manufacturing,and testing of a 3D-printed conformal microstrip array antenna for high-temperature environments is presented.3D printing technology is used to fabricate a curved cerami...In this study,the design,analysis,manufacturing,and testing of a 3D-printed conformal microstrip array antenna for high-temperature environments is presented.3D printing technology is used to fabricate a curved ceramic substrate,and laser sintering and microdroplet spraying processes are used to add the conductive metal on the curved substrate.The problems of gain loss,bandwidth reduction,and frequency shift caused by high temperatures are addressed by using a proper antenna design,with parasitic patches,slots,and metal resonant cavities.The antenna prototype is characterized by the curved substrates and the conductive metals for the power dividers,the patch,and the ground plane;its performance is examined up to a temperature of 600℃in a muffle furnace and compared with the results from the numerical analysis.The results show that the antenna can effectively function at 600℃and even higher temperatures.展开更多
Investigating highly effective electrocatalysts for high-temperature proton exchange membrane fuel cells(HT-PEMFC)requires the resistance to phosphate acid(PA)poisoning at cathodic oxygen reduction reaction(ORR).Recen...Investigating highly effective electrocatalysts for high-temperature proton exchange membrane fuel cells(HT-PEMFC)requires the resistance to phosphate acid(PA)poisoning at cathodic oxygen reduction reaction(ORR).Recent advancements in catalysts have focused on alleviating phosphoric anion adsorption on Pt-based catalysts with modified electronic structure or catalytic interface and developing Fe-N-C based catalysts with immunity of PA poisoning.Fe-N-C-based catalysts have emerged as promising alternatives to Pt-based catalysts,offering significant potential to overcome the characteristic adsorption of phosphate anion on Pt.An overview of these developments provides insights into catalytic mechanisms and facilitates the design of more efficient catalysts.This review begins with an exploration of basic poisoning principles,followed by a critical summary of characterization techniques employed to identified the underlying mechanism of poisoning effect.Attention is then directed to endeavors aimed at enhancing the HT-PEMFC performance by well-designed catalysts.Finally,the opportunities and challenges in developing the anti-PA poisoning strategy and practical HT-PEMFC is discussed.Through these discussions,a comprehensive understanding of PA-poisoning bottlenecks and inspire future research directions is aim to provided.展开更多
This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standar...This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standard system was established for comprehensive quality evaluation of HTD.There were obvious changes in the physicochemical properties,enzyme activities,and volatile flavor components at different storage periods,which affected the sensory evaluation of HTD to a certain extent.The results of high-throughput sequencing revealed significant microbial diversity,and showed that the bacterial community changed significantly more than did the fungal community.During the storage process,the dominant bacterial genera were Kroppenstedtia and Thermoascus.The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality.Lactococcus,Candida,Pichia,Paecilomyces,and protease activity played a crucial role in the formation of isovaleraldehyde.Acidic protease activity had the greatest impact on the microbial community.Moisture promoted isobutyric acid generation.Furthermore,the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics.Consequently,this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor Baijiu.展开更多
Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,a...Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.展开更多
We first present preparation of MnOx–CeO_2–Al_2O_3 catalysts with varying Mn contents through a self-propagating high-temperature synthesis(SHS) method, and studied the application of these catalysts to the selectiv...We first present preparation of MnOx–CeO_2–Al_2O_3 catalysts with varying Mn contents through a self-propagating high-temperature synthesis(SHS) method, and studied the application of these catalysts to the selective catalytic reduction of NOxwith NH3(NH_3-SCR).Using the catalyst with 18 wt.% Mn(18 MnCe1Al2), 100% NO conversion was achieved at 200°C and a gas hourly space velocity of 15384 hr-1, and the high-efficiency SCR temperature window, where NO conversion is greater than 90%, was widened to a temperature range of 150–300°C. 18 MnCe1Al2 showed great resistance to SO_2(100 ppm)and H_2O(5%) at 200°C. The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller(BET) analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and H_2 temperature programmed reduction. The characterization results showed that the surface atomic concentration of Mn increased with increasing Mn content, which led to synergism between Mn and Ce and improved the activity in the SCR reaction. 18 MnCe1Al2 has an extensive pore structure,with a BET surface area of approximately 135.4 m^2/g, a pore volume of approximately 0.16 cm^3/g, and an average pore diameter of approximately 4.6 nm. The SCR reaction on 18 MnCe1Al2 mainly followed the Eley-Rideal mechanism. The performances of the MnOx–CeO_2–Al_2O_3 catalysts were good, and because of the simplicity of the preparation process,the SHS method is applicable to their industrial-scale manufacture.展开更多
Reverse water gas shift（RWGS） reaction can be served as a pivotal stage of transitioning the abundant CO;resource into chemicals or hydrocarbon fuels, which is attractive for the CO;utilization and of eventually sig...Reverse water gas shift（RWGS） reaction can be served as a pivotal stage of transitioning the abundant CO;resource into chemicals or hydrocarbon fuels, which is attractive for the CO;utilization and of eventually significance in enabling a rebuilt ecological system for unconventional fuels. This concept is appealing when the process is considered as a solution for the storage of renewable energy, which may also find a variety of potential end uses for the outer space exploration. However, a big challenge to this issue is the rational design of high temperature endurable RWGS catalysts with desirable CO product selectivity. In this work, we present a comprehensive overview of recent publications on this research topic,mainly focusing on the catalytic performance of RWGS reaction over three major kinds of heterogeneous catalysts, including supported metal catalysts, mixed oxide catalysts and transition metal carbides. The reaction thermodynamic analysis, kinetics and mechanisms are also described in detail. The present review attempts to provide a general guideline about the construction of well-performed heterogeneous catalysts for the RWGS reaction, as well as discussing the challenges and further prospects of this process.展开更多
High-nickel ternary cathodes hold a great application prospect in solid-state lithium metal batteries to achieve high-energy density,but they still suffer from structural instability and detrimental side reactions wit...High-nickel ternary cathodes hold a great application prospect in solid-state lithium metal batteries to achieve high-energy density,but they still suffer from structural instability and detrimental side reactions with the solid-state electrolytes.To circumvent these issues,a continuous uniform layer polyacrylonitrile(PAN)was introduced on the surface of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) via in situ polymerization of acrylonitrile(AN).Furthermore,the partial-cyclized treatment of PAN(cPAN)coating layer presents high ionic and electron conductivity,which can accelerate interfacial Li+and electron diffusion simultaneously.And the thermodynamically stabilized cPAN coating layer cannot only effectively inhibit detrimental side reactions between cathode and solid-state electrolytes but also provide a homogeneous stress to simultaneously address the problems of bulk structural degradation,which contributes to the exceptional mechanical and electrochemical stabilities of the modified electrode.Besides,the coordination bond interaction between the cPAN and NCM811 can suppress the migration of Ni to elevate the stability of the crystal structure.Benefited from these,the In-cPAN-260@NCM811 shows excellent cycling performance with a retention of 86.8%after 300 cycles and superior rate capability.And endow the solid-state battery with thermal safety stability even at hightemperature extreme environment.This facile and scalable surface engineering represents significant progress in developing high-performance solid-state lithium metal batteries.展开更多
High-temperature industries,as the primary consumers of energy,are greatly concerned with energy savings.Designing refractory linings with low thermal conductivity to reduce heat dissipation through high-temperature f...High-temperature industries,as the primary consumers of energy,are greatly concerned with energy savings.Designing refractory linings with low thermal conductivity to reduce heat dissipation through high-temperature furnace linings is a critical concern.In this study,a series of novel entropy-stabilized spinel materials are reported,and their potential applications in high-temperature industries are investigated.XRD and TEM results indicate that all materials possess a cubic spinel crystal structure with the■space group.Furthermore,these materials exhibit good phase stability at high temperatures.All entropy-stabilized spinel aggregates demonstrated high refractoriness(>1800℃)and a high load softening temperature(>1700℃).The impact of configurational entropy on the properties of entropy-stabilized spinel materials was also studied.As configurational entropy increased,the thermal conductivity of the entropy-stabilized spinel decreased,while slag corrosion resistance deteriorated.For the entropy-stabilized spinel with a configurational entropy value of 1.126R,it showed good high-temperature stability,reliable resistance to slag attack,and a low thermal conductivity of 2.776 W·m^(-1)·K^(-1)at 1000℃.展开更多
In this study,nitrogen doped electrochemically exfoliated reduced graphene oxide and carbon black supported platinum(Pt/Nr EGO_(2)-CB_(3))has been prepared to enhance the performance and durability of hightemperature ...In this study,nitrogen doped electrochemically exfoliated reduced graphene oxide and carbon black supported platinum(Pt/Nr EGO_(2)-CB_(3))has been prepared to enhance the performance and durability of hightemperature PEMFCs with lower Pt loading.On the one hand,Pt/Nr EGO_(2)-CB_(3)with the strong interaction between the Pt and nitrogen(N)prevent agglomeration of Pt particles and Pt particles is 5.46±1.46 nm,which is smaller than that of 6.78±1.34 nm in Pt/C.Meanwhile,ECSA of Pt/Nr EGO_(2)-CB_(3)decrease 13.65%after AST,which is much lower than that of 97.99%in Pt/C.On the other hand,the Nr EGO flakes in MEAac act as a barrier to mitigate phosphoric acid redistribution,which improves the formation of triple-phase boundaries(TPBs)and gives stable operation of the MEAacwith a lower decay rate of 0.02 mV h^(-1)within100 h.After steady-state operation,the maximum power density of Pt/Nr EGO_(2)-CB_(3)(0.411 W cm^(-2))is three times higher than that of conventional Pt/C(0.134 W cm^(-2))in high-temperature PEMFCs.After AST,the mass transfer resistance of Pt/Nr EGO_(2)-CB_(3)electrode(0.560Ωcm^(2))is lower than that in Pt/C(0.728Ωcm^(2)).展开更多
The austenite(γ)reversely transformed from lath martensite(LM),lath bainite(LB),granular bainite(GB)and pearlite+ferrite(P+F)in a high-strength steel was studied at high temperatures using in-situ electron backscatte...The austenite(γ)reversely transformed from lath martensite(LM),lath bainite(LB),granular bainite(GB)and pearlite+ferrite(P+F)in a high-strength steel was studied at high temperatures using in-situ electron backscatter diffraction(EBSD).The memory effect of initial γ significantly affects the nucleation of the reverted γ in LM and GB structures,while a weak influence on that of LB and P+F structures.This results in a significant difference in γ grain size after complete austenitization,with the first two obtaining larger γ grains while the latter two are relatively small.Crystallographic analysis revealed that the reverted γ with acicular morphology(γA),most of which maintained the same orientation with the prior γ,dominated the reaustenitization behavior of LM and GB structures through preferential nucleation within γ grains and coalesced growth modes.Although globular reverted γ(γ_(G))with random orientation or large deviation from the prior γ can nucleate at the grain boundaries or within the grains,it is difficult for it to grow and play a role in segmenting and refining the prior γ due to the inhibition of γ_(A) coalescing.For LB and P+F structures,the nucleation rate of intragranular γ_(G) increases with increasing temperature,and always shows a random orientation.These γ_(G) grains can coarsen simultaneously with the intergranular γ_(G),ultimately playing a role in jointly dividing and refining the finalγgrains.Research also found that the differences in the effects of four different microstructures on revertedγnucleation are closely related to the variant selection of the matrix structure,as well as the content and size of cementite(θ).High density of block boundaries induced by weakening of variant selection and many fineθformed in the lath are the key to promoting LB structure to obtain more intragranular γ_(G) formation,as well as the important role of the large-sized θ in P+F structure.展开更多
Currently,the design of high-temperature superconducting(HTS)maglev trains adopts a U-shaped track operation mode,and the height of the side track significantly impacts the train’s aerodynamic characteristics.In this...Currently,the design of high-temperature superconducting(HTS)maglev trains adopts a U-shaped track operation mode,and the height of the side track significantly impacts the train’s aerodynamic characteristics.In this study,we used computational fluid dynamics(CFD)methods,based on the 3D Reynolds-averaged Navier-Stokes(RANS)method and shear stress transport(SST)k-ωturbulence model,to deeply investigate the effects of the presence or absence of a U-shaped track and different side track heights(800,880,and 960 mm)on the pressure distribution,velocity distribution,and flow field structure of HTS maglev trains at a speed of 400 km/h under crosswinds.The numerical methods were verified using a scaled ICE-2 model wind tunnel test.First,the aerodynamic characteristics of the train under different wind direction angles with and without side tracks were studied.We found that the aerodynamic performance of the train is the most adverse when the wind direction angle is 90°.The presence of a U-shaped track can effectively reduce the lateral force,lift,and yawing moment of the train.The aerodynamic performance of the first suspension bogie at the bottom,which is the worst,will also be effectively improved.Next,the aerodynamic effects of different side track heights on the HTS maglev train were studied.An increase in side track height will reduce the lift and lateral force of the train,while the increase in drag is relatively small.Under the premise of ensuring passengers can conveniently alight,we found that a U-shaped track with a side track height of 960 mm has the best aerodynamic performance.The research findings offer a valuable reference for the engineering application and design of the track structure of HTS maglev train systems.展开更多
The high-temperature mechanical behaviors of Multi-Layer Composite Panels(MCP)and Corrugated Sandwich Panels(CSP)of Continuous Glass Fiber-Reinforced Polypropylene(CGFRPP)are critical for their application in aerospac...The high-temperature mechanical behaviors of Multi-Layer Composite Panels(MCP)and Corrugated Sandwich Panels(CSP)of Continuous Glass Fiber-Reinforced Polypropylene(CGFRPP)are critical for their application in aerospace fields,which have been rarely mentioned in previous studies.High-temperature quasi-static tensile and compression tests on CGFRPP MCP are conducted first.The results showed that the tensile and compression strength,stiffness,and tensile modulus of MCP decreased with increasing temperature.The Gibson model was found to be more suitable for predicting the high-temperature mechanical performance of MCP after comparing the calculated results of different theoretical models with experimental data.Secondly,hightemperature planar compression tests were conducted on the CGFRPP CSP,revealing that the main failure modes were corrugated core buckling and delamination between the face panel and core material,with delamination being intensified at higher temperatures.Therefore,we proposed a strength theoretical model that considers structural buckling failure and interface delamination failure,and introduced the influence factor to evaluate the effect of interface delamination on structural strength.展开更多
Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temper...Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.展开更多
The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(S...The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.展开更多
With the laser remelting of cast alloys combined with non-equilibrium liquidus projection thermodynamic calculations,a high-strength and heat-resistant Al-3Fe-2Mn alloy was designed.Incorporating Mn atoms into the met...With the laser remelting of cast alloys combined with non-equilibrium liquidus projection thermodynamic calculations,a high-strength and heat-resistant Al-3Fe-2Mn alloy was designed.Incorporating Mn atoms into the metastable nanoscale Al_(6)Fe phase,occupying some lattice sites,enhances its thermal stability.Additionally,during rapid solidification of laser powder bed fusion(L-PBF),the solubility of Fe and Mn elements in the aluminum alloy increases significantly,forming a supersaturated solid solution with improved strength.This alloy demonstrates excellent processability,achieving a relative density of over 99%,and tensile strengths of 295 MPa at 200℃ and 230 MPa at 300℃.The Al-3Fe-2Mn alloy holds great potential for wide applications due to its high strength at high temperature.展开更多
Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose har...Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose hardness is 65 HRC and flexural strength is 1450 MPa.The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope.The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet,but also impede the internal diffusion during oxidation by forming a dense composite oxide layer,thereby enhancing the oxidation resistance.The TiC-NiCr cermet exhibits a dense protective oxide layer at 900℃ and can endure continuous oxidation for approximately 1000 h.A methodology for fabricating TiC-NiCr metal matrix composites is proposed,and their oxidation resistance is evaluated,providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.展开更多
High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limit...High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.展开更多
基金National Natural Science Foundation of China(52071274)Key Research and Development Projects of Shaanxi Province(2023-YBGY-442)Science and Technology Nova Project-Innovative Talent Promotion Program of Shaanxi Province(2020KJXX-062)。
文摘To mitigate the impact of interdiffusion reactions between the silicide slurry and Ta12W alloy substrate during vacuum sintering process on the oxidation resistance of the silicide coating,a micro-arc oxidation pretreatment was employed to construct a Ta_(2)O_(5)ceramic layer on the Ta12W alloy surface.Subsequently,a slurry spraying-vacuum sintering method was used to prepare a Si-Cr-Ti-Zr coating on the pretreated substrate.Comparative studies were conducted on the microstructure,phase composition,and isothermal oxidation resistance(at 1600℃)of the as-prepared coatings with and without the micro-arc oxidation ceramic layer.The results show that the Ta_(2)O_(5)layer prepared at 400 V is more continuous and has smaller pores than that prepared at 350 V.After microarc oxidation pretreatment,the Si-Cr-Ti-Zr coating on Ta12W alloy consists of three distinct layers:an upper layer dominated by Ti_(5)Si_(3),Ta_(5)Si_(3),and ZrSi;a middle layer dominated by TaSi_(2);a coating/substrate interfacial reaction layer dominated by Ta_(5)Si_(3).Both the Si-Cr-Ti-Zr coatings with and without the Ta_(2)O_(5)ceramic layer do not fail after isothermal oxidation at 1600℃for 5 h.Notably,the addition of the Ta2O5 ceramic layer reduces the high-temperature oxidation rate of the coating.
基金supported by the Key R&D Program of Shandong Province,China(No.2025CXGC 010412)the National Key Research and Development Program of China(No.2022YFB3709300)the National Natural Science Foundation of China(No.U21A2048).
文摘The limited high-temperature oxidation resistance of Mg alloys is a key factor restricting their development and application.The addition of some rare earth elements(REs),owing to their unique physical and chemical properties,can significantly enhance the oxidation resistance of Mg alloys.Based on our previous study,we conclude that REs such as Gd,Y,and Ce enhance the oxidation resistance of Mg-RE alloys.This article comprehensively reviews recent research progress on high-temperature oxidation behavior and the potential mechanism in Mg-RE alloys.Based on the thermodynamic and kinetic analyses,the evolution of the complex oxide system formed during the high-temperature oxidation of Mg-RE alloys is first summarized.The diffusion behavior and concentration control mechanisms of REs during the oxidation process and how these mechanisms affect the sustained growth of the oxide film and antioxidant properties were elucidated.Moreover,the different structures of the oxide films were classified,and their properties were discussed.Finally,this paper introduces the applications of commonly used REs in Mg alloys and frontier research on their oxidation mechanisms.Based on the above review,we propose that future research perspectives can be explored in terms of expanding the experimental temperature range for oxidation tests,optimizing the chemical composition by adding trace REs to study their synergistic mechanism,revealing the underlying oxidation mechanism through advanced in situ microscopic characterization methods,and investigating the mechanical properties of oxide films using diverse approaches.
基金supported by the Original Exploratory Program of the National Natural Science Foundation of China(No.52450012)。
文摘TiB_(2)coatings can significantly enhance the high-temperature oxidation resistance of molybdenum,which would broaden the application range of molybdenum and alloys thereof.However,traditional methods for preparing TiB_(2)coatings have disadvantages such as high equipment costs,complicated processes,and highly toxic gas emissions.This paper proposes an environmentally friendly method,which requires inexpensive equipment and simple processing,for preparing TiB_(2)coating on molybdenum via electrophoretic deposition within Na3AlF6-based molten salts.The produced TiB_(2)layer had an approximate thickness of 60μm and exhibited high density,outstanding hardness(38.2 GPa)and robust adhesion strength(51 N).Additionally,high-temperature oxidation experiments revealed that,at900℃,the TiB_(2)coating provided effective protection to the molybdenum substrate against oxidation for 3 h.This result indicates that the TiB_(2)coating prepared on molybdenum using molten salt electrophoretic deposition possesses good high-temperature oxidation resistance.
基金National Natural Science Foundation of China(No.U2241205)the Natural Science Basic Research Program of Shaanxi(Nos.2022JC-33,2023-GHZD-35,and 2024JC-ZDXM-25)+1 种基金the Fundamental Research Funds for the Central Universitiesthe National 111 Project to provide fund for conducting experiments。
文摘In this study,the design,analysis,manufacturing,and testing of a 3D-printed conformal microstrip array antenna for high-temperature environments is presented.3D printing technology is used to fabricate a curved ceramic substrate,and laser sintering and microdroplet spraying processes are used to add the conductive metal on the curved substrate.The problems of gain loss,bandwidth reduction,and frequency shift caused by high temperatures are addressed by using a proper antenna design,with parasitic patches,slots,and metal resonant cavities.The antenna prototype is characterized by the curved substrates and the conductive metals for the power dividers,the patch,and the ground plane;its performance is examined up to a temperature of 600℃in a muffle furnace and compared with the results from the numerical analysis.The results show that the antenna can effectively function at 600℃and even higher temperatures.
文摘Investigating highly effective electrocatalysts for high-temperature proton exchange membrane fuel cells(HT-PEMFC)requires the resistance to phosphate acid(PA)poisoning at cathodic oxygen reduction reaction(ORR).Recent advancements in catalysts have focused on alleviating phosphoric anion adsorption on Pt-based catalysts with modified electronic structure or catalytic interface and developing Fe-N-C based catalysts with immunity of PA poisoning.Fe-N-C-based catalysts have emerged as promising alternatives to Pt-based catalysts,offering significant potential to overcome the characteristic adsorption of phosphate anion on Pt.An overview of these developments provides insights into catalytic mechanisms and facilitates the design of more efficient catalysts.This review begins with an exploration of basic poisoning principles,followed by a critical summary of characterization techniques employed to identified the underlying mechanism of poisoning effect.Attention is then directed to endeavors aimed at enhancing the HT-PEMFC performance by well-designed catalysts.Finally,the opportunities and challenges in developing the anti-PA poisoning strategy and practical HT-PEMFC is discussed.Through these discussions,a comprehensive understanding of PA-poisoning bottlenecks and inspire future research directions is aim to provided.
文摘This study investigated the physicochemical properties,enzyme activities,volatile flavor components,microbial communities,and sensory evaluation of high-temperature Daqu(HTD)during the maturation process,and a standard system was established for comprehensive quality evaluation of HTD.There were obvious changes in the physicochemical properties,enzyme activities,and volatile flavor components at different storage periods,which affected the sensory evaluation of HTD to a certain extent.The results of high-throughput sequencing revealed significant microbial diversity,and showed that the bacterial community changed significantly more than did the fungal community.During the storage process,the dominant bacterial genera were Kroppenstedtia and Thermoascus.The correlation between dominant microorganisms and quality indicators highlighted their role in HTD quality.Lactococcus,Candida,Pichia,Paecilomyces,and protease activity played a crucial role in the formation of isovaleraldehyde.Acidic protease activity had the greatest impact on the microbial community.Moisture promoted isobutyric acid generation.Furthermore,the comprehensive quality evaluation standard system was established by the entropy weight method combined with multi-factor fuzzy mathematics.Consequently,this study provides innovative insights for comprehensive quality evaluation of HTD during storage and establishes a groundwork for scientific and rational storage of HTD and quality control of sauce-flavor Baijiu.
基金National Natural Science Foundation of China(52071126)Natural Science Foundation of Tianjin City,China(22JCQNJC01240)+2 种基金Central Guidance on Local Science and Technology Development Fund of Hebei Province(226Z1009G)Special Funds for Science and Technology Innovation in Hebei(2022X19)Anhui Provincial Natural Science Foundation(2308085ME135)。
文摘Co-based alloy coating was prepared on Zr alloy using laser melting and cladding technique to study the difference in the high-temperature oxidation behavior between pure metal Co coatings and Co-T800 alloy coatings,as well as the wear resistance of the coatings.Besides,the effect of changing the laser melting process on the coatings was also investigated.The oxidation mass gain at 800–1200℃and the high-temperature oxidation behavior during high-temperature treatment for 1 h of two coated Zr alloy samples were studied.Results show that the Co coating and the Co-T800 coating have better resistance against high-temperature oxidation.After oxidizing at 1000℃for 1 h,the thickness of the oxide layer of the uncoated sample was 241.0μm,whereas that of the sample with Co-based coating is only 11.8–35.5μm.The friction wear test shows that the depth of the abrasion mark of the coated sample is only 1/2 of that of the substrate,indicating that the hardness and wear resistance of the Zr substrate are greatly improved.The disadvantage of Co-based coatings is the inferior corrosion resistance in 3.5wt%NaCl solution.
基金supported by the National High Technology Research and Development Program of China (863 program) (No.2015AA03A401)the Program for Changjiang Scholars and Innovative Research Team in University (No.IRT_15R46)the program of Science and Technology Innovation Team in Bingtuan (No.2015BD003)
文摘We first present preparation of MnOx–CeO_2–Al_2O_3 catalysts with varying Mn contents through a self-propagating high-temperature synthesis(SHS) method, and studied the application of these catalysts to the selective catalytic reduction of NOxwith NH3(NH_3-SCR).Using the catalyst with 18 wt.% Mn(18 MnCe1Al2), 100% NO conversion was achieved at 200°C and a gas hourly space velocity of 15384 hr-1, and the high-efficiency SCR temperature window, where NO conversion is greater than 90%, was widened to a temperature range of 150–300°C. 18 MnCe1Al2 showed great resistance to SO_2(100 ppm)and H_2O(5%) at 200°C. The catalysts were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, Brunauer–Emmett–Teller(BET) analysis, scanning electron microscopy, Fourier transform infrared spectroscopy, and H_2 temperature programmed reduction. The characterization results showed that the surface atomic concentration of Mn increased with increasing Mn content, which led to synergism between Mn and Ce and improved the activity in the SCR reaction. 18 MnCe1Al2 has an extensive pore structure,with a BET surface area of approximately 135.4 m^2/g, a pore volume of approximately 0.16 cm^3/g, and an average pore diameter of approximately 4.6 nm. The SCR reaction on 18 MnCe1Al2 mainly followed the Eley-Rideal mechanism. The performances of the MnOx–CeO_2–Al_2O_3 catalysts were good, and because of the simplicity of the preparation process,the SHS method is applicable to their industrial-scale manufacture.
基金supported by the National Natural Science Foundation of China(Nos.21506204 and 21476226)China Ministry of Science and Technology under contact of 2016YFB0600902+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020400)State Grid Cooperation of China(SGRI-DL-71-16-015)Dalian Science Foundation for Distinguished Young Scholars(2016RJ04)the Youth Innovation Promotion Association of CAS
文摘Reverse water gas shift（RWGS） reaction can be served as a pivotal stage of transitioning the abundant CO;resource into chemicals or hydrocarbon fuels, which is attractive for the CO;utilization and of eventually significance in enabling a rebuilt ecological system for unconventional fuels. This concept is appealing when the process is considered as a solution for the storage of renewable energy, which may also find a variety of potential end uses for the outer space exploration. However, a big challenge to this issue is the rational design of high temperature endurable RWGS catalysts with desirable CO product selectivity. In this work, we present a comprehensive overview of recent publications on this research topic,mainly focusing on the catalytic performance of RWGS reaction over three major kinds of heterogeneous catalysts, including supported metal catalysts, mixed oxide catalysts and transition metal carbides. The reaction thermodynamic analysis, kinetics and mechanisms are also described in detail. The present review attempts to provide a general guideline about the construction of well-performed heterogeneous catalysts for the RWGS reaction, as well as discussing the challenges and further prospects of this process.
基金financially supported by the National Natural Science Foundation of China(Nos.22102212 and 22479067).
文摘High-nickel ternary cathodes hold a great application prospect in solid-state lithium metal batteries to achieve high-energy density,but they still suffer from structural instability and detrimental side reactions with the solid-state electrolytes.To circumvent these issues,a continuous uniform layer polyacrylonitrile(PAN)was introduced on the surface of LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2) via in situ polymerization of acrylonitrile(AN).Furthermore,the partial-cyclized treatment of PAN(cPAN)coating layer presents high ionic and electron conductivity,which can accelerate interfacial Li+and electron diffusion simultaneously.And the thermodynamically stabilized cPAN coating layer cannot only effectively inhibit detrimental side reactions between cathode and solid-state electrolytes but also provide a homogeneous stress to simultaneously address the problems of bulk structural degradation,which contributes to the exceptional mechanical and electrochemical stabilities of the modified electrode.Besides,the coordination bond interaction between the cPAN and NCM811 can suppress the migration of Ni to elevate the stability of the crystal structure.Benefited from these,the In-cPAN-260@NCM811 shows excellent cycling performance with a retention of 86.8%after 300 cycles and superior rate capability.And endow the solid-state battery with thermal safety stability even at hightemperature extreme environment.This facile and scalable surface engineering represents significant progress in developing high-performance solid-state lithium metal batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.52472032 and 52172023)the Key Program of Natural Science Foundation of Hubei Province(No.2024AFA083)
文摘High-temperature industries,as the primary consumers of energy,are greatly concerned with energy savings.Designing refractory linings with low thermal conductivity to reduce heat dissipation through high-temperature furnace linings is a critical concern.In this study,a series of novel entropy-stabilized spinel materials are reported,and their potential applications in high-temperature industries are investigated.XRD and TEM results indicate that all materials possess a cubic spinel crystal structure with the■space group.Furthermore,these materials exhibit good phase stability at high temperatures.All entropy-stabilized spinel aggregates demonstrated high refractoriness(>1800℃)and a high load softening temperature(>1700℃).The impact of configurational entropy on the properties of entropy-stabilized spinel materials was also studied.As configurational entropy increased,the thermal conductivity of the entropy-stabilized spinel decreased,while slag corrosion resistance deteriorated.For the entropy-stabilized spinel with a configurational entropy value of 1.126R,it showed good high-temperature stability,reliable resistance to slag attack,and a low thermal conductivity of 2.776 W·m^(-1)·K^(-1)at 1000℃.
基金supported by the Engineering and Physical Sciences Research Council(EPSRC)(EP/P009050/1 and EP/S021531/1)Tthe Henry Royce Institute for Advanced Materials,funded through the EPSRC grants(EP/R00661X/1,EP/S019367/1,EP/P025021/1 and EP/P025498/1)。
文摘In this study,nitrogen doped electrochemically exfoliated reduced graphene oxide and carbon black supported platinum(Pt/Nr EGO_(2)-CB_(3))has been prepared to enhance the performance and durability of hightemperature PEMFCs with lower Pt loading.On the one hand,Pt/Nr EGO_(2)-CB_(3)with the strong interaction between the Pt and nitrogen(N)prevent agglomeration of Pt particles and Pt particles is 5.46±1.46 nm,which is smaller than that of 6.78±1.34 nm in Pt/C.Meanwhile,ECSA of Pt/Nr EGO_(2)-CB_(3)decrease 13.65%after AST,which is much lower than that of 97.99%in Pt/C.On the other hand,the Nr EGO flakes in MEAac act as a barrier to mitigate phosphoric acid redistribution,which improves the formation of triple-phase boundaries(TPBs)and gives stable operation of the MEAacwith a lower decay rate of 0.02 mV h^(-1)within100 h.After steady-state operation,the maximum power density of Pt/Nr EGO_(2)-CB_(3)(0.411 W cm^(-2))is three times higher than that of conventional Pt/C(0.134 W cm^(-2))in high-temperature PEMFCs.After AST,the mass transfer resistance of Pt/Nr EGO_(2)-CB_(3)electrode(0.560Ωcm^(2))is lower than that in Pt/C(0.728Ωcm^(2)).
基金financially supported by the National Natural Science Foundation of China(Nos.52271089 and 52001023)the Basic Research and Application Basic Research Foundation of Guangdong Province(Nos.2022A1515240016 and 2023B1515250006)the Fundamental Research Funds for the Central Universities(No.FRF-BD-23-01).
文摘The austenite(γ)reversely transformed from lath martensite(LM),lath bainite(LB),granular bainite(GB)and pearlite+ferrite(P+F)in a high-strength steel was studied at high temperatures using in-situ electron backscatter diffraction(EBSD).The memory effect of initial γ significantly affects the nucleation of the reverted γ in LM and GB structures,while a weak influence on that of LB and P+F structures.This results in a significant difference in γ grain size after complete austenitization,with the first two obtaining larger γ grains while the latter two are relatively small.Crystallographic analysis revealed that the reverted γ with acicular morphology(γA),most of which maintained the same orientation with the prior γ,dominated the reaustenitization behavior of LM and GB structures through preferential nucleation within γ grains and coalesced growth modes.Although globular reverted γ(γ_(G))with random orientation or large deviation from the prior γ can nucleate at the grain boundaries or within the grains,it is difficult for it to grow and play a role in segmenting and refining the prior γ due to the inhibition of γ_(A) coalescing.For LB and P+F structures,the nucleation rate of intragranular γ_(G) increases with increasing temperature,and always shows a random orientation.These γ_(G) grains can coarsen simultaneously with the intergranular γ_(G),ultimately playing a role in jointly dividing and refining the finalγgrains.Research also found that the differences in the effects of four different microstructures on revertedγnucleation are closely related to the variant selection of the matrix structure,as well as the content and size of cementite(θ).High density of block boundaries induced by weakening of variant selection and many fineθformed in the lath are the key to promoting LB structure to obtain more intragranular γ_(G) formation,as well as the important role of the large-sized θ in P+F structure.
基金supported by the National Natural Science Foundation of China(No.U23A20681)the S&T Program of Hebei Province,China(No.23567602H).
文摘Currently,the design of high-temperature superconducting(HTS)maglev trains adopts a U-shaped track operation mode,and the height of the side track significantly impacts the train’s aerodynamic characteristics.In this study,we used computational fluid dynamics(CFD)methods,based on the 3D Reynolds-averaged Navier-Stokes(RANS)method and shear stress transport(SST)k-ωturbulence model,to deeply investigate the effects of the presence or absence of a U-shaped track and different side track heights(800,880,and 960 mm)on the pressure distribution,velocity distribution,and flow field structure of HTS maglev trains at a speed of 400 km/h under crosswinds.The numerical methods were verified using a scaled ICE-2 model wind tunnel test.First,the aerodynamic characteristics of the train under different wind direction angles with and without side tracks were studied.We found that the aerodynamic performance of the train is the most adverse when the wind direction angle is 90°.The presence of a U-shaped track can effectively reduce the lateral force,lift,and yawing moment of the train.The aerodynamic performance of the first suspension bogie at the bottom,which is the worst,will also be effectively improved.Next,the aerodynamic effects of different side track heights on the HTS maglev train were studied.An increase in side track height will reduce the lift and lateral force of the train,while the increase in drag is relatively small.Under the premise of ensuring passengers can conveniently alight,we found that a U-shaped track with a side track height of 960 mm has the best aerodynamic performance.The research findings offer a valuable reference for the engineering application and design of the track structure of HTS maglev train systems.
基金co-supported by the National Natural Science Foundation of China(Nos.12372127,12202085,12302464)the Fundamental Research Funds for the Central Universities,China(No.2024CDJXY009)+1 种基金the Chongqing Outstanding Youth Fund,China(No.CSTB2024NSCQ-JQX0028)the Chongqing Natural Science Foundation,China(Nos.cstc2021ycjh-bgzxm0117,CSTB2022NSCQ-MSX0608)。
文摘The high-temperature mechanical behaviors of Multi-Layer Composite Panels(MCP)and Corrugated Sandwich Panels(CSP)of Continuous Glass Fiber-Reinforced Polypropylene(CGFRPP)are critical for their application in aerospace fields,which have been rarely mentioned in previous studies.High-temperature quasi-static tensile and compression tests on CGFRPP MCP are conducted first.The results showed that the tensile and compression strength,stiffness,and tensile modulus of MCP decreased with increasing temperature.The Gibson model was found to be more suitable for predicting the high-temperature mechanical performance of MCP after comparing the calculated results of different theoretical models with experimental data.Secondly,hightemperature planar compression tests were conducted on the CGFRPP CSP,revealing that the main failure modes were corrugated core buckling and delamination between the face panel and core material,with delamination being intensified at higher temperatures.Therefore,we proposed a strength theoretical model that considers structural buckling failure and interface delamination failure,and introduced the influence factor to evaluate the effect of interface delamination on structural strength.
基金supported by the National Natural Science Foundation of China(Grant No.U21B2062)supported by the Key Laboratory for Carbonate Reservoirs of China National Petroleum Corporation。
文摘Burial dissolution is a critical diagenetic process influencing ultra-deep carbonate reservoir development and preservation.Artificial carbonate samples with different internal structures were prepared,and high-temperature and highpressure dissolution kinetic simulations were conducted.The results demonstrate that the intensity of burial dissolution is controlled by temperature and pressure,while tectonic-fluid activity influences the development pattern of burial dissolution,ultimately determining the direction of its differential modification.Extensive burial dissolution is likely to occur primarily at relatively shallow depths,significantly influencing reservoir formation,preservation,modification,and adjustment.The development of faults facilitates the maintenance of the intensity of burial dissolution.The maximum intensity of burial dissolution occurs at the tips and overlap zones of faults and intersections of multiple faults.The larger the scale of the faults,the more conducive it is to the development of burial dissolution.Burial dissolution fosters the formation of fault networks characterized by enhanced reservoir capacity and permeability.Burial dissolution controlled by episodic tectonic-fluid activity is a plausible explanation for forming the Tarim Basin's ultra-deep fault-controlled“stringbead-like”reservoirs.
基金supported by the National Key R&D Program of China(No.2022YFB3707700)National Natural Science Foundation of China(No.52302121)+3 种基金Shanghai Sailing Program(No.23YF1454700)Shanghai Natural Science Foundation(No.23ZR1472700)Shanghai Post-doctoral Excellent Program(No.2022664)Shanghai Science and Technology Innovation Action Plan(No.21511104800).
文摘The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity.Herein,the lightweight silicon carbide nanowires(SiC_(nws))/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiC_(nws)skeleton,which collaborative configuration by 3D printing and freeze casting assembly.The con-structed porous structure optimizes the impedance matching degree and scattering intensity,the maximum effective absorption bandwidth(EAB_(max))of 5.9 GHz and the minimum reflection loss(RL_(min))of−41.4 dB can be realized.Considering the inherent oxidation resistance of SiC,the composites present well-maintained absorption performance at 600℃.Even at 1100℃,the EAB_(max)of 4.9 GHz and RLmin of−30.4 dB also demonstrate the high-temperature absorption stability of the composites,indicating exceptional wave absorption properties and thermal stability.The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant.This work clarifies the impact of structure and component synergy on wave absorption behavior,and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.
基金supported by the National Natural Science Foundation of China(No.U21B2073)the Science and Technology Project of the Science and Technology Department of Hubei Province,China(No.2022EHB020)。
文摘With the laser remelting of cast alloys combined with non-equilibrium liquidus projection thermodynamic calculations,a high-strength and heat-resistant Al-3Fe-2Mn alloy was designed.Incorporating Mn atoms into the metastable nanoscale Al_(6)Fe phase,occupying some lattice sites,enhances its thermal stability.Additionally,during rapid solidification of laser powder bed fusion(L-PBF),the solubility of Fe and Mn elements in the aluminum alloy increases significantly,forming a supersaturated solid solution with improved strength.This alloy demonstrates excellent processability,achieving a relative density of over 99%,and tensile strengths of 295 MPa at 200℃ and 230 MPa at 300℃.The Al-3Fe-2Mn alloy holds great potential for wide applications due to its high strength at high temperature.
基金National Natural Science Foundation of China(52376076)Open Fund of Material Corrosion and Protection Key Laboratory of Sichuan Province(2023CL13)Laiwu Vocational and Technical College Teachers Research Fund(2023jsky05)。
文摘Powder metallurgy was used to fabricate TiC-NiCr cermets and the oxidation behavior at 900℃ was investigated.Results reveal that TiC-NiCr cermets have uniform structures with excellent mechanical properties,whose hardness is 65 HRC and flexural strength is 1450 MPa.The high-temperature oxidation mechanism of TiC-based cermets was investigated through an X-ray diffractometer and scanning electron microscope.The added elements Ni and Cr along with their solid solutions not only bond with the hard phase TiC to ensure the physical performance of the cermet,but also impede the internal diffusion during oxidation by forming a dense composite oxide layer,thereby enhancing the oxidation resistance.The TiC-NiCr cermet exhibits a dense protective oxide layer at 900℃ and can endure continuous oxidation for approximately 1000 h.A methodology for fabricating TiC-NiCr metal matrix composites is proposed,and their oxidation resistance is evaluated,providing a theoretical and practical basis for simultaneously enhancing the mechanical properties and oxidation resistance and reducing production costs.
文摘High-temperature piezoelectric sen-sors are very important in severe environments such as fire safety,aerospace and oil drills,however,most current sensors are not heat res-istant(<300℃)and are fragile,which limits their use,especially in high-temperature environ-ments.A high-temperature resistant flexible piezoelectric film based on graphene oxide(GO)/polyacrylonitrile(PAN)composites was prepared by electrospinning and thermal treat-ment.It was packed into a micro-device,which could work continuously at 500℃.The intro-duction of GO significantly increased the mechanical properties of the PAN nanofibers because the oxygen-containing func-tional groups(electronegative groups)on the surface of the GO initiated a nucleophilic attack on the PAN molecule during heat treatment,enabling the GO to initiate the cyclization of the PAN at lower heat-treatment temperatures.In addition,the abund-ant oxygen-containing functional groups on GO acted as pro-oxidants to hasten the oxidation of PAN during heat treatment.The effects of GO content and heat treatment temperature on the properties of the nanofiber films were investigated.A GO/PAN nanofiber piezoelectric sensor heat-treated at 300℃had a 9.10 V and 2.25μA peak output,which are respectively 101.3%and 78.6%higher than those of the untreated films.Cyclic testing over 5000 cycles at 350℃confirmed the stable out-put performance of the GO/PAN nanofiber piezoelectric sensor.Furthermore,a sensor heat-treated at 400℃had a sensitivity of 1.7 V/N,which is 83.5%higher than that of an untreated one.The results show that the prepared GO/PAN nanofiber piezo-electric sensor combines high temperature resistance,high flexibility,stability and high sensitivity,and may have broad applic-ations in high temperature environments such as the aerospace and petroleum industries.
