High-insulation,long-life thermal barrier coatings(TBCs)decrease the service temperature of superalloys and improve the service life of gas turbines.Improvement in the thermal insulation properties of the coating main...High-insulation,long-life thermal barrier coatings(TBCs)decrease the service temperature of superalloys and improve the service life of gas turbines.Improvement in the thermal insulation properties of the coating mainly depends on the optimization of the TBC structure.An important challenge for TBCs is maintaining a high performance during thermal exposure without degradation,as the pore-rich structure of the topcoat would inevitably be transformed by sintering.A low-thermalconductivity anti-sintering coating can overcome the tradeoff between thermal insulation and sinter degradation.In this review,the design,preparation,and serviceability evaluation of a low-thermal-conductivity anti-sintering coating will be discussed.Furthermore,directions for potential development are introduced.This paper provides a comprehensive understanding of the structured tailoring of TBCs for better thermal insulation and anti-sintering performance.展开更多
We design some graphene superlattice structures with ultra-low thermal conductivity 121 W//mK, which is only 6~ of the straight graphene nanoribbons. The thermal conductivity of graphene superlattice nanoribbons （GS...We design some graphene superlattice structures with ultra-low thermal conductivity 121 W//mK, which is only 6~ of the straight graphene nanoribbons. The thermal conductivity of graphene superlattice nanoribbons （GSNRs） is investigated by using molecular dynamics simulations. It is reported that the thermal conductivity of graphene superlattiee nanoribbons is significantly lower than that of the straight graphene nanoribbons （GNRs）. Compared with the phonon spectra of straight GNRs, GSNRs have more forbidden bands. The overlap of phonon spectra between two supercells is shrinking.展开更多
The microporous corundum material was prepared using alumina micro-powder as the main raw material, alumina sol and starch as binders by a wet process, achieving the bulk density of 3.05 g · cm^-3, the apparent p...The microporous corundum material was prepared using alumina micro-powder as the main raw material, alumina sol and starch as binders by a wet process, achieving the bulk density of 3.05 g · cm^-3, the apparent porosity of 9. 1%, the closed porosity of 12.3%, the median pore diameter of 0. 43 μm, and the thermal conductivity of 6. 5 W· m^-1· K^-1 at 800 ℃ which is 41.6% lower than that of common corundum. The slag resistance of the microporous corundum material was studied by immersion and compared with that of the common corundum aggregate, and the slag resistant mechanism of microporous corundum material was revealed. The results show that the slag resistance of the microporous corundum material is superior to that of the common corundum aggregate, the SEM and EDX show that on the reaction interface between microporous corundum and molten, slag, a continuous isolation layer with a large quantity of CA2 and CA6 columnar crystals is formed; while the common corundum aggregate reacts with the molten slag interface to form a discontinuous isolation layer of columnar crystals, through which a lot of molten slag corrodes or permeates into the aggregate. The mechanism is mainly that the microporous structure is more advantageous to nucleation and growth of CA2 and CA6 columnar crystals; in the reaction with the aggregate, the molten slag gets saturated and the critical solution thickness of the microporous corundum and the common corundum is 0. 16 μm and 0. 34 μm, respectively, this is caused by the smaller microporous corundum aggregate pores; and the smaller pores also increase the second phase ripening rate of microporous corundum, which is 9. 7 times of that of the common corundum.展开更多
The use of low electrically conducting liquids is more and more widespread.This is the case for molten glass,salt or slag processing,ionic liquids used in biotechnology,batteries in energy storage and metallurgy.The p...The use of low electrically conducting liquids is more and more widespread.This is the case for molten glass,salt or slag processing,ionic liquids used in biotechnology,batteries in energy storage and metallurgy.The present paper deals with the design of a new electromagnetic induction device that can heat and stir low electricallyconducting liquids.It consists of a resistance-capacity-inductance circuit coupled with a low-conducting liquid load.The device is supplied by a unique electric power source delivering a single-phase high frequency electric current.The main working principle of the circuit is based on a double oscillating circuit inductor connected to the solid-state transistor generator.This technique,which yields a set of coupled oscillating circuits,consists of coupling a forced phase and an induced phase,neglecting the influence of the electric parameters of the loading part(i.e.,the low-conductivity liquid).It is shown that such an inductor is capable to provide a two-phase AC traveling magnetic field at high frequency.To better understand the working principle,the present work improves a previous existing simplified theory by taking into account a complex electrical equivalent diagram due to the different mutual couplings between the two inductors and the two corresponding induced current sets.A more detailed theoretical model is provided,and the key and sensitive elements are elaborated.Based on this theory,equipment is designed to provide a stirring effect on sodium chloride-salted water at 40 S/m.It is shown that such a device fed by several hundred kiloHertz electric currents is able to mimic a linear motor.A set of optimized operating parameters are proposed to guide the experiment.A pure electromagnetic numerical model is presented.Numerical modelling of the load is performed in order to assess the efficiency of the stirrer with a salt water load.Such a device can generate a significant liquid motion with both controlled flow patterns and adjustable amplitude.Based on the magnetohydrodynamic theory,numerical modeling of the salt water flow generated by the stirrer confirms its feasibility.展开更多
The poly(epoxy-N-methylaniline)conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste.Then,this was mixed with different proportions of silver powder to prepare the low...The poly(epoxy-N-methylaniline)conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste.Then,this was mixed with different proportions of silver powder to prepare the low-temperature conductive silver paste.Afterwards,the effect of the conductive organic carrier on the properties of the low-temperature conductive silver paste was determined by IR,DMA and SEM.The results revealed that the prepared conductive paste has good conductivity,film-forming performance,printing performance,low-temperature curing performance,and anti-aging performance.When the mass percentage of the bonding phase/conductive phase was 40/60,the lowest volume resistivity of the conductive silver paste was 4.9×10^(−6)Ω⋅cm,and the conductivity was the best.展开更多
Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger ...Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger negative TEC is used to combine with Al to obtain a low thermal expansion composite with high conductivity. The TEC of Al is reduced by 19%for a ratio Al：Y2Mo3O12 of 0.3118. When the mass ratio of Al：Y2Mo3O12 increases to 2.0000, the conductivity of the composite increases so much that a transformation from capacitance to pure resistance appears. The results suggest that Y2Mo3O12 plays a dominant role in the composite for low content of Al（presenting isolate particles）, while the content of Al increases enough to contact each other, the composite presents mainly the property of Al. For the effect of high content Al, it is considered that Al is squeezed out of the cermets during the uniaxial pressure process to form a thin layer on the surface.展开更多
Thermoelectric and thermal materials are essential in achieving carbon neutrality. However, the high cost of lattice thermal conductivity calculations and the limited applicability of classical physical models have le...Thermoelectric and thermal materials are essential in achieving carbon neutrality. However, the high cost of lattice thermal conductivity calculations and the limited applicability of classical physical models have led to the inefficient development of thermoelectric materials. In this study, we proposed a two-stage machine learning framework with physical interpretability incorporating domain knowledge to calculate high/low thermal conductivity rapidly. Specifically, crystal graph convolutional neural network(CGCNN) is constructed to predict the fundamental physical parameters related to lattice thermal conductivity. Based on the above physical parameters, an interpretable machine learning model–sure independence screening and sparsifying operator(SISSO), is trained to predict the lattice thermal conductivity. We have predicted the lattice thermal conductivity of all available materials in the open quantum materials database(OQMD)(https://www.oqmd.org/). The proposed approach guides the next step of searching for materials with ultra-high or ultralow lattice thermal conductivity and promotes the development of new thermal insulation materials and thermoelectric materials.展开更多
Low sperm motility is one of the main causes of male infertility. Cystic fibrosis transmembrane conductance regulator (CFTR, an anion channel protein) is related to the progressive motility of sperm. CFTR disruptor CF...Low sperm motility is one of the main causes of male infertility. Cystic fibrosis transmembrane conductance regulator (CFTR, an anion channel protein) is related to the progressive motility of sperm. CFTR disruptor CFTRinh-172 or forskolin (FSK) in this study were used to treat human sperm separately, and the rates of sperm autophagy and progressive motility, mitochondrial membrane potential (MMP) and ATP concentration, and the expression levels of related factors were detected to explore their relationship. It was showed that sperms treated with CFTRinh-172 or FSK reduced the levels of cAMP, CFTR and PKA, but increased sperm autophagy rate, expression levels of AMPK and LC3B. However, reactive oxygen species content had no significant difference. It was indicated that low level of CFTR performed with cAMP and its downstream effectors such as PKA and AMPK to regulate mitochondrial structure and function, leading to increased autophagy rate and reduced vitality of sperm.展开更多
This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method.A KCl flux-assisted high-temperature ...This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method.A KCl flux-assisted high-temperature melting and slow-cooling strategy was employed to fabricate nanolayered Cu_(2)Se(KCl)_(x)materials(x=0-3,denoted as S_(0)-S_(3)).Systematic characterization reveals that the coexistence ofαandβphases at room temperature creates favorable conditions for optimizing carrier transport.XPS analysis confirms the substitution of low-binding-energy Se_(2)-by high-binding-energy Cl^(-)ions within the lattice,effectively suppressing copper ion migration and remarkably improving the material's structural stability.Microstructural investigations demonstrate that all samples exhibit nanolayered stacking architectures abundant with edge dislocations.This multiscale defect architecture induces strong phonon scattering effects.Hall measurements indicate that the KCl flux-assisted processing facilitates the formation of highly ordered nanostructures,thereby enhancing carrier mobility and structural stability.Although the carrier concentration exhibits a slight decrease compared with the flux-free samples,the significant improvement in microstructural quality plays a crucial role in the synergistic optimization of electrical conductivity and the Seebeck coefficient.Notably,sample S_(2)exhibited a considerable electrical conductivity,reaching approximately 1.0×10^(5)S·m^(-1)at 300 K.More strikingly,the cooperative effect of high-density edge dislocations and dopant atoms elevates material entropy,enabling sample S_(3)to attain an ultralow lattice thermal conductivity of 0.55 W·m^(-1)·K^(-1)at 350 K.Through multi-mechanism coordination,sample S_(2)achieved a high ZT value of 1.45 at 700 K,representing a 2.7-fold improvement compared with traditional synthesis methods.This work provides new insights into performance optimization of liquid-like thermoelectric materials through defect engineering and entropy manipulation.展开更多
Materials with intrinsically low thermal conductivity are of fundamental interests.Here we report a new sort of simple one-dimensional(1 D)crystal structured bismuth selenohalides(Bi Se X,X=Br,I)with extremely low the...Materials with intrinsically low thermal conductivity are of fundamental interests.Here we report a new sort of simple one-dimensional(1 D)crystal structured bismuth selenohalides(Bi Se X,X=Br,I)with extremely low thermal conductivity of^0.27 W m^-1K^-1 at 573 K.The mechanism of the extremely low thermal conductivity in 1 D Bi Se X is elucidated systematically using the first-principles calculations,neutron powder-diffraction measurements and temperature tunable aberration-corrected scanning transmission electron microscopy(STEM).Results reveal that the1 D structure of Bi Se X possesses unique soft bonding character,low phonon velocity,strong anharmonicity of both acoustic and optical phonon modes,and large off-center displacement of Bi and halogen atoms.Cooperatively,all these features contribute to the minimal phonon transport.These findings provide a novel selection rule to search low thermal conductivity materials with potential applications in thermoelectrics and thermal barrier coatings.展开更多
Yttrium aluminum perovskite(YAl O3)is a promising candidate material for environmental barrier coatings(EBCs)to protect Al2 O3 f/Al2 O3 ceramic matrix composites(CMCs)from the corrosion of high-temperature water vapor...Yttrium aluminum perovskite(YAl O3)is a promising candidate material for environmental barrier coatings(EBCs)to protect Al2 O3 f/Al2 O3 ceramic matrix composites(CMCs)from the corrosion of high-temperature water vapor in combustion environments.Nevertheless,the relatively high thermal conductivity is a notable drawback of YAl O3 for environmental barrier coating application.Herein,in order to make REAl O3 more thermal insulating,a novel high-entropy rare-earth aluminate ceramic(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 was designed and synthesized.The as-prepared(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 ceramic possesses close thermal expansion coefficient(9.02×10-6/oC measured from room temperature to 1200℃)to that of Al2 O3.The thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 at room temperature is 4.1 W·m-1K-1,which is almost one third of the value of YAl O3.Furthermore,to effectively prevent the penetration of water vapor from possible pores/cracks of coating layer,which are often observed in T/EBCs,a tri-layer EBC system REAl O3/RE3 Al5 O12/(Al2 O3 f/Al2 O3 CMCs)is designed.Close thermal expansion coefficient to Al2 O3 and low thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3,as well as the formation of dense garnet layer at(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3/Al2 O3 interface,indicate that this new type of high-entropy ceramic is suitable as a candidate environmental barrier coating material for Al2 O3 f/Al2 O3 CMCs.展开更多
Due to advancements of hypersonic vehicles,ultra-high temperature thermal insulation materials are urgently requested to shield harsh environment with superhigh heat flux.Toward this target,ultra-high temperature cera...Due to advancements of hypersonic vehicles,ultra-high temperature thermal insulation materials are urgently requested to shield harsh environment with superhigh heat flux.Toward this target,ultra-high temperature ceramics(UHTCs)are the only choice due to their excellent capability at ultra-high temperatures.We herein report a novel highly porous high entropy(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C fabricated by foam-gelcasting-freeze drying technology combined with in-situ pressureless reaction sintering.The porous(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C exhibited ultra-high porosity of 86.4%-95.9%,as well as high strength and low thermal conductivity of 0.70–11.77 MPa and 0.164–0.239 W/(m·K),respectively.Specifically,Si C sintering additive only locates at the pit of the surface of sintering neck between UHTC grains,and there is no secondary phase or intergranular film at the grain boundary.Besides,the oxidation resistance of high entropy carbide powders is greatly improved compared with that of the mixed five carbide powders.This work clearly highlights the merits of highly porous high entropy(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C as an ultra-high temperature thermal insulation material.展开更多
Searching for new materials with extra low thermal conductivities is significant in numerous fields like thermal barrier coatings and thermoelectric devices.Traditional multiple-component design has successfully reduc...Searching for new materials with extra low thermal conductivities is significant in numerous fields like thermal barrier coatings and thermoelectric devices.Traditional multiple-component design has successfully reduced the thermal conductivity,but it also dramatically increases the complexity of manufactural technologies and the risk of material failures.In this work,a specific category known as ABO_(4) scheelites that with both simple crystal structure and the structural signature of the low lattice thermal conductivity is explored.High-throughput calculations are employed to screen for the materials with the targeted performance by multi-dimensional mechanical/thermal property criteria and a database of 46 stable scheelites is constructed.Seven scheelites with both ultra-low thermal conductivities(<1.2 W/(m∙K))and quasi-ductility are predicted to be novel thermal insulation materials.Low thermal conductivities prefer the scheelites with large valence disparity between“A”and“B”cations and/or small ionic radius ratio.The adopted strategy starting from the structural fingerprint and the data-driven material selection is expected to be a reference of future structural and functional ceramics design.展开更多
Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibro...Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.展开更多
To develop an efficient way to overcome the contradiction among flame retardancy,smoke suppression,and thermal insulation in expanded polystyrene(EPS)foams,which are widely used insulation materials in buildings,a nov...To develop an efficient way to overcome the contradiction among flame retardancy,smoke suppression,and thermal insulation in expanded polystyrene(EPS)foams,which are widely used insulation materials in buildings,a novel"green"porous bio-based flame-retard ant starch(FRS)coating was designed from starch modified with phytic acid(PA)that simultaneously acts as both a flame retardant and an adhesive.This porous FRS coating has open pores,which,in combination with the closed cells formed by EPS beads,create a hierarchically porous structure in FRS-EPS that results in superior thermal insulation with a lower thermal conductivity of 27.0 mW·(m·K)^(-1).The resultant FRS-EPS foam showed extremely low heat-release rates and smoke-production release,indicating excellent fire retardancy and smoke suppression.The specific optical density was as low as 121,which was 80.6%lower than that of neat EPS,at 624.The FRS-EPS also exhibited self-extinguishing behavior in vertical burning tests and had a high limiting oxygen index(LOI)value of 35.5%.More interestingly,after being burnt with an alcohol lamp for 30 min,the top side temperature of the FRS-EPS remained at only 140℃with ignition,thereby exhibiting excellent fire resistance.Mechanism analysis confirmed the intumescent action of FRS,which forms a compact phosphorus-rich hybrid barrier,and the phosphorus-containing compounds that formed in the gas phase contributed to the excellent flame retardancy and smoke suppression of FRS-EPS.This novel porous biomass-based FRS system provides a promising strategy for fabricating polymer foams with excellent flame retardancy,smoke suppression,and thermal insulation.展开更多
CuPbBi_(5)S_(9) compounds have been investigated as gladite for years.However,there have been no significant studies on their physical and chemical properties.This work demonstrates that upon alloying with moderate Cu...CuPbBi_(5)S_(9) compounds have been investigated as gladite for years.However,there have been no significant studies on their physical and chemical properties.This work demonstrates that upon alloying with moderate Cu,Pb,Bi,and S using an appropriate preparation method,quaternary CuPbBi_(5)S_(9) compounds can exhibit excellent figure of merit ZT within the temperature range 298-723 K.A low average velocity,low Young’s modulus and Debye temperature,and large Grüneisen parameter,determined experimentally,indicate strong lattice anharmonicity in CuPbBi_(5)S_(9) crystals.Furthermore,density functional theory calculations(local vibration of low-frequency acoustic phonons)justify the low lattice thermal conductivity of CuPbBi_(5)S_(9) compounds.Because of the low thermal conductivity(0.514 W m^(-1)K^(-1))and a relatively high power factor(293 μW m^(-1)K^(-2)),a maximum ZT of 0.42 was achieved at 723 K for CuPbBi_(5)S_(9) prepared by mechanical alloying combined with solid-state melting.Thus,CuPbBi_(5)S_(9) materials are promising candidates for use as high-performance thermoelectric materials in the intermediate-temperature range.展开更多
Using recent data of geoscience transaction in Northeast China, the author analyses and studies the crust-upper mantle structure feature of the North Tanlu fault zone. The result shows the crust-mantle structure are o...Using recent data of geoscience transaction in Northeast China, the author analyses and studies the crust-upper mantle structure feature of the North Tanlu fault zone. The result shows the crust-mantle structure are obvious difference at both sides of the North Tanlu fault zone. The fault activity and segmentation are closely related with abruptly change zone of the crust-upper mantle structure. There is a clear mirror image relationship between the big geomorphic shape and asthenosphere undulate, the former restricts tectonic stability and tectonic style of dif- ferent crustal units. The significantly strengthening seismicity of north set and south set in the North Tanlu fault zone just correspond to the low-velocity and high conductivity layer of crust-upper mantle. In the North Tanlu fault zone, the main controlling structure of the mid-strong seismic generally consists of the active fault sectors, whose crust-mantle structure is more complicated in rigidity massif.展开更多
The intensification of energy crises and environmental pollution inspire researchers’attention to environment-friendly SnTe thermoelectric materials.In this work,we achieved a lower lattice thermal conductivity and o...The intensification of energy crises and environmental pollution inspire researchers’attention to environment-friendly SnTe thermoelectric materials.In this work,we achieved a lower lattice thermal conductivity and optimized the power factor via the synergistic optimization of bonding characteristic,VSn,and resonant level for the SnTe system,respectively.Pb-introduction produces weak bonding strength,mass fluctuation,and stress distortion,which result in lower thermal conductivity.The lowest lattice thermal conductivity achieves 0.66 W m^(–1) K^(–1) at 773 K.Further introduced VSn relieves loss of electrical conductivity caused by Pb-introduction,and it also makes the bigger g(E)and up-shift of resonance level.The VSn,enhanced g(E),and resonant level make electrical conductivity and Seebeck coefficient enhance simultaneously.Finally,the further optimization of thermal and electronic transport performance contributes to a higher ZT value of∼0.86 at 773 K in the Sn_(0.685)Pb_(0.285)In_(0.015)Te_(0.7)Se_(0.3) sample.The strategy of bonding characteristic,VSn,and resonant level synergistic engineering will be widely applicable to various TE systems for achieving better thermoelectric performance.展开更多
In the current aera of rapid development in the field of electric vehicles and electrochemical energy storage,solid-state battery technology is attracting much research and attention.Solid-state electrolytes,as the ke...In the current aera of rapid development in the field of electric vehicles and electrochemical energy storage,solid-state battery technology is attracting much research and attention.Solid-state electrolytes,as the key component of next-generation battery technology,are favored for their high safety,high energy density,and long life.However,finding high-performance solid-state electrolytes is the primary challenge for solid-state battery applications.Focusing on inorganic solid-state electrolytes,this work highlights the need for ideal solid-state electrolytes to have low electronic conductivity,good thermal stability,and structural and phase stability.Traditional experimental and theoretical computational methods suffer from inefficiency,thus machine learning methods become a novel path to intelligently predict material properties by analyzing a large number of inorganic structural properties and characteristics.Through the gradient descent-based XGBoost algorithm,we successfully predicted the energy band structure and stability of the materials,and screened out only 194 ideal solid-state electrolyte structures from more than 6000 structures that satisfy the requirements of low electronic conductivity and stability simultaneously,which greatly accelerated the development of solid-state batteries.展开更多
The sol-gel method is used to prepare a new nano-alumina aerogel structure and the thermal properties of this nanomaterial are investigated comprehensively using electron microscope scanning,thermal analysis,X-ray and...The sol-gel method is used to prepare a new nano-alumina aerogel structure and the thermal properties of this nanomaterial are investigated comprehensively using electron microscope scanning,thermal analysis,X-ray and infrared spectrometer analysis methods.It is found that the composite aerogel alumina material has a multi-level porous nano-network structure.When employed for the thermal insulation of high-rise buildings,the alumina nanocomposite aerogel material can lead to effective energy savings in winter.However,it has almost no energy-saving effect on buildings where energy is consumed for cooling in summer.展开更多
基金financially supported by the Natural Science Basic Research Program of Shaanxi(No.2019JQ380)the Fundamental Research Funds for the Central Universities,CHD(No.300102500102)
文摘High-insulation,long-life thermal barrier coatings(TBCs)decrease the service temperature of superalloys and improve the service life of gas turbines.Improvement in the thermal insulation properties of the coating mainly depends on the optimization of the TBC structure.An important challenge for TBCs is maintaining a high performance during thermal exposure without degradation,as the pore-rich structure of the topcoat would inevitably be transformed by sintering.A low-thermalconductivity anti-sintering coating can overcome the tradeoff between thermal insulation and sinter degradation.In this review,the design,preparation,and serviceability evaluation of a low-thermal-conductivity anti-sintering coating will be discussed.Furthermore,directions for potential development are introduced.This paper provides a comprehensive understanding of the structured tailoring of TBCs for better thermal insulation and anti-sintering performance.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11004082 and 11291240477the Natural Science Foundation of Guangdong Province under Grant No 2014A030313367the Fundamental Research Funds for the Central Universities under Grant No 11614341
文摘We design some graphene superlattice structures with ultra-low thermal conductivity 121 W//mK, which is only 6~ of the straight graphene nanoribbons. The thermal conductivity of graphene superlattice nanoribbons （GSNRs） is investigated by using molecular dynamics simulations. It is reported that the thermal conductivity of graphene superlattiee nanoribbons is significantly lower than that of the straight graphene nanoribbons （GNRs）. Compared with the phonon spectra of straight GNRs, GSNRs have more forbidden bands. The overlap of phonon spectra between two supercells is shrinking.
基金Financial supports from the National Natural Science Foundation of China(Nos.51474165 and 51204126)
文摘The microporous corundum material was prepared using alumina micro-powder as the main raw material, alumina sol and starch as binders by a wet process, achieving the bulk density of 3.05 g · cm^-3, the apparent porosity of 9. 1%, the closed porosity of 12.3%, the median pore diameter of 0. 43 μm, and the thermal conductivity of 6. 5 W· m^-1· K^-1 at 800 ℃ which is 41.6% lower than that of common corundum. The slag resistance of the microporous corundum material was studied by immersion and compared with that of the common corundum aggregate, and the slag resistant mechanism of microporous corundum material was revealed. The results show that the slag resistance of the microporous corundum material is superior to that of the common corundum aggregate, the SEM and EDX show that on the reaction interface between microporous corundum and molten, slag, a continuous isolation layer with a large quantity of CA2 and CA6 columnar crystals is formed; while the common corundum aggregate reacts with the molten slag interface to form a discontinuous isolation layer of columnar crystals, through which a lot of molten slag corrodes or permeates into the aggregate. The mechanism is mainly that the microporous structure is more advantageous to nucleation and growth of CA2 and CA6 columnar crystals; in the reaction with the aggregate, the molten slag gets saturated and the critical solution thickness of the microporous corundum and the common corundum is 0. 16 μm and 0. 34 μm, respectively, this is caused by the smaller microporous corundum aggregate pores; and the smaller pores also increase the second phase ripening rate of microporous corundum, which is 9. 7 times of that of the common corundum.
基金This study was supported by the Instrument and Equipment Development Project of the Chinese Academy of Sciences(YJKYYQ20200053)the“Double First-Class”Construction Fund(111800XX62)the Mechanical Engineering Discipline Construction Fund(111800M000).
文摘The use of low electrically conducting liquids is more and more widespread.This is the case for molten glass,salt or slag processing,ionic liquids used in biotechnology,batteries in energy storage and metallurgy.The present paper deals with the design of a new electromagnetic induction device that can heat and stir low electricallyconducting liquids.It consists of a resistance-capacity-inductance circuit coupled with a low-conducting liquid load.The device is supplied by a unique electric power source delivering a single-phase high frequency electric current.The main working principle of the circuit is based on a double oscillating circuit inductor connected to the solid-state transistor generator.This technique,which yields a set of coupled oscillating circuits,consists of coupling a forced phase and an induced phase,neglecting the influence of the electric parameters of the loading part(i.e.,the low-conductivity liquid).It is shown that such an inductor is capable to provide a two-phase AC traveling magnetic field at high frequency.To better understand the working principle,the present work improves a previous existing simplified theory by taking into account a complex electrical equivalent diagram due to the different mutual couplings between the two inductors and the two corresponding induced current sets.A more detailed theoretical model is provided,and the key and sensitive elements are elaborated.Based on this theory,equipment is designed to provide a stirring effect on sodium chloride-salted water at 40 S/m.It is shown that such a device fed by several hundred kiloHertz electric currents is able to mimic a linear motor.A set of optimized operating parameters are proposed to guide the experiment.A pure electromagnetic numerical model is presented.Numerical modelling of the load is performed in order to assess the efficiency of the stirrer with a salt water load.Such a device can generate a significant liquid motion with both controlled flow patterns and adjustable amplitude.Based on the magnetohydrodynamic theory,numerical modeling of the salt water flow generated by the stirrer confirms its feasibility.
基金fund for this work was provided by the“Research on Key Technologies of Photosensitive Conductive Silver Paste Based on Domestic Circuit Protection Micro Chip Components”(Project No.BE2020008 and Supporting Author:Chen P).
文摘The poly(epoxy-N-methylaniline)conductive organic carrier was used as the bonding phase of the low-temperature conductive silver paste.Then,this was mixed with different proportions of silver powder to prepare the low-temperature conductive silver paste.Afterwards,the effect of the conductive organic carrier on the properties of the low-temperature conductive silver paste was determined by IR,DMA and SEM.The results revealed that the prepared conductive paste has good conductivity,film-forming performance,printing performance,low-temperature curing performance,and anti-aging performance.When the mass percentage of the bonding phase/conductive phase was 40/60,the lowest volume resistivity of the conductive silver paste was 4.9×10^(−6)Ω⋅cm,and the conductivity was the best.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.10974183 and 11104252)the Doctoral Fund of the Ministry of Education of China(Grant No.20114101110003)+2 种基金the Fund for Science&Technology Innovation Team of Zhengzhou,China(Grant No.112PCXTD337)the Industrial Science and Technology Research Projects of Kaifeng,Henan Province,China(Grant No.1501049)the Key Research Projects of Henan Higher Education Institutions,China(Grant No.18A140014)
文摘Low thermal expansion composites are difficult to obtain by using Al with larger positive thermal expansion coefficient（TEC） and the materials with smaller negative TECs. In this investigation, Y2Mo3O12 with larger negative TEC is used to combine with Al to obtain a low thermal expansion composite with high conductivity. The TEC of Al is reduced by 19%for a ratio Al：Y2Mo3O12 of 0.3118. When the mass ratio of Al：Y2Mo3O12 increases to 2.0000, the conductivity of the composite increases so much that a transformation from capacitance to pure resistance appears. The results suggest that Y2Mo3O12 plays a dominant role in the composite for low content of Al（presenting isolate particles）, while the content of Al increases enough to contact each other, the composite presents mainly the property of Al. For the effect of high content Al, it is considered that Al is squeezed out of the cermets during the uniaxial pressure process to form a thin layer on the surface.
基金support of the National Natural Science Foundation of China(Grant Nos.12104356 and52250191)China Postdoctoral Science Foundation(Grant No.2022M712552)+2 种基金the Opening Project of Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology(Grant No.Ammt2022B-1)the Fundamental Research Funds for the Central Universitiessupport by HPC Platform,Xi’an Jiaotong University。
文摘Thermoelectric and thermal materials are essential in achieving carbon neutrality. However, the high cost of lattice thermal conductivity calculations and the limited applicability of classical physical models have led to the inefficient development of thermoelectric materials. In this study, we proposed a two-stage machine learning framework with physical interpretability incorporating domain knowledge to calculate high/low thermal conductivity rapidly. Specifically, crystal graph convolutional neural network(CGCNN) is constructed to predict the fundamental physical parameters related to lattice thermal conductivity. Based on the above physical parameters, an interpretable machine learning model–sure independence screening and sparsifying operator(SISSO), is trained to predict the lattice thermal conductivity. We have predicted the lattice thermal conductivity of all available materials in the open quantum materials database(OQMD)(https://www.oqmd.org/). The proposed approach guides the next step of searching for materials with ultra-high or ultralow lattice thermal conductivity and promotes the development of new thermal insulation materials and thermoelectric materials.
文摘Low sperm motility is one of the main causes of male infertility. Cystic fibrosis transmembrane conductance regulator (CFTR, an anion channel protein) is related to the progressive motility of sperm. CFTR disruptor CFTRinh-172 or forskolin (FSK) in this study were used to treat human sperm separately, and the rates of sperm autophagy and progressive motility, mitochondrial membrane potential (MMP) and ATP concentration, and the expression levels of related factors were detected to explore their relationship. It was showed that sperms treated with CFTRinh-172 or FSK reduced the levels of cAMP, CFTR and PKA, but increased sperm autophagy rate, expression levels of AMPK and LC3B. However, reactive oxygen species content had no significant difference. It was indicated that low level of CFTR performed with cAMP and its downstream effectors such as PKA and AMPK to regulate mitochondrial structure and function, leading to increased autophagy rate and reduced vitality of sperm.
基金Project supported by the National Natural Science Foundation of China(Grant No.62464013)。
文摘This study achieves a notable enhancement in the thermoelectric performance of copper selenide compounds exhibiting liquid-like characteristics via an innovative processing method.A KCl flux-assisted high-temperature melting and slow-cooling strategy was employed to fabricate nanolayered Cu_(2)Se(KCl)_(x)materials(x=0-3,denoted as S_(0)-S_(3)).Systematic characterization reveals that the coexistence ofαandβphases at room temperature creates favorable conditions for optimizing carrier transport.XPS analysis confirms the substitution of low-binding-energy Se_(2)-by high-binding-energy Cl^(-)ions within the lattice,effectively suppressing copper ion migration and remarkably improving the material's structural stability.Microstructural investigations demonstrate that all samples exhibit nanolayered stacking architectures abundant with edge dislocations.This multiscale defect architecture induces strong phonon scattering effects.Hall measurements indicate that the KCl flux-assisted processing facilitates the formation of highly ordered nanostructures,thereby enhancing carrier mobility and structural stability.Although the carrier concentration exhibits a slight decrease compared with the flux-free samples,the significant improvement in microstructural quality plays a crucial role in the synergistic optimization of electrical conductivity and the Seebeck coefficient.Notably,sample S_(2)exhibited a considerable electrical conductivity,reaching approximately 1.0×10^(5)S·m^(-1)at 300 K.More strikingly,the cooperative effect of high-density edge dislocations and dopant atoms elevates material entropy,enabling sample S_(3)to attain an ultralow lattice thermal conductivity of 0.55 W·m^(-1)·K^(-1)at 350 K.Through multi-mechanism coordination,sample S_(2)achieved a high ZT value of 1.45 at 700 K,representing a 2.7-fold improvement compared with traditional synthesis methods.This work provides new insights into performance optimization of liquid-like thermoelectric materials through defect engineering and entropy manipulation.
基金supported by the National Key Research and Development Program of China(2018YFA0702100 and 2018YFB0703600)the National Natural Science Foundation of China(51772012 and 51632005)+5 种基金Shenzhen Peacock Plan team(KQTD2016022619565991)Beijing Natural Science Foundation(JQ18004)China Postdoctoral Science Foundation Grant(2019M650429)111 Project(B17002)the National Science Foundation for Distinguished Young Scholars(51925101)the financial support from Singapore Ministry of Education Tier 1grant(R-284-000-212-114)for Lee Kuan Yew Postdoctoral Fellowship。
文摘Materials with intrinsically low thermal conductivity are of fundamental interests.Here we report a new sort of simple one-dimensional(1 D)crystal structured bismuth selenohalides(Bi Se X,X=Br,I)with extremely low thermal conductivity of^0.27 W m^-1K^-1 at 573 K.The mechanism of the extremely low thermal conductivity in 1 D Bi Se X is elucidated systematically using the first-principles calculations,neutron powder-diffraction measurements and temperature tunable aberration-corrected scanning transmission electron microscopy(STEM).Results reveal that the1 D structure of Bi Se X possesses unique soft bonding character,low phonon velocity,strong anharmonicity of both acoustic and optical phonon modes,and large off-center displacement of Bi and halogen atoms.Cooperatively,all these features contribute to the minimal phonon transport.These findings provide a novel selection rule to search low thermal conductivity materials with potential applications in thermoelectrics and thermal barrier coatings.
基金financial supported by the National Natural Science Foundation of China(Nos.51672064 and 51972089)。
文摘Yttrium aluminum perovskite(YAl O3)is a promising candidate material for environmental barrier coatings(EBCs)to protect Al2 O3 f/Al2 O3 ceramic matrix composites(CMCs)from the corrosion of high-temperature water vapor in combustion environments.Nevertheless,the relatively high thermal conductivity is a notable drawback of YAl O3 for environmental barrier coating application.Herein,in order to make REAl O3 more thermal insulating,a novel high-entropy rare-earth aluminate ceramic(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 was designed and synthesized.The as-prepared(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 ceramic possesses close thermal expansion coefficient(9.02×10-6/oC measured from room temperature to 1200℃)to that of Al2 O3.The thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3 at room temperature is 4.1 W·m-1K-1,which is almost one third of the value of YAl O3.Furthermore,to effectively prevent the penetration of water vapor from possible pores/cracks of coating layer,which are often observed in T/EBCs,a tri-layer EBC system REAl O3/RE3 Al5 O12/(Al2 O3 f/Al2 O3 CMCs)is designed.Close thermal expansion coefficient to Al2 O3 and low thermal conductivity of(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3,as well as the formation of dense garnet layer at(Y0.2Nd0.2Sm0.2Eu0.2Er0.2)AlO3/Al2 O3 interface,indicate that this new type of high-entropy ceramic is suitable as a candidate environmental barrier coating material for Al2 O3 f/Al2 O3 CMCs.
基金financial support from the National Key R&D Program of China(No.2017YFB0703201)Liao Ning Revitalization Talents Program(No.XLYC2002018)。
文摘Due to advancements of hypersonic vehicles,ultra-high temperature thermal insulation materials are urgently requested to shield harsh environment with superhigh heat flux.Toward this target,ultra-high temperature ceramics(UHTCs)are the only choice due to their excellent capability at ultra-high temperatures.We herein report a novel highly porous high entropy(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C fabricated by foam-gelcasting-freeze drying technology combined with in-situ pressureless reaction sintering.The porous(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C exhibited ultra-high porosity of 86.4%-95.9%,as well as high strength and low thermal conductivity of 0.70–11.77 MPa and 0.164–0.239 W/(m·K),respectively.Specifically,Si C sintering additive only locates at the pit of the surface of sintering neck between UHTC grains,and there is no secondary phase or intergranular film at the grain boundary.Besides,the oxidation resistance of high entropy carbide powders is greatly improved compared with that of the mixed five carbide powders.This work clearly highlights the merits of highly porous high entropy(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C as an ultra-high temperature thermal insulation material.
基金the National Natural Science Foundation of China(No.51602188 and 51621091)the Program for Professor of Special Appointment(Eastern Scholar)by Shanghai Municipal Education Commission(No.TP2015040).
文摘Searching for new materials with extra low thermal conductivities is significant in numerous fields like thermal barrier coatings and thermoelectric devices.Traditional multiple-component design has successfully reduced the thermal conductivity,but it also dramatically increases the complexity of manufactural technologies and the risk of material failures.In this work,a specific category known as ABO_(4) scheelites that with both simple crystal structure and the structural signature of the low lattice thermal conductivity is explored.High-throughput calculations are employed to screen for the materials with the targeted performance by multi-dimensional mechanical/thermal property criteria and a database of 46 stable scheelites is constructed.Seven scheelites with both ultra-low thermal conductivities(<1.2 W/(m∙K))and quasi-ductility are predicted to be novel thermal insulation materials.Low thermal conductivities prefer the scheelites with large valence disparity between“A”and“B”cations and/or small ionic radius ratio.The adopted strategy starting from the structural fingerprint and the data-driven material selection is expected to be a reference of future structural and functional ceramics design.
基金National Natural Science Foundation of China(No.52203056)。
文摘Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.
基金financially supported by the National Natural Science Foundation of China(51827803,51320105011,51790504,and 51721091)the Young Elite Scientists Sponsorship Program by CASTFundamental Research Funds for the Central Universities。
文摘To develop an efficient way to overcome the contradiction among flame retardancy,smoke suppression,and thermal insulation in expanded polystyrene(EPS)foams,which are widely used insulation materials in buildings,a novel"green"porous bio-based flame-retard ant starch(FRS)coating was designed from starch modified with phytic acid(PA)that simultaneously acts as both a flame retardant and an adhesive.This porous FRS coating has open pores,which,in combination with the closed cells formed by EPS beads,create a hierarchically porous structure in FRS-EPS that results in superior thermal insulation with a lower thermal conductivity of 27.0 mW·(m·K)^(-1).The resultant FRS-EPS foam showed extremely low heat-release rates and smoke-production release,indicating excellent fire retardancy and smoke suppression.The specific optical density was as low as 121,which was 80.6%lower than that of neat EPS,at 624.The FRS-EPS also exhibited self-extinguishing behavior in vertical burning tests and had a high limiting oxygen index(LOI)value of 35.5%.More interestingly,after being burnt with an alcohol lamp for 30 min,the top side temperature of the FRS-EPS remained at only 140℃with ignition,thereby exhibiting excellent fire resistance.Mechanism analysis confirmed the intumescent action of FRS,which forms a compact phosphorus-rich hybrid barrier,and the phosphorus-containing compounds that formed in the gas phase contributed to the excellent flame retardancy and smoke suppression of FRS-EPS.This novel porous biomass-based FRS system provides a promising strategy for fabricating polymer foams with excellent flame retardancy,smoke suppression,and thermal insulation.
基金supported by the National Natural Science Foundation of China(Grant No.11764025).
文摘CuPbBi_(5)S_(9) compounds have been investigated as gladite for years.However,there have been no significant studies on their physical and chemical properties.This work demonstrates that upon alloying with moderate Cu,Pb,Bi,and S using an appropriate preparation method,quaternary CuPbBi_(5)S_(9) compounds can exhibit excellent figure of merit ZT within the temperature range 298-723 K.A low average velocity,low Young’s modulus and Debye temperature,and large Grüneisen parameter,determined experimentally,indicate strong lattice anharmonicity in CuPbBi_(5)S_(9) crystals.Furthermore,density functional theory calculations(local vibration of low-frequency acoustic phonons)justify the low lattice thermal conductivity of CuPbBi_(5)S_(9) compounds.Because of the low thermal conductivity(0.514 W m^(-1)K^(-1))and a relatively high power factor(293 μW m^(-1)K^(-2)),a maximum ZT of 0.42 was achieved at 723 K for CuPbBi_(5)S_(9) prepared by mechanical alloying combined with solid-state melting.Thus,CuPbBi_(5)S_(9) materials are promising candidates for use as high-performance thermoelectric materials in the intermediate-temperature range.
文摘Using recent data of geoscience transaction in Northeast China, the author analyses and studies the crust-upper mantle structure feature of the North Tanlu fault zone. The result shows the crust-mantle structure are obvious difference at both sides of the North Tanlu fault zone. The fault activity and segmentation are closely related with abruptly change zone of the crust-upper mantle structure. There is a clear mirror image relationship between the big geomorphic shape and asthenosphere undulate, the former restricts tectonic stability and tectonic style of dif- ferent crustal units. The significantly strengthening seismicity of north set and south set in the North Tanlu fault zone just correspond to the low-velocity and high conductivity layer of crust-upper mantle. In the North Tanlu fault zone, the main controlling structure of the mid-strong seismic generally consists of the active fault sectors, whose crust-mantle structure is more complicated in rigidity massif.
基金supported by the National Natural Science Foundation of China(Nos.U2106216,51971121)the Natural Science Foundation of Shandong Province(Grant No.ZR2020ME012)。
文摘The intensification of energy crises and environmental pollution inspire researchers’attention to environment-friendly SnTe thermoelectric materials.In this work,we achieved a lower lattice thermal conductivity and optimized the power factor via the synergistic optimization of bonding characteristic,VSn,and resonant level for the SnTe system,respectively.Pb-introduction produces weak bonding strength,mass fluctuation,and stress distortion,which result in lower thermal conductivity.The lowest lattice thermal conductivity achieves 0.66 W m^(–1) K^(–1) at 773 K.Further introduced VSn relieves loss of electrical conductivity caused by Pb-introduction,and it also makes the bigger g(E)and up-shift of resonance level.The VSn,enhanced g(E),and resonant level make electrical conductivity and Seebeck coefficient enhance simultaneously.Finally,the further optimization of thermal and electronic transport performance contributes to a higher ZT value of∼0.86 at 773 K in the Sn_(0.685)Pb_(0.285)In_(0.015)Te_(0.7)Se_(0.3) sample.The strategy of bonding characteristic,VSn,and resonant level synergistic engineering will be widely applicable to various TE systems for achieving better thermoelectric performance.
基金supported by the National Natural Science Foundation of China(No.21421063,No.21473166,No.21573211,No.21633007,No.21790350,No.21803067,No.91950207)the Chinese Academy of Sciences(QYZDB-SSW-SLH018)+3 种基金the Anhui Initiative in Quantum Information Technologies(AHY090200)the USTC-NSRL Joint Funds(UN2018LHJJ)the Anhui Provincial Natural Science Foundation(2108085QB63)Numerical Theoretical simulations were done in the Supercomputing Center of USTC.
文摘In the current aera of rapid development in the field of electric vehicles and electrochemical energy storage,solid-state battery technology is attracting much research and attention.Solid-state electrolytes,as the key component of next-generation battery technology,are favored for their high safety,high energy density,and long life.However,finding high-performance solid-state electrolytes is the primary challenge for solid-state battery applications.Focusing on inorganic solid-state electrolytes,this work highlights the need for ideal solid-state electrolytes to have low electronic conductivity,good thermal stability,and structural and phase stability.Traditional experimental and theoretical computational methods suffer from inefficiency,thus machine learning methods become a novel path to intelligently predict material properties by analyzing a large number of inorganic structural properties and characteristics.Through the gradient descent-based XGBoost algorithm,we successfully predicted the energy band structure and stability of the materials,and screened out only 194 ideal solid-state electrolyte structures from more than 6000 structures that satisfy the requirements of low electronic conductivity and stability simultaneously,which greatly accelerated the development of solid-state batteries.
文摘The sol-gel method is used to prepare a new nano-alumina aerogel structure and the thermal properties of this nanomaterial are investigated comprehensively using electron microscope scanning,thermal analysis,X-ray and infrared spectrometer analysis methods.It is found that the composite aerogel alumina material has a multi-level porous nano-network structure.When employed for the thermal insulation of high-rise buildings,the alumina nanocomposite aerogel material can lead to effective energy savings in winter.However,it has almost no energy-saving effect on buildings where energy is consumed for cooling in summer.
