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low-thermal-conductivity thermal barrier coatings with a multi-scale pore design and sintering resistance following thermal exposure

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Rare Metals 2020年第4期39卷 352-367页

作者： Wei-Wei Zhang Zhi-Yuan Wei Li-Yuan Zhang Ya-Zhe Xing Qiang Zhang School of Materials Science and Engineering Chang'an UniversityXi'an 710064China State Key Laboratory for Mechanical Behavior of Materials School of Materials Science and EngineeringXi’an Jiaotong UniversityXi'an 710049China College of Chemistry and Chemical Engineering Neijiang Normal UniversityNeijiang 641112China AECC Beijing Institute of Aeronautical Material Beijing 100095China

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.

关键词： thermal barrier coatings Multi-scale pore Sintering resistance low thermal conductivity

Discovery of ABO_(4)scheelites with the extra low thermal conductivity through high-throughput calculations

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Journal of Materiomics 2020年第4期6卷 702-711页

作者： Yuchen Liu Dechang Jia Yu Zhou Yanchun Zhou Juanli Zhao Qian Li Bin Liu Institute for Advanced Ceramics School of Materials Science and EngineeringHarbin Institute of TechnologyHeilongjiangHarbin150080China School of Materials Science and Engineering Shanghai UniversityShanghai200444China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials and Processing TechnologyBeijing100076China

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(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.

关键词： Scheelite High-throughput screening low thermal conductivity Mechanical property

Preparation,Performance and Slag Resistant Mechanism of low thermal conductivity Microporous Corundum

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China's Refractories 2015年第4期24卷 23-30页

作者： FU Lyuping HUANG Ao GU Huazhi ZHANG Meijie LI Zhengkun ZHAO Yi The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and Technology Jiangsu Jingxin New Material Co. Ltd. Zhejiang Zili Co. Ltd.

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.

关键词： low thermal conductivity microporous corundum preparation performance slag resistant mechanism

High entropy ultra-high temperature ceramic thermal insulator(Zr_(1/5)Hf_(1/5)Nb_(1/5)Ta_(1/5)Ti_(1/5))C with controlled microstructure and outstanding properties

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Journal of Materials Science & Technology 2022年第24期119卷 190-199页

作者： Zhuojie Shao Zhen Wu Luchao Sun Xianpeng Liang Zhaoping Luo Haikun Chen Junning Li Jingyang Wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Science and Technology on Advanced Functional Composites Laboratory Aerospace Research Institute of Materials and Processing TechnologyBeijing 100076China

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.

关键词： High entropy UHTCs High porosity High strength low thermal conductivity Oxidation resistance

A simple Pb-doping to achieve bonding evolution, VSn and resonant level shifting for regulating thermoelectric transport behavior of SnTe

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Journal of Materials Science & Technology 2023年第20期151卷 66-72页

作者： Xu-Ye Xin Jun Ma Hong-Quan Liu Yi-Jie Gu Yan-Fang Wang Hong-Zhi Cui College of Materials Science and Engineering Shandong University of Science and TechnologyQingdao 266590China School of Mechanical-electronic and Vehicle Engineering Weifang UniversityWeifang 261061China School of Materials Science and Engineering China University of Petroleum HuadongQingdao 266580China

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.

关键词： SnTe-based material low thermal conductivity Projected crystal orbital hamiltonian populations VSn Resonant level

Analysis of the Performances of a New Type of Alumina Nanocomposite Structural Material Designed for the thermal Insulation of High-Rise Buildings

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Fluid Dynamics & Materials Processing 2023年第3期19卷 697-709页

作者： Yue Yu Eastern Liaoning University Faculty of Urban ConstructionDandong118001China

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.

关键词： Alumina nanomaterials low thermal conductivity high-rise building insulation materials sol-gel method

An Effective Green Porous Structural Adhesive for thermal Insulating,Flame-Retardant,and Smoke-Suppressant Expandable Polystyrene Foam

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Engineering 2022年第10期17卷 151-160页

作者： Meng-En Li Hai-Bo Zhao Jin-Bo Cheng Ting Wang Teng Fu Ai-Ning Zhang Yu-Zhong Wang The Collaborative Innovation Center for Eco-Friendly and Fire-Safety Polymeric Materials(MoE)&State Key Laboratory of Polymer Materials Engineering&National Engineering Laboratory of Eco-Friendly Polymeric Materials(Sichuan) College of ChemistrySichuan UniversityChengdu 610064China

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.

关键词： Biomass porous coating Expanded polystyrene foam low thermal conductivity Flame retardancy Smoke suppression

Preparation of Cellulose Acetate Butyrate Porous Micro/Nanofibrous Membranes and Their Properties

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Journal of Donghua University(English Edition) 2023年第5期40卷 461-466页

作者：张晓晓苏亚洲石凌翔王玉洁黄长芬王新厚孙晓霞 College of Textiles Donghua UniversityShanghai 201620China College of Mechanical Engineering Donghua UniversityShanghai 201620China

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.

关键词： electrospinning cellulose acetate butyrate(CAB) porous material waterproof and permeable membrane low thermal conductivity

Preparation and properties of CMAS resistant bixbyite structured high-entropy oxides RE_(2)O_(3)(RE=Sm,Eu,Er,Lu,Y,and Yb):Promising environmental barrier coating materials for Al_(2)O_(3)f/Al_(2)O_(3) composites

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Journal of Advanced Ceramics 2021年第3期10卷 596-613页

作者： Yanan SUN Huimin XIANG Fu-Zhi DAI Xiaohui WANG Yan XING Xiaojun ZHAO Yanchun ZHOU School of Materials Science and Engineering Central South UniversityChangsha 410083China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China New Energy Technology Engineering Laboratory of Jiangsu Province Nanjing University of Posts and TelecommunicationsNanjing 210023China

Y_(2)O_(3) is regarded as one of the potential environmental barrier coating(EBC)materials for Al_(2)O_(3)f/Al_(2)O_(3)ceramic matrix composites owing to its high melting point and close thermal expansion coefficient to Al_(2)O_(3).However,the relatively high thermal conductivity and unsatisfactory calcium-magnesium-aluminosilicate(CMAS)resistance are the main obstacles for the practical application of Y_(2)O_(3).In order to reduce the thermal conductivity and increase the CMAS resistance,four cubic bixbyite structured high-entropy oxides RE_(2)O_(3),including(Eu_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3),(Sm_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3),(Sm_(0.2)Eu_(0.2)Er_(0.2)Y_(0.2)Yb_(0.2))2O_(3),and(Sm_(0.2)Eu_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3)were designed and synthesized,among which(Eu_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3)and(Sm_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3)bulks were prepared by spark plasma sintering(SPS)to investigate their mechanical and thermal properties as well as CMAS resistance.The mechanical properties of(Eu_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3)and(Sm_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3) are close to those of Y_(2)O_(3) but become more brittle than Y_(2)O_(3).The thermal conductivities of(Eu_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb_(0.2))2O_(3) and(Sm_(0.2)Er_(0.2)Lu_(0.2)Y_(0.2)Yb02)2O_(3)(5.1 and 4.6 W·m^(-1)·K^(-1))are only 23.8%and 21.5%respectively of that of Y_(2)O_(3)(21.4 W·m^(-1)·K^(-1)),while their thermal expansion coefficients are close to those of Y_(2)O_(3) and A12O_(3).Most importantly,HE RE_(2)O_(3) ceramics exhibit good CMAS resistance.After being attacked by CMAS at 1350℃for 4 h,the HE RE_(2)O_(3) ceramics maintain their original morphologies without forming pores or cracks,making them promising as EBC materials for Al_(2)O_(3)f/Al_(2)O_(3) composites.

关键词： high-entropy ceramics rare earth oxides low thermal conductivity thermal expansion coefficient CMAS resistance