检索结果-南通市图书馆

Electronic structure,bonding characteristics,and mechanical behaviors of a new family of Si-containing damage-tolerant MAB phases M_(5)SiB_(2)(M=IVB-VIB transition metals)

引用

Journal of Advanced Ceramics 2022年第10期11卷 1626-1640页

作者： Na NI Hanchao ZHANG Yanchun ZHOU School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China

MAB phases are layered ternary compounds with alternative stacking of transition metal boride layers and group A element layers.Until now,most of the investigated MAB phases are concentrated on compounds with Al as the A element layers.In this work,the family of M_(5)SiB_(2)(M=IVB-VIB transition metals)compounds with silicon as interlayers were investigated by density functional theory(DFT)methods as potential MAB phases for high-temperature applications.Starting from the known Mo5SiB2,the electronic structure,bonding characteristics,and mechanical behaviors were systematically investigated and discussed.Although the composition of M_(5)SiB_(2) does not follow the general formula of experimentally reported(MB)_(2z)A_(x)(MB_(2))_(y)(z=1,2;x=1,2;y=0,1,2),their layered structure and anisotropic bonding characteristics are similar to other known MAB phases,which justifies their classification as new members of this material class.As a result of the higher bulk modulus and lower shear modulus,Mo_(5)SiB_(2) has a Pugh’s ratio of 0.53,which is much lower than the common MAB phases.It was found that the stability and mechanical properties of M_(5)SiB_(2) compounds depend on their valence electron concentrations(VECs),and an optimum VEC exists as the criteria for stability.The hypothesized Zr and Hf containing compounds,i.e.,Zr_(5)SiB_(2) and Hf_(5)SiB_(2),which are more interesting in terms of high-temperature oxidation/ablation resistance,were found to be unfortunately unstable.To cope with this problem,a new stable solid solution(Zr_(0.6)Mo_(0.4))_(5)SiB_(2) was designed based on VEC tuning to demonstrate a promising approach for developing new MAB phases with desirable compositions.

关键词： borides MAB phases density functional theory(DFT) thermodynamic stability electronic structure mechanical properties

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Secrets of high thermal emission of transition metal disilicides TMSi_(2)(TM=Ta,Mo)

引用

Journal of Materials Science & Technology 2021年第30期89卷 114-121页

作者： Huimin Xiang Fuzhi Dai Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials and Processing TechnologyBeijing 100076China

TMSi_(2)(TM=Ta,Mo)are extensively used as thermal emissivity agents in high emission coatings due to their well-known"high"emissivity in infrared range.However,there is a paucity of the high temperature(HT)emissivity property of these two silicides.Moreover,room temperature(RT)spectrometer measurements have demonstrated that the emittance in infrared range of two silicides was considerably low.Therefore,providing critical HT data and satisfactory elucidation on the emission incompatibility of TMSi_(2)is eagerly needed.In this contribution,combining first principles calculations and Drude model,the reflectance spectra of TMSi_(2)were predicted at both RT and HT.Consistent with spectrometer measurements,the intrinsic emittance of silicides was relatively low in the entire investigated temperatures.To explain the incompatible emission behavior,two simplified models including the majority of high emissivity coating,SiO_(2),were proposed.Intriguingly,with SiO_(2)considered in simulations,no matter covered on the surface or blended in the composites,the emittance of the TMSi_(2)enhanced significantly.Our theoretical results demonstrate the non-negligible significance of oxides on the high temperature performance of silicides and provide the guidelines for improving the emission performance of silicides and searching for potential high emissivity agents.

关键词： Disilicide Optical properties Thermal emission First-principles calculations Drude model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Segregation of solute atoms in ZrC grain boundaries and their effects on grain boundary strengths

引用

Journal of Materials Science & Technology 2022年第6期101卷 234-241页

作者： Fu-Zhi Dai Yinjie Sun Yixiao Ren Huimin Xiang Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China

ZrC is a promising candidate for the application in ultra-high temperature regime due to its unique combination of excellent properties,such as high melting point,good chemical inertness and high temperature stability.The rapid decrease of strength at high temperatures,however,is one of the obstacles that impedes its practical services.Strengthening of grain boundaries by solute segregation is believed to be an effective way to improve its high temperature performance.Therefore,the segregation tendency of ten solid solute atoms,including Sc,Ti,V,Cr,Y,Nb,Mo,Hf,Ta,W,in Zr C grain boundaries,and the strengthening/weakening effects on grain boundaries due to segregation are investigated by first-principles calculations.The segregation tendency is found dominated by the size effect,which is confirmed by both a qualitative analysis and a quantitative approach based on support vector regression.It means that big atoms tend to segregate to grain boundary sites with local expansions,while small atoms tend to segregate to grain boundary sites with local compressions.Simulations on stress-strain responses indicate that segregation of small atoms(Ti,V,Cr,Nb,Ta,Mo,W)can usually improve grain boundary strengths by inducing compression strains to grain boundaries,even though there is also an exception.In contrast,segregation of Sc and Y will soften grain boundaries.The results reveal that strengthening of grain boundaries by solute segregation is a valuable avenue to enhance high temperature mechanical properties of ZrC,providing guidelines for further design of ZrC based materials.

关键词： ZrC Grain boundary Segregation Strength First-principles calculation Machine learning

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Y_5Si_3C and Y_3Si_2C_2: Theoretically predicted MAX phase like damage tolerant ceramics and promising interphase materials for SiC_f/SiC composites

引用

Journal of Materials Science & Technology 2019年第3期35卷 313-322页

作者： Yanchun ZHOU Huimin Xiang Fu-Zhi Dai Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials & Processing Technology

Researching for interphase materials that can protect SiC fibers from oxygen and water vapor attacks has become one of the most important issues for the applications of SiC_f/SiC composites in high-temperature combustion environment. However, such kinds of interphase materials are not available yet. Herein,we report theoretically predicted properties of two promising interphase materials Y_5Si_3 C and Y_3Si_2C_2.Although crystallizing in different structures, they share the common features of layered structure,anisotropic chemical bonding, anisotropic electrical and mechanical properties, and low shear deformation resistance. The bulk moduli for Y_5Si_3C and Y_3Si_2C_2 are 78 and 93 GPa, respectively; while their shear moduli are 52 and 50GPa, respectively. The maximum to minimum Young's modulus ratios are1.44 for Y_5Si_3C and 3.27 for Y_3Si_2C_2. Based on the low shear deformation resistance and low Pugh's ratios(G/B = 0.666 forY_5Si_3C and 0.537 for Y_3Si_2C_2; G: shear modulus; B: bulk modulus), they are predicted as damage tolerant and soft ceramics with predicted Vickers hardness of 9.6 and 6.9 GPa, respectively.The cleavage plane and possible slip systems are(000 l) and(0001)[1120] and(1010)[0001] forY_5Si_3C,and those for Y_3Si_2C_2 are {h00} and(010)[101]. Since the oxidation products are water-vapor resistant Y2 Si2 O7, Y2 SiO5 and/or Y_2 O_3 upon oxidation, and the volume expansions are ca 140% and ca 26% for Y_5Si_3C and Y_3Si_2C_2, they are expected to seal the interfacial cracks in SiC_f/SiC composites. The unique combination of easy cleavage, low shear deformation resistance, volume expansions upon oxidation, and the resistance of the oxidation products to water vapor attack warrant them promising as interphase materials of SiC_f/SiC composites for water-vapor laden environment applications.

关键词： Y5Si3C Y3Si2C2 Interphase material Damage tolerant ceramics Electronic structure

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Structural defects in MAX phases and their derivative MXenes:A look forward

引用

Journal of Materials Science & Technology 2020年第3期38卷 205-220页

作者： Hui Zhang Tao Hu Xiaohui Wang Yanchun ZHOU Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Energy Geoscience Division Lawrence Berkeley National LaboratoryCA 94720USA Institute for Materials Science and Devices Suzhou University of Science and TechnologySuzhou 215009China Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China

MAX phases and corresponding 2 D derivative MXenes have attracted considerable interests due to not only their fascinating mechanical,physical and chemical properties but also their unique atomically laminated structures.As the most important way to tailor the materials properties,the structural defects in MAX phases and MXenes have been extensively investigated but lack of systematic survey although six reviews and two books in this field have been published.To make the defect-engineering based materials design and exploration more efficient and targeted,this paper provides a review of the recent progress on the nature of different-dimensional structural defects and their influence on the properties,in the hope of facilitating the conversion of established experiment and simulation results into practical guideline for optimizing defects in a broad range of demand-oriented materials development in the future.Also,unsolved issues on the structural defects of these scientifically and technologically important materials are also highlighted for the future study.

关键词： Crystal defects Carbides TEM MAX phases MXenes

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theoretical investigation on the stability, mechanical and thermal properties of the newly discovered MAB phase Cr4AlB4

引用

Journal of Materials Science & Technology 2020年第4期39卷 161-166页

作者： Fu-Zhi Dai Haiming Zhang Huimin Xiang Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing100076China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing100044China

The nanolaminated MAB phases have attracted great research interests in recent years due to their similarities to MAX phases,which display both metallic and ceramic-like properties.In the present work,a newly discovered MAB phase Cr4AlB4 was investigated by first principles calculations.Energy evaluations indicate that Cr4AlB4 can be synthetized in Al lean condition,which can further transform to Cr2AlB2 in Al rich condition.The full set of elastic properties and their dependences on temperature,ideal strengths under different tensile and shear deformations,and thermal expansions of Cr4AlB4 were predicted.The results reveal that the properties of Cr4AlB4 are dominated by the layered crystal structure and weak bonding nature between Al and Cr2B2 layers,including low elastic stiffness and large thermal expansion along[010]direction(the stacking direction of Al and Cr2B2 layers),low shear resistances in(010)plane,and preferentially cleavage along and/or shear in(010)plane.Therefore,it suggests that Cr4AlB4 displays similar mechanical properties to MAX phases,including readily machinable,thermal shock resistant,and damage tolerant.In combination with the fact that Cr,Al and B all can form dense oxides to protect the material from further oxidation,Cr4AlB4 is regarded as a promising high temperature ceramic.

关键词： MAB phase Cr4AlB4 First-principles Mechanical properties Thermal properties

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Grain boundary segregation induced strong UHTCs at elevated temperatures:A universal mechanism from conventional UHTCs to high entropy UHTCs

引用

Journal of Materials Science & Technology 2022年第28期123卷 26-33页

作者： Fu-Zhi Dai Bo Wen Yinjie Sun Yixiao Ren Huimin Xiang Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China DP Technology Beijing 100044China

Ultra-high temperature ceramics(UHTCs)exhibit a unique combination of excellent properties,including ultra-high melting point,excellent chemical stability,and good oxidation resistance,which make them promising candidates for aerospace and nuclear applications.However,the degradation of hightemperature strength is one of the main limitations for their ultra-high temperature applications.Thus,searching for mechanisms that can help to develop high-performance UHTCs with good high-temperature mechanical properties is urgently needed.To achieve this goal,grain boundary segregation of a series of carbides,including conventional,medium entropy,and high entropy transition metal carbides,i.e.,Zr_(0.95)W_(0.05)C,TiZrHfC_(3),ZrHfNbTaC_(4),TiZrHfNbTaC_(5),were studied by atomistic simulations with a fitted Deep Potential(DP),and the effects of segregation on grain boundary strength were emphasized.For all the studied carbides,grain boundary segregations are realized,which are dominated by the atomic size effect.In addition,tensile simulations indicate that grain boundaries(GBs)will usually be strengthened due to segregation.Our simulation results reveal that grain boundary segregation may be a universal mechanism in enhancing the high-temperature strength of both conventional UHTCs and medium/high entropy UHTCs,since GBs play a key role in controlling the fracture of UHTCs at elevated temperatures.

关键词： UHTCs High entropy ceramics Grain boundary segregation High-temperature strength Machine learning potential

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Achieving ultra-broadband electromagnetic wave absorption in high-entropy transition metal carbides (HE TMCs)

引用

Journal of Advanced Ceramics 2022年第4期11卷 545-555页

作者： Weiming ZHANG Huimin XIANG Fu-Zhi DAI Biao ZHAO Shijiang WU Yanchun ZHOU Science and Technology on Advanced Functional Composite Laboratory Aerospace Research Institute of Materials&Processing TechnologyBeijing 100076China Henan Key Laboratory of Aeronautical Materials and Application Technology School of Material Science and EngineeringZhengzhou University of AeronauticsZhengzhou 450046China Zibo Firststar New Material Incorporated Co. Ltd.Zibo 255000China

Electronic devices pervade everyday life,which has triggered severe electromagnetic(EM)wave pollution.To face this challenge,developing EM wave absorbers with ultra-broadband absorption capacity is critically required.Currently,nano-composite construction has been widely utilized to realize impedance match and broadband absorption.However,complex experimental procedures,limited thermal stability,and interior oxidation resistance are still unneglectable issues.Therefore,it is appealing to realize ultra-broadband EM wave absorption in single-phase materials with good stability.Aiming at this target,two high-entropy transition metal carbides(HE TMCs)including(Zr,Hf,Nb,Ta)C(HE TMC-2)and(Cr,Zr,Hf,Nb,Ta)C(HE TMC-3)are designed and synthesized,of which the microwave absorption performance is investigated in comparison with previously reported(Ti,Zr,Hf,Nb,Ta)C(HE TMC-1).Due to the synergistic effects of dielectric and magnetic losses,HE TMC-2 and HE TMC-3 exhibit better impedance match and wider effective absorption bandwidth(EAB).In specific,the exclusion of Ti element in HE TMC-2 endows it optimal minimum reflection loss(RL_(min))and EAB of−41.7 dB(2.11 mm,10.52 GHz)and 3.5 GHz(at 3.0 mm),respectively.Remarkably,the incorporation of Cr element in HE TMC-3 significantly improves the impedance match,thus realizing EAB of 10.5,9.2,and 13.9 GHz at 2,3,and 4 mm,respectively.The significance of this study lays on realizing ultra-broadband capacity in HE TMC-3(Cr,Zr,Hf,Nb,Ta),demonstrating the effectiveness of high-entropy component design in tailoring the impedance match.

关键词： transition metal carbide(TMC) high-entropy ceramics electromagnetic(EM)wave absorption dielectric and magnetic loss coupling ultra-broadband absorption

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Theoretical Investigation on Mechanical and Thermal Properties of a Promising Thermal Barrier Material:Yb_3Al_5O_(12)

引用

Journal of Materials Science & Technology 2014年第7期30卷 631-638页

作者： Yanchun ZHOU Huimin Xiang Zhihai Feng Science and Technology of Advanced Functional Composite Laboratory Aerospace Research Institute of Materials and Processing Technology

An investigation on the mechanical and thermal properties of Yb3Al5O12 is conducted by a combination of first- principles calculations and chemical bond theory calculation. Density functional theory （DFT） computations were performed for the structural, mechanical, and thermal properties, and the results are confirmed by chemical bond theory. Based on the calculated equilibrium crystal structure, heterogeneous bonding nature is revealed. The full set of elastic constants and mechanical properties of Yb3Al5O12 are presented for the first time. The thermal expansion coefficient of Yb3Al5O12 is calculated to be 7.5 × 10^-6 K-1 by chemical bond theory. In addition, the minimum thermal conductivity of Yb3Al5O12 is estimated to be 1.22 W m-t K-1, and the origin of such low thermal conductivity is discussed. Our theoretical results highlight the potential of Yb3Al5O12 as a prospective thermal barrier coating material.

关键词： Thermal barrier coating Ytterbium aluminum garnet First principles calculations Chemical bond theory

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Improved damage tolerance and oxidation resistance of (Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC by introducing chopped carbon fibers

引用

Journal of Advanced Ceramics 2024年第1期13卷 101-112页

作者： Feilong Huang Hailong Wang Cheng Fang Mingliang Li Gang Shao Jinpeng Zhu Yanchun ZHOU School of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China

High-entropy diborides(HEBs)are considered as promising high-temperature structure materials owing to their high melting point and excellent thermal stability.However,the intrinsic brittleness is the main obstacle that seriously limits their practical applications.To overcome with this obstacle,carbon fibers(Cf)with outstanding mechanical properties are used in the present work as a first attempt to improve the damage tolerance of HEBs.The as-prepared C_(f)/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC composite(C_(f)/HEB–SiC)shows high relative density(97.9%)and good mechanical properties with flexural strength of 411±3 MPa and fracture toughness of 6.15±0.11 MPa·m^(1/2).More importantly,the damage tolerance parameter(Dt)has increased from 0.10 m^(1/2) for HEB–SiC to 0.29 m^(1/2) for C_(f)/HEB–SiC.Through microstructural analysis and Vickers indentation of the composite,the toughening mechanisms are disclosed.The carbon fibers coated with carbon coatings demonstrate unique capacity for prolonging the crack propagation path,which promotes the reliability of the composite effectively.Moreover,the C_(f)/(Ti_(0.2)Zr_(0.2)Hf_(0.2)Nb_(0.2)Ta_(0.2))B_(2)–SiC composite also exhibits good static oxidation resistance in the temperature range of 1100–1500℃in air due to the formation of the protective oxide layer constituting of multicomponent oxides(Zr)HfTiO4 and(Zr)Hf_(6)Ta_(2)O_(17) embedded in a continuous SiO_(2) glass.These results are promising,and this primary work can be used as a reference to the synthesis of C_(f)/HEBs for thermal protection materials under hightemperature serving conditions.

关键词： high-entropy ceramics carbon fibers(Cf) toughening mechanisms oxidation resistance

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：