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Fabrication and mechanical behavior of 2D-C_(f)/Ta_(x)Hf_(1−x)C–SiC composites by a low-temperature and highly-efficient route

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Journal of Advanced Ceramics 2023年第10期12卷 1961-1972页

作者： Xuegang Zou dewei ni Bowen Chen Feiyan Cai Le Gao Ping He Yusheng Ding Xiangyu Zhang Shaoming Dong State Key Laboratory of High-Performance Ceramics&Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Structural Ceramics and Composites Engineering Research Center Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhouChina

C_(f)/Ta_(x)Hf_(1−x)C–SiC composites are ideal thermal structural materials for service under extreme conditions of hypersonic vehicles.However,how to synthesize TaxHf1-xC powders and efficiently fabricate C_(f)/Ta_(x)Hf_(1−x)C–SiC composites still faces some challenges.Furthermore,mechanical properties and thermophysical properties of Ta_(x)Hf_(1−x)C vary with the composition,but not monotonically.In-depth analysis of mechanical behaviors of the C_(f)/Ta_(x)Hf_(1−x)C–SiC composites is extremely important for their development and applications.In this study,the Ta_(x)Hf_(1−x)C powders(x=0.2,0.5,0.8)were successfully synthesized via solid solution of TaC and HfC at a relatively low temperature of 1800℃,with a small amount of Si as an additive.Subsequently,the efficient fabrication of 2D-C_(f)/Ta_(x)Hf_(1−x)C–SiC composites was achieved by slurry impregnation and lamination(SIL)combined with precursor infiltration and pyrolysis(PIP).In addition,the mechanical behavior of the composites was investigated systematically.It is demonstrated that the composites present remarkable non-brittle fractures,including a large number of fiber pull out and interphase debonding.Also,the fracture failure involves a complex process of microcrack generation and propagation,matrix cracking,and layer fracture.Moreover,the interfacial bonding between the fibers and the matrix is enhanced as the Ta∶Hf ratio decreases from 4∶1 to 1∶4.As a result,C_(f)/Ta_(0.2)Hf_(0.8)C–SiC composites exhibit exceptional flexural strength of 437±19 MPa,improved by 46%compared with C_(f)/Ta_(0.8)Hf_(0.2)C–SiC(299±19 MPa).This study provides a new perception of design and fabrication of ultra-high-temperature ceramic(UHTC)matrix composites with high performance.

关键词： mechanical properties microstructure fabrication 2D-C_(f)/Ta_(x)Hf_(1−x)C-SiC composites

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高熵碳化物超高温陶瓷的研究进展

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无机材料学报 2024年第6期39卷 591-608页

作者：蔡飞燕倪德伟董绍明中国科学院上海硅酸盐研究所高性能陶瓷和超微结构国家重点实验室上海200050 中国科学院上海硅酸盐研究所结构陶瓷及复合材料工程研究中心上海200050 中国科学院大学北京100049 国科大杭州高等研究院杭州310024

高速飞行技术的发展对高性能热结构材料提出了迫切需求。高熵碳化物(HECs)陶瓷作为近年来发展迅速的一类新型材料,兼具高熵陶瓷与超高温陶瓷的优良特性,在极端服役环境中具有广阔的应用前景,因此得到国内外学者的广泛关注。相比仅含有... 详细信息

高速飞行技术的发展对高性能热结构材料提出了迫切需求。高熵碳化物(HECs)陶瓷作为近年来发展迅速的一类新型材料,兼具高熵陶瓷与超高温陶瓷的优良特性,在极端服役环境中具有广阔的应用前景,因此得到国内外学者的广泛关注。相比仅含有一种或两种过渡金属元素的传统超高温碳化物陶瓷,HECs综合性能有所提升,且具有更强的组成和性能可设计性,因此具备较大的发展潜力。经过对HECs的不断探索,研究人员获得了许多有趣的结果,开发了多种HECs的制备方法,对HECs的显微结构和性能的认识也更加深入。本文综述了HECs的基本理论以及从实验过程中获得的规律;对HECs粉体、HECs块体、HECs涂层及薄膜,以及纤维增强HECs基复合材料的制备方法进行了梳理和归纳;并对HECs的力学、热学等性能,尤其是与高温应用相关的抗氧化、抗烧蚀性能的研究进展进行了综述和讨论。最后,针对HECs研究中有待进一步完善的科学问题,对HECs的未来发展提出了展望。

关键词：高熵碳化物超高温陶瓷力学性能抗氧化性能抗烧蚀性能综述

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Advances in ultra-high temperature ceramics,composites,and coatings

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Journal of Advanced Ceramics 2022年第1期11卷 1-56页

作者： dewei ni Yuan CHENG Jiaping ZHANG Ji-Xuan LIU Ji ZOU Bowen CHEN Haoyang WU Hejun LI Shaoming DONG Jiecai HAN Xinghong ZHANG Qiangang FU Guo-Jun ZHANG State Key Laboratory of High Performance Ceramics&Superfine Microstructure Structural Ceramics and Composites Engineering Research CenterShanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Center for Composite Materials and StructuresHarbin Institute of TechnologyHarbin 150001China Shaanxi Key Laboratory of Fiber Reinforced Light Composite Materials Northwestern Polytechnical UniversityXi’an 710072China State Key Laboratory for Modification of Chemical Fibers and Polymer Materials Institute of Functional MaterialsDonghua UniversityShanghai 201620China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China University of Chinese Academy of Sciences Beijing 100049China

Ultra-high temperature ceramics(UHTCs)are generally referred to the carbides,nitrides,and borides of the transition metals,with the Group IVB compounds(Zr&Hf)and TaC as the main focus.The UHTCs are endowed with ultra-high melting points,excellent mechanical properties,and ablation resistance at elevated temperatures.These unique combinations of properties make them promising materials for extremely environmental structural applications in rocket and hypersonic vehicles,particularly nozzles,leading edges,and engine components,etc.In addition to bulk UHTCs,UHTC coatings and fiber reinforced UHTC composites are extensively developed and applied to avoid the intrinsic brittleness and poor thermal shock resistance of bulk ceramics.Recently,high-entropy UHTCs are developed rapidly and attract a lot of attention as an emerging direction for ultra-high temperature materials.This review presents the state of the art of processing approaches,microstructure design and properties of UHTCs from bulk materials to composites and coatings,as well as the future directions.

关键词： ultra-high temperature ceramics(UHTCs) coatings composites high-entropy ultra-high temperature ceramics

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结构陶瓷——承载人类文明的基石

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无机材料学报 2024年第6期39卷 569-570页

作者：董绍明王京阳倪德伟中国科学院上海硅酸盐研究所上海200050 中国科学院金属研究所沈阳110016

陶瓷,作为人类文明史上具有里程碑意义的人工合成材料,不仅承载着中华民族的骄傲,更是中华民族智慧和创新精神的集中体现。经过数千年的沉淀与演化,陶瓷已发展成为一个博大精深、丰富多彩的材料体系。传统陶瓷与先进陶瓷交相辉映,共同... 详细信息

陶瓷,作为人类文明史上具有里程碑意义的人工合成材料,不仅承载着中华民族的骄傲,更是中华民族智慧和创新精神的集中体现。经过数千年的沉淀与演化,陶瓷已发展成为一个博大精深、丰富多彩的材料体系。传统陶瓷与先进陶瓷交相辉映,共同构筑起人类文明的物质基石。其中,先进结构陶瓷更是以其耐高温、抗腐蚀以及优异的力学性能等特性.

关键词：结构陶瓷先进陶瓷人工合成材料传统陶瓷力学性能抗腐蚀创新精神耐高温

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Microstructure and mechanical properties of 3D Cf/SiBCN composites fabricated by polymer infiltration and pyrolysis

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Journal of Advanced Ceramics 2021年第1期10卷 28-38页

作者： Bowen CHEN Qi DING dewei ni Hongda WANG Yusheng DING Xiangyu ZHANG Shaoming DONG State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Structural Ceramics and Composites Engineering Research Center Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of SciencesBeijing 100049China

In this work,three-dimensional(3D)Cf/SiBCN composites were fabricated by polymer infiltration and pyrolysis(PIP)with poly(methylvinyl)borosilazane as SiBCN precursor.The 3D microstructure evolution process of the composites was investigated by an advanced X-ray computed tomography(XCT).The effect of dicumyl peroxide(DCP)initiator addition on the crosslinking process,microstructure evolution,and mechanical properties of the composites were uncovered.With the addition of a DCP initiator,the liquid precursor can cross-linking to solid-state at 120℃.Moreover,DCP addition decreases the release of small molecule gas during pyrolysis,leading to an improved ceramic yield 4.67 times higher than that without DCP addition.After 7 PIP cycles,density and open porosity of the final Cf/SiBCN composite with DCP addition are 1.73 g.cm^(-3)and〜10%,respectively,which are 143.0%higher and 30.3%lower compared with the composites without DCP addition.As a result,the flexural strength and elastic modulus of Cf/SiBCN composites with DCP addition(371 MPa and 31 GPa)are 1.74 and 1.60 times higher than that without DCP addition(213 MPa and 19.4 GPa),respectively.

关键词： Cf/SiBCN ceramic matrix composites dicumyl peroxide(DCP) X-ray computed tomography(XCT)

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Reaction mechanism and microstructure development of ZrSi_(2) melt-infiltrated C_(f)/SiC-ZrC-ZrB_(2) composites:The influence of preform pore structures

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Journal of Materiomics 2018年第3期4卷 266-275页

作者： Xiaowu Chen dewei ni Yanmei Kan Youlin Jiang Haijun Zhou Zhen Wang Shaoming Dong State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai200050China Structural Ceramics and Composites Engineering Research Center Shanghai Institute of CeramicsChinese Academy of SciencesShanghai200050China University of Chinese Academy of Sciences Beijing100049China

Reactive melt infiltration(RMI)is an effective method for fabrication of highly dense carbon fiber reinforced ultra-high temperature ceramic matrix composites(Cf/UHTCs).In this work,C_(f)/SiC-ZrC-ZrB_(2)composites were fabricated by infiltrating ZrSi_(2)melt into porous C_(f)/B_(4)C-C preforms,where the physical and chemical reactions involved during the RMI process were identified and analyzed.Inhomogeneous infiltration between the inter-and intra-bundle pores was revealed,and was found to be strongly related to the pore structures of the C_(f)/B_(4)C-C preform.It is indicated that the inhomogeneous infiltration can be mitigated remarkably with increasing porosity and pore size of the preform.The effect of pore size on the RMI process was also investigated by a quantitative model,which agrees very well with the experiment results.It further indicates that the inhomogeneous infiltration can also be relieved at elevated RMI temperature.However,excessive infiltration at elevated temperature or more porous preform may cause serious erosion on interphase and fibers,leading to mechanical properties deterioration of the final composites.

关键词： Reactive melt infiltration(RMI) Inhomogeneous infiltration Pore structures Mechanical properties

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3D C_f/SiBCN composites prepared by an improved polymer infiltration and pyrolysis

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Journal of Advanced Ceramics 2018年第3期7卷 266-275页

作者： Qi DING dewei ni Zhen WANG Hao ZHONG Hongda WANG Haijun ZHOU Yanmei KAN Shaoming DONG State Key Laboratory of High Performance Ceramics and Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of Sciences Structural Ceramics and Composites Engineering Research Center Shanghai Institute of CeramicsChinese Academy of Sciences University of Chinese Academy of Sciences ShanghaiTech University

Using liquid poly(methylvinyl)borosilazanes(PMVBSZ)as precursor,carbon fiber reinforced SiBCN matrix composites(C_f/SiBCN)were fabricated by a modified polymer infiltration and pyrolysis(PIP)process.With dicumyl peroxide added as cross-linking agent,the PMVBSZ could be solidified at a low temperature of 120℃,leading to a high ceramic yield of～70%.The cross-linking mechanism and ceramization processes of the precursor were investigated in detail.Moreover,a modified infiltration technology was developed,which improved the efficiency and protected the precursor against moist air during PIP.Consequently,the obtained C_f/SiBCN composites had an oxygen content of around 1.22 wt%.Benefiting from the high ceramic yield and high efficiency of the modified PIP,C_f/SiBCN composites with an open porosity of～10%and uniform microstructure were obtained after only 7 cycles of PIP.The flexural strength and fracture toughness of the derived C_f/SiBCN composites were 371 MPa and 12.9 MPa·m^(1/2),respectively.This work provides a potential route for the fabrication of high performance C_f/SiBCN composites.

关键词： Cf/SiBCN ceramic matrix composites (CMCs) polymer infiltration and pyrolysis (PIP) dicumyl peroxide (DCP)

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Fabrication and microstructure evolution of C_(sf)/ZrB_(2)-SiC composites via direct ink writing and reactive melt infiltration

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Journal of Advanced Ceramics 2021年第6期10卷 1371-1380页

作者： Jun LU dewei ni Chunjing LIAO Haijun ZHOU Youlin JIANG Bowen CHEN Xuegang ZOU Feiyan CAI Yusheng DING Shaoming DONG State Key Laboratory of High Performance Ceramics&Superfine Microstructure Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China Structural Ceramics and Composites Engineering Research Center Shanghai Institute of CeramicsChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China Hangzhou Institute for Advanced Study University of Chinese Academy of SciencesHangzhou 310000China

Fiber damage and uniform interphase preparation are the main challenges in conventional short fiber reinforced ceramic matrix composites.In this work,we develop a novel processing route in fabrication of short carbon fiber reinforced ZrB_(2)-SiC composites(C_(sf)/ZrB_(2)-SiC)overcoming the above two issues.At first,C_(sf) preforms with oriented designation and uniform PyC/SiC interphase are fabricated via direct ink writing(DIW)of short carbon fiber paste followed by chemical vapor infiltration.After that,ZrB_(2) and SiC are introduced into the preforms by slurry impregnation and reactive melt infiltration,respectively.Microstructure evolution and optimization of the composites during fabrication are investigated in detail.The as-fabricated C_(sf)/ZrB_(2)-SiC composites have a bulk density of 2.47 g/cm^(3),with uniform weak interphase and without serious fiber damage.Consequently,non-brittle fracture occurs in the C_(sf)/ZrB_(2)-SiC composites with widespread toughening mechanisms such as crack deflection and bridging,interphase debonding,and fiber pull-out.This work provides a new opportunity to the material design and selection of short fiber reinforced composites.

关键词： short fiber reinforced composites ultra-high temperature ceramics(UHTCs) interphase orientation

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An epi-allele of SMS causes Sanming dominant genic male sterility in rice

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Science China(Life Sciences) 2023年第12期66卷 2701-2710页

作者： Yachun Yang Cheng Zhang Hao Li Zeyuan Yang Zuntao Xu dewei Tai Dahu ni Pengcheng Wei Chengxin Yi Jianbo Yang Yong Ding Rice Research Institute Anhui Academy of Agricultural SciencesHefei 230036China Institute of Health and Medicine Hefei Comprehesive National Science CenterHefei 230031China Ministry of Education Key Laboratory for Membraneless Organelles and Cellular Dynamics School of Life SciencesDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefei 230027China

Male sterility is an important trait in rice for hybrid rice(Oryza sativa)breeding.However,the factors involved in dominant male sterility are largely unknown.Here,we identified a gene from Sanming dominant genic male sterile rice,named Sanming dominant male sterility(SMS),and reported that an epi-allele of this locus contributes to male sterility.Segregation analysis attributed dominant male sterility to a single locus,SMS,which we characterized using a male-sterile near isogenic line(niL)of rice cultivar 93-11.The SMS locus was heterozygous in the male-sterile 93-11 niL,containing an epi-allele identical to that in 93-11,and an epi-allele identical to that in rice cultivar nipponbare,which we refer to as SMS9 and SMSN,respectively.SMS9is silent and hyper-methylated,whereas SMSnis expressed and hypo-methylated in the 93-11 niL.Overexpressing SMSNled to male sterility.Mutations in SMS rescued the male sterility of the 93-11 niL.Interestingly,we observed the duplication of SMSN in nipponbare,but did not observe the duplication of SMS9in 93-11.Together,these findings suggest that the reduced methylation and enhanced expression of the SMSNepi-allele in the 93-11 niL is responsible for its role in conferring dominant male sterility.

关键词： male sterility rice epi-allele Sanming DNA methylation

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碱金属阳离子对硝酸根还原产氨反应的元素依赖性影响

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Science Bulletin 2024年第8期69卷 1100-1108页

作者：张意达马镇涛杨绍康王青雨刘利民柏彧饶德伟王功名李洪良郑旭升 National Synchrotron Radiation Laboratory University of Science and Technology of ChinaHefei 230029China Hefei National Research Center for Physical Sciences at the Microscale University of Science and Technology of ChinaHefei 230026China College of Chemistry and Materials Science Experimental Center of Engineering and Material ScienceUniversity of Science and Technology of ChinaHefei 230026China School of Materials Science and Engineering Jiangsu UniversityZhenjiang 212013China

Catalytic conversion of nitrate(NO_(3)^(-))pollutants into ammonia(NH_(3))offers a sustainable and promising route for both wastewater treatment and NH_(3)synthesis.Alkali cations are prevalent in nitrate solutions,but their roles beyond charge balance in catalytic NO_(3)^(-)conversion have been generally ignored.Herein,we report the promotion effect of K^(+)cations in KNO_(3)solution for NO_(3)^(-)reduction over a TiO_(2)-supported ni single-atom catalyst(ni_(1)/TiO_(2)).For photocatalytic NO_(3)^(-)reduction reaction,ni_(1)/TiO_(2)exhibited a 1.9-fold NH_(3)yield rate with nearly 100%selectivity in KNO_(3)solution relative to that in NaNO_(3)solution.Mechanistic studies reveal that the K^(+)cations from KNO_(3)gradually bonded with the surface of ni_(1)/TiO_(2),in situ forming a K-O-ni moiety during reaction,whereas the Na^(+)ions were unable to interact with the catalyst in NaNO_(3)solution.The charge accumulation on the ni sites induced by the incorporation of K atom promoted the adsorption and activation of NO_(3)^(-).Furthermore,the K-O-ni moiety facilitated the multiple proton-electron coupling of NO_(3)^(-)into NH_(3)by stabilizing the intermediates.

关键词： nitrate reduction Alkali cations Potassium ni single-atom catalyst Ammonia

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