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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 ***,how to synthesize TaxHf1-xC powders and efficiently fabricate C_(f)/Ta_(x)Hf_(1−x)C–SiC composites still faces some ***,mechanical properties and thermophysical properties of Ta_(x)Hf_(1−x)C vary with the composition,but not ***-depth analysis of mechanical behaviors of the C_(f)/Ta_(x)Hf_(1−x)C–SiC composites is extremely important for their development and *** 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 ***,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 *** is demonstrated that the composites present remarkable non-brittle fractures,including a large number of fiber pull out and interphase ***,the fracture failure involves a complex process of microcrack generation and propagation,matrix cracking,and layer ***,the interfacial bonding between the fibers and the matrix is enhanced as the Ta∶Hf ratio decreases from 4∶1 to 1∶*** 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

C_(f)/(CrZrHfNbTa)C-SiC high-entropy ceramic matrix composites for potential multi-functional applications

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Journal of Materials Science & Technology 2024年第15期182卷 132-140页

作者： Yang Hu Dewei Ni Bowen Chen Feiyan Cai Xuegang Zou Fan Zhang 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

In this work,C_(f)/(CrZrHfNbTa)C-SiC high-entropy ceramic matrix composites with good load-bearing,elec-tromagnetic shielding and ablation resistance were designed and reported for the first *** compos-ites were fabricated by an efficient combined processing of slurry infiltration lamination(SIL)and precur-sor infiltration and pyrolysis(PIP).Density and porosity of the as-fabricated composites are 2.72 g/cm^(3) and 12.44 vol.%,respectively,and the flexural strength is 185±13 *** to the carbon fiber rein-forcement with high conductivity and strong reflection,and high-entropy(CrZrHfNbTa)C ceramic matrix with strong absorbability,the total Electromagnetic interference shielding efficiency(SET)of the compos-ites with a thickness of 3 mm are as high as 88.2 dB and 90 dB respectively in X-band and *** means that higher than 99.999999%electromagnetic shielding is achieved at 8-18 GHz,showing excel-lent electromagnetic shielding *** C_(f)/(CrZrHfNbTa)C-SiC composites also present excellent ablation resistance,with the linear and mass ablation rates of 0.9μm/s and 1.82 mg/s after ablation at the heat flux of 5 MW/m^(2) for 300 s(∼2450℃).This work opens a new insight for the synergistic de-sign of structural and functional integrated materials with load-bearing,electromagnetic shielding and ablation resistance,etc.

关键词： High-entropy ceramic matrix composites Mechanical property Electromagnetic shielding Ablation resistance

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 *** 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 *** 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 *** that,ZrB_(2) and SiC are introduced into the preforms by slurry impregnation and reactive melt infiltration,*** evolution and optimization of the composites during fabrication are investigated in *** 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 ***,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 *** 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

The Sinian——Cambrian Boundary of China (Summarized in English)

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中国地质科学院地质研究所文集

中国地质科学院地质研究所文集 1984年 190-205页

作者： Xing yusheng ding Qixiu Luo Huilin He Tinggui and Wang Yangeng

The Sinian and Cambrian systems within the Yangtze stratigraphic pro- vince represent continuous deposits,and the strata above and below the bo- undary between them are rich in *** all the relevant boundary sections,the Meishucun section in Jinning County,Yunnan Province serves as the stratotype section for the Sinian-Cambrian boundary and also the Chinese Candidate for global stratotype section and point for Precambrian- Cambrian *** present paper,with the various charts and tables, elaborates on several typical Sinian-Cambrian boundary sections and the dis- tribution of fossils in them.

关键词： Cambrian The Sinian sections stratigraphic fossil strata charts assemblage Yangtze 地质研究所

The Sinian——Cambrian Boundary of China （Summarized in English）

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The Sinian——Cambrian Boundary of China （Summarized in Eng...

基于锁相环相位补偿的光伏逆变器低电压穿越快速无功控制

作者： Xing yusheng ding Qixiu Luo Huilin He Tinggui and Wang Yangeng

＜正＞The Sinian and Cambrian systems within the Yangtze stratigraphic pro- vince represent continuous deposits,and the strata above and below the bo- undary between them are rich in *** all the relevant boundary sections,the Meishucun section in Jinning County,Yunnan Province serves as the stratotype section for the Sinian-Cambrian boundary and also the Chinese Candidate for global stratotype section and point for Precambrian- Cambrian *** present paper,with the various charts and tables, elaborates on several typical Sinian-Cambrian boundary sections and the dis- tribution of fossils in them.

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电力系统保护与控制 2024年第24期52卷 85-96页

作者：勾奕昀郑竞宏刘壮丁禹升清华大学电机工程与应用电子技术系北京100084

在低电压穿越故障恢复阶段,针对弱网下光伏并网系统无功回撤速度慢易导致暂态过电压的问题,提出了基于锁相环相位补偿的光伏逆变器低电压穿越快速无功改进控制策略。首先从相位跳变、锁相环动态、电网强度几个方面分析了常规光伏逆变器... 详细信息

在低电压穿越故障恢复阶段,针对弱网下光伏并网系统无功回撤速度慢易导致暂态过电压的问题,提出了基于锁相环相位补偿的光伏逆变器低电压穿越快速无功改进控制策略。首先从相位跳变、锁相环动态、电网强度几个方面分析了常规光伏逆变器无功回撤速度不足的原因。然后根据光伏逆变器出口内电势与锁相环相角关系的机理分析,提出了基于相位补偿的锁相环改进控制策略。从无功控制需求出发推导了补偿相位的确定方法,并建立光伏并网系统单机电磁暂态仿真模型,验证了所提出的改进控制策略在三相对称、不对称、线路切除等故障场景下的有效性。最后基于RT-Lab搭建光伏发电并网系统半实物仿真平台,进一步验证了改进控制策略的有效性。该控制策略使光伏逆变器获得了更快的无功回撤能力,可有效抑制低电压故障恢复阶段的暂态过电压问题。

关键词：光伏逆变器锁相环相位补偿前馈控制低电压穿越暂态无功特性

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韧性城市理论视域下地下空间研究现状综述

地下空间与工程学报 2023年第S1期19卷 78-86页

作者：邵峰丁玉生史平阳董策青岛理工大学建筑与城乡规划学院山东青岛266033

随着中国城市的飞速发展,城市人口快速增长,各种城市突发灾害事件频发,对城市的基础设施、资源利用和可持续发展带来巨大的威胁和挑战。城市地下空间作为城市空间的重要部分,是城市系统中宝贵的空间资源,也为城市的韧性发展提供支持和... 详细信息

随着中国城市的飞速发展,城市人口快速增长,各种城市突发灾害事件频发,对城市的基础设施、资源利用和可持续发展带来巨大的威胁和挑战。城市地下空间作为城市空间的重要部分,是城市系统中宝贵的空间资源,也为城市的韧性发展提供支持和保障。城市地下空间和城市韧性的研究在国外的研究较早,且国外学者较早地将城市韧性引入到地下空间研究的领域中,但国内相关的研究仍处于起步阶段且存在一定研究空白和不足。本文通过文献分析研究对文献资料进行整合归纳,对国内外城市地下空间研究的历程和现状进行综述,并对“韧性城市”理论的概念特点及评价方法和指标体系进行论述。最后,对国内基于韧性城市理论对地下空间的研究进行综述分析,提出目前研究中存在的问题及其解决策略建议和研究展望。

关键词：地下空间韧性城市研究综述韧性提升

C_f/SiC复合材料SiC/Yb_2SiO_5抗氧化复合涂层研究

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稀有金属材料与工程 2009年第9期38卷 1580-1583页

作者：温海明董绍明丁玉生张翔宇何平高乐中国科学院上海硅酸盐研究所上海200050 中国科学院研究生院北京100049

硅酸镱(Yb2SiO5)是Cf/SiC复合材料非常理想的抗氧化涂层材料。用脉冲CVD法在Cf/SiC复合材料上先制备SiC粘附层。用溶胶凝胶法制备粒径为200～300nm的单相Yb2SiO5粉体,然后用PCS-SiC-Yb2SiO5浆料浸涂法制备SiC-Yb2SiO5过渡层,因PCS粘结... 详细信息

硅酸镱(Yb2SiO5)是Cf/SiC复合材料非常理想的抗氧化涂层材料。用脉冲CVD法在Cf/SiC复合材料上先制备SiC粘附层。用溶胶凝胶法制备粒径为200～300nm的单相Yb2SiO5粉体,然后用PCS-SiC-Yb2SiO5浆料浸涂法制备SiC-Yb2SiO5过渡层,因PCS粘结强度大,且热解后能在原位生成SiC,故能大大增加涂层的结合力。配备低粘度、高固含量的Yb2SiO5浆料,并用浆料浸涂烧结法制备致密、细晶粒的Yb2SiO5涂层。1500℃静态空气中氧化实验表明:SiC/Yb2SiO5复合涂层具备优异的抗氧化性能。

关键词： Cf/SiC复合材料抗氧化涂层硅酸镱浆料浸涂法

粉末冶金泡沫Al-Si-Cu发泡过程的微观结构演变

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稀有金属材料与工程 2021年第6期50卷 2134-2143页

作者：丁宇升高坤元王华东宋鹏陈明梁岳莹彭海春航天特种材料及工艺技术研究所北京100074 北京工业大学材料与制造学部工业大数据应用技术国家工程实验室北京100124

采用扫描电镜和能谱分析了泡沫Al-Si-Cu合金发泡过程的微观结构演变。将Al粉、Cu粉、Si粉按照89:6:5(质量比)混粉,并添加发泡剂2%TiH_(2) (质量分数)和增稠剂1.5%MnO_(2) (质量分数),经过500℃热压后,泡沫铝可在640℃/12-20min发泡。微... 详细信息

采用扫描电镜和能谱分析了泡沫Al-Si-Cu合金发泡过程的微观结构演变。将Al粉、Cu粉、Si粉按照89:6:5(质量比)混粉,并添加发泡剂2%TiH_(2) (质量分数)和增稠剂1.5%MnO_(2) (质量分数),经过500℃热压后,泡沫铝可在640℃/12-20min发泡。微观结构分析显示,发泡前泡沫铝呈现球形的Si、Al_(2)Cu、块状Ti H_(2)和扁片状Mn O_(2)相,发泡后泡沫铝孔壁内存在3类析出相:晶内细小的Si、Al_(2)Cu颗粒;晶界粗大离异共晶Si、Al_(2)Cu相;随机分布的块状Al-Mn相、MnO_(2)相和球形富Ti相。其中富Ti相是由Ti H_(2)分解H_(2)后,与铝液反应产生的,具有2种不同的类型。2类析出相心部都为Ti颗粒,第1类内壳为τ2(Al14Ti33Si53)相薄层,外壳呈现枝晶形貌的τ1(Al_(2)0Ti32Si48)和τ2相;第2类外部为块状交替分布的τ1和(Al, Si)3Ti相。第1类富Ti相的Si成分明显高于第2类,可能是2类富Ti相分别形成于铝液中的富Si和贫Si区造成的。对泡沫铝发泡过程微观结构的分析有助于设计高性能可强化的泡沫铝。

关键词：泡沫铝发泡微观结构析出相