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Preparation and interface modification of Si3N4f/SiO2 composites

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Journal of Materials Science & Technology 2019年第12期35卷 2767-2771页

作者： Yubo Houa Xuejin Yang Bin Li Duan Li shitao gao Zhongshuai Wu Science and Technology on Advanced Ceramic Fibers and Composites Laboratory National University of Defense TechnologyChangsha410073China School of Materials Sun Yat-sen UniversityGuangzhou510275China

In order to modify the interface, Si ON coating was introduced on the surface of silicon nitride fiber by perhydropolysilazane conversion method. Si-3N4f/SiO2 and Si-3N4f/Si ONc/SiO2 composites were prepared by sol-gel method to explore the influence of Si ON coating on the mechanical properties of *** results show that with the protection of Si ON coating, Si-3N4fiber enjoys a strength increase of up to 24.1% and Si-3N4f/Si ONc/SiO2 composites have a tensile strength of 170.5 MPa and a modulus of26.9 GPa, respectively. After 1000℃ annealing in air for 1 h, Si-3N4f/Si ONc/SiO2 composites retain 65.0%of their original strength and show a better toughness than Si-3N4f/SiO2 composites. The improvement of mechanical properties is attributing to the healing effect of Si ON coating as well as its intermediate coefficient of thermal expansion between Si-3N4fiber and SiO2 matrix.

关键词： Si3N4 fiber Perhydropolysilazane SiON coating Interface Mechanical properties

KD-S SiC_f/SiC composites with BN interface fabricated by polymer infiltration and pyrolysis process

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Journal of Advanced Ceramics 2018年第2期7卷 169-177页

作者： Honglei WANG shitao gao Shuming PENG Xingui ZHOU Haibin ZHANG Xiaosong ZHOU Bin Li Innovation Research Team for Advanced Ceramics Institute of Nuclear Physics and ChemistryChina Academy of Engineering Physics Science and Technology on Advanced Ceramic Fibers and Composites Laboratory National University of Defense Technology

Continuous silicon carbide fiber reinforced silicon carbide matrix(SiC_f/SiC) composites are attractive candidate materials for aerospace engine system and nuclear reactor system. In this paper, SiC_f/SiC composites were fabricated by polymer infiltration and pyrolysis(PIP) process using KD-S fiber as the reinforcement and the LPVCS as the precursor, while the BN interface layer was introduced by chemical vapor deposition(CVD) process using borazine as the single precursor. The effect of the BN interface layer on the structure and properties of the SiC_f/SiC composites was comprehensively investigated. The results showed that the BN interface layer significantly improved the mechanical properties of the KD-S SiC_f/SiC composites. The flexure strength and fracture toughness of the KD-S SiC_f/SiC composites were evidently improved from 314±44.8 to 818±39.6 MPa and 8.6± 0.5 to 23.0±2.2 MPa·m^(1/2), respectively. The observation of TEM analysis displayed a turbostratic structure of the CVD-BN interface layer that facilitated the improvement of the fracture toughness of the SiC_f/SiC composites. The thermal conductivity of KD-S SiC_f/SiC composites with BN interface layer was lower than that of KD-S SiC_f/SiC composites without BN interface layer, which could be attributed to the relative low thermal conductivity of BN interface layer with low crystallinity.

关键词： silicon carbide(SiC) composites interface layer polymer infiltration and pyrolysis(PIP) boron nitride(BN)

Oxalic acid functionalization of BaTiO_(3) nanobelts for promoting their piezo-degradation organic contaminants

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Journal of Materiomics 2021年第6期7卷 1275-1283页

作者： shitao gao Hongjie Xing Jingji Zhang Yapi Liu Huiwei Du Zejie Zhu Jiangying Wang Xu Li Suwei Zhang Yaxuan Yao Lingling Ren College of Materials and Chemistry China Jiliang UniversityHangzhou310018China Center for Advanced Measurement Science National Institute of MetrologyBeijing100013China

Surface functionalization of piezoelectric greatly determines its piezo-catalytic activity and selectivity in that functional group affect specific reactants’surface adsorption and activation ***,we propose chemical functionalization on the surface of nano-scaled BaTiO_(3) piezoelectric via a one-pot hydrothermal process using polyethylene glycol as surfactant,and evaluate its piezo-catalytic activity and selectivity by degrading model antibiotic and dye reactants under ultrasonic *** or/and oxalic unidentate ligands on the surface of BaTiO_(3) nanobelts can be formed by controlling precursor and hydrothermal ***,oxalic acid functionalized BaTiO_(3) nanobelts presented a high piezo-catalytic rate constant of 0.068 min^(-1) for Rhodamine B solution and maintained>87%degradation efficiency within 30 min under the condition of ultrasonic bath with 40 kHz and 100 W,which was mainly ascribed to piezo-sensitization *** work provides references for the preparation of chemical functionalized catalysts and also contributes to the development of novel catalysts for special applications.

关键词： BaTiO_(3)nanobelts Surface functionalization Piezo-catalysis Piezo-sensitization

类石墨烯结构二维氮化硼材料:结构特性、合成方法、性能及应用

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材料导报 2016年第11期30卷 143-148页

作者：杨雅萍李斌张长瑞高世涛宋阳曦国防科学技术大学航天科学与工程学院长沙410072 总装备部重庆军事代表局重庆400060

石墨烯的发现和成功制备引起了人们对二维材料的研究热潮。六方氮化硼(h-BN)薄膜作为类石墨烯结构的二维层状材料,也是当前的研究热点。介绍了h-BN及其相应的低维纳米结构,并概述了近期对二维BN纳米材料的形貌、合成、性能和应用的研究... 详细信息

石墨烯的发现和成功制备引起了人们对二维材料的研究热潮。六方氮化硼(h-BN)薄膜作为类石墨烯结构的二维层状材料,也是当前的研究热点。介绍了h-BN及其相应的低维纳米结构,并概述了近期对二维BN纳米材料的形貌、合成、性能和应用的研究进展。目前对一维和二维纳米材料的研究表明,BN纳米材料具有诸多优异性能,包括高温稳定性、低介电常数、高力学性能、高热导率、高硬度和高耐腐蚀性,BN纳米材料系统已成为最具前景的非碳纳米系统,在不远的将来将有广泛的应用。

关键词：二维材料六方氮化硼(h-BN) BN纳米材料

PIP工艺制备C/Zr_(0.5)Hf_(0.5)C-SiC复合材料及其微观结构和弯曲性能

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材料工程 2023年第8期51卷 155-161页

作者：刘星煜万帆高世涛王衍飞李端李俊生刘荣军国防科技大学空天科学学院长沙410073 中国人民解放军96901部队31分队北京100094

基于自制Zr_(0.5)Hf_(0.5)C先驱体和商业化液态聚碳硅烷,通过先驱体浸渍裂解(PIP)工艺成功制备C/Zr_(0.5)Hf_(0.5)C-SiC复合材料,研究纤维表面热解C涂层厚度对复合材料微观结构及弯曲性能的影响。结果表明:自制Zr_(0.5)Hf_(0.5)C先驱体... 详细信息

基于自制Zr_(0.5)Hf_(0.5)C先驱体和商业化液态聚碳硅烷,通过先驱体浸渍裂解(PIP)工艺成功制备C/Zr_(0.5)Hf_(0.5)C-SiC复合材料,研究纤维表面热解C涂层厚度对复合材料微观结构及弯曲性能的影响。结果表明:自制Zr_(0.5)Hf_(0.5)C先驱体在1400℃下即可转化生成单一Zr_(0.5)Hf_(0.5)C固溶体。因具有良好的渗透性,转化生成的Zr_(0.5)Hf_(0.5)C基体同时存在于C/Zr_(0.5)Hf_(0.5)C-SiC复合材料的纤维束内和束间,呈包裹SiC基体的层状形貌。C/Zr_(0.5)Hf_(0.5)C-SiC复合材料主要由C,SiC和Zr_(0.5)Hf_(0.5)C相组成;具有不同热解C涂层厚度(0.67,0.84,1.36μm)的3组复合材料密度分别为2.07,1.99,1.98 g/cm^(3);随热解C涂层厚度的增加复合材料中SiC含量减少。弯曲加载中3组不同热解C涂层厚度复合材料均呈现假塑性断裂模式,弯曲强度,弯曲模量和断裂韧度分别在410 MPa,60 GPa和15.6 MPa·m^(1/2)以上。良好的界面结合和预先引入的SiC基体是C/Zr_(0.5)Hf_(0.5)C-SiC复合材料获得优良弯曲性能的关键。

关键词： Zr_(0.5)Hf_(0.5)C 超高温陶瓷先驱体浸渍裂解微观结构弯曲性能

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3D打印天线罩技术研究进展

材料导报 2022年第22期36卷 76-85页

作者：李俊生李端李学超高世涛王衍飞万帆刘荣军国防科技大学空天科学学院新型陶瓷纤维及其复合材料重点实验室长沙410073 中国人民解放军96901部队31分队北京100094

天线罩是位于飞行器头部集防热、透波、承载等多功能于一体的结构/功能部件,高性能天线罩的设计与制备成为新型飞行器研制的瓶颈之一。3D打印技术是近年来发展的增材制造新技术,能够实现复杂结构的一体化成型,克服传统成型工艺的各种局... 详细信息

天线罩是位于飞行器头部集防热、透波、承载等多功能于一体的结构/功能部件,高性能天线罩的设计与制备成为新型飞行器研制的瓶颈之一。3D打印技术是近年来发展的增材制造新技术,能够实现复杂结构的一体化成型,克服传统成型工艺的各种局限性,在天线罩领域具有广阔的应用前景。本文概括了常用3D打印技术的特点,分别从3D打印天线罩模具制备、3D打印天线罩结构设计、3D打印天线罩材料成型、3D打印设备优化四个方面,综述了3D打印技术在天线罩领域的研究现状,并对其未来发展趋势进行了展望。

关键词： 3D打印天线罩模具透波材料设计

Conjoint analysis of crowbar switching scheme and its resistancebased on statistical sampling for LVRT of DFIG

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Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 558-567页

作者： Yanbin QU Le gao Guangfu MA Huihui SONG shitao WANG School of Information and Electrical Engineering Harbin Institute of Technology at WeihaiNo.2West Wenhua RoadWeihai 264209China Department of Control Science and Engineering Harbin Institute of TechnologyNo.92West Dazhi StreetNangang DistrictHarbin 150001China State Grid of China Technology College No.500ErhuanSouth RdJinanChina

An active crowbar protective circuit is an effective and common approach for low voltage ride through(LVRT) of a doubly-fed induction generator(DFIG). The crowbar resistance value and its switching scheme both have crucial effects on safety recovery. The effects encountered are correlative dependence and interplay so that analyzing them from a single factor, as most existing LVRT control methods would do, obtains a partial optimal solution. This paper combines these two factors toanalyze their coordination effects on the LVRT control,and to also investigate whether the global optimal performance of these factors can be achieved. The principles for resistance selection and the schemes for crowbar switching are discussed first. Next, the coupling relationship is ana-lyzed based on statistical sampling simulation data with different resistance values and various switching *** results demonstrate that their coordination has critical influence on rotor peak current, DC-link voltage and reactive power. The optimal coordination will be different according to specific requirements. Hence the global optimal combination could be achieved when all requirements are taken into consideration.

关键词： Doubly-fed induction generator(DFIG) Active crowbar Switching scheme Resistance value Statistical sampling data

Baeyer-Villiger Oxidation of Cyclic Ketones Catalyzed by Amino Acid Ionic Liquids

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Chemical Research in Chinese Universities 2020年第5期36卷 865-869页

作者： YU Fengli CHI Yujie gao Chong CHEN Ruirui XIE Congxia YU shitao State Key Laboratory Base of Eco-chemical Engineehng College of Chemistry and Molecular EngineeringQingdao University of Science and TechnologyQingdao 266042P.R.China College of Chemical Engineering Qingdao University of Science and TechnologyQingdao 266042P.R.China

A series of amino-acid-based ionic liquids was synthesized via one-step protonation of the corresponding L-amiiio acid by utilizing an array of proton *** catalytic activity of the amino-acid-based ionic liquids for the Baeyer-Villiger oxidation of cyclic ketones was investigated using cyclopentanone as a model ***-based ionic liquid[ProH]CF3SO3 was shown to exliibit thebest catalytic *** reaction condition was optimized to give the following reagent ratio of h(cyclopentanone):n(catalyst):w(H2O2)=1:0.06:4,60℃and 6 *** the optimum conditions,the conversion of cyclopentanone was 96.57%and the selectivity forδ-valerolactone was 73.01%.The catalytic activity was shown to be constant after 4 cycles.A simple treatment was allowed for the recover and the reuse of[ProH]*** successful utilization of[ProH]CF3SO3 to catalyze a host of cyclic ketones via Baeyer-Villiger oxidation clearly demonstrated the capacity of[ProH]CF3S03 to tolerate variation in the substrate.

关键词： Amino acid ionic liquid Baeyer-Villiger oxidation Cyclic ketone Lactone

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大型换流变压器安装中的问题分析及解决

电力建设 2011年第7期32卷 113-116页

作者：高士涛姚莉娜朱莹张建锋刘华李克明河南送变电建设公司郑州市450051 郑州轻工业学院郑州市450002 郑州供电公司郑州市450051

分析±500kV荆门换流站换流变内部分解开关绝缘件的更换、换流变本体渗漏油和注油中的假油位问题,提出解决方案。工程实践表明方案具有很好的可行性。分析过程和解决方案可供相关技术人员参考。

关键词：换流站换流变压器分接开关渗漏油假油位