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Imaging the interphase of carbon fiber composites using transmission electron microscopy:Preparations by focused ion beam, ion beam etching, and ultramicrotomy

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Chinese Journal of Aeronautics 2015年第5期28卷 1529-1538页

作者： Wu Qing Li Min gu yizhuo Wang Shaokai Zhang Zuoguang Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beihang University

Three sample preparation techniques, focused ion beam （FIB）, ion beam （IB） etching, and ultramicrotomy （UM） were used in comparison to analyze the interphase of carbon fiber ＇epoxy composites using transmission electron microscopy. An intact interphase with a relatively uniform thickness was obtained by FIB. and detailed chemical analysis of the interphase was investigated by electron energy loss spectroscopy. It shows that the interphase region is 200 mn wide with an increasing oxygen-to-carbon ratio from 10% to 19% and an almost constant nitrogen-to-carbon ratio of about 3%. However, gallium implantation of FIB tends to hinder fine structure analysis of the interphase. For IB etching, the interphase region is observed with transition morphology frona amorphous resin to nano-crystalline carbon fiber, but the uneven sample thickness brings difficulty for quantitative chemical analysis. Moreover, UM tends to cause damage and/or deformation on the interphase. These results are meaningful for in-depth understanding on the interphase characteristic of carbon fiber composites.

关键词： Carbon fiber compositeChemical analysis Focused ion beams lnterphase Ion beam etching Microstructure Ultramicrotomy

Investigation of carbon fiber composite stiffened skin with vacuum assisted resin infusion/prepreg co-curing process

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Science China(Technological Sciences) 2014年第10期57卷 1956-1966页

作者： MA XuQiang gu yizhuo LI Min LI YanXia ZHANG Zuoguang Key Laboratory of Aerospace Advanced Materials and Performance (Ministry of Education) School of Materials Science and EngineeringBeihang University

Co-cured vacuum assisted resin infusion process(co-VARI process),which combined vacuum assisted resin infusion(VARI)with prepreg vacuum bag only process(VBO),was adopted to fabricate T-shaped stiffened skin with non-crimp fabric(NCF)stiffener and prepreg *** compaction stage of co-VARI process,prepreg resin impregnated fiber fabric under elevated temperature and vacuum *** phenomenon was characterized by fluorescent micrographs with different holding temperature and *** influences on processing quality and mechanical performance for co-VARI stiffened skin with different filler materials at triangular region were further analyzed by optical micrographs and pull-off test,*** results show that increasing holding temperature and prolonging holding time can promote prepreg resin impregnation in fiber *** prepreg resin impregnation is favorable to reduce resin rich region and increase fiber volume fraction at prepreg-fabric ***,prepreg resin impregnation effect plays significant roles on pull-off performance for co-VARI stiffened skin with fabric filler but has negligible influences on specimens with prepreg *** addition,compared with stiffened skin with fabric filler,superior processing quality and pull-off performances are achieved for co-VARI stiffened skin with prepreg core *** results are helpful to optimize processing procedures and fabricate composite structure by coVARI process.

关键词： polymer-matrix composites prepreg vacuum assisted resin infusion stiffened skin structure co-curing

Influence of processing temperature on interfacial behavior of HKT800 carbon fiber with BMI and epoxy matrices

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Chinese Journal of Aeronautics 2015年第4期28卷 1255-1262页

作者： Gao Aijun gu yizhuo Wu Qing Yuan Chao Li Min Zhang Zuoguang Key Laboratory of Aerospace Advanced Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beihang University

This paper aims to study the effect of processing temperature on interfacial behavior of HKT800 carbon fiber composites with epoxy and Bismaleimide（BMI） *** to the processing conditions of the composite, various processing-heat treatments were conducted on HKT800 and the extracted sizing content declines with increasing *** analysis shows that the HKT800 sizing is epoxy-type and reactive at 200 *** interfacial shear strength（IFSS） of HKT800/epoxy and HKT800/BMI was investigated by micro-droplet method, for which the composites were fabricated with modeling temperature schemes referring to different diffusion, cure and post-cure *** shows that diffusion temperature and conversion degree of the resin both enhance the interfacial adhesion of HKT800/epoxy *** the HKT800/BMI composite,the diffusion temperature shows a insignificant effect on the *** analysis indicates that sufficient reactions are achieved between HKT800-sizing and epoxy resin, however only partial reactions are observed between the sizing and ***, the presence of the sizing can evidently improve the wettability of HKT800 with epoxy resin but is unfavorable for HKT800 with BMI.

关键词： Bismaleimide Carbon fiber Epoxy Interfacial shear strength Temperature scheme

Influence of Surface State on Moisture Sensitivity of Carbon Fiber and Its Composite Interfacial Properties

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Journal of Wuhan University of Technology(Materials Science) 2016年第4期31卷 757-764页

作者：王星星李敏 wu qing gu yizhuo li yanxia wang shaokai zhang zuoguang Key Laboratory of Aerospace Materials and Performance (Ministry of Education) School of Materials Science and Engineering Beihang University Beijing 100191 China

The influence of surface state on the moisture sensitivity of carbon fiber was analyzed by applying a T800 grade carbon fiber with five different surface conditions,namely,with and without surface oxidation,in the presence or absence of sizing *** interfacial properties of their composites in the presence of two epoxy matrices（respectively EP07 and EP10） were also characterized by micro-droplet *** overall results show that both oxidized and sizing-coated fibers have higher moisture equilibrium content than that of the pristine unsurface-treated fiber,due to higher amount of activated carbon *** moisture absorption of the carbon fibers,almost all the fiber/epoxy systems show decrease in the interfacial shear strength and the unsurface-treated fiber system exhibits the largest ***,both interfacial shear strength and interlaminar shear strength of carbon fiber/EP10 composite demonstrate better water resistance performance than that of the carbon fiber/EP07 composite,consistent with DSC results of the two resins.

关键词： moisture sizing epoxy resins interfacial coated sized curing applying droplet

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复合材料热压成型过程的树脂压力测试系统

复合材料学报 2007年第2期24卷 23-27页

作者：顾轶卓张佐光李敏北京航空航天大学材料科学与工程学院北京100083

在树脂基复合材料的成型工艺中大多涉及到树脂的流动过程,而树脂压力是反映这一过程的重要参数,监测成型过程中树脂压力的变化可以为工艺参数的选择和构件质量的控制提供指导。本文中针对热压工艺,根据液体传压原理和特点,自行研制了复... 详细信息

在树脂基复合材料的成型工艺中大多涉及到树脂的流动过程,而树脂压力是反映这一过程的重要参数,监测成型过程中树脂压力的变化可以为工艺参数的选择和构件质量的控制提供指导。本文中针对热压工艺,根据液体传压原理和特点,自行研制了复合材料成型过程树脂压力测试系统,对系统的精度和动态响应性能进行了研究,并以该系统为测试手段,初步研究了玻璃纤维单向层板中树脂压力的变化规律。结果表明,该系统具有准确度高和动态响应敏感的特点,满足热压成型过程树脂压力的测试要求,为研究工艺过程树脂流动行为提供了有力的测试与验证手段。

关键词：复合材料热压工艺树脂流动压力测试

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L形层板真空袋成型缺陷的实验研究

复合材料学报 2007年第4期24卷 34-39页

作者：邓火英张佐光顾轶卓李敏北京航空航天大学材料科学与工程学院北京100083

采用真空袋阳模成型法在不同条件下制备了90°的L形玻纤单向布/环氧树脂层板,对层板不同位置处纤维密实和缺陷状况进行了研究,考察了成型过程主要工艺条件对缺陷的影响规律。结果表明,富树脂、孔隙、厚度分布不均和纤维屈曲变形是L形层... 详细信息

采用真空袋阳模成型法在不同条件下制备了90°的L形玻纤单向布/环氧树脂层板,对层板不同位置处纤维密实和缺陷状况进行了研究,考察了成型过程主要工艺条件对缺陷的影响规律。结果表明,富树脂、孔隙、厚度分布不均和纤维屈曲变形是L形层板中主要的缺陷类型,加压时机、层板尺寸、铺层方式以及边界条件对纤维密实和缺陷的形成都有重要的影响。对以上各种缺陷的产生机制进行了初步分析:剪切流动的存在导致层板厚度分布不均匀而且出现富树脂区;纤维的屈曲变形是由于轴向受压缩力;本文实验条件下孔隙的主要来源是夹杂空气。研究结果对热压工艺中缺陷的预测与控制以及工艺参数的优化具有重要的指导意义。

关键词：复合材料成型缺陷真空袋成型 L形层板

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热固性树脂体系流变特性随贮存条件变化规律

复合材料学报 2007年第4期24卷 40-45页

作者：周文张佐光顾轶卓李敏北京航空航天大学材料科学与工程学院北京100083

热固性树脂体系在贮存期间会发生物理或化学变化,这会影响树脂体系的流变特性,进而影响其成型工艺性。本文中针对几种典型热压工艺用高性能热固性树脂体系,采用平板流变仪研究了贮存期对树脂体系流变特性的影响,并利用差示扫描量热法、... 详细信息

热固性树脂体系在贮存期间会发生物理或化学变化,这会影响树脂体系的流变特性,进而影响其成型工艺性。本文中针对几种典型热压工艺用高性能热固性树脂体系,采用平板流变仪研究了贮存期对树脂体系流变特性的影响,并利用差示扫描量热法、红外光谱法和凝胶色谱法分析了流变特性变化的具体原因;同时以流动度为表征参数,考察了树脂体系工艺性随贮存期的变化规律。结果表明,树脂体系的贮存特性主要由其固化反应特性和添加剂的贮存特性决定。该研究结果为热压工艺参数的选择和优化提供了重要实验依据。

关键词：复合材料热压工艺热固性树脂贮存期流变特性

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多壁碳纳米管改性环氧树脂胶黏剂实验研究

复合材料学报 2011年第3期28卷 20-26页

作者：肖杰顾轶卓李敏张佐光北京航空航天大学材料科学与工程学院空天材料与服役教育部重点实验室北京100191

将一种环氧树脂和表面羟基化的多壁碳纳米管(MWCNTs)按照质量比100∶0.1进行配比,以超声波分散法制备MWCNTs/环氧树脂胶黏剂,考察了两种硅烷偶联剂KH550和KH560对MWCNTs改性效果的影响。采用FTIR、DSC、DMA、流变仪研究了MWCNTs对胶黏... 详细信息

将一种环氧树脂和表面羟基化的多壁碳纳米管(MWCNTs)按照质量比100∶0.1进行配比,以超声波分散法制备MWCNTs/环氧树脂胶黏剂,考察了两种硅烷偶联剂KH550和KH560对MWCNTs改性效果的影响。采用FTIR、DSC、DMA、流变仪研究了MWCNTs对胶黏剂固化行为和流变特性的影响,并结合断口形貌观察,测试分析了MWCNTs对胶黏剂拉伸剪切强度和冲击强度的影响。结果表明:硅烷偶联剂能与MWCNTs表面的羟基发生缩合反应,增强了MWCNTs与环氧树脂基体的亲和性,从而影响胶黏剂固化反应及黏度-剪切速率曲线;经KH550改性的MWCNTs明显提高了胶黏剂与金属的界面粘结性,Al-Al拉伸剪切强度较无MWCNTs的胶黏剂提高了46.4%;添加MWCNTs使胶黏剂的冲击断面更为粗糙,开裂面积更大;添加MWCNTs+KH550的胶黏剂冲击强度提高了44.1%,说明MWCNTs/环氧树脂间界面性能对发挥MWCNTs的增韧效果非常重要。

关键词：多壁碳纳米管环氧树脂胶黏剂界面力学性能

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碳纤维复合材料C形结构热隔膜成型工艺

北京航空航天大学学报 2013年第1期39卷 95-99,104页

作者：姚双李敏顾轶卓马晓星北京航空航天大学材料科学与工程学院北京100191 上海飞机制造有限公司航空制造技术研究所上海200436

采用自行设计的热隔膜成型工艺实验装置,制备了C形结构碳纤维复合材料预成型体,测试了成型过程中预成型体和模具温度的变化规律,并考察了成型温度、预成型体尺寸对C形预成型体表面质量和内部缺陷的影响.结果表明:热隔膜成型过程中,采用... 详细信息

采用自行设计的热隔膜成型工艺实验装置,制备了C形结构碳纤维复合材料预成型体,测试了成型过程中预成型体和模具温度的变化规律,并考察了成型温度、预成型体尺寸对C形预成型体表面质量和内部缺陷的影响.结果表明:热隔膜成型过程中,采用模具预热的方法与红外灯辐射相配合,可保证预浸料温度的分布均匀性;成型温度过低时,预浸料粘性大、层间滑移能力差,导致预成型体拐角处出现纤维褶皱,并且内部孔隙偏多;预成型体的外形尺寸与模具尺寸接近,则预成型体易受隔膜架桥、变形量过大影响而出现翘曲等缺陷,因此预成型体与模具之间的尺寸比例应控制在一定范围内.

关键词：碳纤维复合材料热隔膜成型工艺 C形结构预浸料预成型体