Effect of Lamina Thickness of Prepreg on the Surface Accuracy of Carbon Fiber Composite Space Mirrors

Composite space mirror can completely replicate the high-precision surface of mould by replication process, but the actual surface accuracy of the replication composite mirror always decreases. Lamina thickness of prepreg affects the layers and layup sequence of composite space mirror, and which would affect surface accuracy of space mirror. In our research, two groups of contrasting cases through finite element analyses (FEA) and comparative experiments were studied; the effect of different lamina thicknesses of prepreg and corresponding lay-up sequences was focused as well. We describe a special analysis model, validated process and result analysis. The simulated and measured surface figures both get the same conclusion. Reducing lamina thickness of prepreg used in replicating composite space mirror is propitious to optimal design of layup sequence for fabricating composite mirror, and could improve its surface accuracy.     

Eddy Current Testing of Delamination in Carbon Fiber Reinforced Polymer (CFRP): A Finite Element Analysis

Carbon fiber reinforced polymer (CFRP) is widely used thanks to its excellent material properties. However, damages, especially delamination, can cause significant reduction in strength of CFRP structures. This article attempts to study the nondestructive testing of delamination using eddy current (EC) method. To this end, we design a novel probe consisting of dual coplanar rectangular coils placed perpendicular to sample surface, and make use of the vertical sections of the coils to induce vertical EC in the test sample. Perturbation of the vertical EC by delamination gives us a chance to detect delamination. Simulation results by the finite element method demonstrate the feasibility of the proposed method.     

Anisotropic Dielectric Properties of Carbon Fiber Reinforced Polymer Composites during Microwave Curing

Microwave cuing technology is a promising alternative to conventional autoclave curing technology in high efficient and energy saving processing of polymer composites. Dielectric properties of composites are key parameters related to the energy conversion efficiency during the microwave curing process. However, existing methods of dielectric measurement cannot be applied to the microwave curing process. This paper presented an offline test method to solve this problem. Firstly, a kinetics model of the polymer composites under microwave curing was established based on differential scanning calorimetry to describe the whole curing process. Then several specially designed samples of different feature cure degrees were prepared and used to reflect the dielectric properties of the composite during microwave curing. It was demonstrated to be a feasible plan for both test accuracy and efficiency through extensive experimental research. Based on this method, the anisotropic complex permittivity of a carbon fiber/epoxy composite during microwave curing was accurately determined. Statistical results indicated that both the dielectric constant and dielectric loss of the composite increased at the initial curing stage, peaked at the maximum reaction rate point and decreased finally during the microwave curing process. Corresponding mechanism has also been systematically investigated in this work.     

聚合物基碳纤维复合材料废弃物的几种处理方法分析

从环保和可持续发展角度出发,并结合我国碳纤维(CF)生产与使用实际情况,对聚合物基碳纤维复合材料(CFRP)废弃物处理必要性作了较为详尽的阐述。根据CFRP废弃物种类,提出了机械材料再循环法、材料再循环与能量回收法、能量回收焚烧法三种可行处理方法,并从处理费用、环境影响、替代用途三方面对多种处理方案进行了合理评估。综合考虑处理环境影响、经济效益及替代物使用性能等因素,材料再循环与能量回收法为处理CFRP废弃物最合适的方法。此外,为推进其后期处理工作的顺利进行,还从内部、外部因素两方面提出相关建议。     

影响碳纤维增强复合材料摩擦系数的因素

本研究对碳纤维的体积比、分布方向及温度对增强热固性环氧树脂摩擦系数的影响作了试验及分析讨论 ,结果表明 ,碳纤维加入后可显著降低复合材料的摩擦系数 ,随碳纤维加入方式不同 ,碳纤维对摩擦系数的影响作用也不同     

碳纤维表面接枝聚合物及其对复合材料界面的影响

综述了碳纤维表面接枝聚合物的各种方法,包括电聚合、电沉积、等离子体接枝聚合、化学接枝聚合等;探讨了接枝聚合物层对复合材料界面的影响.     

Manufacturing Influence on the Delamination Fracture Behavior of the T800H/3900-2 Carbon Fiber Reinforced Polymer Composites

'Torayca' T800H/3900-2 is the first material qualified on Boeing Material Specification (BMS 8-276) which utilizes the thermoplastic-particulate interlayer toughening technology. Two manufacturing processes, the autoclave process and the fast heating rated Quickstep™ process, were employed to cure this material. The Quickstep process is a unique composite production technology which utilizes the fast heat transfer rate of fluid to heat and cure polymer composite components. The manufacturing influence on the mode I delamination fracture toughness of laminates was investigated by performing double cantilever beam tests. The composite specimens fabricated by two processes exhibited dissimilar delamination resistance curves (R-curves) under mode I loading. The initial value of fracture toughness G_IC-INIT was 564 J/m² for the autoclave specimens and 527 J/m² for the Quickstep specimens. However, the average propagation fracture toughness G_IC-PROP was 783 J/m² for the Quickstep specimens, which was 2.6 times of that for the autoclave specimens. The mechanism of fracture occurred during delamination was studied under scanning electron microscope (SEM). Three types of fracture were observed: the interlayer fracture, the interface fracture, and the intralaminar fracture. These three types of fracture played different roles in affecting the delamination resistance curves during the crack growth. More fiber bridging was found in the process of delamination for the Quickstep specimens. Better fiber/matrix adhesion was found in the Quickstep specimens by conducting indentation-debond tests.     

玄武岩纤维表面生长碳纳米管及其复合材料性能的研究

针对玄武岩纤维(CBF)表面光滑且惰性,在与树脂基体复合制备复合材料时二者结合能力较低的问题,采用化学镀镍在玄武岩纤维表面均匀加载镍催化剂,借助化学气相沉积(CVD)生长碳纳米管(CNTs)。用场发射扫描电镜(FESEM)、透射电镜(TEM)、拉曼光谱(Raman)等方法对生长的CNTs进行表征,并测试复合材料的界面剪切强度。结果表明化学镀镍工艺能在CBF表面均匀加载镍催化剂,有利于CVD生长CNTs。工艺最佳条件为施镀时间15min、500℃下生长10min,此条件下生长的CNTs整齐排列在CBF表面,结晶性较好且呈中空管状。采用生长了CNTs的CBF制备复合材料的界面强度提高了10%。     

碳纤维增强Cu-Ti3SiC2复合材料的研究

采用电镀Cu碳纤维(Cf)与化学镀Cu的Ti3SiC2粉及Cu粉进行湿混,通过真空热压烧结法制备Cf增强的Cu-Ti3SiC2复合材料.研究了其致密度、电阻率、维氏硬度随Cf,Ti3SiC2含量变化的规律.实验结果表明,Ti3SiC2体积含量为20%,Cf体积含量为8%时,制备的Cf增强Cu-Ti3SiC2复合材料综合性能最好.Cf镀Cu和Ti3SiC2镀Cu改善了它们和Cu的润湿性,从而提高了相互之间的结合强度是复合材料获得良好综合性能的基本原因.     

碳纤维表面化学镀电磁屏蔽复合材料的研究进展

综述了近些年碳纤维复合材料金属化的国内外研究进展、研究现状及研究历程;阐述了各种金属化碳纤维材料的性能特点和作用;指出了目前研究中存在的问题及今后的发展趋势和研究方向.     

表面处理对玄武岩纤维增强酚醛树脂复合材料界面结合强度的影响

研究了不同浓度盐酸刻蚀处理纤维表面后再进行硅烷KH550、铝锆偶联剂处理对玄武岩纤维增强酚醛树脂基复合材料力学性能的影响,并用扫描电子显微镜观察复合材料表面的胶合情况.结果表明:随着盐酸浓度的提高,玄武岩纤维增强酚醛树脂(BF-PF)复合材料拉伸性能先降低后升高,在12 mol/L时达到最大值,弯曲性能和ILSS均降低,在6mol/L时为最大值.铝锆偶联剂处理的BF-PF复合材料的拉伸性能优于KH550处理的复合材料,但弯曲性能和ILSS低于KH550处理的复合材料.     

碳纤维增强复合材料中改性木质素的应用

目的 解决碳纤维增强环氧树脂复合材料中由双酚A合成的环氧树脂成本高、危害环境与健康、耐化学性差的问题,使木质素代替双酚A合成环氧树脂来制备碳纤维复合材料。方法 通过综述木质素在环氧树脂合成中的改性方法与合成方案的研究进展,分析碳纤维复合材料成型工艺的优缺点。结论 采用不同方法对木质素进行化学改性,可在降低成本的同时提高热稳定性与耐化学性等各项性能。用改性或降解木质素来合成碳纤维复合材料的环氧树脂基体为碳纤维增强材料的研究提供了新的研究方向,对碳纤维增强材料降低成本、提高性能和促进行业发展都具有积极作用。     

碳纤维表面结构对复合材料吸湿性能的影响

通过改变阳极氧化处理程度得到了具有不同表面结构的碳纤维, 然后将其与环氧树脂加工成碳纤维/树脂基复合材料, 研究了碳纤维的化学结构与湿热环境下复合材料吸湿之间的关系。结果显示: 阳极氧化处理后碳纤维表面的活性显著提高, 碳纤维表面含氧官能团的含量大幅增加, 尤其是-OH由处理前18.62%提高到处理后的34.84%。随着湿热处理条件的改变, 复合材料的吸湿机理也有所差异, 且温度是影响复合材料吸湿的重要因素。碳纤维表面活性越高, 复合材料达到吸湿平衡时的平衡吸湿量越大, 而平衡吸湿量的增加又会导致复合材料层间剪切强度(ILSS)下降幅度增大。     

Evaluation of Bonding Quality in the Carbon Fiber--Reinforced Polymer (CFRP) Composite Laminates by Measurements of Local Vibration Nonlinearity

A new approach to monitoring the quality of adhesive bonding in the carbon fiber--reinforced polymer (CFRP) is developed by using a local nonlinear response of the laminate. It is shown that a degraded (contaminated) boundary layer of the adhesive contributes to an overall nonlinear response of the laminate that enables to evaluate and quantify bonding quality caused by various types and levels of single contaminations. In the context of aviation applications, two typical stages during the life of a structural part for which the adhesive properties of a bonding joint could be degraded were considered: the production process and the maintenance/repair scenario. All kinds of single contaminations studied result in enhancement of the nonlinear response of the CFRP laminate, which is an indication of deterioration of the bonding quality. The effect of multiple contaminations confirms a cumulative decline of adhesion caused by increase of the contents of single contamination components.     

导热型碳纤维增强聚合物基复合材料的研究进展

综述了导热型连续碳纤维增强聚合物基复合材料(CFRP)的研究与应用现状和进展,阐述了CFRP的声子导热和光子导热机理,介绍了不同铺层角度和铺层比的CFRP面内和厚度方向热导率计算模型及测试方法,分析了环氧树脂、氰酸酯、双马来酰亚胺等3类树脂体系和聚丙烯腈基(PAN)碳纤维、中间相沥青基碳纤维、气相生长碳纤维、碳纳米管纤维等4类增强体以及工艺方法等因素对CFRP热导率的影响。     

真空压力浸渗制备车板用CF/A365铝合金组织和力学性能分析

选择A365铝合金作为基底材料,采用真空压力浸渗方式通过M40J碳纤维(CF)对其进行加强,实验测试的方式分析了不同CF含量下A365铝合金的界面结构及其力学强度的变化。研究结果表明:密度最高的是5%CF的A365铝合金,达到了高比强度的力学特性。所有不同CF含量纤维增强基底都获得了高于98%的致密度,获试样中密度最大的是5%CF的A365铝合金。经过高温浸渗处理后,SiC纤维接触到界面区域的铝液后会发生以下反应,得到Al₄C₃组织。CF含量5%时,各个纤维束达到了充分浸渗,纤维束间隙也被基底较好填充,此时在Cf/A365铝合金中并没有产生明显界面结构。CF含量5%铝合金的断口区域也形成了凹凸不平的结构,属于韧性断裂,拉伸期间纤维和基底存在脱粘的情况,能够有效发挥纤维增强效果。     

Numerical Investigation of Delamination in Drilling of Carbon Fiber Reinforced Polymer Composites

Drilling of carbon fiber reinforced polymer (CFRP) is a challenging task in modern manufacturing sector and machining induced delamination is one of the major problems affecting assembly precision. In this work, a new three-dimensional (3D) finite element model is developed to study the chip formation and entrance delamination in drilling of CFRP composites on the microscopic level. Fiber phase, matrix phase and equivalent homogeneous phase in the multi-phase model have different constitutive behaviors, respectively. A comparative drilling test, in which the cement carbide drill and unidirectional CFRP laminate are employed, is conducted to validate the proposedmodel in terms of the delamination and the similar changing trend is obtained. Microscopic mechanism of entrance delamination together with the chip formation process at four special fiber cutting angles (0°, 45°, 90° and 135°) is investigated. Moreover, the peeling force is also predicted. The results show that the delamination occurrence and the chip formation are both strongly dependent on the fiber cutting angle. The length of entrance delamination rises with increasing fiber cutting angles. Negligible delamination at 0° is attributed to the compression by the minor flank face. For 45° and 90°, the delamination resulted from the mode III fracture. At 135°, serious delamination which is driven by the mode I and III fractures is more inclined to occur and the peeling force reaches its maximum. Such numerical models can help understand the mechanism of hole entrance delamination further and provide guidance for the damage-free drilling of CFRP.     

热解碳涂层碳纤维增强碳化硅复合材料热压工艺研究

采用经妥碳涂层的Ｍ４０ＪＢ碳纤维，以有机硅先驱体聚碳硅烷为粘结剂，絷压烧结制备了Ｃｔ／ＳｉＣ复合材料。测试了复合材料的性能并进行了对比，同时运用ＳＥＭ，ＴＥＭ等分析手段对复合材料的微观结构进行了表生。结果表明，所采用的碳纤维热解碳涂层对复合材料的性能有较大的影响，较好的热压温度为１８５０℃，压力为２５ＭＰａ。     

碳纳米管/连续纤维增强树脂基复合材料力学性能设计

本文综述了碳纳米管/连续纤维增强树脂基复合材料力学性能影响因素,同时对目前公开发表的几种预测碳纳米管/连续纤维增强复合材料模量及破坏强度的分析方法进行了介绍与分析。最后,对今后研究动向进行了展望。