Drilling delamination and thermal damage of carbon nanotube/carbon fiber reinforced epoxy composites processed by microwave curing

The drilling-induced delamination and thermal damage of carbon fiber reinforced epoxy composite materials are serious problems especially for high value components of the aviation industry. To suppress the delamination and drilling ablation, an innovative approach was employed in this study. The multiwalled carbon nanotubes (MWCNTs) were introduced to the matrix resin to improve the interlaminar strength and thermal conductivity. The as-prepared composite was processed by microwave curing to enhance the interface strength between carbon fiber and the carbon nanotubes modified matrix. During the drilling processes, optical fiber Bragg grating sensors were utilized to precisely measure the drilling temperature. Experimental results indicated that the interlaminar fracture toughness was increased by more than 66% compared to that of the traditional thermal cured samples without MWCNTs. And the delamination factor was decreased by 16% according to the computerized tomography scanning results. The maximum drilling temperature of the MWCNTs reinforced composite was below the glass transition temperature of the matrix resin and declined by 23 °C compared to traditional composites. With this novel method of carbon nanotube modification and microwave curing, we provide the capability of reducing the drilling delamination and thermal damage of carbon fiber composites simultaneously, and explored the possibility of manufacturing and machining integration.     

碳纤维复合贴片的界面行为研究

采用低温等离子体法对碳纤维进行表面处理,并在微波固化条件下将碳纤维与环氧树脂复合成形,制得碳纤维复合贴片.采用X射线光电子能谱仪对碳纤维表面的元素组成进行了表征,采用扫描电镜和能量散射光谱(EDS)对碳纤维/树脂界面区的形貌和元素分布进行了表征.结果表明:碳纤维经处理后,其表面氨基官能团的含量增大,有利于纤维与树脂的化...     

纳米银对环氧树脂的增韧改性及其微波固化行为

在80℃双酚A型环氧树脂E-51中,通过还原原位构筑了超分散稳定纳米银(n-Ag);用冷冻蚀刻电镜、离心实验对其进行表征和分散稳定性评价;用间歇微波对分散系中n-Ag的微波吸收特性和环氧树脂的微波固化行为进行研究;通过拉伸试验和冲击试验考察n-Ag对环氧树脂的增韧改性行为。结果表明:银为30nm的粒状颗粒,大小均匀,有理想的分散稳定性;n-Ag对环氧树脂有显著地增韧作用,当其含量为2.0%～2.5%(质量分数)时,增韧改性效果最佳,复合材料的断裂伸长率可提高l10%～130%;原位合成n-Ag有良好的微波吸收特性,它的存在能明显减少环氧树脂的微波固化时间,当n-Ag含量超过2.5%时,微波固化时间可缩短38%;微波固化环氧树脂速度比传统加热固化速度快数倍,其抗拉伸强度和抗冲击强度也好于热固化,但拉伸断裂伸长率比热固化的小。     

微波修复技术研究与发展

微波修复技术作为一项新兴的战场抢修手段,越来越受到国内外研究人员的高度关注。文中概述了微波修复技术的产生背景及国内外研究现状,着重介绍了该技术的最新研究成果。研制了便携式大功率微波腔外操作设备,采用原子力显微镜(AFM)、扫描电子显微镜(SEM)等测试手段分析了碳纤维表面处理及微波固化对复合贴片性能的影响。利用该技术修复不同材料的损伤,其静强度恢复率达到90%以上。     

C/CF/Cu复合材料界面和抗拉强度研究

采用树脂碳化方法制备了碳/碳纤维(C/CF)先驱丝,用压力浸渗凝固成型方法制备了碳/碳纤维/铜(C/CF/Cu)复合材料,借助抗拉强度测试及扫描电镜下复合材料界面和相组成物分布观察,探讨了C、CF和Cu三组元复合界面特性以及碳纤维丝类型和C/CF先驱丝体积分数对C/CF/Cu复合材料抗拉强度的影响.结果表明,C/CF/Cu复合材料的微观界面是碳纤维单丝-树脂碳化碳-铜双复合界面,此界面属于无化学反应的弱复合界面,铜对C/CF先驱丝的机械锁紧力是提高界面强度和复合材料强度的关键因素.当凝固成型压力为28.5MPa时,1k碳纤维丝的C/CF先驱丝体积分数为25%和3k碳纤维丝的C/CF先驱丝体积分数为44.7%的复合材料的抗拉强度达到较高值,分别为595MPa和587MPa,均为纯铜抗拉强度的3倍以上.3k丝制成的一次C/CF先驱丝内碳纤维丝的数量较多,影响复合材料的界面强度,而选用1k碳纤维丝比较有利.     

热固性预浸料模压成型工艺参数实验研究

通过研究热固性预浸料模压成型(Propreg Compression Molding,PCM)复合材料层合板制备过程中固化压力与树脂流失量之间的关系,对比不同树脂含量的预浸料在模压成型后的力学性能,发现最佳力学性能对应的预浸料树脂含量为38%。为了进一步提高PCM模压制品力学性能的稳定性,将模压后树脂含量保持在38%的固化压力作为固定参数,对模具温度和固化时间进行了16组正交实验,检测层合板的力学性能,并分析树脂与纤维织物界面之间的微观结合情况。结果表明:当固化压力为3800 kN时,可以将树脂含量为40%的预浸料在模压后的树脂含量控制在38%左右,并在模具温度为155℃、预热时间为40 s、保压时间为440 s时,得到抗拉强度为520.18 MPa、冲击韧性为32.35 J·cm^-2、综合力学性能最好同时微观缺陷最少的样品。经现场工艺验证,实验得到的规律和工艺参数组合可应用于热固性复合材料汽车电池包上盖的批量生产中。     

Fiber Reinforced Polyester Resins Polymerized by Microwave Source

Polyester resin based composite materials are widely used in the manufacture of fiberglass boats. Production time of fiberglass laminate components could be strongly reduced by using an intense energy source as well as microwaves. In this work a polyester resin was used with 2% by weight of catalyst and reinforced with chopped or woven glass fabric. Pure resin and composite samples were cured by microwaves exposition for different radiation times. A three point bending test was performed on all the cured samples by using an universal testing machine and the resulting fracture surfaces were observed by means of scanning electron microscopy (SEM). The results of mechanical and microscopy analyses evidenced that microwave activation lowers curing time of the composite while good mechanical properties were retained. Microwaves exposition time is crucial for mechanical performance of the composite. It was evidenced that short exposition times suffice for resin activation while long exposure times cause fast cross linking and premature matrix fracture. Furthermore high-radiation times induce bubbles growth or defects nucleation within the sample, decreasing composite performance. On the basis of such results microwave curing activation of polyester resin based composites could be proposed as a valid alternative method for faster processing of laminated materials employed for large-scale applications.     

含环氧树脂微胶囊自修复涂层的制备及其性能

目的制备含环氧树脂微胶囊的二元自修复涂层,并对其力学性能和自修复性能进行研究。方法将自制环氧树脂E-51/三聚氰胺-脲醛树脂微胶囊和潜伏型固化剂(2-甲基咪唑)按一定比例添加到环氧树脂基体中,制备二元自修复环氧树脂涂层。利用漆膜弹性试验机、漆膜冲击试验机和万能拉伸试验机对涂层的弯曲性能、耐冲击性能和拉伸性能进行测试。利用扫描电子显微镜(SEM)、光学显微镜(OM)对涂层的自修复性能进行考察。采用EIS对涂层的电化学性能进行测试。结果成功制备了含环氧树脂微胶囊二元自修复涂层,当涂层中微胶囊的质量分数为3%时,涂层的冲击强度和拉伸强度分别提高了10.6%和14.6%。当涂层中2-甲基咪唑和微胶囊质量分数分别为6%和5%时,涂层的自修复性能较佳。当微胶囊质量分数为9%时,涂层的电化学阻抗值可达1.2×105?。结论微胶囊的加入可有效提高涂层的冲击强度和拉伸强度。随着涂层中潜伏型固化剂含量的增大,涂层的自修复性能增强。当潜伏型固化剂含量达到一定值时,涂层的自修复性能随着微胶囊含量的增大而增强。随着微胶囊含量的增加,涂层的电化学阻抗值增大。     

Analysis and optimization of temperature distribution in carbon fiber reinforced composite materials during microwave curing process

Vacuum assisted microwave curing technologies and modified optical sensing systems have been employed to investigate the influence of ply orientation and thickness on through-thickness temperature distribution of carbon fiber reinforced composite laminates. Two different types of epoxy systems have been studied. The results demonstrated that the ply orientation did not affect the temperature distribution of composite materials. However, the thickness was an important influencing factor. Nearly 10 °C temperature difference was found in 22.5 mm thick laminates. Through analyzing the physical mechanisms during microwave curing, the temperature difference decreased when the heat-loss in surface laminates was reduced and the absorption of microwave energy in the center laminates was improved. The maximum temperature difference of the samples formed using the modified microwave curing technologies in this research could be reduced by 79% to 2.1 °C. Compared with the 5.29 °C temperature difference of laminates using thermal heating process, the maximum temperature difference in laminates using modified microwave curing technologies was reduced by 60%, and the curing time was cut down by 25%.     

纤维增强环氧树脂复合材料抗固体颗粒流冲蚀磨损研究进展

在生产生活中,固体颗粒流冲蚀磨损会造成经济损失,并且存在安全隐患。环氧树脂复合材料具有较好的强度和耐冲蚀性能,被广泛地应用于颗粒流冲蚀磨损工况下。为进一步提升环氧树脂的耐冲蚀性能,通常通过填料来改性环氧树脂,其中纤维增强环氧树脂表现出优异的耐固体颗粒流冲蚀性能,使得环氧树脂复合材料的应用更加广阔。根据纤维的种类可以将其分为无机纤维(玻璃纤维或碳纤维)、自然纤维及混和纤维增强环氧树脂复合材料。综述了纤维增强环氧树脂复合材料抗固体颗粒流冲蚀性能的研究现状,讨论了不同的纤维增强复合材料表现出的冲蚀行为(塑性、脆性、半塑性、半脆性),重点分析和对比了不同纤维填料特性(纤维类型、纤维含量、纤维取向)增强环氧树脂复合材料在不同工况条件(冲蚀角度、冲蚀速度、磨粒特性)下的耐冲蚀磨损性能,阐明了不同纤维增强环氧复合材料的冲蚀模式和抗冲蚀机理,指出其现存的问题并展望其发展方向和前景。     

挤压熔体浸渗法制备金属涂覆碳纤维增强铝基复合材料的润湿性和力学性能改善

为了改善碳纤维与铝基体之间界面的润湿性和结合性能,采用挤压熔体浸渗法制备镍和铜涂覆碳纤维增强铝基复合材料,对两种不同涂层碳纤维增强铝基复合材料的界面润湿性、显微组织和力学性能进行比较和研究.显微组织结构分析表明,与无涂层碳纤维增强铝基复合材料相比,在相同的浸渗工艺条件下,在碳纤维表面涂覆两种金属均可以显著改善碳纤维与铝...     

海因环氧树脂固化铜尾矿的力学性能及微观结构演变（英文）

基于强度和微观试验,系统研究海因环氧树脂掺量和养护龄期对铜尾矿试样力学性能及微观结构的影响规律。结果表明,当海因环氧树脂掺量为30%(质量分数)时,固化体试样强度达到20.84 MPa。当海因环氧树脂掺量为10%(质量分数)的固化体的养护龄期为7和14 d时,其强度分别为6.33和6.67 MPa,均满足其作为基础填料和建筑材料的要求。微观试验结果表明,随着海因环氧树脂掺量的增加,团粒化作用加强,固化体孔隙减少,从而大大提高了固化体强度。     

高温蒸养对粉煤灰水泥基材料水化产物结构的影响

运用基本力学及导热系数测定实验系统对高温蒸养作用后的粉煤灰水泥基材料的抗压强度和热导率进行了试验研究,并借助于X射线衍射（XRD）、扫描电镜（SEM）和热重-差热分析（TG-DTA）等手段对水化产物的微观结构对其宏观性能的决定性机理进行了分析。结果表明：随蒸养温度的增加,粉煤灰水泥基材料的强度和保温性能均增强。钙矾石（AFt）转变为单硫型水化硫铝酸钙（AFm）,粉煤灰释放珠状的铝、硅成分形成莫来石,水化产物失水后重新结合,晶相、晶形稳定性增强是蒸养后强度及保温性能增强的主要原因。     

碳纤维复合材料在笔记本电脑外壳上的应用

介绍了短碳纤维增强复合塑料、热固性连续性碳纤维复合板材、热塑性连续性碳纤维复合板材、碳纤维复合薄膜等4种碳纤维复合材料在笔记本电脑外壳上的应用,并作出了展望。碳纤维与工程塑料、环氧树脂、PMMA等树脂复合后制备的笔记本电脑外壳,在同等强度条件下,相比传统工程塑料制备的笔记本电脑外壳,厚度可减薄50%~60%,重量减轻40%~50%,而且拥有良好的耐候性和耐腐蚀性。指出碳纤维复合材料研究的快速发展将会推动笔记本电脑市场的巨大变革,使笔记本电脑向着"更轻、更薄、更强"方向快速发展。     

汽车前地板后本体复合模压成形工艺

针对汽车前地板后本体在线复合模压成形工艺,探究采用螺杆机混合浸润挤出的LFT-D高温坯料与单向碳纤维预浸料增强片的多元复合模压过程,通过正交实验法,研究复合模压成形的主要工艺参数(入模料温、模压压力、合模速度和保压时间等)对成形缺陷的影响,结合力学性能实验进行筛选,确定出了优化后的成形工艺组合参数为:单向碳纤维预浸料增...     

Microstructural,thermal and mechanical characterization of TiB2–SiC composites doped with short carbon fibers

Spark plasma sintering method, at the temperature of 1800 °C under the pressure of 40 MPa for 7 min, was employed for fabrication of TiB₂–SiC-based composites. The influences of short carbon fiber (C_f) addition (2 wt%) on microstructural, mechanical and thermal properties of TiB₂–SiC ceramics were studied. Carbon fiber addition increased the relative density of sintered composite which observed to have direct effect on mechanical and thermal properties. The mechanical properties of composites were measured by nanoindentation method. Hardness and elastic modulus of TiB₂/SiC interfaces in carbon fiber doped composite were measured 27.1 GPa and 445 GPa, respectively, while these values were obtained 24.2 GPa and 422 GPa for carbon-free sample. The thermal diffusivity of samples was measured by laser flash technique (LFT). It was found that TiB₂–SiC–C_f composite has a higher thermal conductivity (55 w/m.K) compared to TiB₂–SiC ceramic with a value of 54.8 w/m.K.     

TiC增强Cf/SiC复合材料与钛合金钎焊接头工艺分析

采用Ag-Cu-Ti-（Ti＋C）混合粉末作钎料,在适当的工艺参数下真空钎焊Cf/SiC复合材料与钛合金,利用SEM,EDS和XRD分析接头微观组织结构,利用剪切试验检测接头力学性能.结果表明,钎焊后钎料中的钛与Cf/SiC复合材料发生反应,接头中主要包括TiC,Ti3SiC2,Ti5Si3,Ag,TiCu,Ti3Cu4和Ti2Cu等反应产物,形成石墨与钛原位合成TiC强化的致密复合连接层.TiC的形成缓解了接头的残余热应力,并且提高了接头的高温性能.接头室温、500℃和800℃高温抗剪强度分别达到145,70,39 MPa,明显高于Cf/SiC/Ag-Cu-Ti/TC4钎焊接头.     

氨基链修饰氧化石墨烯/环氧树脂界面性能的分子动力学模拟

目的 对氨基链修饰氧化石墨烯与DGEBA/3,3′-DDS环氧树脂复合材料界面的形成过程和性能进行理论研究,为环氧树脂涂层的性能改性提供理论依据.方法 利用Materials Studio 2019软件的Amorphous Cell模块建立了复合材料界面模型,采用分子动力学模拟方法对界面的结构、能量变化、界面处基团运动...     

碳纤维增强树脂基复合材料层压板冲击损伤模式的试验研究

针对两种典型的碳纤维增强树脂基复合材料（T300/5405和T700/5428）层压板进行不同能量水平的落锤冲击试验,通过对冲击后试样的外部损伤形态、内部损伤情况等的检测以及纤维/树脂微观界面剪切强度的检测,讨论了两种碳纤维复合材料层压板的冲击损伤模式。试验结果表明,当冲击载荷达到一定程度时:在T300/5405体系中,由于T300纤维拉伸强度相对较低,纤维所受作用率先达到破坏载荷,因而冲击损伤表现出以穿透性为主的破坏特征;在T700/5428体系中,由于T700纤维拉伸强度较高,尽管其微观界面剪切强度略高,但是由于冲击载荷未使纤维达到破坏载荷时已使T700/5428界面率先遭到破坏,因此表现出以分层为主的破坏特征。     

Microwave processing of adhesive joints using a temperature controlled feedback system

Previous experiments have shown that microwave curing of epoxies reduces the curing time and could lead to improvements in the mechanical properties of the cured epoxies. Precise temperature control is important as inadequate control may lead to thermal “run-away”, resulting in localized material damage. Consequently, the main objective of the present work is to use temperature for controlling the intensity of microwave radiation during the adhesive curing process. Using microwave energy delivered through a slotted waveguide at a frequency of 2.45 GHz, and with the power varied between 300 and 600 W, three engineering thermoplastics or adherends were joined by curing two types of “two-pack” epoxy adhesives. Subsequently, the bond strengths of the microwave cured samples were compared to those of the specimens cured in ambient conditions by subjecting the joined samples to shear loading. The results obtained indicate that the samples cured with microwave under a temperature feedback control protocol achieved higher bond strengths after curing for only a fraction of the time required for ambient curing. It can therefore be inferred that, with an adequate temperature control strategy, increased efficiency of curing, higher quality of adhesive joint, and improved bond strength can be achieved when joining thermoplastics.