碳纤维表面复合镀镍研究

采用电镀法在碳纤维表面沉积一层纯Ni镀层,然后将纤维剪短,采用化学镀法使短纤维表面以及两端包覆一层Ni-P合金镀层,并使纤维表面金属层加厚,来满足保护纤维的需要.通过不同正交体系研究碳纤维增重率,得到了优化的镀镍工艺.观察了镀层的表面形貌,测试了镀层的结合力,并对镀层的成分进行了分析.结果表明,纤维表面镀层均匀、致密、表面光亮和结合力强;电镀获得了纯Ni镀层,而复合镀获得了Ni-P合金镀层.     

纤维涂层处理SiCf/SiC复合材料

分别采用酚醛和沥青为先驱体,在连续SiC纤维表面进行涂层制备,采用SEM、表面能谱等分析手段系统研究了涂层组成、结构及其对SiC纤维力学性能的影响.以含碳涂层的SiC纤维和聚碳硅烷(PCS)为原料通过先驱体转化法(PIP)制备SiCf/SiC复合材料,对其微观结构及性能进行了表征.结果表明,经过涂层处理后,在连续SiC纤维表面涂敷了一层无定形碳,纤维表面缺陷得到改善,抗拉强度有所提高.采用碳涂层SiC纤维制备SiCk/SiC复合材料后,断裂韧性明显提高.通过涂层处理有效地改善了SiCf/SiC复合材料的韧性.     

控制含钇碳化硅纤维直径及纤维性能

通过乙酰丙酮钇与聚碳硅烷反应,得到分子量适中(Mw=2816)、GPC曲线呈双峰分布、具有优异可纺性的新型先驱体含钇聚碳硅烷,在控制纺丝温度和压力后,得到表面光滑、无裂纹、直径为5.3 μm的原纤维.讨论了原纤维直径对纤维制备工艺及性能的影响.降低纤维直径,有利于减少纤维缺陷,提高纤维强度和柔顺性.当纤维直径为6.20 μm时,抗张强度为3.52 GPa,且随直径减小,抗张强度呈线性增长趋势,为制备新型含异质元素耐超高温SiC纤维奠定了基础.     

PET纤维表面化学镀镍工艺及其性能研究

在超声波作用下对涤纶(PET)纤维表面进行预处理,并对化学镀镍工艺进行了实验研究,确定了最佳的工艺参数,讨论了镀液成分和工艺条件对镀层沉积速度的影响.实验表明,该实验条件下在PET纤维表面化学镀镍可以得到理想的镍镀层,镀镍纤维具有良好的耐热性和导电性.     

表面涂碳及复合材料制备对SiC纤维性能的影响

采用化学气相沉积法对SiC(W芯)纤维进行表面涂碳处理,分别用未涂碳SiC纤维和涂碳SiC纤维作为增强体,通过真空热压制备了SiC/Ti-6Al-4V复合材料,然后从复合材料中萃取出SiC纤维.拉伸实验表明,纤维表面涂碳有效地增加了SiC纤维的抗拉强度,但萃取出的SiC纤维强度明显降低.统计研究表明,SiC纤维的强度服从威布尔分布,碳涂层使纤维的威布尔模数增大但复合材料制备降低了威布尔模数.扫描电镜观察证明SiC纤维的断口呈现出明显的脆性断裂特征,涂碳处理明显减少了SiC纤维的表面缺陷,从而提高了其强度,减少了强度分散性,涂碳处理还可以减少Ti基复合材料制备过程中对纤维表面的损伤.     

碳纤维和芳纶纤维的蚀刻改性及其复合材料界面结合性能研究进展

纤维作为复合材料中的增强体,在实现应力传递、承担外部载荷等方面发挥了重要作用.通常纤维与树脂基体的结合性能极大地取决于纤维表面的微观形貌和化学性质,其界面结合的强度则决定了复合材料的综合性能和应用范围.为了最大提升纤维材料与树脂基体的界面结合能力,在应用前需对纤维材料进行有效的表面改性处理.其中,蚀刻法同时涉及了纤维表面的物理变化和化学变化,具有高效的表面改性能力,能显著地改变纤维表面的物理化学性质.综述了表面蚀刻这一改性思路分别在碳纤维和芳纶纤维中的实际应用,针对两种纤维各自的性质,提出了酸性溶液蚀刻、有机溶液蚀刻、电化学阳极氧化、等离子体处理、微波辐射、超声波蚀刻等常用蚀刻改性方法,对各方法的优缺点和应用进行了讨论.总结并对比了蚀刻介质、蚀刻工艺对纤维表面微观形貌、化学性质、力学性能以及复合材料界面结合性能等方面的影响.讨论了当前纤维材料与树脂基体界面结合的机理与界面表征方法的研究现状.此外,还对未来的发展方向和要求进行了展望,提出应该聚焦纤维表面腐蚀行为,优化传统改性方法,开发多种方法协同作用的改性新工艺.同时基于现有技术,发展更为先进的界面表征手段,进一步加深对纤维表面腐蚀行为与复合材料界面性能之间影响机制的理解.     

高比表面积氧化锌纳米线的制备

以聚乙烯吡咯烷酮作为络合剂与醋酸锌混合,并且加入适当催化剂,制得纺丝液.采用静电纺丝的方法,制得聚乙烯吡咯烷酮/醋酸锌复合纤维,通过热处理得到氧化锌纤维.对所制得的纤维成分、形貌、晶粒大小,分别采用X射线粉末衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)等分析测试手段进行表征.实验结果表明,500 ℃下煅烧得到表面粗糙、充满细小管道的纯氧化锌纳米纤维,平均晶粒尺寸5 nm,拥有超高比表面积.     

原位反应法制备的碳化硅涂层/三维编织碳纤维的氧化性能研究

采用原位反应法在三维编织碳纤维(原纤维)表面制得β-SiC涂层,通过XRD,SEM,等温氧化失重和非等温热重分析等测试手段研究了制备方法对涂层性能的影响.结果表明:利用此法可得到均匀、完整,界面结合良好的涂层,涂层厚度增加,涂层/三维编织碳纤维(复合纤维)抗氧化性能增强.并对复合纤维氧化反应的机理进行了研究.     

SiC纤维表面电镀铜的研究

分别研究了在SiC纤维表面直接硫酸盐镀铜,以及在SiC纤维表面溅射沉积约为1.5μm厚的Ti6Al4V合金后再进行硫酸盐镀铜的工艺,并测试了镀铜纤维的抗拉强度,利用扫描电镜(SEM)观察了镀层表面及断口形貌.研究结果表明:适当的前处理可使纤维表面均匀、连续地镀上铜;电流密度越小,镀铜纤维的抗拉强度越高,镀层中的孔隙越小,晶粒堆积得越紧密.实际应用时采用1～2 A·dm-2的电流密度较好.     

PBO纤维表面改性处理的研究进展

聚对苯撑苯并二噁唑(PBO)纤维因其比强度高、比模量高、耐热性好、阻燃性好以及优异的介电性能,现已在安全防护、建筑汽车等领域得到广泛应用。由于PBO纤维表面光滑、化学惰性,导致其与基体树脂界面结合差,进一步影响复合材料的整体性能,这大大限制了PBO纤维优异综合性能的发挥,所以对PBO纤维表面进行改性处理显得尤为重要。介绍了近年来国内外针对PBO纤维不同表面改性方法及对应复合材料性能改善程度的研究进展,从PBO纤维改性方法的分类入手,阐述了各种方法的基本原理。通过对这些处理方法的比较,阐述了国内PBO纤维表面改性的研究进展,指出了国内外在PBO纤维表面改性处理上的差距,为未来的发展方向提供了参考。PBO纤维表面改性方法包括化学刻蚀法、等离子体处理、表面涂层法、化学接枝法、紫外刻蚀法、上浆剂处理等。各种改性技术各有利弊,在选择改性方法时,理应考虑达到工艺快捷有效、经济环保和无损纤维性能等指标。未来,在PBO纤维表面改性的处理方法领域,将逐步向绿色环保的上浆剂处理方向发展。     

复合材料用碳纤维等离子体表面改性技术进展

近年来复合材料得到了广泛的应用,尤其在航空工业领域,已成为了世界强国竞相发展的核心技术。碳纤维树脂基复合材料作为复合材料中的优秀代表,由于其独特的性能优势,具有很大的发展潜力,但是界面结合强度是制约其应用的关键瓶颈。等离子体表面改性技术能提高碳纤维与树脂基的界面结合强度。总结了国内外学者工作,从等离子体处理装备发展和工艺参数影响两个角度对碳纤维等离子体表面改性技术的研究进展进行了阐述。在装备发展方面,重点介绍了在碳纤维表面处理研究中三类处理装置,包括射频等离子体处理装置、DBD等离子体处理装置和滑动弧射流等离子体处理装置,分析了各自的优缺点。在工艺参数方面,重点介绍了不同等离子体种类、等离子体处理时间、等离子体放电功率对碳纤维表面状态的影响规律。在此基础上,对碳纤维等离子体表面处理技术的未来发展方向进行了展望。     

Optimization of the injection molding process of short glass fiber reinforced polycarbonate composites using grey relational analysis

This paper presents a fast and effective methodology for the optimization of the injection molding process parameters of short glass fiber reinforced polycarbonate composites. Various injection molding parameters, such as filling time, melt temperature, mold temperature and ram speed were considered. The methodology combines the use of the GRA (grey relational analysis) method and a CAE flow simulation software, to simulate the injection molding process and to predict the fiber orientation. This method can replace the traditional “change-one-parameter-at-a-time” approach, which is very inefficient, costly, time consuming and almost impracticable to yield an optimum solution. At the same time, the fiber orientation was examined by CAE simulation to forecast the shear layer thickness, and simultaneously to check the accuracy of the GRA. The results indicated that three distinct layers (a frozen layer, a shear layer and a core layer) are observed from the surface to the core for various injection molding conditions. The fiber orientation is perpendicular to the melt flow direction in the frozen layer and the core layer, but it has the opposite direction in the shear layer. From the CAE analysis, the optimum process parameters to obtain the thickest shear layer are found, which is the target of the present research.     

The effect of polypyrrole coatings on the adhesion and structure properties of UHMWPE fiber

To improve the adhesion between ultrahigh molecular weight polyethylene (UHMWPE) fiber and polymer matrix, pyrrole is oxidatively polymerized on the UHMWPE fiber surface continuously. The micro-composite of polypyrrole (PPy)-coated fiber/epoxy was prepared and the fiber was studied by interfacial shear strength (IFSS) through a single fiber pull-out method. Compared with the UHMWPE fiber as-received, the mean value of IFSS between PPy-coated UHMWPE and epoxy increased from 1.06 MPa to 5.72 MPa. In addition, the surface morphology and structure of PPy-coated UHMWPE fiber were studied by SEM, FT-IR, DSC and DMA. The results showed that PPy-coated UHMWPE fiber surface was observed with some particles attached. Although there is no chemical interaction between PPy and UHMWPE chains, PPy has some interaction with UHMWPE molecular chains according to the results of DMA. The PPy coatings have an effect on the adhesion may be associated with the roughened surface of the fiber and upon intermolecular interaction.     

汽车同步器齿环摩擦材料碳纤维表面结构分析

汽车同步器齿环摩擦材料是一个复杂的复合体系,填料加入的数量能够明显地影响其加工和使用性能.为了表征该配方体系中所使用的主要填料碳纤维表面存在的基团种类和数量,从而研究碳纤维与酚醛树脂的相溶性、粘接性等性能.采用扫描电镜(SEM)、X射线衍射及X光光电子能谱(XPS)等表征方法,分析了碳纤维表面结构.结果表明:汽车同步器齿环摩擦材料所选用的碳纤维增强材料为非结晶结构,表面含有C、O、N、Si等元素,是PAN基碳纤维,在碳骨架的表面含有C=O及C-O-C极性基团,另有少量杂质SiO2.结论为:碳纤维表面极性基团的存在有利于碳纤维与酚醛树脂基体的粘接,提高摩擦材料的综合性能.     

Influence of corrosion on the interface between zinc phosphate steel fiber and cement

The interface bond between steel fibers and concrete matrix is a key factor influencing bearing capacity of steel fiber reinforced concrete (SFRC). In order to improve the interface bond strength and corrosion resistance, a kind of method was put forward by depositing zinc phosphate (ZnPh) coating on steel fiber surface in this paper. The corrosion behavior was investigated in 5% NaCl solution by using linear polarization measurement. Microstructure analysis (SEM and EDX) and fiber pull‐out test in combination with linear polarization measurement were carried out. The results prove that ZnPh coatings fabricated on the carbon steel surface can not only protect steel fiber against corrosion, but also enhance the mechanical interlocking bonds between fibers and matrix.     

铝硅基复合材料中硅相形貌研究

在金相显微镜和扫描电子显微镜上观察和研究了氧化铝／铝硅合金复合材料中的硅相形貌。结果表明氧化铝纤维与硅相之间存在共格界面,可作为硅相非自发形核的衬底;复合材料中的初生硅可在纤维表面形核生长为颗粒状;复合材料中的纤维在铝硅共晶体的共生生长过程中,可触发孪晶,导致纤维附近的共晶硅呈变质形态。     

Microstructure of carbon fiber preform and distribution of pyrolytic carbon by chemical vapor infiltration

The carbon/carbon composites were made by chemical vapor infiltration(CVI) with needled felt preform. The distribution of the pyrolytic carbon in the carbon fiber preform was studied by polarized light microscope (PLM) and scanning electronic microscope(SEM). The experimental results indicate that the amount of pyrolytic carbon deposited on the surface of chopped carbon fiber is more than that on the surface of long carbon fiber. The reason is the different porosity between the layer of chopped carbon fiber and long carbon fiber. The carbon precursor gas which passes through the part of chopped carbon fibers decomposes and deposits on the surface of chopped carbon fiber. The pyrolytic carbon on the surface of long carbon fibers is produced by the carbon precursor gas diffusing from the chopped fiber and the Z-d fiber. Uniform pore distribution and porosity in preform are necessary for producing C/C composites with high properties.     

Chemical and mechanical alterations of SiC Nicalon fiber properties during the CVD/CVI process for boron nitride

To improve the interfacial properties in SiC/SiC composites, BN is an appropriate interphase material to control the fiber/matrix bond. Unfortunately, the gaseous phase (NH₃,BF₃,HF,Ar) used to deposit BN acts aggressively upon Si–C–O (ex-PCS) Nicalon fiber surfaces, and weakens that bond through the formation of a complex interfacial sequence (SiO₂/C), which actually controls the localization of debonds. The reactions between each gas involved and the fiber surface have been studied. Further, if the fiber surface consists of SiC or any silicon-containing compound, the BF₃ gas reacts through a substitution of the silicon by boron in the initial fiber composition. Then, the surface evolves from a (C,O,Si) composition to a (B,C,O,Si) glassy layer. Such a reaction occurs mainly before the BN nucleation, and it alters the reinforcing potential of fibers in composites. This boron-containing glass is shown to be very unstable in the presence of HF gas (the main reaction product).