石墨粉化学镀铜工艺的研究

在石墨粉表面化学镀铜,以解决金属-石墨复合材料制造中的界面结合力问题并提高其综合性能.由于石墨粉具有微小疏水、表面惰性的性质,对其镀铜很困难.以CuSO4为主盐,锌粉为还原剂,分别研究了4种添加剂:A(烷基苯磺酸盐)、B(烷基磺酸盐)、C(十二烷基脂肪酸盐)和D(十二烷基脂肪酸盐 醋酸钠)对石墨粉镀铜的影响.结果表明,D型添加剂最有利于石墨粉化学镀铜;扫描电镜观察镀铜石墨层发现,镀层和石墨结合良好.     

碳纳米管表面处理及其在铜基复合材料中的应用

碳纳米管因特殊结构带来的优异性能而被海内外学者广泛关注,以碳纳米管为增强相制备铜基复合材料是使铜基导体同时具有高强度和高导电性能的有效途径。然而,由于碳纳米管表面能高、表面反应活性低,碳纳米管/铜复合材料制备的过程中存在增强体分散性差和界面结合强度弱两大问题,从而阻碍了复合材料高性能的实现。在碳纳米管/铜复合材料的制备过程中,采用适当的方法对碳纳米管进行表面处理能改变碳纳米管的表面结构和反应活性,在改善碳纳米管的分散性的同时增强碳纳米管与铜基体的界面结合,从而提高碳纳米管的增强效率,保证复合材料良好的综合性能。然而,表面处理过程可能会破坏碳纳米管的结构完整性,影响碳纳米管的本征性能,进而影响其增强效果,或可能在基体中引入其他杂质,影响复合材料的导电和导热性能。因此,在进行表面处理时应综合考虑其对碳纳米管结构性能及复合材料增强作用的影响。近年来,研究者们通过优化碳纳米管表面处理工艺突破了碳纳米管/铜复合材料在制备过程的难点,在保证铜基体优异的导电、导热性能的同时,大幅提高了碳纳米管/铜复合材料的力学性能。碳纳米管表面处理工艺类型大致可分为机械球磨、化学表面改性、表面镀层和联合表面处理四类。传统的机械球磨表面处理对碳纳米管的结构破坏较大;化学表面改性又分为共价表面改性和非共价表面改性,非共价表面改性在保持碳纳米管完整的管状结构和优异性能的同时,提高了碳纳米管在溶液中的分散性,但用于复合材料制备时会给基体引入有机杂质,影响复合材料性能;共价表面改性和表面镀层是铜基复合材料制备过程中最为常用和有效的表面处理方法,其能够在提高碳纳米管在基体中的分散性能的同时改善碳纳米管表面的反应活性,从而形成碳纳米管和铜基体之间强度较高的反应结合界面,实现碳纳米管/铜复合材料高强高导的综合性能。此外,可通过综合利用各种表面处理方法,结合各表面处理工艺的优势,获得更为优异的改性效果。本文从碳纳米管表面处理工艺的基本类型以及碳纳米管表面处理对铜基复合材料结构和性能的影响两方面阐述了碳纳米管表面处理在铜基复合材料中的应用和研究进展,并对其未来的研究方向进行了展望。     

EVA/MMT-ODA+AUA纳米复合材料的制备与性能

采用复合插层剂十八烷基胺(ODA)和氨基十一烷酸(AUA)处理蒙脱土(MM T)。通过离子交换反应,复合插层剂进入了蒙脱土片层间,使蒙脱土片层间距增大。把该有机改性蒙脱土(MM T-ODA AUA)与EVA熔融共混,EVA分子链进入MM T-ODA AUA片层间使其间距进一步增大。EVA/MM T-ODA AUA纳米复合材料中的MM T片层与基体EVA之间的界面相互作用强,其复合材料的拉伸强度和撕裂强度比EVA有较大提高。由于纳米硅酸盐片层的阻隔作用,EVA/MM T-ODA AUA纳米复合材料的吸水率比EVA低。     

表面改性对螺旋碳纳米管/环氧树脂复合材料力学性能的影响

螺旋碳纳米管(HCNTs)由于其独特的三维螺旋形态及碳纳米管结构可望在新型功能和高强度复合材料领域发挥重要作用。文中研究了不同方式的HCNTs表面改性对环氧树脂复合材料力学性能的影响,并进一步分析了其强韧化机理。研究表明,通过γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)或聚乙烯亚胺(PEI)对HCNTs进行表面改性后与环氧树脂(EP)共混,能够显著提高复合材料的力学性能。KH560改性的HCNTs/EP复合材料冲击强度和拉伸强度分别提高了118. 4%与54. 1%; PEI改性的HCNTs/EP复合材料冲击强度和拉伸强度分别提高了101. 3%与70. 0%。分析认为,表面改性能够改善HCNTs与环氧树脂之间的界面相互作用,有利于两者之间的应力传递,从而使其力学性能得到进一步提高。     

基于紫外-臭氧辐射的高分子材料表面改性研究进展

随着高分子复合材料的广泛应用,界面性能成为影响其综合表现的重要因素。紫外-臭氧辐射法(UVO)是一种简单经济的表面改性工艺,可激发高分子表面分子链,从而赋予其不同于本体性能的表面特性(如表面润湿性、与其他材料的界面相容性等),也为进一步的界面偶联提供反应位点。本文首先概述了国内外学者在电子、生物医疗等领域中采用UVO工艺改性不同种类高分子材料(聚酯类高分子材料、聚烯烃高分子材料、有机硅高分子材料、合成橡胶、纺织材料)表面的研究现状及相应研究成果;在此基础上,梳理了改性高分子材料表面与不同种类硅烷偶联剂(甲基丙烯酰氧基、环氧基、氨基、巯基硅烷偶联剂)的反应条件及复合材料界面性能;最后,对UVO工艺未来可能的应用空间进行了展望。     

SiCp表面化学镀对SiCp/Al复合材料微结构及热性能影响

为了改善SiCp与Al基体之间的界面,在碱性条件下,甲醛作为还原剂,采用化学镀的方法在SiCp表面沉积铜层,然后采用无压渗透方法制备SiCp/Al复合材料。采用X射线衍射仪、3D立体视频显微镜、扫描电子显微镜来分析化学镀后SiCp和复合材料的表面、界面形貌、组织结构及物相,并通过EDS能谱对复合材料表面元素成分分析,利用激光闪光法测定复合材料导热系数。结果表明,相比酒石酸钾钠单一络合剂,采用酒石酸钾钠和EDTA-2Na组成的双络合剂的SiCp镀层更致密,且镀层未被氧化,复合材料界面结合良好,界面厚度为2.5~3μm,有AlCu2相生成,无Al4C3脆性相存在。室温下,镀铜后的复合材料热导率达到181 W/(m·K),远高于没有表面改性的复合材料热导率102 W/(m·K)。     

Ti镀层对金刚石-铜基合金复合材料界面结构和性能的作用

为了提高金刚石-铜合金复合材料的界面粘结强度,本文用差热分析(DTA)、X射线衍射分析、SEM观察及磨削试验研究了金刚石表面的Ti镀层对金刚石-铜基合金复合材料界面结构及性能的影响.结果表明,在600～1200℃镀Ti层与金刚石发生界面反应,在金刚石表面外延生成岛状TiC,从而实现了金刚石与铜基合金的冶金结合.镀Ti金刚石与铜合金的粘结强度可达8×107Pa.用镀Ti金刚石制成的铜基合金磨块对花岗岩的磨削比与不镀钛金刚石相比提高30%.     

玻璃纤维/环氧树脂复合材料与镀层界面的Ni颗粒强化工艺

针对玻璃纤维/环氧树脂复合材料与镀层结合界面强度低的问题,基于复合材料/镀层间的机械互锁原理及传统塑料基体化学镀工艺,提出通过增强颗粒的桥接作用,增加含有增强颗粒的过渡层来强化镀层界面的复合材料金属化方法。对金属化后的玻璃纤维/环氧树脂复合材料试件采用拉伸试验法测量镀层的结合强度,并通过截面和断面的显微观测,分析了增强颗粒对于镀层界面的强化机制;同时获得了玻璃纤维/环氧树脂复合材料表面粗糙度和增强颗粒质量分数对含有过渡层的镀层结合强度的影响规律。结果表明:采用上述金属化方法可以显著提高镀层的界面强度,与传统的金属化工艺制备试件相比,玻璃纤维/环氧树脂复合材料在不同表面粗糙度下,镀层结合强度平均提高161%;同时,镀层的结合强度随着增强颗粒质量分数的增加,呈现先增大后减小的趋势,当增强颗粒的质量分数为50%时,镀层的结合强度达到最大。      

化学镀法制备电磁屏蔽木材-Ni-P复合材料研究

用化学镀镍方法在落叶松木材单板表面沉积Ni-P合金制备了木材-Ni-P复合材料.用能谱(EDS)分析了镀层成分,采用扫描电镜(SEM)表征了复合材料的表面形貌,用X射线衍射研究了镀层的微结构,用低电阻测定仪和频谱仪分别测定了复合材料的表面电阻及电磁屏蔽效能,利用直拉法测定了镀层与木材的结合强度.结果表明:所得复合材料依然保持着木材的多孔性结构,表面镀层均匀;镀层为晶态结构的Ni-P合金,其中P的含量为1.53%;复合材料的表面电阻率在10-1～100Ω/cm2,电磁屏蔽效能在9 kHz～1.5 GHz的频段可达60 dB,且镀层与木材表面结合牢固.     

两种先驱体低温裂解制备石英纤维增强氮化硅复合材料

以全氢聚硅氮烷( PHPS) 和聚甲基硅氮烷( PHMS) 为陶瓷先驱体, 通过循环浸渍和600 ℃低温裂解分别制备了三维石英纤维增强氮化硅复合材料, 对比研究了复合材料的力学性能和微观结构。结果表明: 由PHPS 制备的复合材料密度为1. 83 g/ cm3 , 气孔率10 % , 弯曲强度45. 4 MPa , 材料断口平整, 纤维基体界面结合强; 而由PHMS 制备的复合材料密度仅为1. 66 g/ cm3 , 气孔率16 % , 却具有更高的弯曲强度56. 3 MPa , 材料断面较粗糙,界面结合较弱。先驱体活性不同是导致复合材料界面结合强弱及力学性能不同的主要原因。      

Preparation and Properties of Plasma Spraying Cu-Al2O3 Gradient Coatings

In order to overcome the limitations of low adhesion strength and poor thermal-shock resistance of pure ceramic coatings, Cu-Al2O3 gradient coatings were fabricated by plasma spraying. The microstructure and distribution of Cu-Al2O3 gradient coatings were analyzed. The adhesion strength, thermal-shock resistance and porosity of the coatings were tested. The results show that the composition of the gradient coatings has a gradient distribution along the thickness of coatings. As copper has a relatively low melting point and the molten copper has good wettability on the surface of Al2O3, it can be melted sufficiently and could fill the interstices and pores among the spraying particles effectively, thus improves the adhesion strength, thermal shock resistance and reduces the porosity. The adhesion strength of the gradient coating is 15.2 MPa which is two times of that of the double-layer structure coating.     

碳纤维复合板表面前处理方法对漆膜附着力的影响

为了增加碳纤维复合板表面与常用漆膜的结合力,分别采用化学氧化法、等离子体法及中车475活化液对其表面前处理后,再涂覆SG65-7035/0环氧底漆或SG64-1002/3聚氨酯底漆,并应用国家标准方法进行了相应的检测。结果表明:3种处理方式均能提高板材的表面能,均能增强其表面的润湿性和附着性,漆膜的附着力均达到4 MPa以上,环氧底漆的附着力高于聚氨酯底漆;碳纤维复合板先经打磨再经中车475活化液活化最有利于动车车体的工业化生产。     

Ultrasonic cavitation test applied to thin metallic films for assessing their adhesion with mercaptosilanes and surface roughness

Evaluating the adhesion of micrometer or nanometer thick coatings is a challenging question which concerns many application fields. This is especially true for thin films deposited on a substrate of elastic modulus higher than that of the film, or for granular coatings, that do not allow the use of common adhesion tests. Usually, applied to characterize the wear resistance of bulk materials or thick coatings, the ultrasonic cavitation test is applied here to evaluate the adhesion strength of gold and copper thin films (~200 nm) that are evaporated on a silicon substrate. The test is shown to be sensitive enough to discriminate the influence of the surface chemistry on the adhesion strength of gold and copper films. Particularly, the role of (3-mercaptopropyl)triethoxysilane as an effective adhesion promotor is demonstrated. Furthermore, the role of surface roughness of the substrate is characterized and discussed in order to get further insights on the way this parameter interferes with the ultrasonic test and determines the adhesive strength of the coating. An estimate of the adhesive strength is given on the basis of the coating delamination kinetics.     

Bond Analysis of Timber Structures Strengthened with FRP Systems

Abstract: This study focuses on the adhesion analysis of glued joints between Norway Spruce and Carbon fibre reinforced polymer (CFRP) regarding timber reinforcement. An experimental programme was carried out on two different test series to evaluate the behaviour of timber‐CFRP bonded joints. ‘Pull‐Off’ tests were achieved to evaluate the strength of the adhesion connection between materials. Two strengthening techniques [externally bonded reinforcement (EBR), near‐surface mounted (NSM)] and several composite systems (laminate, sheets and textile) were analysed. Through ‘Four Point Bending’ tests, the adhesion behaviour of timber‐CFRP joints along the fibres direction was evaluated. Three trials were performed on models strengthened with different criteria (one EBR and two NSM series), each with three different bonding lengths. The maximum anchor strength of the composite, the effective bonding length between the materials, the medium shear strength developed along the interface and the maximum composite strain for the EBR and NSM reinforcements were obtained. The experimental results were compared with equivalent values from concrete‐CFRP joints found in literature. Furthermore, the theoretical model proposed in Fib Bulletin 14 was calibrated to predict the maximum anchor strength of the composite according to its bonding length. Finally, some recommendations are proposed for the design of timber structures reinforced with CFRP systems.     

链长对炭纤维/聚芳基乙炔复合材料界面性能的影响

采用在炭纤维表面接枝含有不同链长的偶联剂的方法, 研究了链长对炭纤维/聚芳基乙炔复合材料界面性能的影响。纤维和树脂的浸润性通过纤维表面能的测定以及纤维表面能和浸润性的讨论进行了评价。通过复合材料界面剪切强度测试以及断口形貌分析对炭纤维/聚芳基乙炔复合材料的界面性能进行了研究。结果表明, 随着炭纤维表面链长的增长, 炭纤维/聚芳基乙炔复合材料的界面粘结性能随之提高。界面粘结性能的提高主要归因于接枝于炭纤维表面的偶联剂的分子链和聚芳基乙炔树脂分子链发生了物理缠结作用, 并且这种缠结作用随着纤维表面分子链的长度的增加而增强。      

埋入光纤对CFRP抗弯性能影响实验研究

埋入光纤传感器的碳纤维复合材料作为一种智能材料,集智能,耐腐蚀及比强度高等优异性能于一体而倍受关注.其应用的前提是二者的相容性.在应用中,CFRP主要承担弯曲载荷,所以在我们的实验中,仅对埋入光纤对CFRP弯曲性能的影响作研究.通过埋入不同直径光纤,不同光纤埋入方向,不同光纤涂层以及不同光纤根数等对CFRP弯曲强度影响的试验,以确定埋入光纤对CFRP弯曲性能影响的程度以及如何使之减到最小,为工程优化应用提供依据.     

Investigation into the mechanism of bacterial adhesion to hydrogel-coated surfaces

As a model for hydrogel-coated biomaterials, self-assembled monolayers of polyoxyethylene (POE) derivatives on sheets of polymeric biomaterials were prepared. The POE derivatives consisted of hydrophilic chains with different lengths and a long-chain alkyl group that served as an anchor function. The coatings obtained were analyzed with XPS and contact angle measurements showing hydrophilic chains of different lengths extending away from the surface. Bacterial adhesion was measured with a clinically relevant Klebsiella pneumoniae type strain and measurements reproduced 12 times. Bacterial adhesion decreased markedly with increasing hydrophilic chain length. Based upon these findings a new model for bacterial adhesion to hydrogel-coated surfaces is suggested: steric repulsion effects that increase with increasing chain length of grafted hydrophilic chains play an important role in bacterial adhesion to hydrogel-coated surfaces. © 1999 Kluwer Academic Publishers     

The effects of interfacial adhesion strength on the characteristics of an aluminum/CFRP hybrid beam under transverse quasi-static loading

The effects of interfacial adhesion strength on the damage behavior and energy absorption characteristics of an aluminum (Al)/carbon fiber reinforced plastic (CFRP) short square hollow section (SHS) beam under three point bending loading was investigated. An Al SHS beam was wrapped by CFRP with a [0°/+45°/90°/−45°]_n (n = 1 or 2) stacking sequence, and four gradations of interfacial adhesion strength were caused by physical or chemical changes of the Al adherend with different mechanical abrasion and optimal Argon plasma treatment. A different level of appropriate interfacial adhesion strength existed for each hybrid specimen depending on the CFRP laminate thickness to obtain the highest energy absorption capability, and this was verified by detailed observation of the failure mechanism of the hybrid specimen. The specific energy absorbed (SEA) was improved by up to 57.2% in the Al/CFRP [0°/+45°/90°/−45°]₂ SHS beam compared to the Al SHS beam without compromising the crush force efficiency (CFE).     

Rheological Behaviour for Polymer Melts and Concentrated Solutions Part Ⅲ: A New Multiple Entanglement Model to Predict the Dependence of Linear Viscoelastic Function (η_0, Ψ_(10)~0,η_(ext)~0) on the Ranges of Primary Molecular Weights and the

It is shown theoretically that the viscoelasticity of polymer melts is determined by three combining factorst they are the primary molecular weight and its distribution, the number of entanglement sites on polymer chain and the sequence distribution of constituent chains in entanglement spacings. A unified quantity for the three combing factors is the average constrained dimensional number of constituent chains in the long entanglement spacings (v). A new relation of v to the primary molecular weight and the number of testing polymers were derived from the multiple entanglement and reptation model, and a new method for determining v was proposed. The dependences of linear viscoelastic functions on the primary molecular weight and its distribution were derived by the statistical method. When Mn=6Me to 18 Me, the values of (v) can range from 3.33 to 3.70. Their values are in a good agreement with the experiment data, and it can slightjy vary with the different species of polymers and the different ranges of molecular weight of polymers     

A study on coatability of marble dust on metal substrates

Marble dust is a hazardous construction/industrial waste generated during the extraction, cutting and polishing of marble-producing rocks. The present work explores the potential of marble dust to be used as a coating material on metal substrates. For this, the high-velocity oxy-fuel (HVOF) spraying route is adopted to deposit marble dust coatings on four different metallic substrates: mild steel, inconel, aluminum, and copper. Liquefied petroleum gas is used as the fuel and nitrogen as the carrier gas while the coating deposition is performed by varying the spray distance over a range from 50 mm to 250 mm. The coating microstructure is studied using a scanning electron microscope (SEM) and the developed phases are identified using an x-ray diffractometer. The developed coatings are characterized in terms of deposition efficiency, coating thickness and adhesion strength. It is found that the coatings exhibit fairly good interfacial adhesion and thickness values that varied quite significantly with the spray distance. Maximum deposition efficiency of about 68 % is obtained for the copper substrate when the deposition is performed at a spray distance of 100 mm. This experimental investigation thus shows that despite being a waste, marble dust is eminently coatable on several metallic substrates.