Fabrication and mechanical properties of Cu-coatedwoven carbon fibers reinforced aluminum alloy composite

Cu-coatedwoven carbon fibers/aluminum alloy composite (C_f/Al) was prepared by spark plasma sintering. Microstructure and mechanical properties of the composite were investigated. Microstructure observation indicates that the interface reaction is evidently inhibited by Cu coating. Woven carbon fibers are adhered to the matrix alloy by anchor locking effect of matrix alloy immersing into the interstices between carbon fibers. Under the quasi-static and dynamic compressive conditions, the composite exhibits excellent ductility even when the strain reaches 0.8. Adding carbon fibers into ZL205A alloy has no obvious influence on compressive flow stress of the composite. The compressive true stress–true strain curves show that the composite is a strain rate insensitive material. During the tensile tests, the elongation of the composite shows a sharp increase from 4.5% to 13.5% due to the adding of woven carbon fibers. Meanwhile, the tensile strength of the composite is increased slightly from 168 MPa to 202 MPa compared to that of ZL205A alloy. The good ductility of the composite is ascribed to the cracks deflection, fibers pulling out, debonding and breakage mechanisms.     

Galvanic Corrosion and Mechanical Behavior of Fiber Metal Laminates of Metallic Glass and Carbon Fiber Composites

The possibility of galvanic corrosion typically prohibits the pairing of carbon fiber and aluminum in a fiber metal laminate (FML). In this study, the authors describe a new type of FML comprised of alternating layers of bulk metallic glass (BMG) and carbon fiber reinforced polymer (CFRP) composite. The authors compare the galvanic coupling and mechanical behavior of an Al‐based FML and a BMG‐CFRP FML. Results show that when paired with CFRPs, BMG exhibits far less galvanic corrosion than aluminum paired with CFRP. In fact, the corrosion between BMG and CFRP is similar in magnitude to the corrosion between aluminum and glass fiber, the two constituent materials of GLARE, the most widely used FML. While interlaminar shear strength and flexural strength are similar for both FML types, the tensile strength and modulus of BMG‐based FMLs are greater than those of Al‐based FMLs.

     

纤维涂层法制备SiCf/Cu复合材料及其性能分析

为研究纤维涂层法制备SiCf/Cu复合材料的性能特点,通过磁控溅射法先后将Ti6Al4V界面改性层和基体Cu涂层涂覆到SiC纤维表面,并通过真空热压法将被涂覆的纤维制备成SiCf/Cu复合材料.对Ti6Al4V涂层、Cu涂层以及复合材料进行了微观分析,并测试了复合材料的拉伸强度.研究表明,复合材料的Cu基体由致密而细小的晶粒组成;Ti6Al4V提高了纤维/基体界面结合强度,复合材料轴向抗拉强度高达500 MPa,界面脱粘主要发生在纤维表面的碳涂层与纤维之间.     

化学气相浸渗2D Cf/(SiC-C)复合材料的微观结构与强韧性

采用等温等压化学气相浸渗法(ICVI)制备了二维碳纤维增韧碳化硅碳二元基复合材料(2D C_f/(SiC-C)).利用扫描电镜(SEM)和背散射电子成像(BSE)研究了其基体的微观结构, 并与二维碳纤维增韧碳化硅陶瓷基复合材料(2D C_f/SiC)比较了室温力学性能和断口形貌.结果表明：2D C_f/(SiC-C)复合材料的基体是由SiC与热解碳(PyC)组成的多层结构, PyC基体层分布均匀而连续, 且与SiC基体层结合紧密.纤维束内部PyC基体层较厚的2D C_f/(SiC-C)复合材料具有较高的强韧性, 其拉伸强度、断裂应变、断裂韧性和断裂功分别比2D C_f/SiC复合材料的提高了3%、142%、22%和58%.SiC与PyC组成的多层基体使2D C_f/(SiC-C)复合材料的纤维在拔出过程中发生了两次集中拔出, 且第一次集中拔出的纤维对复合材料的强韧性起主要作用.     

Microstructure and mechanical properties of graphite fiber-reinforced high-purity aluminum matrix composite

Industrial pure aluminum (0.5 wt% impurity elements) was utilized in many investigations of aluminum matrix composites at home and abroad. However, impurity elements in industrial pure aluminum may influence the interface during fabrication of composite at high temperature. Thereby, it is necessary to use high-purity aluminum (impurity elements less than 0.01%) as matrix to enable study the interface reaction between reinforcement and matrix. In this study, stretches of brittle Al₄C₃ at the fiber/matrix interfaces in Gr_f/Al composite were observed. The fracture surface of the composite after tensile and bending tests was flat with no fiber pull-out, which revealed characteristic of brittle fracture. This was related to Al₄C₃, as this brittle phase may break before the fiber during loading and become a crack initiation point, while the corresponding crack may propagate in the fiber and the surrounding aluminum matrix, finally resulting in low stress fracture of composites.     

Tensile behavior of carbon fiber bundles at different strain rates

Quasi-static and high strain rate tensile tests have been performed on T700 carbon fiber bundles and complete stress-strain curves at the strain rate range of 0.001 s^− 1 to 1300 s^− 1 were obtained. Results show that strain rate has negligible effect on both ultimate strength and failure strain, and T700 carbon fiber can be regarded as strain rate insensitive materials. On the basis of the fiber bundles model and the statistic theory of fiber strength, a damage constitutive model based on Weibull distribution function has been developed to describe tensile behavior of T700 fiber bundles. And the method to determine the statistic parameters of fibers by tensile tests of fiber bundles is established, too.     

应变率对T300/Al(L2)复合丝拉伸性能的影响

利用MTS810试验机和自行研制的冲击拉伸试验装置对T300／Al复合丝实施了不同应变率下的拉伸试验,获得了材料从0．001s^-1到1300s^-1应变率范围内完整的应力应变曲线。结果表明：T300／Al是一种应变率敏感复合材料,随着应变率的提高,材料的拉伸强度、失稳应变均相应提高,具有明显的应变率强化效应和动态韧性现象,这主要是由铝基体的应变率强化效应和应变率历史效应引起的。根据材料在不同应变率下的试验结果以及对其不同变形阶段机理的分析,提出了弹塑性复合丝束模型,并由此建立了相应的应变率相关的一维统计损伤本构方程,模型拟合结果与试验结果一致。     

Study on graphite fiber and Ti particle reinforced Al composite

Graphite fiber and Ti particle-reinforced aluminum matrix composite were produced by squeeze casting technology. A small amount of needle aluminum carbide at graphite fiber and Al interface was observed, and TiAl₃ intermetallic compound at Ti particle and Al interface was detected. Tensile strength and bending strength of the composite have been measured. The fracture surface of the composite after tensile and bending tests was observed; graphite fiber-reinforced Al was brittle fracture, whereas Ti particle-reinforced Al was ductile fracture. The corresponding fracture mechanism was discussed.     

Orthogonal experimental design applied for wear characterization of aluminum/C<Subscript>sf</Subscript> metal composite fabricated by the thixomixing method

High silicon content aluminum alloy (hypereutectic) possess good tribological characteristics with low coefficients of friction, when embedded with short carbon fiber (C_sf), making this composite a good material choice where good wear and high strength properties are required in light weight components. There is no previously published information available, to the knowledge of the authors, regarding the influence of wear parameters and their interactions on the tribological behavior of C_sf reinforced metal matrix composites. In this study a Taguchi design of experiment (DoE) was conducted to optimize and analyze the effects of the wear parameters on the tribological properties of Al/C_sf metal matrix composite. A novel thixomixing method which was used to process the metal within the semisolid state was employed to embed short carbon fibers homogenously into the metal matrix. The influences of the sliding speed, applied load and volume fraction, of C_sf on the specific wear rate and coefficient of friction were examined, with each of these input parameters tested at three levels(0, 4.2, 8.1%vol.). The results were indicated that Al/C_sf composite had better tribological properties than Al alloy due to which contains carbon as solid lubricant. According to the statistical analysis, the influence of volume fraction of carbon fiber on wear parameters was ranked first; so the load and sliding speed are at the following rankings. The contribution percentage for each parameter was determined by the analysis of variance. The relatively good interfacial adherence of carbon fiber and matrix alloy were demonstrated. The coherent and adherent graphite-rich layer on the worn surface was characterized using scanning electron microscopy (SEM).     

Process and mechanical properties of carbon/carbon–silicon carbide composite reinforced with carbon nanotubes grown in situ

A hierarchical C_f/C–SiC composite was fabricated via in situ growth of carbon nanotubes (CNTs) on fiber cloths following polymer impregnation and pyrolysis process. The effects of CNTs grown in situ on mechanical properties of the composite, such as flexural strength, fracture toughness, crack propagation behavior and interfacial bonding strength, were evaluated. Fiber push-out test showed that the interfacial bonding strength between fiber and matrix was enhanced by CNTs grown in situ. The propagation of cracks into and in fiber bundles was impeded, which results in decreased crack density and a “pull-out of fiber bundle” failure mode. The flexural strength was increased while the fracture toughness was not improved significantly due to the decreased crack density and few interfacial debonding between fiber and matrix, although the local toughness can be improved by the pull-out of CNTs.     

Effect of strain rate on tensile behavior of carbon fiber reinforced aluminum laminates

In this paper, the tensile behavior of carbon fiber reinforced aluminum laminates (CRALL) has been determined at a strain rate range from 0.001 s^− 1 to 1200 s^− 1. Experimental results show that CRALL composite is a strain rate sensitive material, and the tensile strength and failure strain both increased with increasing strain rate. A linear strain hardening model has been combined with Weibull distribution function to establish a constitutive equation for CRALL at different strain rates. The analysis of the model shows that the Weibull scale parameter, σ₀, increased with increasing strain rate, but Weibull shape parameter, β, can be regarded as a constant.     

Influence of strain amplitude on damping property of aluminum foams reinforced with copper-coated carbon fibers

Aluminum foams containing 0.35, 1.0, 1.7 vol.% copper-coated carbon fibers were fabricated by a melt route. The room temperature damping property of Al/C_f foam was studied at different strain amplitude in two directions. The experimental results show that the critical strain amplitude decreases and the damping capacity of Al/C_f foam increases with the copper-coated carbon fibers contents. It can be attributed to the interfacial micro-slip increasing with the C_f contents and the microplasticity deformation arises from the micro-crack among the C_f–Al interface. Moreover, the damping property in the transverse direction is higher than that in the longitudinal direction. The ratio of longitudinal loss factor to transverse loss factor is almost independent of the C_f contents and strain amplitude.     

The Experimental Study of the Strain-Rate Dependence of a Unidirectional Reinforced Gr/Al Metal Matrix Composite

Loading and loading-unloading tests of a unidirectional reinforced Gr/Al metal matrix composite have been carried out using a self-designed tensile impact apparatus, and quasi-static tensile tests have been performed on the Shimadzu-5000 testing apparatus. The stress/strain curves of composites have been obtained in strain rate range from 0. 0005 s^{– 1} to 1300 s^–1. The experimental results show that complete stress/strain curves of the material can be divided into two parts: the nonlinear elastic brittle deformation and residual deformation. The tests results also clearly indicate that the Gr/Al composite is a rate-sensitive material; namely the strength, failure strain and residual strength of composite all depend on strain rate. Statistical analysis and models were used to obtain the mechanical parameters for composites and their relationship with strain rate from experimental results. The simulated stress/strain curves from the model are in good agreement with the test data. The theoretical model and test results show that the shape parameter and the scale parameter ₀ are both independent of strain rate. The constituent, Gr fibers in Gr/Al composites, can be regarded as a rate-insensitive material, and the strain rate effect of Gr/Al composites is mainly caused by the Al alloy matrix.     

碳纤维/铝复层材料的组织和力学性能

在1060系铝基体表面镀镍碳纤维作为增强体,进行真空热压扩散制备出碳纤维/铝复层材料。研究了制备工艺参数(加热温度、保温时间、压力大小)和碳纤维体积分数对碳纤维/铝复层材料的微观组织、界面结合、性能强度和断口形貌的影响。结果表明：碳纤维与铝基体界面结合良好,镀镍层与铝基体在碳纤维附近反应生成的Al₃Ni阻止了铝基体与碳纤维之间生成脆性相Al₄C。随着碳纤维体积分数的提高,材料的抗弯强度先提高后降低。     

一种碳纤维织物增强复合材料的层间冲击拉伸力学性能实验研究

为获得一种碳纤维二维正交平纹机织布增强树脂基复合材料准静态和动态下的层间拉伸力学性能,对垂直于碳布平面方向 ( 横向),分别利用Instron试验机和SHTB实验技术,进行了准静态拉伸和动态拉伸实验。得到了从低应变率 (10-3/s) 到较高应变率 (约3×102/s) 下的拉伸应力-应变曲线和拉伸强度。通过分析发现,拉伸破坏总是发生在相邻铺层的层间界面处,层间拉伸模量和拉伸强度都具有一定的应变率强化效应,但是层间拉伸破坏应变几乎不存在应变率效应。      

Fabrication of multi-walled carbon nanotube-reinforced carbon fiber/silicon carbide composites by polymer infiltration and pyrolysis process

Multi-walled carbon nanotube (MWNT)-reinforced carbon fiber/silicon carbide (C_f/SiC) composites were prepared using a polymer infiltration and pyrolysis (PIP) process. The MWNTs used in this study were modified using a chemical treatment. The MWNTs were found to be well dispersed in the matrix after ultrasonic dispersion, and the mechanical properties of the C_f/SiC composite were significantly improved by the addition of MWNTs. The addition of 1.5 wt.% of MWNTs to the C_f/SiC composite led to a 29.7% increase in the flexural strength, and a 27.9% increase in the fracture toughness.     

Optimal fiber distribution for tensile properties of injection molded composite

The survival rate of a composite is the residual fiber length divided by the initial fiber length, and it decreases with the initial fiber length and fiber volume content (V_f) during injection molding processes. The degree of damage is higher for carbon fiber than for glass fiber, and the survival rate increases with a hyperbolic tangent relationship as the nozzle diameter increases. Higher survival rate corresponds to a stronger material. Five different lengths of fiber with 29 different size fibers were selected based on the distribution and shape of residual fiber in experimental works. These were examined to study the effects of fiber distribution on the tensile properties of a short-fiber reinforced composite (SFRC). Compared with the experimental results, the modulus predicted using the Halpin-Tsai relation shows reasonable agreement with the prediction obtained using the residual fiber length instead of the initial fiber length. It was found that the tensile modulus and strength generally differ by a factor of up to 3.2, depending on the fiber distribution patterns with V_f = 30%, and the trend is more significant as the fiber aspect ratio increases. The interactions between the fiber and matrix and the staggered-type distribution are the most important factors in the reinforcement of the SFRC. With the same combination of short fiber length, an optimized fiber distribution pattern is suggested.     

碳纤维静、动态加载下拉伸力学性能的试验研究

利用岛津试验机和自行研制的旋转盘式击拉伸试验装置,对Ｔ３００和Ｍ４０Ｊ两种碳纤维实施了应变速率范围为０．００１－１３００ｓ＾－１的静、动态拉伸试验,获得了两种材料在不同应变速率下的完整的应力变曲线。     

碳(石墨)/铝复合材料的高温拉伸强度

本文初步研究了C/LD₂和M40/LD₂复合材料高温拉伸强度。在室温至400℃温度范围内,C/LD₂和M40/LD₂均能保持其室温强度。在500℃时C/LD₂的强度保持率为84.10%。      

Effect of strain rate on the mechanical behaviors of SiC fiber

In the present paper, tensile experiments of SiC fiber bundles under different strain rates (quasi-static: 10^–4–10^–3 s^–1, dynamic: 200–1200 s^–1) are carried out and the corresponding stress-strain curves are obtained. It is found that the mechanical properties of SiC fiber bundles are rate-dependent: the elastic modulus E, strength _b and the failure strain _b remain unchanged under quasi-static condition, while they apparently increase with increasing strain rate under dynamic condition. Based on the fiber bundles model and the statistical theory of fiber strength, a bi-modal Weibull statistical model of the strain rate dependence is adopted to describe the strength distribution of SiC fiber, and the Weibull parameters are obtained by the fiber bundles testing method. Consistency between the simulated and experimental results indicates that the model and the method are valid and reliable.