Fiber Reinforced Copper Matrix Composites Research Articles

Effect of tungsten carbide interface decoration on thermal and mechanical properties of carbon fiber reinforced copper matrix composites

The use of carbon fiber (CF)/copper (Cu) composites as thermal management materials shows significant promise. However, inadequate interface bonding hinders their thermal properties. This study introduces a novel method to create tungsten carbide–coated CFs (CF(WC)) using the molten salt method. These coated fibers are then used to develop a CF(WC)/Cu composite through vacuum hot-pressing sintering. Results reveal that the WC coating, formed at 1100 ℃ for 60 min with a tungsten trioxide/CF molar ratio of 1/10, is continuous, crack-free, and has an appropriate thickness. The WC coating facilitates excellent interface bonding between Cu and CF, thus effectively improving the initial poor interface bonding. With similar 50 % fiber content, the CF(WC)/Cu composite exhibits better thermal and mechanical properties than the CF/Cu composite. The in-plane direction thermal conductivity and bending strength of the CF(WC)/Cu composite are 398.7 ± 8.1 W m−1 K−1 and 195.3 ± 6.2 MPa, which are 35.3 % and 90.4 % higher, respectively, than those of the CF/Cu composite. Additionally, the in-plane direction coefficient of thermal expansion is 6.5 ± 0.3 × 10−6 K−1, representing a notable reduction of 37.5 %. These exceptional properties, coupled with the simplicity and efficacy of the preparation process, offer valuable insights for the advancement of carbon/Cu thermal management materials.

Flow induced fiber orientation in short carbon fiber reinforced copper matrix composites

This study investigated the effect of a distinctive design of mold to align short carbon fiber in copper matrix composite produced via metal injection molding. The mold was designed to improve the fiber orientation during flow in the core region of test samples. The composite feedstocks comprising polymeric binder and Cu powder reinforced with 0, 5 and 10 vol. % carbon fiber, prepared in Z-blade mixer, were injection molded to fabricate green samples. Green samples were debound to remove the binder and sintered in sintering furnace at 1050 °C in Argon atmosphere. Dispersion of carbon fibers was examined in composite feedstocks and TGA was used to determine the degradation temperature of binder. Uniform dispersion of carbon fibers was observed in compounded feedstocks, green and sintered samples. Fiber orientation was quantified at various locations of skin and core of the green and sintered samples. Quantification of fiber orientation showed the best value of more than 90% of short fibers aligned in green test samples whereas sintered samples demonstrated just above 70% of fiber alignment in the flow direction in Cu-10%CF at section N. Overall, the results showed fiber alignment within ±22.5° in both green and sintered samples without significant skin-core effect. Moreover, the calculated mechanical properties increased with an increase in alignment of carbon fiber in the Cu matrix. Conclusively, fiber alignment can be improved by controlling flow of molten feedstock during molding with potentially high mechanical properties of composite.

Effect of fiber alignment on mechanical properties of chopped graphite fiber-reinforced copper-matrix composites: Designing fiber alignment in various stress conditions

Carbon-reinforced copper-matrix composites must provide improved mechanical properties if used as a structural part of machinery. However, little research has been conducted on the effect of the alignment of graphite fibers (GFs) with a high aspect ratio on the mechanical properties of composites. In this work, the effects of the alignment and volume fraction of GFs on the mechanical properties of GF/Cu composites subjected to tensile and compressive loading were analyzed and compared. The yield strength was highest when the composite with a GF volume fraction of 5% was subjected to compressive loading in the through-plane direction. The yield strength during tensile deformation was higher in the in-plane direction than in the through-plane direction. However, during compression testing, the yield strength was higher in the through-plane direction. Thus, the effects of the alignment and volume fraction of GFs on the tensile and compressive deformation behaviors of GF/Cu composites were revealed. These results are expected to provide a practical guide for optimizing the mechanical properties of GF/Cu composites subjected to various stress conditions as materials for the structural parts of machinery.

Flow Induced Fiber Orientation in Short Carbon Fiber Reinforced Copper Matrix Composites

Flow Induced Fiber Orientation in Short Carbon Fiber Reinforced Copper Matrix Composites

Cyclic plastic behavior of unidirectional SiC fibre-reinforced copper composites under uniaxial loads: An experimental and computational study

Silicon carbide continuous fiber-reinforced copper matrix composites (Cu/SiCf) offer huge potential as heat sink material for high-heat-flux applications at elevated temperatures (>300 °C) owing to the beneficial combination of strong, stiff and refractory SiC fibers with a highly conductive and ductile copper matrix. As high-heat-flux components are normally subjected to large temperature fluctuations combined with thermal strain variations, degradation of the Cu/SiCf composites caused by fatigue damages under cyclic loads may affect the structural integrity of the component. In this study, the robustness of the Cu/SiCf composites under cyclic loads at different temperatures was evaluated by means of uniaxial cyclic loading tests. The stability of the cyclic deformation hysteresis curves was used as a measure of material’s durability. The experimentally observed global deformation behavior was interpreted with the help of a micromechanics-based theoretical model. It was shown that the Mori-Tanaka type mean field theory could describe the cyclic loading behavior of the composite quite well with a good fitting quality between the measured and simulated saturated cyclic curves. The effects of fiber content, applied strain range and test temperature are discussed.

Impact of long-term thermal exposure on a SiC fiber-reinforced copper matrix composite

Silicon carbide long fiber-reinforced copper matrix composites offer huge potential as a heat sink material of divertor for applications at temperatures above 300°C thanks to the beneficial combination of strong ceramic fibers and highly conductive copper. For applications at higher operation temperatures, long term thermal stability is an issue, as thermal exposure may cause a detrimental change in microstructure in terms of chemistry and integrity of the constituents leading to overall deterioration of composite strength. The aim of this study is to investigate the impact of long term thermal exposure at an elevated temperature on a Cu/SiCf composite material. To this end, composite samples were fabricated and subjected to a heat treatment at 550°C for 400h. Extensive tensile tests were conducted for a wide range of fibers volume fractions to evaluate the strength before and after the heat treatment. Acoustic emission was detected in situ during tensile tests for tracking the failure events. Microscopic analysis was carried out to capture the chemical change and damage. It turned out that the applied heat treatment caused significant reduction of strength. Microanalysis revealed that infiltration and diffusion of copper into the fibers via the cracks of the damaged fibers are the direct cause of the embrittlement.

The effect of interface modification on fracture behavior of tungsten fiber reinforced copper matrix composites

Abstract Wf/Cu composites, Wf(Ni)/Cu composites and Wf/Cu82Al10Fe4Ni4 composites were fabricated by penetrating casting method. Bending strength and dynamic compressive strength of the composites were tested. Fracture mode and microstructure were investigated by scanning electron microscope (SEM) and transmission electron microscope (TEM). The result showed that the interface strength of Wf(Ni)/Cu composites and Wf/Cu82Al10Fe4Ni4 composites were higher than Wf/Cu composites. In Wf(Ni)/Cu composites, nickel plated on the surface of tungsten fibers has diffused into the inner of tungsten fibers, and a large number of tungsten grains and Ni4W intermetallic compounds appeared within tungsten fibers. In Wf/Cu82Al10Fe4Ni4 composites, Fe–Ni solid solutions precipitated on the interface between matrix and tungsten fibers, and tungsten has diffused into the Fe–Ni solid solutions. Dynamic compression test showed that the dynamic compressive strength and plasticity of Wf/Cu82Al10Fe4Ni4 composites were highest among the three kinds of composites.

High temperature fracture behavior of tungsten fiber reinforced copper matrix composites under dynamic compression

W f/Cu 82Al 10Fe 4Ni 4 composite was fabricated by flow casting method. Dynamic compression tests with strain rate of 1600 s −1 at 20 °C, 200 °C, 400 °C and 600 °C were finished by means of Split Hopkinson Pressure Bar (SHPB). The results showed that the composites possessed obvious high temperature softening behaviors. The damages of W f/Cu 82Al 10Fe 4Ni 4 composites all occurred within the tungsten fibers when compressed at 20 °C, 200 °C and 400 °C, indicating that the interface strength of the composites was high. While the damages of the composites occurred either in the tungsten fibers or in the matrix at 600 °C, in addition, the melt of matrix alloy also occurred. Microstructure of the composites after dynamic compressing at 600 °C was analyzed by transmission electron microscope (TEM), observation revealed that there were a lot of high-density dislocations, stacking faults and twins existing in the matrix. It was also found that the precipitated phase in the matrix played the role of the second phase strengthening.

The fabrication and properties of short carbon fiber reinforced copper matrix composites

Short carbon fibers (SCFs) reinforced copper matrix composites, fiber volume fraction of which ranged from 10% to 30%, were prepared by electroless copper plating plus cold press and sintering technique. SCFs were copperized directly by electroless plating using hypophosphite as reducing agent. The effects of SCFs volume fraction on mechanical, thermal, and electrical properties of the composites were discussed. The results indicated that the microhardness and thermal expansion property of Cu/SCFs composites increased with increasing fibers content, owing to the high strength of SCF. However, thermal conductivity and electrical conductivity reversed, it was attributed to the performance of carbon fiber itself; furthermore, more defects and interfaces in the matrix acted as barriers to heat and electronic transfer.

Wear and Mechanical Properties of Short Carbon Fiber Reinforced Copper Matrix Composites

The mechanical properties and wear behavior of short carbon fiber reinforced copper matrix composites was studied. In order to avoid any interfacial pronlems in the carbon fibre reinforced composites, the carbon fibers were coated with copper. The fibers were coated by electroless coating method and then characterized. Composites containing different amounts of carbon fibers were prepared by hot pressing technique. The results show that Carbon fiber/Cu–Ni–Fe composites showed higher hardness, higher wear resistance and bending strength than the common copper alloy when carbon fibers content is less than 15 vol.%. The predominant wear mechanisms were identified as adhesive wear in the alloy and adhesive wear accompanied with oxidative wear in the 12 vol.% carbon fiber/Cu–Ni–Fe composites.

Application of a fiber-reinforced copper matrix composite cooling tube to a water-cooled mono-block divertor component: A design study

Fiber-reinforced copper matrix composites are considered as a promising heat sink material for future divertor. In this article the structural reliability of a water-cooled tungsten mono-block divertor component with a composite cooling tube is treated. An integrated modeling scheme for multi-scale failure analysis is presented. The applied micromechanics-based FEM technique could be successfully combined with various failure analysis models to predict the failure risk on different length scales. It was demonstrated that the composite divertor component is a reasonable design concept in terms of structural reliability.

An analysis of thermal residual stresses in SiC f/Cu composites when TiC or Ni as binder

The interfacial bonding strength of SiC fiber reinforced copper matrix composites is extremely weak. Using Ti or other metallic elements such as Fe, Ni, Mo can improve the fiber/matrix bonding strength because these elements can form carbides or an interdiffusion zone between the fiber and the matrix though a heat treatment. In this paper, a TiC reaction layer or Ni interlayer is introduced as a binder, and thermal residual stresses (TRS) in the SiC fiber, TiC or Ni interlayers, and matrix are simulated by means of finite element method. The results indicate that the matrix undergoes significant plastic deformation when the composite is cooled to room temperature from the bonding temperature, and the residual plastic strains are highest around the interlayers and decrease as distance from the interlayer increases; the values and distributions of hoop stresses and Von Mises stresses in the matrix are nearly identical when different interlayers are used , while the magnitudes of these stresses are significantly different in different kinds of interlayers. The distribution characteristics of axial residual stresses in the matrix change when different interlayers are used, and Ni is superior to TiC as the axial stresses greatly decrease near the axial end of the composite.

Effect of nickel on the interface and mechanical properties of SiCf/Cu composites

Abstract Continuous SiC fiber reinforced copper matrix composites were fabricated at three different temperatures by fiber-coating method (FCM) with or without Ni interlayers. Ni and Cu coatings were prepared by electroplating, respectively. The tensile strengths at room temperature were established for the composites. The fracture surfaces, fiber surfaces, SiC f /Ni/Cu interface and phase composition were analyzed by means of optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffractometer (XRD). The results indicate that the tensile strengths of the composites with Ni interlayers prepared below 700 °C changed little in comparison with those of the composites without Ni interlayers, while those of the composites with Ni interlayers prepared at 800 °C were drastically degraded. The great degradation was caused mainly by two reasons. One is that Ni resulted in serious degradation of the strength of SiC fibers (Ni not only induced the graphitization of carbon coatings of SiC fibers, but also reacted with interior SiC to form Ni silicides and graphite), the other is that extensive interfacial reaction between Ni and SiC fiber reduced the interfacial bonding strength due to the microcracks generated in the matrix near the interface.

The fabrication and property of SiC fiber reinforced copper matrix composites

SiC fiber reinforced copper matrix composites were prepared by foil-fiber-foil method (FFF) and, fiber-coating method (MCF) with and without a Ti6Al4V interlayer, respectively. The copper coating was prepared by different electroplating processes and the Ti6Al4V interlayer by magnetron sputtering. The results show that the tensile strengths of specimens without Ti6Al4V interlayer are nearly identical and poor, between 250 and 290 MPa, while the ones of specimen with Ti6Al4V interlayer can be greatly improved, over 500 MPa. This great increase attributes to the improvement of the SiC/Cu interfacial bonding strength because the interfacial reactions occur at Cu/Ti6Al4V interface and Ti6Al4V/SiC interface. Additionally, there are generally many micropores produced by hydrogen and oxygen in the electroplated coating, which would influence the density of the matrix. Therefore, the densification of the matrix was worth investigating since it would influence the thermal and electrical conductivity of the composite, though it has only a little contribution to the tensile strength. Experiments indicate that proper heat-treatment before hot pressing could improve the densification of the matrix.

Titanium as coupling agent in SiC fibre reinforced copper matrix composites

SiC fibre reinforced copper matrix composites are candidate materials for heat sinks in future fusion reactors, as they combine high thermal conductivity and high mechanical strength for operating temperatures of up to 550 °C under neutron irradiation. To improve their properties via interlayer design, titanium as coupling agent was deposited on carbon-coated SiC fibres by magnetron sputtering, followed by a copper deposition using electroplating. After a heat treatment at 550 °C for the formation of TiC and the reduction of porosity, the wrapped fibres were packed in a copper capsule and hot-isostatically pressed at 650 °C to form a composite. The interlayer between fibre and matrix was characterised by high-resolution and analytical transmission electron microscopy and by push-out tests. During the heat treatment, the titanium completely reacts with the carbon coating of the fibre, forming TiC which enhances the bonding between the SiC fibre and the copper matrix. The resulting bonding strength is about 10-fold higher for composites with titanium interlayers compared to those without such layers.

Prediction of plastic deformation of fiber-reinforced copper matrix composites

Copper alloys have been considered as a structural material for the heat sink of the actively cooled plasma facing components due to its high thermal conductivity. However, the decrease of strength at elevated temperatures and their large thermal expansion are detrimental aspects. The fiber-reinforced copper matrix composites (FRCMC) can be a potential candidate as heat sink material. In this article, the non-linear constitutive behavior of the FRCMCs reinforced with continuous SiC fibers is predicted. To this end, a simulation tool was developed using analytical micro-mechanics theory. The effects of thermal residual stress and of the matrix flow stress are estimated. The results show that these composites have a significantly increased work-hardening rate compared to the unreinforced matrix metals. The thermal residual stress has a marked influence on the initial yield surface as well as on the stress–strain curve showing asymmetry in tension and compression.

Effects of fiber volume fraction, hot pressing parameters and alloying elements on tensile strength of carbon fiber reinforced copper matrix composite prepared by continuous three-step electrodeposition

Carbon fiber reinforced copper matrix composites have been produced by continuous three-step electrodeposition plus hot pressing technique. Iron or nickel element was added to copper matrix to improve interfacial bonding of the composite. The effects of fiber volume fraction and hot pressing parameters (temperature, pressure and time) on the tensile strength of the composite were investigated. Emphasis was placed on the influence of alloying elements on the tensile strength of the composite. The composite was found to exhibit the highest strength at an optimum V f, hot pressing parameter temperature, pressure, or time by keeping other parameters constant. This optimum value was related to the alloying element incorporated in the copper matrix. It is observed that incorporation of alloying elements does not change the general trends, but changes the mechanism governing the decreasing trends of the tensile strength of the composites as the hot pressing temperature exceeds the optimum value. Further, the alloying elements affect the highest strength values ( σ max). C/Cu(Ni) composite with the medium interfacial bonding strength exhibits the highest σ max. It is concluded from our experiments that a diffusion bonding is preferable since the fiber–matrix interaction can be easily controlled and the fiber degradation is limited during hot pressing process.

Effect of thermal cycling on the microstructure of continuous carbon fibre reinforced copper matrix composites

Copper reinforced by continuous carbon fibres is a candidate material for heat sinks of electronic modules. The thermal expansion can be matched to the adjacent ceramics and the thermal conductivity is higher than that of alternative materials. Because the material is expected to work in cyclic thermal conditions during application its structure must withstand such a load without any severe damage. The structure of unidirectionally and cross-ply fibre reinforced samples was observed before and after thermal cycling by optical microscopy and Scanning Electron Microscopy (SEM). SEM was used for examining the fibre-matrix interface before and after thermal cycling. Optical microscopy showed the arrangement of individual monolayers. The influence of adding copper foils between individual monolayers on the structure of the material is reflected in a reduction in the number of cracks in monolayers.

Correlation between Interfacial Microstructure and Conditions of Bonding in Carbon Fibre-Copper Composites

Carbon fibre reinforced copper matrix composites have been produced to provide materials with high thermal conductivity for use in semiconductors (diodes and thyristors) and electrical contacts. The problem of poor wettability of the carbon fibres by the copper matrix was overcome by admixing the matrix with zirconium which react with the carbon fibres to form carbides. The amount of carbides formed in the interface layer and, thus, the properties of the composite can be controlled by controlling the amount of the active element added, or by modifying appropriately the process parameters. This latter method has been examined in the present study. The experimental results have been verified by calculating and analysing the thermodynamic parameters of the process.

Thermal conductivity and thermal expansion of graphite fiber-reinforced copper matrix composites

The high specific conductivity of graphite fiber/copper matrix (Gr/Cu) composites offers great potential for high heat flux structures operating at elevated temperatures. To determine the feasibility of applying Gr/Cu composites to high heat flux structures, composite plates were fabricated using unidirectional and cross-plied pitch-based P-100 graphite fibers in a pure copper matrix. Thermal conductivity of the composites was measured from room temperature to 1073 K, and thermal expansion was measured from room temperature to 1050 K. The longitudinal thermal conductivity, parallel to the fiber direction, was comparable to pure copper. The transverse thermal conductivity, normal to the fiber direction, was less than that of pure copper and decreased with increasing fiber content. The longitudinal thermal expansion decreased with increasing fiber content. The transverse thermal expansion was greater than pure copper and nearly independent of fiber content.