Nickel-coated Carbon Fibers Research Articles

Low-pressure processing and microstructural evaluation of unidirectional carbon fiber-reinforced aluminum-nickel matrix composites

Continuous carbon fiber-reinforced aluminum-nickel matrix composites were manufactured by immersion of an interlayered layup design of aluminum foils, nickel mesh strips and nickel-coated carbon fibers in an aluminum melt at 900 °C for 15 s. Samples with and without fibers were compared. Scanning electron microscopy (SEM) revealed a strong bond at the matrix/reinforcement interface, indicated through no defects and no sign of debonding. Light microscopy (LM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and Vickers microhardness tests indicated the presence of Ni2Al3 and NiAl intermetallic phases in the composite, with hardness of 970 ± 27 and 450 ± 23 HV respectively, in agreement with values on reactive diffusion reported in literature. Microstructural analysis of the interfacial region and image binarization suggested an achievable fiber content between 15% and 40% vol, as well as a potential interface improvement by further homogenization of the fiber distribution.

Effect of nickel coating on the stress-dependent electric permittivity, piezoelectricity and piezoresistivity of carbon fiber, with relevance to stress self-sensing

This paper unprecedentedly reports the effect of metal (nickel) coating on the stress-dependent electric permittivity, piezoelectricity and piezoresistivity of carbon fiber. Both permittivity (2 kHz) and DC conductivity of carbon fiber are increased by nickel coating. For 7-μm diameter carbon fiber, nickel coating (0.25-μm thickness) increases the relative permittivity from 12,200 to 63,200, and decreases the resistivity from 1.5 × 10−5 to 1.5 × 10−7 Ω.m. The relative permittivity of the nickel coating (Rule of Mixtures) is 404,600 - similar to 405,300 for nickel wire (160-μm diameter). The resistivity of the nickel coating (Rule of Mixtures) is 2.0 × 10−8 Ω.m - lower than 8.8 × 10−8 Ω.m for the nickel wire - probably because of the higher degree of preferred crystallographic orientation in the nickel coating. The nickel structure affects the conduction more than polarization. The piezoelectric and piezoresistive effects are diminished by the nickel coating, which governs these effects. The nickel coating changes the stress dependence of the permittivity (for capacitance-based self-sensing) from positive to negative and changes the piezoresistivity (for resistance-based self-sensing) from negative (gage factor −1830) to positive (gage factor +1650). The piezoelectricity of the nickel-coated carbon fiber and nickel wire are similar, but the piezoresistivity is weak for the latter (gage factor +30).

Textile yarn thermocouples for use in fabrics

Thermocouples are mainly used for accurate temperature measurements, but they can also be used for the generation of electric energy at low voltage and low power. If inserted into wearable garments, these thermocouples can be used to supply the electric energy required by portable electronic devices. The heat from the human body gives rise to a temperature gradient which can be converted into electric power. In this article, we study the possibility to create a thermocouple and thermopile from pure conductive textile yarns. Among the materials tested, nickel-coated carbon fiber in combination with stainless steel yarn, polypyrrole-coated carbon fiber, or carbon fiber has good potential to be a textile-based thermocouple. We also successfully made a 10-pair carbon fiber–nickel-coated carbon fiber junction thermopile from a single nickel-coated carbon fiber yarn by removing the nickel selectively through etching process.

Effect of T6 Heat Treatment on Hardness Wear and Fatigue Behaviour of Nickel Coated Carbon Fiber Reinforced Al-7079 MMC

Effect of T6 Heat Treatment on Hardness Wear and Fatigue Behaviour of Nickel Coated Carbon Fiber Reinforced Al-7079 MMC

Seebeck coefficient of thermopile made of nickel-coated carbon fiber

A textile-based thermopile has been fabricated by etching the nickel layer of a nickel coated carbon fiber (NiCF) selectively to form a series of CF-NiCF junctions along the NiCF. The pristine NiCF was inserted into the polyester woven fabric manually. Each half part of the float yarns was covered with Lurapret® D579 dropwise to form a 36-pair CF-NiCF thermopile. After drying in the oven, the sample was etched in the etching solution, then rinsed with water and air dried. The Seebeck coefficient resulting from 36-pair CF-NiCF thermopile is 93.04 µV/K. This proofs that creating a flexible thermoelectric generator from a conductive textile yarn is possible.

Eliminating lightning strike damage to carbon fiber composite structures in Zone 2 of aircraft by Ni-coated carbon fiber nonwoven veils

By using standardized Waveforms C and D, this study explored the lightning strike protection (LSP) effectiveness of nickel coated carbon fiber nonwoven veils (Ni-CFNVs) on protecting the carbon fiber composite structures in Zone 2 (aircraft lightning zoning). The post-lightning damage was evaluated by visual inspection, ultrasonic scan and residual strength test. Results showed that the Ni-CFNV of 70 g/m2 eliminated lightning strike damage inflicted by both waveforms and it even performed better than the commercial expanded copper foil of 73 g/m2. Therefore, the Ni-CFNV will be a promising alternative to metal mesh for eliminating lightning strike damage to the structures in Zone 2. The remarkable LSP effectiveness of Ni-CFNV can be explained by its integration of high electrical conductivity of Ni-coating and prominent ablation resistance of carbon fiber. The experiments indicate that not only the electrical conductivity, but also the ablation resistance of LSP layer greatly influences the LSP effectiveness.

A comprehensive study of metal-coated short carbon fibers, graphite particles, and hybrid fillers for induction heating

Induction heating or welding can be performed by considering the combined effect of ferromagnetic heating due to magnetic hysteresis losses and eddy current heating due to conductive material. Nonconducting thermoplastic composite parts can be joined or welded by induction heating using a susceptor sheet filled with nickel-coated carbon fibers (NiCCFs) and nickel-coated graphite particles (NiCGPs) or both with polypropylene (PP) thermoplastic matrix. Above the percolation threshold, NiCCFs can serve as conductive materials and nickel coating will provide the ferromagnetic heating. NiCCF/PP and NiCCF/NiCGP/PP susceptor sheets were developed via melt mixing using a twin-screw extruder and sheets were produced by Calendering process. Induction heating tests were performed on a circular pancake coil and at frequencies below 1 MHz. In induction heating, fiber heating by Joule loss, junction heating (i.e. dielectric heating and contact resistance heating), as well as magnetic hysteresis effect were observed in both the cases. Heating in hybrid filler was higher at lower filler concentrations; however, with higher concentrations, heating reduced. Reduction in induction heating maybe due to a reduction in electrical conductivity was observed. Electrical conductivity was measured in fibers direction by a Keithley electrometer using a four-point measuring method and temperature was measured by an infrared thermal camera. Microstructure characterization was performed by X-ray computed microtomography and light microscopy.

Effect of Magnetic Field on the Fiber Orientation during the Filling Process in Injection Molding, Part 1: Simulation and Mold Design

Conductive polymer composite material is increasingly applied in a variety of fields, and its related processing technology has been a focus of research and development. Regarding magnetic fiber, because the orientation and distribution of the fiber affect the electrical and mechanical properties of products, the control of fiber orientation and distribution has been regarded as a key technology. This study used magnetic-assisted injection molding to control the orientation of magnetic fibers during the melt-polymer filling process. A special mold containing a magnetic apparatus was simulated and designed. Its material and thickness of various spacing blocks as well as the optimal layout of magnets in the mold were determined. An actual mold with the same magnet layout was then manufactured accordingly, and the measured magnetic flux density was compared with simulated results. This study also examined the coupled effect of magnetic and flow fields on the orientation of nickel-coated carbon fibers, calculating the magnetic moment produced due to the influence of the magnetic field on the fibers when melt polymer flowed through various positions in the cavity during the filling process. The flow trajectories of the fibers, which were affected by the magnetic field, were also predicted.

Seebeck Coefficient of Thermocouples from Nickel-Coated Carbon Fibers: Theory and Experiment.

Thermocouples made of etched and non-etched nickel-coated carbon yarn (NiCCY) were investigated. Theoretic Seebeck coefficients were compared to experimental results from measurements of generated electric voltage by these thermocouples. The etching process for making thermocouples was performed by immersion of NiCCY in the solution containing a mixture of hydrochloric acid (HCl) (37% of concentration), and hydrogen peroxide (H2O2) in three different concentrations—3%, 6%, and 10%. Thirty minutes of etching to remove Ni from NiCCY was followed by washing and drying. Next, the ability to generate electrical voltage by the thermocouples (being a junction of the etched and the non-etched NiCCY) was measured in different ranges of temperatures, both a cold junction (291.15–293.15 K) and a hot junction (293.15–325.15 K). A formula predicting the Seebeck coefficient of this thermocouple was elaborated, taking into consideration resistance values of the tested samples. It was proven that there is a good agreement between the theoretical and experimental data, especially for the yarns etched with 6% and 10% peroxide (both were mixed with HCl). The electrical resistance of non-fully etched nickel remaining on the carbon fiber surface () can have a significant effect on the thermocouples’ characteristics.

Influence of Stripping Solution’s Concentration on the Seebeck Coefficient of Nickel-Coated Carbon Fibers

Sensors and actuators made out of textile materials are the subjects of many research activities, especially because of the specific properties possessed by the textiles. In this context, yarns with a different Seebeck coefficient can be applied for making a textilebased thermopile. Preliminary experiments have shown that a pairof nickel-coated carbon fibers (NiCF) and carbon fibers (CF) has a good Seebeck coefficient. In this paper, we study the influence of the concentration of the solution used to strip off the Ni from the NiCF. Experiments show that a mixture of 37% HCl and 10% H2O2 (1:1) result in the highest Seebeck coefficient.

镀镍碳纤维功能一体化复合材料的工艺及性能研究

镀镍碳纤维功能一体化复合材料的工艺及性能研究

Influence of Surface Oxidation of Nickel-Coated Carbon Fibre on Oxygen Evolution Reaction in Alkaline Solution

Influence of Surface Oxidation of Nickel-Coated Carbon Fibre on Oxygen Evolution Reaction in Alkaline Solution

Removing nickel from nickel-coated carbon fibers

Conductive fibers/yarns are one of the most important materials for smart textiles because of their electrically conductive functionality combined with flexibility and light weight. They can be applied in many fields such as the medical sector, electronics, sensors and even as thermoelectric generators. Temperature sensors, for example, can be made using the thermocouple or thermopile principle which usually uses two different metal wires that can produce a temperature-dependent voltage. However, if metal wires are inserted into a textile structure, they will decrease the flexibility properties of the textile product. Nickel-coated Carbon Fiber (NiCF), a conductive textile yarn, has a potential use as a textile-based thermopile if we can create an alternating region of carbon and nickel along the fiber which in turn it can be used for substituting the metallic thermopile. The idea was to remove nickel from NiCF in order to obtain a yarn that contains alternating zones of carbon and nickel. Due to no literature reporting on how to remove nickel from NiCF, in this paper we investigated some chemicals to remove nickel from NiCF.

Effects of processing methods on the electrical conductivity, electromagnetic parameters, and EMI shielding effectiveness of polypropylene/nickel-coated carbon fiber composites

The effects of composite preparation methods on the electrical conductivities, the electromagnetic parameters and the electromagnetic interference (EMI) shielding effectiveness of polypropylene (PP)/nickel-coated carbon fiber (CF) composites were investigated. The composites were prepared by injection molding machine, internal mixer, and screw extruder. The electrical properties results showed the PP/CF (70/30, wt%) composites prepared by injection molding demonstrated the highest electrical conductivity and EMI shielding effectiveness, which were 1.75×101 S/cm and 48.4 dB at the frequency of 10 GHz, respectively. These results seem mainly due to the increased CF length when the PP/CF composite was prepared by injection molding, which was advantageous in forming a conductive network of the composite. The results of the electromagnetic parameters of the PP/CF composites showed that the increased electrical conductivity of the composite prepared by injection molding was mainly due to the increased dielectric constants (e' and e") of the PP/ CF composite. This enhancement in dielectric constants seems related to the percolation at a lower concentration of the CF, which was affected by the increased CF length of the composite prepared by injection molding process. The results of dielectric loss and magnetic loss factors of the PP/CF composite showed that the major electromagnetic absorbing mechanism was dielectric loss, namely dipole polarization and interface polarization between filler and matrix, which resulted in improved EMI absorption values. The total EMI shielding effectiveness (SET) of the PP/CF composite comprised 85.1% EMI shielding effectiveness by absorption (SEA), and 14.9% EMI shielding effectiveness by reflection (SER), which suggests that the EMI shielding was predominantly by the absorbing mechanism of the incident electromagnetic wave.

Short fiber reinforced 3d printed ceramic composite with shear induced alignment.

This paper accounts for utilization of shear induced alignment method during ceramic stereolithography. Lateral oscillation mechanism, combined with 3d printed wall pattern, was employed to generate necessary shear to align fiber in desired direction. First, semicircular channel pattern was printed to assess the effect of difference between wall direction and oscillation direction on the fiber alignment. Then, flexural strength of ceramic matrix was tested with nickel coated carbon fiber and ceramic fiber reinforcements. The results demonstrated that the shear induced alignment further improves the flexural strength compare to randomly distributed samples. Flexural strength of aligned samples with 1.0 wt% carbon fiber loading was improved by ~90% compared to randomly orientated samples and by ~333% compared to unreinforced samples. Finally, fracture surface morphology of the flexural strength test specimens was evaluated. The main fracture mechanism was observed as fiber pull-out.

Light-weight epoxy/nickel coated carbon fibers conductive foams for electromagnetic interference shielding

A light-weight and electromagnetic interference (EMI) shielding conductive epoxy resin (EP) composite foam was firstly fabricated by loading nickel coated carbon fibers (NCCFs). The foamed EP/NCCFs composites with a uniform foam cell containing various NCCFs contents (0–5.03 vol%) have been fabricated via chemical foaming. The foams exhibit densities of as low as 0.45 g cm− 3. Owning to the high aspect ratio of carbon fibers and selective distribution of NCCFs in the foam structure, NCCFs could easily connect with each other and construct the conductive network in polymer matrix. As a result, the composite foams exhibit an EMI shielding effectiveness of ~33 dB and a corresponding specific EMI shielding effectiveness of as high as 77.4 dB cm3 g− 1 in the microwave frequency range of 8.2–12.4 GHz. Such composite foam would be considered as a promising lightweight and EMI shielding material in aerospace and electronics.

NiO Formation by Simple Air Oxidation of Nickel Coated Carbon Fibers

NiO Formation by Simple Air Oxidation of Nickel Coated Carbon Fibers

Ni-Coated Carbon Fiber as an Alternative Cathode Electrode Material to Improve Cost Efficiency of Microbial Fuel Cells

Electrode material is a key component in microbial fuel cells (MFCs), and exploring cost-effective electrode materials will greatly help with MFC development, especially the scaling up. In this study, a commercially available material – nickel-coated carbon fiber (Ni-CF) has been investigated as an alternative cathode electrode material to carbon cloth (CC). Both three-electrode cell and MFC tests are carried to examine electrochemical performance and actual electricity generation of the prepared cathode electrodes. It is found that Ni-CF exhibited higher current generation in linear sweep voltammetry (LSV) and lower resistance in electrochemical impedance spectroscopy (EIS) tests than those of CC and CF. When being coated with AC, Ni-CF has the highest actual loading amount among the tested materials. As a result, AC/Ni-CF leads to lower charge transfer resistance (95.1Ω) and higher current density (8.07mAm−2) than AC/CC (115.3Ω and 3.40mAm−2). In the MFC test, the cathode using AC/Ni-CF results in the maximum power density of 6.50Wm−3, higher than AC/CC at 4.29Wm−3. This high power output gives cost efficiency of AC/Ni-CF at 299.0mW $−1, nearly twice that of AC/CC (151.7mW $−1). The initial AC coating amount of 4g is found to be the optimal amount to achieve optimally actual AC loading amount on the cathode electrode with balanced catalytic ability and (possible) oxygen transfer. Those results encourage further investigation of Ni-CF for MFC applications towards improved performance and cost efficiency.

Magnetic alignment of short carbon fibres in curing composites

Abstract Alignment of magnetic particles into a viscous fluid by a homogeneous magnetic field has been studied both experimentally and theoretically, but very few studies have investigated the effects of viscosity changes on the capability of achieving complex fibre assemblies in composite materials. In this paper, we study the alignment of short carbon fibres into a viscous matrix whose viscosity is made dependent on the time, in order to simulate the curing process of the composite. A simple model is derived which gives the evolution of fibre position and orientation in terms of the external field and shows good agreement with the experimental evidence on nickel coated carbon fibres embedded in PDMS. The model is used to predict the fibre distribution at curing and hence could be a useful tool to predict the mechanical, electrical and magnetic properties of the composite. A closed form expression of the minimum magnetic field intensity necessary to achieve the desired orientation is derived in terms of the magnetic and geometric properties of the fibres. This equation can be used to guide experiments, and offers a way to discriminate which matrix/fibre configuration can be most proficiently used to have a highly ordered composite.

Fabrication and characterisation of short fibre reinforced elastomer composites for bending and twisting magnetic actuation

Polydimethylsiloxane (PDMS) films reinforced with short Nickel-coated Carbon Fibres (NiCF) were successfully fabricated, with the fibres aligned along different directions using an external magnetic field. The fibres were dispersed in the host matrix using sonication and mechanical mixing before being cured for 48h in the magnetic field; thanks to the nickel functionalisation, the fibre orientation was achieved by a low intensity field (<0.2T) which required an inexpensive experimental set-up. The main focus of this study was looking at the actuation potential of this magnetic composite material; successful actuation was achieved, showing its large displacement capability. The results confirm the presence of an instability controlled by the magnetic torque, as predicted by the introduced model. The composite films undergo a transition from a bending-only deformed configuration for the 0° fibre specimen, to a twisting-only configuration, achieved for fibres at 90°, whereas all the intermediate angles show both bending and twisting. This behaviour mirrors that which is used to propel a selection of marine mammals.