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Article
Publication date: 9 August 2019

Ijlal Şimşek

This paper aims to investigate the effects of second phase precipitate size on microstructure, hardness, density, corrosion and electrical conductivity of 7075 aluminum…

Abstract

Purpose

This paper aims to investigate the effects of second phase precipitate size on microstructure, hardness, density, corrosion and electrical conductivity of 7075 aluminum alloy fabricated by the powder metallurgy method and aged at 120°C for various aging periods.

Design/methodology/approach

For the aging process (T6), these alloys were solution-treated at 485°C for 2 h, quenched, aged at 120°C for four various periods and finally air cooled. After the aging process, these alloys were examined with scanning electron microscope, X-ray diffraction, density and hardness measurements. The corrosion tests were carried out using the potentiodynamic polarization technique; electrical conductivity values were measured as IACS%.

Findings

Results showed that the precipitate size increased with increasing aging period and the maximum precipitate size was achieved for the sample aged for 28 h. The maximum hardness was attained for the sample aged for 24 h, while the same specimen obtained the lowest electrical conductivity and corrosion resistance.

Originality/value

In this research, second phase precipitates of heat treatment processing affected the electrical conductivity and corrosion behavior of the 7075 aluminum alloy. Also it is understood that the heat treatment period is an effective parameter on these properties.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 5
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 22 July 2020

Igor Lesiuk and Andrzej Katunin

This paper aims to present a numerical analysis and comparison of two types of conductive fillers of polymeric composites subjected to lightning strikes.

Abstract

Purpose

This paper aims to present a numerical analysis and comparison of two types of conductive fillers of polymeric composites subjected to lightning strikes.

Design/methodology/approach

Two types of conductive fillers were considered in the developed numerical models of electrically conductive composites: carbon nanotubes and polyaniline. For these fillers, the representative volume elements were developed to consider distribution of the particles that ensures percolation and homogenization of the materials within the Eshelby-based semi-analytical mean-field homogenization approach. The performed numerical analyses allowed determination of effective volume fractions of conducting particles, resistivity and conductivity tensors, and finally the current density for the simulated materials subjected to lightning strike.

Findings

The obtained results allowed for comparison of electrical conductivity of two simulated materials. It was observed that besides fair results obtained in the previous studies for intrinsically conducting polymers as fillers of composites dedicated for lightning strike protection, the composites filled with carbon nanotubes reveal much better conductivity.

Practical implications

The presented simulation results can be considered as initial information for further experimental tests on electrical conductivity of such materials.

Originality/value

The originality of the paper lies in the proposed design and simulation procedures of conductive composites as well as the comparison of selected composites dedicated for lightning strike protection as the most intensively developed materials for this purpose.

Details

Aircraft Engineering and Aerospace Technology, vol. 92 no. 10
Type: Research Article
ISSN: 1748-8842

Keywords

Article
Publication date: 16 November 2012

Gerard Cummins and Marc P.Y. Desmulliez

The purpose of this paper is to present an exhaustive review of research studies and activities in the inkjet printing of conductive materials.

7684

Abstract

Purpose

The purpose of this paper is to present an exhaustive review of research studies and activities in the inkjet printing of conductive materials.

Design/methodology/approach

This paper gives a detailed literature survey of research carried out in inkjet printing of conductive materials.

Findings

This article explains the inkjet printing process and the various types of conductive inks. It then examines the various factors that affect the quality of inkjet printed interconnects such as printing parameters, materials and substrate treatments. Methods of characterising both the inkjet printing process and the electrical properties of printed conductive materials are also presented. Finally relevant applications of this technology are described.

Originality/value

Inkjet printing is currently one of the cheapest direct write techniques for manufacturing. The use of this technique in electronic manufacturing, where interconnects and other conductive features are required is an area of increasing relevance to the fields of electronics manufacturing, packaging and assembly. This review paper would therefore be of great value and interest to this community.

Article
Publication date: 7 November 2016

Ewa Napieralska-Juszczak, Piotr Napieralski, Krzysztof Komeza and Youcef Zeroukhi

The purpose of this paper is to determine the physical design parameters that influence the total resistance of a twisted conductor (cable). One of the physical parameters…

Abstract

Purpose

The purpose of this paper is to determine the physical design parameters that influence the total resistance of a twisted conductor (cable). One of the physical parameters characterizing this type of structures is the uneven distribution of resistivity due to hardening, which is the result of stress exerted on the wires during the manufacturing process.

Design/methodology/approach

The authors have developed a method to take into account the effect of localized hardening on the inhomogeneous distribution of electrical conductivity in the distorted structures of the conductor. To achieve this goal, the authors have implemented a mechanical-electrical simulation method. The resistance characteristics have been measured as a function of mechanical stress.

Findings

As demonstrated by the results of measurements conducted on various samples and with various cable design parameters, the resistance of a given material (copper or aluminum), expressed as a function of stress, does not depend on the type of force applied. Therefore, the same characteristics may be applied to various cable designs.

Practical implications

The method presented in this paper enables more detailed investigation of the influence of particular design parameters on the total resistance of a cable. It also provides the ability to determine optimal settings of design parameters.

Originality/value

The approach is distinct from similar studies because it takes into account the deformed geometry of the conductor and the uneven distribution of the resistivity within a filament. In the literature, it is sometimes stated that the distribution of resistivity in a compacted cable is uneven, but its measurement is deemed impossible. This paper provides a method for determining such a distribution.

Details

COMPEL - The international journal for computation and mathematics in electrical and electronic engineering, vol. 35 no. 6
Type: Research Article
ISSN: 0332-1649

Keywords

Article
Publication date: 4 July 2016

R. Durairaj, Lim Seow Pheng and Liew Jian Ping

The purpose of this paper is to characterise the electrical and mechanical properties of multiwall carbon nanotubes (MWCNTs)-based isotropic conductive adhesives (ICAs)…

Abstract

Purpose

The purpose of this paper is to characterise the electrical and mechanical properties of multiwall carbon nanotubes (MWCNTs)-based isotropic conductive adhesives (ICAs). The paper also compares the electrical and mechanical performance of MWCNTs-based ICAs with silver flakes and silver nanoparticles-based ICAs.

Design/methodology/approach

The ICAs were formulated with dyglycidyl ether bisphenol A epoxy resin and conductive fillers such as silver flakes, silver nanoparticles and MWCNTs. The four-point probe is used to measure the bulk resistivity of the ICAs.

Findings

The results from the study showed that the percolation threshold of the MWCNTs-based ICAs is 1.5 Wt.%. At 3 Wt.%, the drop in bulk resistivity is lower than the conventional ICAs. The addition of silver nanoparticles increased the overall bulk resistivity of the system. The mechanical properties improved with the introduction of carbon nanotubes into the silver flakes–epoxy system.

Practical implications

The results from bulk resistivity and mechanical properties of the MWCNTs could help to formulate MWCNTs-based ICAs with optimum weight fraction.

Originality/value

The paper demonstrates that the addition of MWCNTs to the silver-based ICAs will enhance their mechanical and electrical conductivity. In addition, the optimum weight percentage is also determined, which shows a bulk resistivity value lower along with improved mechanical property with the conventional ICA system.

Article
Publication date: 5 May 2015

Haibao Lu, Yongtao Yao, Shipeng Zhu, Yunhua Yang and Long Lin

The purpose of this paper is a study aimed at overcoming the interface issue between nanopaper and polymer matrix in shape-memory polymer (SMP) composite laminates caused…

Abstract

Purpose

The purpose of this paper is a study aimed at overcoming the interface issue between nanopaper and polymer matrix in shape-memory polymer (SMP) composite laminates caused by their large dissimilarity in electrical/thermal conductive properties. The study attempted to develop an effective approach to fabricate free-standing carbon nanofibre (CNF) assembly in octagon shape formation. The structure design and thermal conductive performance of the resulting octagon-shaped CNF assembly were optimised and simulated.

Design/methodology/approach

The CNF nanopaper was prepared based on a filtration method. The SMP nanocomposites were fabricated by incorporating these CNF assemblies with epoxy-based SMP resin by a resin-transfer modelling technique. Thermal conductivity of the octagon-shaped CNF assembly was simulated using the ANSYS FLUENT software for structure design and optimisation. The effect of the octagon-shaped CNF on the thermomechanical properties and thermally responsive shape-memory effect of the resulting SMP nanocomposites were characterised and interpreted.

Findings

The CNF template incorporated with SMP to achieve Joule heating triggered shape recovery at a low electric voltage of 3-10 V, due to which the electrical resistivity of SMP nanocomposites was significantly improved and lowered to 0.20 O·cm by the CNF template. It was found that the octagon CNF template with 2 mm width of skeleton presented a highest thermally conductive performance to transfer resistive heat to the SMP matrix.

Research limitations/implications

A simple way for fabricating electro-activated SMP nanocomposites has been developed by using an octagon CNF template. Low electrical voltage actuation in SMP has been achieved.

Originality/value

The fabricated CNF template, the structure design and analysis of dynamic thermomechanical properties of SMP are novel.

Details

Pigment & Resin Technology, vol. 44 no. 3
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 28 March 2018

Shiva Akhtarian, Hadi Veladi and Sajedeh Mohammadi Aref

The purpose of the study is to explore the potential possibility of using the conductive and piezoresistive nanocomposites that consist of insulating…

Abstract

Purpose

The purpose of the study is to explore the potential possibility of using the conductive and piezoresistive nanocomposites that consist of insulating poly(dimethylsiloxane), a very popular silicone polymer, and the amazing properties of carbon nanotubes (CNT) in sensing applications. This nanocomposite is prepared by an optimized process to achieve a high-quality nanocomposite with uniform properties.

Design/methodology/approach

The optimized process achieved in this study to provide PDMS/CNT nanocomposite includes the appropriate use of ultrasonic bath, magnetic stirrer, molding and curing in certain circumstances that results in obtaining high-quality nanocomposite with uniform properties. Experiments to characterize the influence of some factors such as pressure, temperature and the impact of CNT’s concentration on the electrical properties of the prepared nanocomposite have been designed and carried out.

Findings

The obtained preparing method of this nanocomposite is found to have better homogeneity in comparison to other methods for CNT/PDMS nanocomposite. This nanocomposite has both desirable properties of the PDMS elastomer and the additional conductive CNT, and it can be used to create all-polymer systems. Furthermore, the conductivity values of these nanocomposites can be changed by varying some factors such as temperature and pressure, so that those can be used in temperature- and pressure-sensoring applications.

Originality/value

In the present research, a convenient, inexpensive and reproducible method for preparing CNT/PDMS nanocomposite was investigated. These nanocomposites with the unique properties of both PDMS elastomer and CNTs and also with high electrical conductivity, piezoresistive properties and temperature dependent resistivity can be used in different sensoring applications.

Details

Sensor Review, vol. 39 no. 1
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 9 October 2009

Ryszard Palka, Stanislaw Gratkowski, Krzysztof Stawicki and Piotr Baniukiewicz

The purpose of this paper is to develop a magnetic induction tomography (MIT) system as well as the conductivity reconstruction algorithms (inverse problem).

Abstract

Purpose

The purpose of this paper is to develop a magnetic induction tomography (MIT) system as well as the conductivity reconstruction algorithms (inverse problem).

Design/methodology/approach

In order to define and verify the solution of the inverse problem, the forward problem is formulated using mathematical model of the system. The forward problem is solved using the finite element method. The optimization of the excitation unit is based on the numerical solutions of the direct problem. All the dimensions and shape of the excitation system are optimized in order to focus the main part of the magnetic field in the vicinity of the receiver. Finally, two formulations of the inverse problem are discussed: based on the inversion of the Biot‐Savart law; and based on the artificial neural networks.

Findings

The formulation of the forward problem of the considered MIT system is given. The construction of the exciter unit that focuses the main part of the magnetic field in the vicinity of the receiver is proposed. Two formulations of the inverse problem are discussed. First using the inversion of the Biot‐Savart law and second using the artificial neural network. The neural networks seem to be promising tools for reconstructing the MIT images.

Originality/value

This paper demonstrates a real‐life MIT system whose performance is satisfactorily predicted by mathematical models. The original design of the exciter is shown. The new approach to the inverse problem in MIT – the use of the artificial neural network – is presented.

Details

Engineering Computations, vol. 26 no. 7
Type: Research Article
ISSN: 0264-4401

Keywords

Article
Publication date: 15 June 2010

Kaushik Alayavalli and David L. Bourell

The purpose of this paper is to produce electrically conductive, fluid impermeable graphite bipolar plates for a direct methanol fuel cell, using indirect selective laser…

Abstract

Purpose

The purpose of this paper is to produce electrically conductive, fluid impermeable graphite bipolar plates for a direct methanol fuel cell, using indirect selective laser sintering (SLS) and suitable post processing techniques.

Design/methodology/approach

Bipolar plates are made by the indirect SLS of graphite powder and phenolic resin mixture. The phenolic resin binder is then burnt off at a high temperature in a vacuum furnace to produce a 100 per cent carbon part. This brown part is then infiltrated using a low‐viscosity (∼5‐10  cps) cyanoacrylate to seal up the open pores, rendering the plates fluid impermeable.

Findings

It has been found that the electrical conductivity increases significantly (> 220 S/cm) with a corresponding increase in pyrolyzing temperature which correlates well with literature on the carbonization of phenol formaldehyde resins. The cyanoacrylate infiltrated parts tested under fluid pressure demonstrated no leakage through the plate, indicating full closure of open porosity.

Originality/value

This work demonstrates the capability of the SLS process to produce working bipolar plates with complex flow field designs that can be tested to verify its efficacy in a working fuel cell, thereby saving time and cost in machining natural graphite.

Details

Rapid Prototyping Journal, vol. 16 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 1 January 1995

K. Gilleo

The electronics assembly industry has fortunately rediscovered conductive adhesives as the search for lead‐free joining materials and improved performance intensifies…

Abstract

The electronics assembly industry has fortunately rediscovered conductive adhesives as the search for lead‐free joining materials and improved performance intensifies. Although these intrinsically clean bonding agents are often first sought for their favourable environmental attributes, many are surprised to find that conductive adhesives can solve old and new problems. Today, new polymer solders for SMT allow low temperature processing, finer pitch assembly and wider processing latitude while providing compatibility with a very much larger range of materials than solder. State‐of‐the‐art adhesives are oxide‐tolerant and absolutely no fluxing or cleaning is required. Adhesives work where solder cannot be used. What's more, polymer‐based solder alternatives can run on existing SMT lines — no new equipment is needed. Z‐axis, or anisotropic, bonding agents are uni‐directional conductive materials that solve fine pitch interconnect problems in several areas. The anisotropics now dominate the flat panel interconnect field. Nearly every LCD and other flat panel display is connected with a polymer adhesive. The Z‐axis adhesives are also beginning to enable high density multilayer circuits and MCMs to be built more effectively. Finally, Z‐axis appears to offer the simplest and most cost‐effective means for flip chip bonding. However, special equipment is required. The paper compares the metallurgical solder joint, the present de facto standard, with the polymer composite bond to highlight similarities and important differences. All types of conductive adhesives are discussed including the latest — Area Array Z‐axis types. Bonding materials, assembly processes and performance are also covered.

Details

Soldering & Surface Mount Technology, vol. 7 no. 1
Type: Research Article
ISSN: 0954-0911

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