Lightweight porous materials for electromagnetic interference (EMI) shielding applications are reviewed. EMI shielding refers to the capability of a material to protect from electromagnetic fields (EMFs) generated by electronic devices. Traditionally conducting metals are used in EMI shielding applications, which are slowly being replaced by conducting polymer based shields. This review is narrowly focused on understanding the approaches related to porous high EMI shielding composite materials that have very low density values. While metallic fillers can increase the EMI shielding capabilities of polymers, they also increase the weight, which can be offset by inducing the porosity in the matrix. Porosity is found to be effective in providing higher shielding effectiveness at low filler volume fraction due to concentrating the filler in the solid polymers. However, use of gas porosity results in composites with low mechanical properties. This problem can be alleviated to some extent by reinforcing polymer foams with lightweight conductivefillers such as carbon nanofibers (CNFs), carbon nanotubes (CNTs) and graphene. But the properties of pores such aspore size and distribution cannot be effectively controlled in such cases. Syntactic foams containing hollow particle fillers seem to be the best combination of EMI shielding capabilities and mechanical properties. These composites can be either filled with a second phase conducting filler, or hollow particles can be coated with a conducting layer, or hollow particles made of conducting materials can be used as fillers. The hollow particle wall thickness and volume fractions can be optimized to obtain the desired combination of properties in syntactic foams to enable their multifunctional applications.

A review of porous lightweight composite materials for electromagnetic interference shielding

Tensile and wear behaviour of in situ Al-7Si/TiB2 particulate composites

Fabrication and characterisation of Al–7Si–0.35Mg/fly ash metal matrix composites processed by different stir casting routes

Dynamic compressive behaviour of cellular materials: A review of phenomenon, mechanism and modelling

Mechanical and thermal characteristics of high density polyethylene-fly ash Cenospheres composites

Compression behaviors of cenosphere–pure aluminum syntactic foams

High strain rate compression of cenosphere-pure aluminum syntactic foams

The cenosphere and precipitator fly ash particulates were used to produce two kinds of aluminum matrix composites with the density of 1.4–1.6 g cm −3 and 2.2–2.4 g cm −3 separately. The electromagnetic interference shielding effectiveness (EMSE) properties of the composites were measured in the frequency range of 30.0 kHz–1.5 GHz. The results indicated the EMSE properties of the two types of composites were nearly the same. By using the fly ash particles, the shielding effectiveness properties of the matrix aluminum have been improved in the frequency ranges 30.0 kHz–600.0 MHz and the increment varied with increasing frequency. The EMSE properties of 2024Al are in the range −36.1 ± 0.2 to −46.3 ± 0.3 dB while the composites are in the range −40.0 ± 0.8 to −102.5 ± 0.1 dB in the frequency range 1.0–600.0 MHz. At higher frequency, the EMSE properties of the composites are similar to that of the matrix. The tensile strength of the matrix aluminum has been decreased by addition of the fly ash particulate and the tensile strength of the composites were 110.2 MPa and 180.6 MPa separately. The fractography showed that one composite fractured brittly and the other fractured in a microductile manner.

Electromagnetic shielding effectiveness of aluminum alloy–fly ash composites

Damping properties of aluminum matrix–fly ash composites

Mechanical properties of SiC/Gr/Al composites fabricated by squeeze casting technology

Zuoyong Dou

Papers

Compression behaviors of cenosphere–pure aluminum syntactic foams

High strain rate compression of cenosphere-pure aluminum syntactic foams

Electromagnetic shielding effectiveness of aluminum alloy–fly ash composites

Damping properties of aluminum matrix–fly ash composites

Mechanical properties of SiC/Gr/Al composites fabricated by squeeze casting technology