Carbon materials and their composites for electromagnetic interference shielding effectiveness in X-band

In the last two decades, fibre-reinforced SiC ceramic-matrix composites (CMCs) have attracted extensive interests. Owing to the designable multi-scale microstructure feature and the tailorable processing methods such as chemical vapour infiltration and polymer derived ceramics, SiC matrix composites attain great potential as multifunctional composites. Through designing the fibre, interphase, matrix and coating, the composite exhibits a multitude of functionalities which are desirable for various technological applications. Besides strengthening and toughening design of CMCs, three inspiring issues of multifunctional CMCs are receiving increasing attention, including crack self-healing, friction self-lubrication, and electromagnetic shielding and absorption, which are the key mechanisms to promote the application of CMCs in hot structures of engines and aerospace vehicles, braking pads/discs, various electronic devices, etc. The present review covers the main mechanisms on strengthening and toughening, cr...

Fibre-reinforced multifunctional SiC matrix composite materials

The fate and role of in situ formed carbon in polymer-derived ceramics

Recent progress on carbon-based composite materials for microwave electromagnetic interference shielding

Composites are, in general, a rapidly evolving and growing technical field with a very wide range of applications across the aerospace, defence, energy, medical and transport sectors as a result of...

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Selection, processing, properties and applications of ultra-high temperature ceramic matrix composites, UHTCMCs – a review

Mechanical and electromagnetic shielding properties of carbon fiber reinforced silicon carbide matrix composites

Effect of heat treatment on the mechanical properties of SiC f /BN/SiC fabricated by CVI

It is difficult for ceramic matrix composites to combine good electromagnetic wave (EMW) absorption properties (reflection coefficient, RC less than -7 dB in X band) and good mechanical properties (flexural strength more than 300 MPa and fracture toughness more than 10 M P·m1/2). To solve this problem, two kinds of wave-absorbing SiC fibers reinforced Si3N4 matrix composites (SiCf/Si3N4) were designed and fabricated via chemical vapor infiltration technique. Effects of conductivity on EM wave absorbing properties and fiber/matrix bonding strength on mechanical properties were studied. The SiCf/Si3N4 composite, having a relatively low conductivity (its conduction loss is about 33% of the total dielectric loss) has good EMW absorption properties, i.e. a relative complex permittivity of about 9.2-j6.4 at 10 GHz and an RC lower than −7.2 dB in the whole X band. Its low relative complex permittivity matches impedances between composites and air better, and its strong polarization relaxation loss ability help it to absorb more EM wave energy. Moreover, with a suitably strong fiber/matrix bonding strength, the composite can transfer load more effectively from matrix to fibers, resulting in a higher flexural strength (380 MPa) and fracture toughness (12.9 MPa▪m1/2).

Electromagnetic wave absorption and mechanical properties of silicon carbide fibers reinforced silicon nitride matrix composites

Oxidation behavior of SiBC matrix modified C/SiC composites with different PyC interphase thicknesses

The mechanical behavior and oxidation resistance of SiC/SiC-SiBC composites were studied in this work. According to the debonding criterion of He and Hutchinson, the debonding could occur at the BN interphase, which insures that the fibers can well play the strengthening and toughening performance. The oxidation resistance of SiC/SiC-SiBC composites consisting of SiC fibers with thermal expansion coefficients (CTE) of 5.1 × 10 −6  K −1 and 4.0 × 10 −6  K −1 was compared. The composites consisting of SiC fibers with higher CTE show slight weight changes at 800, 1000, and 1200 °C, and the corresponding strength retention ratios are 109.6%, 103.2% and 102.9%, exhibiting excellent oxidation resistance. The CTE of composites consisting of SiC fibers with higher CTE matches well with the CTE of SiC coating, so rarely no cracks can be formed in the coating, which inhibits the inward diffusion of oxidizing medium and leads to high strength retention ratios after oxidation tests.

Xiaokang Ma

Papers

Mechanical and electromagnetic shielding properties of carbon fiber reinforced silicon carbide matrix composites

Effect of heat treatment on the mechanical properties of SiC f /BN/SiC fabricated by CVI

Electromagnetic wave absorption and mechanical properties of silicon carbide fibers reinforced silicon nitride matrix composites

Oxidation behavior of SiBC matrix modified C/SiC composites with different PyC interphase thicknesses

Oxidation resistance of SiC/SiC composites containing SiBC matrix fabricated by liquid silicon infiltration