Electromagnetic shielding properties of carbon fiber felt–glass fiber felt based multilayer composites with different layer angle

• Carbon fiber felt/glass fiber felt based composites with layer angle were prepared.
• Variations of electrical and magnetic properties with layer angle were studied.
• Shielding products with sandwich structure should avoid big layer angle.
• Shielding effectiveness and absorbed power can be regulated by layer angle.
• Rotatable units made of this composite can get variable shielding applications.

Carbon fiber felt–glass fiber felt/epoxy resin multilayer composites with different layer angle were prepared to evaluate electromagnetic shielding properties in the X band. Comparison of composites with or without adding carbonyl iron powder was made in electric properties and shielding properties. Carbon fiber felt–glass fiber felt/epoxy resin multilayer composite can get a high shielding effectiveness (76.3 dB) at a suitable thickness (4.00 mm) when layer angle is close to 0°. Shielding effectiveness decreases rapidly with increase in layer angle and power constituent parts have different variations. Variations in dielectric constant and magnetic permittivity were found after adding carbonyl iron powder. Use of carbonyl iron powder can improve shielding effectiveness and absorbed power when layer angle is beyond 35°. Carbonyl iron powder-carbon fiber felt–glass fiber felt/epoxy resin composite can get high absorbed power (62.6%) when layer angle is about 45°.