Development of Porous Carbon Material "Woodceramics", II. Electromagnetic Shielding Characteristics.

The volume resistivity and electromagnetic shielding properties of “Woodceramics” made of porous carbon material were investigated for the purpose of developing a new shielding material.The measured values of volume resistivity depended on the burning temperature, and changed from 1010Ω·cm to 10-2Ω·cm with increasing burning temperature.On the shielding tests with the electromagnetic waves from frequencies of 1000kHz to 1GHz, a good electric shielding effect was observed for those burned above 650°C. When the burning temperature was higher than 700°C, some magnetic shielding effect also appeared. Above 900°C, the shielding effet of more than 40dB on was observed for both of the electric and magnetic shielding in wide frequencies.