Material used to absorb and shield electromagnetic waves - comprising finely divided, electrically nonconducting solid and a finely divided electrically conducting solid

摘要

Material consists of a finely divided, electrically non-conducting solid and a finely divided electrically conducting solid. The novelty is that it comprises 3-30 vol.% C and a balance of CaSO4 . 2H2O. Both have an ave. particle dia. d50 of 10-10,000nm. The electrical conductivity of the material is 0.2-10.0 (pref. 1-4) S/m and is freq. independent in this range. Prodn. of components made of the material is also claimed. The material is produced by dispersing finely divided C in water for 1-20 mins. by stirring, adding CaSO4 with stirring for 1-20 mins. into the C-water dispersion, and casting to mouldings using ultrasound or low freq. oscillations. The casting mould is removed from the moulding and the moulding dried at room temp. and then up to 45 deg.C. The C is in the form of graphite or carbon black with a plurality of more than 96%, pref. more than 98%. USE/ADVANTAGE - The material is used to absorb and shield electromagnetic waves in the range of 10MHz to 100GHz (claimed). The material is made from easily available raw materials.