Carbon-Fiber Cement-Based Materials for Electromagnetic Shielding

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Title: Carbon-Fiber Cement-Based Materials for Electromagnetic Shielding

Author(s): Sivaraja Muthusamy and D. D. L. Chung

Publication: Materials Journal

Volume: 107

Issue: 6

Appears on pages(s): 603-611

Keywords: carbon; electrical resistivity; electromagnetic shielding; fiber; mechanical properties; silica fume; sizing

Date: 11/1/2010

Abstract:
Short carbon fiber is used as an admixture with silica fume to form cement-matrix composites. It is made from pitch or polyacrylonitrile (PAN). PAN-based fiber with a diameter of 7 mm is effective for providing electromagnetic interference (EMI) shielding (1 GHz), low electrical resistivity (DC), and high flexural strength and modulus. Its shielding ability is superior to that of previously studied pitch-based fiber with a diameter of 15 mm (6 × 10–4 in.). Thermally desized PAN-based fiber is less effective than the unsized counterpart for providing shielding, reflection, and low electrical resistivity, but it is more effective as a reinforcement. An increase in the fiber content increases the shielding effectiveness, decreases the resistivity; and increases the flexural strength and modulus. For each fiber content in percentage by mass of cement, the addition of sand causes a slight decrease of the shielding effectiveness; at the same fiber volume fraction, the shielding effectiveness is similar for cases with and without sand.