Development of the carbon nanotube/cement board for electromagnetic interference shielding

Abstract

The proliferation of electronics and instrumentation in commercial, industrial, and healthcare has led to a latent pollution known as electromagnetic interference (EMI). The importance of EMI shielding has been dramatically increased. In the past, metals are most common materials for EMI shielding in the construction field. But they have the disadvantages like high density, susceptibility to corrosion, complex and uneconomic processing. To solve these problems, barium ferrite and carbon nanotubes are chosen as shielding materials in this study. Barium ferrite has high saturation magnetization, high anisotropy field, and excellent magnetic properties. Also, barium ferrite is stable in moist conditions and has corrosion resistance. These properties make it a promising shielding material in construction field. In this study, specimens with four different barium ferrite contents (0.0, 0.3, 0.4, 0.5 % by cement weight) were manufactured and investigated to measure their EMI shielding effectiveness. Moreover, influence of magnetization on barium ferrite/cement paste was examined. Carbon nanotubes (CNTs) are nano-scale structures which have outstanding electric conductivity and high EMI shielding performance. Compared to conventional metal-based EMI shielding materials, CNT composites have distinct advantages such as light weight, resistance to corrosion, and serviceability. As a result of the excellent characteristics of CNT, they can be applicable as an EMI shielding construction material. In the present study, a cement board was designed, fabricated, and measured according to the coaxial transmission measurement. The EMI shielding effectiveness of CNT/cement board was measured by varying the thickness of the air cavity in the board systems in order to find the best impedance matching between CNT/cement boards. Finally, a new dry wall system using CNT/cement board was developed as a multi-functional wall system. A field test was conducted in a shielded anechoic cha...