Multifunctional Ceramic Composite System for Simultaneous Thermal Protection and Electromagnetic Interference Shielding for Carbon Fiber-Reinforced Polymer Composites.Achieving a high electrical conductivity while maintaining a good thermal insulation is often contradictory in the material design for the goal of simultaneous thermal protection and electromagnetic interference shielding.  The reason is that materials with a high electrical conductivity often pertain a high thermal conductivity.  The polymer-derived SiCN ceramic reinforced with yttria-stabilized zirconia fibers serves as the thermal protection and impedance-matching layer, while the yttria-stabilized zirconia fiber-reinforced SiCN ceramic with carbon nanotubes provides the electromagnetic interference shielding.  The thermal conductance of the multilayered ceramic composite is about 22.5% lower compared to that of the carbon fiber-reinforced polymer composites.  The thermal insulation test during the steady-state condition shows that the hybrid composite can be used up to 300 °C while keeping the temperature reaching the surface of carbon fiber-reinforced polymer composites at around 167.8 °C.  The flame test was used to characterize the thermal protection capability under transient conditions.  The movement of electrons was impeded by the top and bottom layers whose thermal conduction relies on the lattice vibrations, resulting in a satisfactory thermal insulation of the composite materials and impedance matching with the free space.  Results of this study showed that materials with a good thermal insulation and electromagnetic interference shielding can be obtained simultaneously by confining the electron movement inside the materials and refraining their movement at the skin surface.
THERM