Effects of Oxidation Curing of Polycarbosilane on Dielectric and Microwave Absorption Properties of PDCs‐SiC Ceramics

Abstract

Polycarbosilane (PCS) was cured by oxidizing at different temperatures and pyrolyzed at 1000°C in vacuum. The dielectric properties of SiC ceramics were studied in X band. The ε′ and ε″ of SiC ceramics derived from oxidation‐curing PCS decreased to 4 and 0.35, respectively, which attribute to the decrease of free carbon content and order. SiC ceramic derived from PCS cured at 180°C showed that reflection loss was lower than −10 dB in the frequency range from 8.2 to 11.3 GHz and the minimum value was −26.7 dB at 9.6 GHz, which exhibits a promising prospect as microwave‐absorbing materials.

Preparation of SiCf/Si–O–C composites by impregnation pyrolysis of polysiloxane and its electromagnetic wave absorption properties

“…The composites were made into standard samples with a size of 22.86 × 10.16 × 2.0 mm 3 as required and their X‐band complex permittivities were obtained by a vector network analyzer (E8362B) using the waveguide method. The value of RL is calculated by the following equation 28 : $$$$\begin{equation} \mathrm{RL} = 20\log \left|\frac{{Z}_{\textit{in}}-{Z}_{0}}{{Z}_{\textit{in}}+{Z}_{\mathit{0}}}\right| \end{equation}$$$$ $$$$\begin{equation}{Z_{in}} = {Z_{\rm{0}}}\sqrt {\frac{{{\mu _r}}}{{{\varepsilon _r}}}} {\rm{tanh}}\left[ {j\left( {\frac{{{\rm{2}}\pi ft}}{c}} \right)\sqrt {{\mu _r}{\varepsilon _r}} } \right]\end{equation}$$$$…”

“…The composites were made into standard samples with a size of 22.86 × 10.16 × 2.0 mm 3 as required and their X-band complex permittivities were obtained by a vector network analyzer (E8362B) using the waveguide method. The value of RL is calculated by the following equation 28 :…”

Thermal oxidation curing polycarbosilane fibers by alternating air and vacuum process

“…Electron beam irradiation in air, partial curing with ozone and chemical vapor curing with active gas can prepare SiC ceramic bers with such structures. [10][11][12] The essence of these processes was cross-linking the out surface layer of the PCS bers. However, these existing methods which mentioned above were technique complex, low efficiency, environment harmful and costly.…”