Effects of multi-walled carbon nanotubes on the crystallization behavior of PDCs-SiBCN and their improved dielectric and EM absorbing properties

Polymer derived siliconboron carbonitride ceramics (PDCs-SiBCN) containing multi-walled carbon nanotubes (MWCNTs-SiBCN) were fabricated and heat treated at 1350 degrees C and 1500 degrees C in nitrogen atmosphere. XRD patterns show the characteristic peaks of SiC appeared in MWCNTs-SiBCN treated at 1500 degrees C, which is 300 degrees C lower than the crystallization temperature of SiC in PDCs-SiBCN. The decrease of temperature can be ascribed to the heterogeneous nucleation promoted by MWCNTs as nucleating agent. Energy change during heterogeneous nucleation is analyzed to explain the acceleration of crystallization. The dielectric and electromagnetic (EM) absorbing properties of the as-prepared MWCNTs-SiBCN are investigated, which show a better wave-absorbing ability than PDCs-SiBCN treated at the same temperature, owing to a distinctive A + B + C microstructure in MWCNTs-SiBCN. This work makes it possible to fabricate the PDCs-SiBCN with good EM absorbing property at a lower temperature, granting them potential as a matrix material candidate in ceramic matrix composite field. (C) 2013 Elsevier Ltd. All rights reserved.