Processing route dramatically influencing the nanostructure of carbon-rich SiCN and SiBCN polymer-derived ceramics. Part I: Low temperature thermal transformation

In this study, the significant effect of the processing route on the nanostructure evaluation of carbon-rich SiCN and SiBCN polymer-derived ceramics is reported. For the first time, bulk carbon-rich SiCN and SiBCN ceramics are successfully produced by warm pressing of polyphenylvinylsilylcarbodiimide and polyborophenylsilylcarbodiimide. The bulk samples were compared with their analogous powder samples with respect to the developed nanostructure. Representative temperatures of 1100 and 1400 °C were chosen in order to investigate the effect of processing route used on the crystallization behavior of those samples. As the solid-state structure of polymer-derived ceramics (PDCs) is highly sensitive to the molecular structure of the precursor, the variation of processing route and pyrolysis temperature during the polymer to ceramic transformation and decomposition enables to alter the nanostructure of PDCs. It was found that the bulk carbon-rich SiCN and SiBCN ceramics show an improved thermal stability against crystallization as compared to their powder analogues.