Résumé
Silicon-based non-oxide ceramics (SiC, Si3N4) have attractedmuch attention due to their good properties and reliability at hightemperatures which can be enhanced by addition of a secondceramic (nano)phase. However, their preparation is a challengingtask as conventional processes lead to inhomogeneities and impuritiesaffecting the properties. The Polymer-Derived Ceramics (PDCs)route is an alternative strategy using a “ceramic through chemistry”concept. Preceramic polymers have allowed obtaining multi-elementceramics with controlled chemical composition by incorporatingelements to provide high temperature resistant materials. In thisstudy, boron is added to polycarbosilazanes to obtain silicoboroncarbonitride (Si/B/(C)/N) ceramics after pyrolysis. We investigatethrough FTIR, solid-state NMR, the chemistry of boron-modifiedpolycarbosilazanes as well as their pyrolysis behavior combining TGexperiments and solid-state NMR. By controlling the boron contentin the polymer at molecular scale, we can deliver after pyrolysis bulkSi/B/(C)/N materials with tailored properties. The high temperaturebehavior is investigated by thermogravimetric analysis, XRD,elementary analysis and Raman spectroscopy and we show how theboron content and the nature of the atmosphere affect the structuralevolution of the Si/B/(C)/N phase at high temperature.