Résumé
Silicon carbide (SiC) has attracted interest for environmental and energy applications due to its good properties at high temperature. The synthesis of SiCwas initiated by Acheson in 1892 and is still today applied to produce commercial SiC powders. Traditional manufacturing techniques such as sintering are energy-intensive, inappropriate for complex shapes and the ability to control purity and crystallinity is also restricted. Future industrial challenges for SiC components require materials with compositions, shapes and microstructures that are tuned on demand. This can be achieved by combining both molecular and materials chemistries. The Polymer-Derived Ceramics (PDCs) route is a good example of this strategy. The chemistry, the processing properties and the reactivity of polymers can be tailored to supply, after shaping and pyrolysis, ceramics with the desired phase composition and distribution. This method was used to prepare boron-modified SiC. The polymers were synthesized by the reaction of allylhydridopolycarbosilane (AHPCS) with borane dimethylsulfide. The boron content has an effect on the chemistry and processability of precursors, as well as on the properties of final materials. Infrared, NMR spectroscopies and elemental analyses give us information about the chemical properties of the boron-modified SiC precursors. Their pyrolysis behavior is investigated by solid-state NMR coupled with thermogravimetric analyses. The final materials are characterized by X-ray diffraction, elementary analysis and Raman spectroscopy. Applications of the PDC route to the processing of ceramic composites will be discussed.