Preparation of polymer-derived Si–B–C–N monoliths by spark plasma sintering technique

• Published in: Journal of the European Ceramic Society 2015-05, Vol.35 (5), p.1361-1374
• Main Authors: Bechelany, Mirna Chaker, Salameh, Chrystelle, Viard, Antoine, Guichaoua, Lise, Rossignol, Fabrice, Chartier, Thierry, Bernard, Samuel, Miele, Philippe
• Format: Article
• Language: English
• Subjects: (Nano)composites; Chemical Sciences; Material chemistry; Polymer-derived ceramics; Properties; Si–B–C–N; Spark plasma sintering
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2014.11.021

The present paper reports the preparation of sintering additive-free Si–B–C–N monoliths by spark plasma sintering (SPS) under nitrogen of polymer-derived Si–B–C–N powders. Powders are synthesized in nitrogen or ammonia atmosphere to modify their carbon content. The nitrogen-treated powders sintered in the temperature range 1500–1900°C lead to monoliths with a density increasing from 2.4 to 2.6g/cm3, Vickers harness and Young's modulus ranging from 0.7 to 5.4GPa and 48 to 102GPa, respectively. SiC was the first phase to nucleate around 1700°C, whereas Si3N4 grew at 1800°C. At this temperature, monoliths are pure electrical conductor nanocomposites mainly composed of Si3N4 and SiC nanophases embedded in a turbostratic BN(C) matrix. Above 1800°C, Si3N4 was not identified. In comparison, ammonia-treated powders sintered at 1800°C represent dense insulator composites mainly composed of Si3N4 and BN with a Vickers hardness as high as 15GPa and an excellent stability in air.