Reaction mechanism for pressureless sintering silicon carbide boron carbide composite

• Main Authors: Taneja, Kshitij, Kumar, Manoj, Mahajan, Sarang B.
• Format: Conference Proceeding
• Language: English
• Subjects: Boron carbide; Low density ceramic composite; Pressureless sintering; Reaction bonded silicon carbide boron carbide; Reaction sintering; Silicon carbide; Silicon carbide boron carbide composite
• ISSN: 2214-7853; 2214-7853
• DOI: 10.1016/j.matpr.2020.08.320

Reaction bonded silicon carbide boron carbide (RBSCBC) composites were prepared, and the reaction mechanism was studied. Reaction sintering was used to sinter boron carbide with in-situ silicon carbide formation reaction. The sample pellets were prepared by mixing and uniaxially pressing 85–90 wt% boron carbide powder and 10–15 wt% graphite powder with binder. The green state ceramic pellets were densified by reaction sintering at 1350 °C to 1450 °C in the presence of silicon powder. The reaction and sintering mechanism was studied using scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). It was observed that molten silicon reacted with graphite, residual carbon from the binder, and boron carbide to produce silicon carbide and silicon carbide boron carbide composite. There was no densification of green ceramic below the melting point of silicon, i.e., 1410 °C. Above this temperature, molten silicon reacted with carbon and formed β-SiC phase. Unreacted silicon was observed on the skin of the pellet.