Abstract: Hot pressing of 2TiC-B4C powder mixture at 1800ºC and 30 MPa leads to TiB2 and graphite formation and allowed in situ obtaining high-E, low-E ceramic composites. To investigate the reaction mechanisms, B4C and TiC plates were annealed together, separated with a graphite ring in vacuum and air at 1200 – 1900ºC. Titanium diboride appeared on titanium carbide plate showing, that boron atoms move to TiC not only by solid-state diffusion through intergranular contacts, but also via gas phase after sublimation from boron carbide. The influence of high (8 GPa) pressure on TiC-B4C reaction kinetics was investigated confirming sublimation-deposition mechanism to be a predominant way of boron to TiC transfer at 1800ºC.
Authors: Oleksii Popov, Alexandra Klepko, Serhii Chornobuk, and Edward Lutsak
Keywords: reactive sintering, phase stability, boron carbide, atomic transport