COMBINED ELEMENTAL SYNTHESIS
OF BORON AND SILICON CARBIDES
D. D. Nesmelov,
E. A. Vlasova,
and S. S. Ordan’yan
Translated from Novye Ogneupory, No. 10, pp. 37 – 41, October, 2016.
Original article submitted February 29, 2016.
Combined synthesis from powders of elements B, C, and Si at 1400, 1500, and 1650°C is used to prepare
heterophase powders in the system SiC–B
C containing 80, 57, and 30 (mol.%) boron carbide. Powders con
taining only SiC and B
C phases are prepared at 1550°C from a mixture with 5% excess silicon given vibra
tion grinding for 60 h. The powder has a unimodal particle size distribution and d
= 3.5 mm with a volume
concentration of 12% submicron particles.
Keywords: boron carbide, silicon carbide, combined synthesis, composite material, ceramic, homo-
Born carbide and silicon carbide due to their own out-
standing properties are used extensively for creating ceramic
superhard and high-strength materials by hot pressing, reac-
tion sintering, and sintering in the presence of an activating
addition. For a number of applications in aerospace, military,
and engineering industries materials are required combining
low density, (less than 3.2 g/cm
) with high hardness,
strength, and crack resistance. Realization of this set of prop
erties in single-phase material is almost impossible. In view
of this within the SiC–B
C system there is currently active
development of heterophase composite materials whose real
ization is connected with formation of a uniform structure
with very fine components, including nanosize components
[1 – 9].
We note that boron carbide and silicon carbide are ther
modynamically compatible phases: the quasibinary section
of the SiC–B
C system is described by a composition dia
gram of the eutectic type (Fig. 1) with a eutectic temperature,
according to data for various sources, 2070 – 2300°C and an
SiC concentration in eutectic of 35 – 43 mol.% [10 – 15].
In order to provide uniformity of the structure and
reproducibility of composite material properties, prepared by
powder technology (ceramic technology) it is extremely im
portant to attain a high degree of SC and B
tion in a charge, which traditionally is accomplished by me-
chanical mixing or combined milling of individual com-
pound powders. Since covalent carbides have high hardness
and abrasion resistance this operation, in spite of high energy
consumption, does not provided and adequate degree of ho-
mogenization; there is fluctuation in component concentra-
tion within the volume of a mix and agglomeration of ground
Refractories and Industrial Ceramics Vol. 57, No. 5, January, 2017
1083-4877/17/05705-0531 © 2017 Springer Science+Business Media New York
FGBOU VPO St. Petersburg State Technological Institute (Tech
nical University), St. Petersburg, Russia.
Fig. 1. Quasibinary section B
C–SiC of the B–Si–C system from
summarized data [10 – 15].