Conclusions
A study was made of the sintering kinetics of grade “ch.” boron carbide, technical boron carbide cleaned of impurities, and boron carbide synthesized from the elements. An investigation was carried out also into the reactive sintering of a mixture of boron and carbon black. Reactive sintering fails to yield dense parts in boron carbide. The best sinterability is exhibited by a fine technical boron carbide powder cleaned of free carbon and other contaminants. Parts with a porosity of less than 5% can be produced from such a powder by pressing and subsequent sintering. However, it is not the presence of free carbon that controls the sintering behavior of boron carbide, since pure and synthesized boron carbide powders containing no free carbon are characterized by poor sinterability. The high activity of the technical powder is probably linked with the presence of structural defects and stresses generated in the course of its manufacture, during milling and quenching. The annealing spectrum of these defects covers a wide temperature range, and consequently the energy of activation for the densification of boron carbide steadily grows with increase in shrinkage.
Similar content being viewed by others
Literature cited
B. L. Grabchuk and P. S. Kislyi, Poroshkovaya Met., No. 8 (1974).
GOST Standard No. 5744-62 [in Russian].
A. N. Rekov and G. V. Samsonov, Poroshkovaya Met., No. 5 (1961).
G. V. Samsonov, L. Ya. Markovskii, et al., Boron and Its Compounds and Alloys [in Russian], Izd-vo AN UkrSSR, Kiev (1960).
P. S. Kislyi and G. V. Samsonov, Fiz. Tverd. Tela,2, No. 8, 1729 (1960).
V. V. Skorokhod, Rheological Principles of Sintering Theory [in Russian], Naukova Dumka, Kiev (1972).
P. S. Kislyi and M. A. Kuzenkova, Poroshkovaya Met., No. 2 (1966).
N. I. Zhuravlev, G. N. Makarenko, G. V. Samsonov, et al., Izv. Akad. Nauk SSSR, Otd. Tekhn. Nauk, Met. i Toplivo, No. 1, 133 (1961).
Author information
Authors and Affiliations
Additional information
Translated from Poroshkovaya Metallurgiya, No. 7 (151), pp. 27–31, July, 1975.