Development of cubic boron nitride synthesis processes using non-traditional technologies (overview)
DOI: 10.62564/M4-OB2312
Ivan Borymskyi, Oleksandr Borymskyi, Sergey Starik
V. Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine
Cubic boron nitride (cBN) powders are widely used for construction and instrumental materials in various fields of science and production. The purpose of this work is to monitor the efficiency of processes for the synthesis of cBN powders using a variety of non-traditional technologies, including mechanically activated reaction mixtures and additional crystallization centers (DCC) [1].
It was established that the use of a mechanically activated reaction charge allows to increase the degree of conversion of hBN→cBN from 30-50 achieved without activation to 85-90 % (by mass) and to obtain a product that mainly consists of micropowders of a deficient narrow grain size range with an average grain size of 3-4 to 10-14 microns.
The possibility of synthesizing lithium bornitride Li3BN2 by mechanical activation of the initial components is shown and the high efficiency of its use in the synthesis of cBN powders is established.
The process of synthesis of mixtures of the Mg3N2–MgО system in the mode of combustion of Mg powder in air was studied and the high efficiency of their manufacture and use as components of the reaction charge in the synthesis of cBN powders was established.
It is shown that the grains obtained by crushing compacts based on dense modifications of boron nitride, such as hexanite-A and kyborite, are effective DCC in the synthesis of cBN.
It was found that the use of hexanite-A grains with a wurtzite content of about 20% (by mass) in the synthesis of cBN as a DCC leads to the formation of two-layered hexanite-cBN grains, which consist of a polycrystalline inner part (hexanite-A) covered with an outer layer that has grown on it layer with cBN. The effectiveness of using such two-layer hexanite-cBN grains as an abrasive tool material is being investigated.
