Catalytic synthesis of graphite-like boron nitride

Abstract

It is well-known [1, 2] that lithium compounds have a strong effect on the process of formation of boron nitride by the carbothermal method from highly dispersed charges produced by the dissolution method. It is therefore interesting to examine the effect of these compounds on the formation and ordering of the structure of boron nitride in other methods of preparation.

Investigations were carried out into the process of nitriding boron and a mixture of boric acid with soot in the presence of lithium compounds. Initial substances were amorphous boron with a purity of 98.6, boric acid of ChDA grade, grade 514 soot, grade ChDA lithium carbonate and hydroxyl, and dried nitrogen and ammonia. Charges were prepared by mixing the components by the dried method. The ratio of the boric acid and soot in the charges was constant (7:2), and the concentration of the addition was varied in the range from 1 to 58% (by mass). Nitriding was carried out in the temperature range 800–1500°C in a gas flow with an optimum speed of 2 litres/h. Temperature was measured with a platinum-platinum/rhodium thermocouple and regulated using an Sh-4501 device. Nitriding products were examined by chemical and x-ray analysis and also electron microscopy.