GB898403A - Improvements relating to the production of boron carbide - Google Patents

Abstract

Boron carbide is prepared by heating at 1400 DEG C. to 1600 DEG C. a mixture of carbon, boric oxide (or boric acid or other boric oxide source), and a catalyst consisting of a compound of one or more of the elements aluminium, magnesium, strontium, ceasium, manganese, chromium, rubidium, potassium, sodium, lithium, lanthanum, silicon, iron, and barium (barium always being used in conjection with sodium), the catalyst being present in an amount of 1% to 10% of the total weight of the mixture. The catalyst may be in the form of an oxide, carbonate, borate, hydroxide or acetate. The mixture may include an organic binder, e.g. molasses, sugar, starch, pitch, asphalt or tar, and also may include a substance which renders it porous by evolution of gas or vapour, e.g. ammonium chloride. The mixture may be heated in a stream of inert gas, e.g. argon, and may be stirred or may be ground during intervals in the heating. The ratio of boric oxide to carbon in the mixture is between 1,6:1 and 3,0:1. In examples, boron carbide is prepared by heating boric oxide and carbon together with alumina, magnesium oxide, strontium carbonate, ceasium carbonate, manganese dioxide, chromium trioxide, rubidium carbonate, potassium carbonate, sodium carbonate, lithium carbonate, lanthanum oxide, silica, ferric oxide, or a mixture of barium carbonate and sodium carbonate, molasses being included in two instances. Specification 870,083 is referred to.