Iron monoboride, FeB

Iron monoboride, FeB, is readily formed by heating iron in a stream of vaporised boron chloride. It also results when iron and boron are heated together in the electric furnace. Obtained in this way iron boride forms brilliant yellow-grey crystals, of density 7.15 at 18° C. It does not alter in dry air or oxygen, but moist air renders it ochreous. Chlorine and bromine attack it at red heat and, when heated in oxygen, it burns brilliantly.

Bromine attacks it at red heat with incandescence; chlorine is less vigorous in its action, whilst iodine and hydrogen iodide have no action, even at 1100° C. The chlorate and nitrate of potassium do not affect it at their melting-points, but at higher temperatures decompose it with incandescence. Fused alkali hydroxides and carbonates decompose it rapidly. Concentrated sulphuric acid is without action in the cold, but with the boiling acid ferrous sulphate is produced. Dilute nitric acid dissolves it when hot, and the concentrated acid acts vigorously. Dilute hydrochloric acid is without action, and the hot concentrated acid acts only slowly.