Chromium dicarbide

There are a number of metallic compounds of chromium that ate used either as the compound itself or as metallurgical constituents in Cr-beating alloys. Trichromium dicarbide [12012-35-0] is important as a wear-resistant gauge material chromium botide(l 1) [12006-79-0] CrB, for oil well drilling ... 

Pentachromium Dicarbide, CrjGg, can be prepared in quantity by melting a mixture of chromium and a finely powdered chromium-carbon alloy containing-11-16 per cent, of carbon in a magnesia crucible at 1800° to 1850° C. After repeatedly washing the product vdth 2N hydrochloric acid until no more chromium dissolves, the carbide, CrjCj, is obtained practically pure. It forms silvery crystals, of density 6-915 at 24-8° C. It is not attacked by aqua regia, and melts without appreciable decomposition at 1665° C. 

Tetrachromium Dicarbide, Cr C -— By melting chromium at temperatures above 1840° C. for fifteen minutes in a crucible of pure carbon, frequently stirring vith a carbon rod, alloys saturated with carbon are obtained. These contain no free chromium, but only carbide and graphite. On washing with hot 24 per cent, hydrochloric acid part of the alloy dissolves, and the ratio of chromium to carbon dissohing indicates that the soluble carbide has the composition Cr Cg, but the existence of this has not been confirmed by isolation. 

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