Vanadium disilicide

Vanadium Disilicide, VSia, is prepared by reducing a mixture of vanadium trioxide and silicon with magnesium vanadium pentoxide can also be employed with the addition of fluorspar to the mixture.12 Gin used a mixture of the pentoxide, silica, and coke.18 Vanadium disilicide is a very stable compound it forms metallic prisms which melt at 1655° C., have a specific gravity of 4-42, and are hard enough to scratch glass. It is attacked by hydrofluoric acid, hydrogen chloride gas, and fused alkalis. 

The silicides of major industrial importance are the disilicides of the refractory metals molybdenum, tantalum, titanium, tungsten, vanadium, and zirconium.pl] These compounds are of great interest par-... 

The vanadium tetrachloride distils over and is purified from any ferric chloride present either by distillation or by extraction of the product with carbon tetrachloride, in which only the vanadium halide is soluble.2 Sulphuryl chloride, thionyl chloride, sulphur monochloride, and phosgene can all be used in the last reaction instead of chlorine, and the ferrovanadium also can be substituted by vanadium carbide, V4C3,3 nitride, VN,4 subsilicide, V2Si,5 disilicide, VSi2,8 or pentoxide.7... 

Vanadium and silicon are miscible in all proportions in the liquid state up to 60 per cent, vanadium. The eutectic point is at 1411° C. near to the silicon end of the series, while the composition at the maximum approximates to the composition of the disilicide, VSia.10 Two compounds of vanadium and silicon, V2Si and VSi2, have been prepared m the electric furnace. 

Vanadium Subsilicide, V2Si, is obtained by fusing a mixture of vanadium trioxide, V2Os, and silicon, with the addition of either a large excess of vanadium or carbon or copper. The carbide or copper alloy produced is decomposed at the temperature employed.11 The silicide forms metallic prisms, of density 5-48 at 17° C., the m.pt. of which is higher than in the ease of the disilicide. It is attacked by the halogens, hydrogen chloride gas, and fused sodium or copper, but hydrochloric acid, nitric acid and sulphuric acid are without action. 

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