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Both carbon and silicon expose a lot of metallic properties like metallic lustre, electrical and heat conductivity, etc, so often considered metalloids. The both form alloys with other metals such as iron.

On the other hand, the usual silicon carbide is not an alloy at all. It is tranparent, electrical insulator etc.

I wonder whether there is a different carbon-silicon compound that has more metallic properties?

Carbon (graphite):

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Silicon:

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Silicon carbide:

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Here you can find a phase diagram for $\ce{Si/C}$ system. It does not have zones with homogeneous non-stohiometric solids. So, there is not thermodinamically stable Si/C isomorphic alloys. However, since the liquid likely to be homogeneous, it is likely for fast cooled liquid to form amorphous alloys. Indeed, google search provides plenty of links for amorphous $\ce{Si/C}$ alloys. However, it is also possible for cooling liquid to form polycrystalline alloy, say, with $\ce{SiC}$ and $\ce{C}$ grains, similar to pig iron.

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  • $\begingroup$ I already saw the diagram, thanks. So do they mix with each other in and only in liquid state? $\endgroup$
    – Anixx
    Nov 17 '14 at 21:40
  • $\begingroup$ Note that the diagram covers only one pressure. $\endgroup$
    – Anixx
    Nov 17 '14 at 21:47
  • $\begingroup$ @Anixx condensed phase is rarely significantly affected by pressure change (water is a pathological case). And yes, judging from the diagram it is that way. $\endgroup$
    – permeakra
    Nov 17 '14 at 21:56
  • $\begingroup$ @Anixx At least as far as pressure does not skyrocket. When it is skyrocketing, weirdest things may happen. $\endgroup$
    – permeakra
    Nov 17 '14 at 22:03
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One might consider reaction-bonded silicon carbide, which is essentially a composite of silicon carbide and elemental silicon, sometimes also containing graphite for sealing applications. To make reaction-bonded silicon carbide, a porous part containing silicon carbide and carbon is permeated with molten silicon. The reaction between the silicon and the carbon binds the material, as does leftover molten silicon which solidifies as it cools. The resulting material is lightweight and has a favorable properties for a variety of high-temperature and mechanical applications, including some cases (such as burner tubes in furnaces) where it competes with metallic alloys.

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