Catalytic graphitisation of amorphous carbon during solar carbide synthesis of VIa group metals (Cr, Mo and W)

We observed earlier the evidence indicative of promoted graphitisation of amorphous carbon (aC) during a solar synthesis of tungsten carbide (WC) from mixed powders of W and aC whereas graphitisation of aC did not proceed during WC formation under a comparable temperature condition in a traditional laboratory electric resistance furnace and thus the observed graphitisation promotion for aC was concluded to be with photochemical-assisted nature. Graphitisation promotion was not observed at all in the synthesis of molybdenum carbide from mixed powders of Mo and aC undertaken in neither solar furnace nor traditional laboratory furnace. Being intrigued by these observations, we decided to undertake the similar experiments with another VIa group metal, Cr. The observed aC graphitisation behaviour with Cr was different from that with Mo and that with W. With Cr, aC graphitisation progressed in both solar furnace and traditional laboratory furnace.