THE REDUCTION BEHAVIOR OF SYNTHETIC CHROMITES BY CARBON.

Chromites reduced by graphite powder under a CO atmosphere:FeCr//2O//4(Sp 1), MgCr//2O//4(Sp 2), (Fe//0//. //5Mg//0//. //5)Cr//2O//4(Sp 3), (Fe//0//. //5Mg//0//. //5)(Cr//0//. //8Al//0//. //2)//2O//4(Sp 4), and Mg (Cr//0//. //6Al//0//. //4)//2O//4(Sp 5). In the case of the pure iron chromite Sp 1, the reduction of FeO preceded that of Cr//2O//3. The metallic products changed in the following order: Austenite yields austenite plus (Fe, Cr)//3C yields (Fe,Cr)//3C plus (Cr, Fe)//7C//3 yields (Cr, Fe)//7C//3. The reduction of complex chromites containing iron oxide (Sp 3 and Sp 4) took place in two stages. In the first stage with the reduction of the FeCr//2O//4 component, FeO and Cr//2O//3 were reduced simultaneously at temperatures higher than 1,150 degree C, C, although the reduction of FeO preceded at lower temperatures. The reduction of the MgCr//2O//4 component started at 1,200 degree C and proceeded rapidly at temperatures higher than 1,250 degree C in the case of Sp 2 and Sp 3. Reduction of MgCr//2O//4 component of Sp 4 and Sp 5 was only at temperatures higher than 1,330 degree C. The product of chromites Sp 3 and Sp 4 was (Cr, Fe)//7C//3 in either reduction stage. The final product of Sp 2 and Sp 5 was Cr//3C//2, while an unidentified phase was considered to be chromium oxycarbide.