Carbothermic reduction of anatase and rutile

The carbothermic reduction of anatase and rutile to TiC was investigated using a combination of thermogravimetric analysis and X-ray diffraction. Samples premilled for 50 h prior to heat treatment showed a much greater extent of reduction compared with the unmilled powders. Heating the rutile up to 800 °C and anatase up to 870 °C showed no evidence for reduction with the observed mass loss attributed to desorption of gas. After heating to 800 °C, most of the anatase has transformed to rutile. The reduction of rutile started at ∼830 °C whilst anatase underwent reduction at 870 °C. The initial identified products were Ti 5O 9 and Ti 4O 7 with the latter being the last apparently stable phase prior to TiC formation. The TiC formed from anatase was apparently stoichiometric whilst that from rutile was clearly sub-stoichiometric. Reasons for the difference in reduction behaviour are discussed.