Phase transition and microstructure evolution during the carbothermal preparation of Ti(C,N) powders in an open system

Abstract Phase transition and microstructure evolution during carbothermal reduction–nitridation of TiO 2 in an open system were investigated using XRD, TGA, SEM and laser particle analysis device. The results show that, the phase evolution sequences are: TiO 2 (anatase) → TiO 2 (rutile) → Ti n O 2 n- 1 ( n  ⩾ 4) → Ti 3 O 5  → Ti(N,O) → Ti(C,N,O) → Ti(C,N). In the reaction process, the predominant reaction mechanism is TiO 2 /C solid–solid reaction in the beginning and subsequent the gas–solid reactions mainly between oxides and CO, C and CO 2 . The synthesizing powders gradually become finer in form of uniform spherical particles with the formation of cubic phase.