Synthesis of Ti3SiC2 Powders: Reaction Mechanism

Titanium silicon carbide (Ti₃SiC₂) and Ti₃SiC₂-based composite powders were synthesized by isothermal treatment in an inert atmosphere as a function of initial compositions (mixtures). A high content of TiC was obtained in the final product when the initial mixtures contained free carbon. The use of TiC as a reagent was unsuccessful in obtaining Ti₃SiC₂. High Ti₃SiC₂ conversion was found for the initial mixtures containing SiC as the main source for silicon and carbon. An initial mixture with a large excess of silicon, 3Ti/1.5SiC/0.5C, was needed to obtain high-purity Ti₃SiC₂. A reaction mechanism, where Ti₃SiC₂ nucleates on Ti₅Si₃C crystals and grows by long-range diffusion of Ti and C, is proposed. The reaction mechanism was proposed to be based on silicon loss during the formation of Ti₃SiC₂.