Synthesis of Ti₃SiC₂ Powders: Reaction Mechanism

Abstract

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.

Phase reactions associated with the formation of Ti3SiC2 from TiC/Si powders

“…8. In previous studies, we have reported that silicon additions in the starting powder may increase the conversion of Ti 3 SiC 2 [24,32], which agree well with the findings of Hwang et al [27] and Córdoba et al [33]. Furthermore, we observed no decomposition of Ti 3 SiC 2 below 1450 8C.…”

Synthesis of Ti3SiC2 bulks by infiltration method

“…Although the reaction mechanism of Ti 3 SiC 2 fabricated by other methods have been previously reported [1,[7][8][9], in our infiltration synthesis study, there is an obviously different feature has been found during the phase formation process, which is that the phase compositions are closely related to the Si-concentration changes along the diffusion path. So we will discuss about the reaction mechanism of infiltration preparation of Ti 3 SiC 2 .…”

Production of Ti3SiC2-based materials by SHS forced compaction of layered composite Ti–SiC

“…Comparing the results obtained and the published data [11,12] it can be concluded that on the whole the mechanism of phase formation in the experimental layered system Ti-SiC is no different from the mechanism operating in powder reaction mixtures of the elements and binary compounds of the system Ti-Si-C. At temperature 1320°C the interaction of the initial reagents, which below 1320°C occurred by diffusion, switches into the SHS interaction regime. The combustion stage is accompanied by the formation of a titanium-silicon-carbon melt followed by crystallization of Ti 3 SiC 2 and TiSi 2 as the melt cools.…”