Synthesis of the Ti3SiC2 MAX Phase via Combustion in the TiO2–Mg–Si–C System

Abstract

Technologically viable principles have been developed for the preparation of the MAX phase Ti3SiC2 by self-propagating high-temperature synthesis (SHS) with a reduction step, using titanium dioxide. We have studied the influence of synthesis conditions (starting-mixture composition and ratio of reactants) on the composition, structure, and particle size of the Ti3SiC2 powder. The results demonstrate that the addition of 10 to 20 wt % excess magnesium to the starting mixture leads to a decrease in the percentage of the TiSi2 and Ti5Si3 silicides in the Ti3SiC2 powder (from 8 to 5 wt %), with the smallest percentage of titanium carbide corresponding to a 10% excess of magnesium in the starting mixture. Raising the amount of silicon in the starting mixture by 10% leads to a decrease in the percentages of the TiSi2 and Ti5Si3 silicides and titanium carbide in the Ti3SiC2 powder. The addition of sodium chloride and magnesium perchlorate to the starting mixture has been shown to influence the percentages of the TiSi2 and Ti5Si3 silicides and TiC in the Ti3SiC2 powder. We have optimized conditions for the synthesis of powder containing 89.1 wt % Ti3SiC2. The powders prepared by SHS with a reduction step consist of agglomerates of layered particles ranging in size from 130 to 770 nm.