Effect of Excess Silicon on the Formation of Ti₃SiC₂Using Free Ti/Si/C Powders Synthesized via Arc Melting

Abstract

The aim of this study is to investigate the effect of excess silicon on the formation of Ti 3 SiC 2 from free Ti/Si/C powders synthesized via arc melting. The reactant mixture was prepared according to the off-stoichiometric ratio of 3Ti : (x + 1)Si : 2C, where x (excess Si) varied from 0 to 0.5. Samples were analyzed using X-ray diffractometry (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive spectroscopy (EDS). The relative density and porosity of products were calculated using the Archimedes method. Through optimization of the arcing schedules (time) and excess Si amounts, 86.9 wt% of Ti 3 SiC 2 with a relative density of 86% was obtained. For all products, Ti 3 SiC 2 was identified as the main phase, while TiC, TiSi 2 , and Ti 5 Si 3 were identified as secondary phases. Ti 3 SiC 2 grains were in the form of elongated platelets; they were nucleated and grew on the surface of equiaxed TiC grains. The microporosity present in the TiC-equiaxed grains affected the density and porosity of the products.

Synthesis and microstructural evolution in ternary metalloceramic Ti3SiC2 consolidated via the Maxthal 312 powder route

“…This proposed loss of Si by deintercalation even at sintering temperature below the melting point of silicon (T m = 1414℃) contributes significantly to the loss of purity in the synthesized sample during the SPS. Investigators have often compensated for the loss of Si during vacuum sintering by silicon over-stoichiometry [47,[61][62][63] (that is, deviation from 3:1:2 stoichiometric ratio for Ti:Si:C) in the starting mixtures to increase the conversion into Ti 3 SiC 2 . Another method involves the systematic addition of a small amount Al in the starting powder mixture [64][65][66].…”