Study of the High Performance Ceramic-Matrix Composites (CMC's) by Combustion in the TiO₂–Al–C System

摘要

The purpose of this work is to decrease or eliminate porosities of ETER-VC (Electrothermal Explosion Reaction-Volume Combustion) products with the sintering additives. The Ti–C system has been synthesized for its advantages for refractory, abrasive and structural applications. We attempted to densify TiC by using iron addition; this metal is introduced through a reaction 3TiO_(3)+Al+C. This mixture reacted exothermically (?H_(298) = -1072.7 kJ) and this heat is released according to the Fe addition using the following reaction: 3TiO_(3)+4Al+3C+xFe→3TiC+2Al_(2)O_(3)+xFe. .X-ray diffraction analysis indicated that intermetallic Fe_(3)Al, TiC and Al_(2)O_(3) are the main phases formed in the reinforced high performance ceramic-matrix composites. The increasing of x wt. % iron decreased the lattice parameter of TiC. Field emission scanning electron microscopy examinations showed that the addition of Fe decreased TiC particle size and changed their growth controlling mechanism. Also, Raman spectroscopy analysis demonstrate that at higher Fe contents, oxygen dissolved in the TiC crystal structure leading to the formation of titanium oxy-carbide with lower lattice parameter and residual un-reacted carbon in the products. The adiabatic temperatures for the reactions containing x wt. % Fe estimated using the thermodynamic data according to Merzhanov criteria. Thus, doping method is finally used to fabricate materials by ETER-VC combustion mode for industrial applications.