Synthesis of dense Ti3SiC2-based ceramics by thermal explosion under pressure

Abstract

Self-propagating high-temperature synthesis (SHS) of Ti3SiC2 from the elemental powders employing different SHS modes: wave propagation and pressureless or pressure-assisted thermal explosion, has been studied. SHS reaction was ignited in the solid state below the melting point of either constituent, and started with the formation of Ti5Si3 and Ti-rich TiC1� x. The formation of Ti3SiC2 took place at the later stage by crystallization from the liquid concurrent with precipitation of the stoichiometric TiC. In neither approach, a single-phase Ti3SiC2 material was obtained, the combustion products containing appreciable amounts of TiC. An additional ‘phase’ with the approximate composition of 35Ti–52Si–14C (at.%), supposedly the Ti3SiC2–TiSi2–SiC eutectic mixture, was detected in all types of samples. A short 1 min application of a moderate 80 MPa pressure during thermal explosion (reactive forging) yielded 595% dense samples containing � 45 vol.% Ti3SiC2. As the samples do not contain open porosity, they can be further used for HIPing without encapsulation at around 1500 � C to produce fully dense single-phase Ti3SiC2. # 2002 Elsevier Science Ltd. All rights reserved.