Fabrication of Ti₃SiC₂‐Ti₄SiC₃‐SiC ceramic composites through carbosilicothermic reduction of TiO₂

Abstract

Dense Ti 3 SiC 2 -SiC, Ti 4 SiC 3 -SiC, and Ti 3 SiC 2 -Ti 4 SiC 3 -SiC ceramic composites were fabricated through carbosilicothermic reduction of TiO 2 under vacuum, followed by hot pressing of the as-synthesized products under 25 MPa at 1600°C. In the reduction step, SiC either alone or in combination with elemental Si was used as a reductant. A one-third excess of SiC was added in the reaction mixtures in order to ensure the presence of approximately 30 vol.% SiC in the products of synthesis. During the hot pressing step, the samples that contained Ti 3 SiC 2 showed better densification compared to those containing Ti 4 SiC 3 . The obtained composites exhibited the strength properties typical of coarse-grained MAX-phase ceramics. The flexural strength values of 424 and 321 MPa were achieved in Ti 3 SiC 2 -SiC, and Ti 3 SiC 2 -Ti 4 SiC 3 -SiC composites, respectively. The fracture toughness values were 5.7 MPa·m ½ .