Sintering of SiC/Ti₃SiC₂ composites with high SiC contents

The SPS reactive sintering of SiC/Ti₃SiC₂ composites with high SiC contents was studied by adding SiC to reactive (2TiC+1Ti+1.2Si+0.2Al) or (3TiC+2.2Si+0.2Al) mixtures. Four final volume percentages of SiC were targeted: 21 %, 50 %, 60 % and 70 % by adding the appropriate amounts of a micro-sized SiC powder to the reactive mixtures. The synthesis and the sintering of SiC/Ti₃SiC₂ composites were realized at 1500 °C/15 min/50 MPa from these mixtures. Due to liquid losses and SiO volatilization, the silicon lack was proven to be a significant limitation in the synthesis of Ti₃SiC₂ + nSiC composites. A deleterious effect of SiC additions was evidenced on both the reaction and the densification. Finally, Ti₃SiC₂ + nSiC composites were successfully obtained up to 50 vol% and 60 vol% of SiC from the (2TiC+1Ti+1.2Si+0.2Al) and (3TiC+2.2Si+0.2Al) mixtures, respectively. The thermodynamic calculations showed that the driving force of formation of SiC was very high which could disturb the syntheses from the (3TiC+2.2Si+0.2Al) mixture.