Microstructure and mechanical properties of spark-plasma-sintered SiC-TiC composites

Abstract

Rapid densification of the SiC-10, 20, 30, 40wt% TiC powder with Al, B and C additives was carried out by spark plasma sintering (SPS). In the present SPS process, the heating rate and applied pressure were kept at 100° C/min and at 40 MPa, while the sintering temperature varied from 1600-1800° C in an argon atmosphere. The full density of SiC-TiC composites was achieved at a temperature above 1800° C by spark plasma sintering. The 3C phase of SiC in the composites was transformed to 6H and 4H by increasing the process temperature and the TiC content. By tailoring the microstructure of the spark-plasma-sintered SiC-TiC composites, their toughness could be maintained without a notable reduction in strength. The strength of 720 MPa and the fracture toughness of 6.3 MPa• m(1/2) were obtained in the SiC-40wt% TiC composite prepared at 1800° C for 20 min.