Effects of Al, B and C Additives on Microstructure and Mechanical Properties of Spark-Plasma-Sintered SiC Ceramics
Densification of the SiC powder without and with additives B+C or Al+B+C was carried out by spark plasma sintering (SPS). The unique features of the process are the possibilities of using a very fast heating rate and a short holding time to obtain fully dense materials. The heating rate and applied pressure were kept at 100°C/ min and 40 MPa, while the sintering temperature and soaking time varied from 1650-1850°C for 10-40 min, respectively. The SPS-sintered specimens with the addition of B+C or Al+B+C at 1850°C reached near-theoretical density. The 3C major crystalline phase of SiC was transformed to 6H at 1800°C and translated to 4H during prolonged annealing at 1850°C. The strength of 531.0 MPa and the fracture toughness of 3.9 MPa·m1/2 were obtained by the addition of Al+B+C to SiC prepared at 1850°C for 10 min.
Hai-Doo Kim, Hua-Tay Lin and Michael J. Hoffmann
K. S. Cho and K. S. Lee, "Effects of Al, B and C Additives on Microstructure and Mechanical Properties of Spark-Plasma-Sintered SiC Ceramics ", Key Engineering Materials, Vol. 287, pp. 329-334, 2005