Technical performance of co-addition of SiC particulates and SiC whiskers in hot-pressed TiB2-based ultrahigh temperature ceramics.

The objective of this research was to evaluate the impact of the morphology of SiC additive on the microstructure development, sintering behavior, hardness, and fracture toughness of TiB 2 -based ceramics. For this purpose, three different samples were produced via the hot-pressing method at 1950 °C under 25 MPa for 120 min. Subsequently, the samples were characterized by XRD, SEM, and optical microscopy. The samples containing SiC particles (SiC p) reached their theoretical densities. XRD results manifested the formation of an in-situ TiC during the hot-pressing. Thermodynamical investigation and SEM fractographs revealed the role of a liquid phase in boosting the sintering behavior of as-sintered ceramics. The SEM images also confirmed the in-situ generation of B 4 C in the specimens doped with SiC whiskers (SiC w). Finally, the most significant Vickers hardness (28.9 GPa) and fracture toughness (6.4 MPa m1/2) was secured for the sample toughened by 30 vol% SiC w , whereas the lowest values, namely a Vickers hardness of 18.1 GPa and a fracture toughness of 5.1 MPa m1/2, were obtained for the composites doped with 30 vol% SiC p , and 15 vol% SiC w + 15 vol% SiC p , respectively. [ABSTRACT FROM AUTHOR]