HRTEM study and mechanical properties of ZrB2-SiC composite: An insight into in-situ carbon formation over the SPS process

Abstract

In this research, we performed studies on the in-situ formation of carbon in the ZrB2-25 vol% SiC composite prepared by the spark plasma sintering (SPS) process at 1850 C. The sintering behavior, microstructure, and mechanical properties of the resulted composite were also evaluated. The sample showed excellent sintering behavior, and a relative density of 99.77% could be obtained. X-ray diffractometry and microstructural results confirmed the in-situ formation of carbon during the SPS process. The source of carbon was found to be a reaction between SiC and its surface oxide. Moreover, the SiO2 and B2O3 compounds could form a low melting point eutectic phase and trigger the liquid phase sintering mechanism. The resulted composite achieved the fracture toughness of 5.63 MPa.m(1/2), the Vickers hardness of 18.93 GPa, the flexural strength of 741 MPa, and the elastic modulus of 481 GPa.