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.m1/2, the Vickers hardness of 18.93 GPa, the flexural strength of 741 MPa, and the elastic modulus of 481 GPa. © 2022