Effects of SiC on densification, microstructure and nano-indentation properties of ZrB2–BN composites

Abstract Introducing the SiC additive resulted in a noticeable enhancement in the sintering behavior of the ZrB2–hBN composite, profiting from the SiC involvement in the surface oxide removal. This research intended to compare two ceramics of ZrB2–hBN and ZrB2–SiC–hBN in terms of sinterability, microstructure, and mechanical features. Both samples were spark plasma sintered at 2000 °C for 5 min under 30 MPa. The SiC-free specimen reached a relative density of lower than 95%, while incorporating SiC improved this value up to 99.3%, resulting in near fully dense material. The role of SiC on oxide removal was found to be the chief cause in enhancing the sinterability of the ZrB2–SiC–hBN sample compared to ZrB2–hBN. According to the field emission scanning electron microscopy (FESEM), field emission-electron probe microanalyzer (FE-EPMA), X-ray diffractometry (XRD), and X-ray photoelectron spectroscopy (XPS) studies, both systems were unreactive, and no major in-situ phase could be produced over the sintering process. The ZrB2–SiC–hBN composite reached an elastic modulus of 374 GPa and a Vickers hardness of 19 GPa.