Spark plasma sintering of quadruplet ZrB2–SiC–ZrC–Cf composites

Abstract

Spark plasma sintering (SPS) route was employed for preparation of quadruplet ZrB2–SiC–ZrC–Cf ultrahigh temperature ceramic matrix composites (UHTCMC). Zirconium diboride and silicon carbide powders with a constant ZrB2:SiC volume ratio of 4:1 were selected as the baseline. Mixtures of ZrB2–SiC were co-reinforced with zirconium carbide (ZrC: 0–10 vol%) and carbon fiber (Cf: 0–5 vol%), taking into account a constant ratio of 2:1 for ZrC:Cf components. The sintered composite samples, processed at 1800 °C for 5 min and 30 MPa punch press under vacuumed atmosphere, were characterized by densitometry, field emission scanning electron microscopy, energy dispersive spectroscopy, X-ray diffractometry as well as mechanical tests such as hardness and flexural strength measurements. The results verified that the composite co-reinforced with 5 vol% ZrC and 2.5 vol% Cf had the optimal characteristics, i.e., it reached a relative density of 99.6%, a hardness of 18 GPa and a flexural strength of 565 MPa.