Structure and mechanical properties of zirconium diboride‐based ceramics produced by the spark plasma sintering

Abstract This article investigates the impact of second‐phase additives on the structure and mechanical properties of zirconium diboride (ZrB 2 )‐based ceramic materials. The materials obtained were characterized by X‐ray diffraction, scanning electron microscopy, and Vickers hardness (HV) analysis. As a result, in the temperature range of 1800–2000°C, dense ceramic materials with a fine‐grained structure and uniform distribution of secondary phases were obtained. Additives such as molybdenum disilicide (MoSi 2 ), silicon carbide (SiC), molybdenum carbide (Mo 2 C), and tungsten carbide (WC) lowered the sintering temperature compared to the sintering of pure ZrB 2 . HV measured at loads from 1 to 20 kg showed a weak dependence of hardness on the load. Maximum hardness values were achieved for the three‐component ceramics ZB 2 + 15 vol.% SiC + 5 vol.% Mo 2 C and ZB 2 + 15 vol.% SiC + 5 vol.% WC (HV 20 = 18.68 GPa and 19.33 GPa, respectively) due to increased density of the materials and small grain sizes. The addition of 15 vol.% MoSi 2 leads to an increase in the fracture toughness (5.04 MPa*m 1/2 ) and grain boundary strength (0.58 GPa). This points to the formation of grain boundary states with increased strength (σ f = 0.48 GPa).