Statistical evaluation of mechanical characteristics of hot-pressed ceramics in ZrB2–SiC system

The effect of the addition of 5 mol.% LaB6 on the Weibull modulus of hot-pressed ceramics in ZrB2-SiC is studied in this paper. The samples with a relative density of 91–92%, a flexural strength of 300–315 MPa, and a Vickers hardness of 14–15 GPa are obtained by hot pressing at an isothermal holding temperature of 1900°C and a pres-sure of 30 MPa within 15 minutes in an argon atmosphere. The addition of LaB6 induces an increase in the Weibull modulus of ceramics from 9.5 up to 15.5 when calculating using the bending strength, and from 22.0 up to 31.4 when calculating using the hardness. The values calculated using the hardness are somewhat overestimated due to the local impact of the Vickers pyramid. An increase in the Weibull modulus with the addition of LaB6 is associated with increasing homogeneity of the ceramic structure due to the formation of a more developed system of interphase boundaries in three-component samples.