Fabrication of (Zr,Ti)B₂-ZrN-BN composites through reactive spark plasma sintering of ZrB₂ and TiN

Mechanical properties and sintering behavior of additive-free and TiN-doped ZrB₂ ceramics were studied. Reactive spark plasma sintering method was applied for manufacturing of ceramics at 1850 °C for 6 min under 40 MPa. The impact of TiN addition on the microstructure evaluation, densification, and mechanical feathers was investigated. A porous monolithic ZrB₂ with a relative density of 76.5 % was manufactured, while the introduction of 5 wt% TiN resulted in enhancement of relative density to 93.1 %. The formation of (Zr,Ti)B₂ solid solution and in-situ h-BN and ZrN phases was proven by microstructural assessments and X-ray diffractometry. Minimizing the grain growth and improving the densification, as the results of TiN addition, led to enhancement in mechanical properties. The values of bending strength, fracture toughness, and Vickers hardness boosted from 187.6 MPa, 1.9 MPa.m^½, and 10.1 GPa for additive-free ZrB₂ to 606.5 MPa, 4.5 MPa.m^½, and 18.8 GPa for (Zr,Ti)B₂-ZrN-BN composite.