Mechanosynthesis and solid-phase synthesis of ceramics based on hafnium and zirconium carbonitride

Ceramics based on hafnium carbonitride and zirconium carbonitride were obtained on the basis of commercial powders of hafnium and zirconium carbides and nitrides by mechanochemical synthesis during processing in a high-energy planetary ball milling, as well as solid-phase synthesis during spark plasma sintering. It was shown that with increasing processing time in a high-energy ball milling the formation of carbonitrides increases and a change in the lattice parameters characteristic of the process of carbonitride formation is observed, correlating according to Vegard's rule. When spark plasma sintering was carried out at a temperature of 2000?C, a complete solid-phase reaction with the formation of hafnium carbonitride and zirconium carbonitride was observed. It was found that the solid-phase reaction of hafnium carbonitride formation starts at a temperature of 1347?C, and zirconium carbonitride at 1562?C. Bulk samples were obtained by spark plasma sintering. The hardness, Young's modulus and fracture toughness measured on the consolidated samples were: 19.51 ? 0.22 GPa, 448.26 ? 3.41 GPa, 7.03 ? 0.26 MPa?m1/2 for HfCN; 16 ? 0.12 GPa, 343.44 ? 4.25 GPa, 3.57 ? 0.14 MPa?m1/2 for ZrCN, respectively.