Densification and properties of superhard B6O materials with cobalt additions

The search for suitable additives for boron suboxide (B6O) materials which could improve densification, reduce sintering temperature and tailor the microstructure has been productive. B6O materials doped with 0-5 vol% cobalt addition were sintered at temperatures up to 1850 °C and pressure of 50 MPa for 20 min. Relationships between the formed phases, microstructures and mechanical properties of the sintered materials were investigated as a function of sintering conditions and added cobalt content. The hardness of the sintered B6O materials increases with sintering temperature, while the fracture toughness increases with increasing cobalt content and reduces with increasing sintering temperature.