Effects of Diamond on Microstructure, Fracture Toughness, and Tribological Properties of TiO[sub.2]-Diamond Composites

The reinforcements represented by graphene nanoplatelets, graphite, and carbon nanotubes have demonstrated the great potential of carbon materials as reinforcements to enhance the mechanical properties of TiO[sub.2]. However, it is difficult to successfully prepare TiO[sub.2]-diamond composites because diamond is highly susceptible to oxidation or graphitization at relatively high sintering temperatures. In this work, the TiO[sub.2]-diamond composites were successfully prepared using high-pressure sintering. The effect of diamond on the phase composition, microstructure, mechanical properties, and tribological properties was systemically investigated. Diamond can improve fracture toughness by the crack deflection mechanism. Furthermore, the addition of diamond can also significantly reduce the friction coefficient. The composite composed of 10 wt.% diamond exhibits optimum mechanical and tribological properties, with a hardness of 14.5 GPa, bending strength of 205.2 MPa, fracture toughness of 3.5 MPa∙m[sup.1/2], and a friction coefficient of 0.3. These results enlarge the family of titania-based composites and provide a feasible approach for the preparation of TiO[sub.2]-diamond composites.