Effects of TiC addition on microstructures, mechanical properties and fracture behaviors of porous titanium carbide ceramics

The porous TiC ceramics were prepared by the powder metallurgy-reaction sintering method, in which TiO2, carbon black, phenolic resin and original TiC powder were used as the raw materials. The results indicate that the addition of original TiC powder can affect the microstructures, densities, porosities, mechanical properties and fracture behaviors. With the increase of the TiC addition content, the grain size of secondary TiC, the bulk density and the pore size increase, meanwhile the pore size distribution broadens and the porosity decreases gradually. However, the bending strength does not display a trend of monotone variation, and the maximum bending strength reaches 54.97 MPa when the amount of TiC addition is 30%. In addition, the fracture morphologies of the bending specimens show that the fracture of the secondary TiC grain is usually an inter granular fracture along the grain boundary. When cracks encounter the original TiC particles, three fracture ways may present, i.e. crack deflection, inter-granular fracture and trans-granular cleavage fracture of the original TiC grains.