In situ TiC dense particles layer tissue properties andtoughening mechanism on gray cast iron surface

Dense titanium carbide reinforced iron-based surface composites were prepared via casting-infiltration and heat treatment process. The phase composition, microstructures and microscopic tissue of samples were researched. Meanwhile, the microhardness and fracture toughness were also studied. The results shows: Titanium carbide dense ceramic layer in situ formed by Ti atoms of titanium plate and C atoms dissolved from graphite sheet diffuse into the metallurgical bonding surface, and the bonding interface of dense layer with titanium plate and substrate are good and clean. The average microhardness of dense ceramic layer is 3 027.08 HV0.1, far greater than the residual titanium plate and matrix hardness. With 20 N loads, the dense ceramic layer longitudinal sectional cracks have initiation and propagation on the top of the indentation. The fracture toughness is between 4.5 MPa·m1/2and 14.2 MPa·m1/2, far higher than normal ceramics.