Graded TiC-based cermets

Two different approaches were used for producing infiltrated, one-dimensionally graded ceramic-metal composites. Graded preforms based on titanium carbide TiC_x over a range of composition (0.50<x<0.80) were infiltrated with molten Cu. The resulting hardness decreased from 1100 HV on the carbon-lean carbide edge of the sample to 500 HV on the stoichiometric TiC side, reflecting the increase in the ceramic content at low values of x. In order to check the validity of an approach that relies on a varying interaction with the molten metal, graded TiC_x preforms based on a narrow carbon-content range, 0.90<x<0.98 were infiltrated with molten Fe-C alloys. The hardness profile across this graded composite extends from 600 HV at the low carbon content side of the carbide to 1450 HV on the stoichiometric TiC side of a heat-treated sample, and fully reflects the changes induced in the metallic matrix. The present study underlines the potential of ceramic phases that extend over a composition range to form the backbone of graded ceramic-metal composites.