In-situ TiC-Graphite-Ni hybrid composites innovatively fabricated by pressureless reactive infiltration method

TiC-Graphite-Ni hybrid composites integrating high hardness of TiC, lubrication of graphite and good fracture toughness of Ni, present excellent tribological properties. This paper innovatively fabricates in-situ TiC-Graphite-Ni composites by pressureless reactive infiltration method, which is simple, low cost and applicable for composites with large and complex shape. The composition of composites is altered by designing C/Ti molar ratio in preforms. In-situ TiC and graphite homogeneously distribute in metal matrix with clean interface. Results show that the graphite content also affects the formation process of in-situ TiC. As C/Ti molar ratio increases from 1 to 1.5, graphite content in composites increases from 0 to 2.7 wt%, and TiC particle size reduces from 3.03 μm to 2.58 μm, resulting in the increase of Vickers hardness of composites from 527 to 664 HV2. With addition of TiC and graphite, tribological properties of Ni-based alloy are improved, which becomes more obvious as graphite content increases. The friction coefficient of composite with 2.7 wt% graphite is 19% lower than that of Ni-based alloy. The main wear mechanism of composites is abrasive wear.