Elevated temperature sliding wear behaviour of TiC-reinforced steel matrix composites

Abstract

TiC-steel matrix particulate composites were processed by direct addition of powder to molten BS970:070M15 steel. This powder was produced using a self-propagating high-temperature synthesis (SHS) reaction and consisted of a dispersion of fine TiC particles (5–10 μm) in an iron binder. Dry reciprocating sliding wear behaviour of the composite material and its unreinforced counterpart was investigated at room temperature, 250 and 500°C against a white cast iron counterface. In situ monitoring of wear, in conjunction with electron microscopy, has been used to interpret wear behaviour in relation to the wear scar microstructures observed. Wear experiments were performed at an average sliding speed of 0.1 m s −1 at different test loads. At room temperature, both materials exhibited a marked increase in wear rate at a particular load, indicative of a transition to a more severe regime of wear. This occurred at a significantly higher load for the TiC-reinforced composite than for the unreinforced steel. Prior to the onset of this transition, the reinforced steel displayed significantly superior wear resistance. Above this transition load, however, the reinforced material exhibited similar wear rates to those of its unreinforced counterpart. At a test temperature of 250°C, the transition to the more severe wear regime was observed to occur at a substantially higher load for the TiC-reinforced steel than for the unreinforced material. At 500°C, wear at the interface is dominated by oxidation and both materials exhibited mild wear (characterised by extremely low wear rates) over the range of loads considered in these experiments.