Microstructure and Wear Resistance of Gray Cast Iron Synergistically Manipulated by Nano-sized TiC–TiB₂ Ceramic Particles

The current research studied the influence of TiC–TiB₂ ceramic nanoparticles on the microstructure and wear properties of gray cast irons. The tribological performance of gray cast irons was evaluated on a universal mechanical tribometer with a ball-on-plate reciprocating sliding test rig. It was found that the addition of nanoparticles effectively refined the as-cast microstructure as the graphite flakes and lamellar structures in pearlite became finer with fewer segregation regions. Using the edge-to-edge matching model, it was found that the interplanar spacing mismatch and interatomic spacing misfit between nanoparticles and main phases in the matrix were less than 10%, which indicated the nanoparticles acted as external cores to promote the nucleation of graphite, austenite and ferrite. For wear resistance, it was observed that introducing the nanoparticles decreased the wear volumes of gray cast irons by up to 43.4% under a normal load of 60 N and sliding speed of 80 mm/s. After examining the wear tracks, it could be seen that the wear mechanisms were dominated by adhesive wear and abrasive wear. The introduction of nanoparticles reduced the spalls, smearing areas and grooves. The nanoparticles harden and toughen the substrates, blocked dislocations, separated the mating surfaces and reduced the size of wear debris. The findings in this research provide a novel approach to prepare high wear-resistant gray cast irons.