Tribological properties of hybrid aluminium matrix composites reinforced with boron carbide and ilmenite particles for brake rotor applications

In the present study, stir casting process was employed to incorporate a blend mixture of ilmenite (FeTiO3) and boron carbide (B4C) particles in the matrix of LM13 base alloy. The study demonstrated the effect of individual reinforcement, weight percentage and mixing proportion on wear behaviour of LM13 alloy for brake rotor applications. Composite with 15 wt.% of reinforcement having 75% proportion of boron carbide (15BI-31 composite) shows change in silicon morphology to globular and highest refinement of silicon structure. Highest wear resistance, highest hardness, lowest coefficient of thermal expansion and lowest friction coefficient values were obtained for 15BI-31 composites. The addition of ilmenite particles enhances the properties of BI composites by making the strong interfacial bonding and enhancing the oxidation rate of sliding surface. However, the increase in dislocation density by boron carbide particles helps in enhancing the hardness of composites which contributes in providing the stability to mechanical mixed layer. The comparable wear property (17% higher wear rate), low processing cost and low material cost of 15BI-31 composite make it a suitable material for brake rotor applications. The predominant wear mechanism for composites was observed to be abrasive wear and delamination wear. However, the severity of wear mechanism changes as the applied load increases.