Comparative study of wear behavior of magnesium matrix composite reinforced with silicon carbide particles and whiskers before and after extrusion

Abstract

In the current study the wear behavior of the ZK60/SiC composites reinforced by particles and whiskers in both as-cast and extruded conditions was examined. Furthermore, the wear behavior of the extruded samples along the extrusion direction and perpendicular to the extrusion direction was studied. The wear tests were performed at temperatures of 100, 200, and 300 °C under loads of 10, 20, and 30 N. The results showed that the whisker-reinforced sample (5.8 × 10^–4 g/[N.m]) had higher wear resistance than the particle-reinforced sample (1.3 × 10^–3 g/[N.m]). The lowest wear rate was observed for the extruded sample in the extrusion direction (3.53 × 10⁻⁴ g/[N.m]). It was also found that the wear rate increased by ∼20 % with increasing temperature, but in the ZK60/SiC_w sample, dynamic precipitation increased the wear resistance. The coefficient of friction was also found to increase with rising temperature, showing an increase of approximately 12.5 % at a 10 N load and 20 % at a 30 N load. Examination of the worn surfaces by scanning electron microscopy showed that the as-cast ZK60 alloy at 100 °C had the oxidative-abrasive as the dominant mechanism. It was found that by extruding the sample, the strength of the sample increased and the mechanism changed to adhesive wear. In the ZK60/SiC_p composite, the viscoplastic wear mechanism was dominant. Although in the extruded sample the dominant mechanism changed to plastic deformation. As temperature increases, the viscoplastic wear mechanism became dominant again. In the as-cast ZK60/SiC_w composite, the abrasive wear mechanism changed to delamination with increasing temperature. By extruding the sample, the dominant mechanism changed to adhesive wear. Finally, dynamic precipitation induced by temperature caused an increase in the wear resistance.