Specific Wear Rate of TaC and HfC Reinforced Mg-AZ91D Composites Under Different Nominal Stress Conditions

In this research work, a comparison of magnesium composites reinforced with Tantalum carbide (TaC) and Hafnium carbide (HfC) was carried out. Two different composites, AZ91D/TaC (5 wt.%) and AZ91D/HfC (5 wt.%), were manufactured utilizing melt ultrasonication assisted stir casting method. XRD analysis, density, and hardness measurement of the composites were carried out prior to the wear test. Dry sliding wear test was conducted using a pin-on-disc tribometer equipped with EN31 steel counterface. Normal loads of 12.5 N, 25 N, 37.5 N, and 50 N were applied on the pins of cross-sectional area of ~50 mm2 in order to create nominal stresses of 0.25 MPa, 0.50 MPa, 0.75 MPa, and 1 MPa, respectively. Specific Wear Rate (SWR) and Coefficient of Friction (COF) were determined for a sliding velocity of 1 m/s and sliding distance of 1000 m, under those varying loads. SWR and COF of the composites decreased as the nominal stress increased. In comparison, SWR was lower for HfC reinforced composite, while COF was lower for TaC reinforced composite. At 50 N (1 MPa), 1 m/s, 1000 m, the wear mechanisms for both composites were abrasion, oxidation, and delamination.