Wear behaviour of AZ91D alloy at low sliding speeds

Effect of low sliding speeds (0.01–1.0 m s−1) on wear behaviour of an AZ91D magnesium alloy was studied under dry sliding condition using a pin-on-disc configuration. The wear rates were measured under a constant load of 10 N but two different sliding distances (1 and 10 km). Analyses of the wear tracks, worn surfaces and wear debris were carried out using scanning electron microscope and X-ray diffractometer. Thermogravimetric analyses were conducted to study oxidation behaviour of the wear debris. The friction coefficient values were found to fluctuate with increase in sliding speed leading to the three different wear transitions. Abrasive wear occurred during sliding at 0.01 m s−1. Oxidational wear was predominant at 0.1 m s−1 sliding speed. High sliding speed, 1.0 m s−1, resulted in delamination wear. The wear rate was highest in abrasive wear and lowest in oxidational wear. Oxide particles of Mg–Al–O and MgO2 were mainly observed in the abrasive wear. The majority of oxidational wear debris were oxides of Mg and Al in the form of MgO and MgAl2O4. The largest amount of uncombined Mg was found in delamination wear debris.