Comparative study on wear behaviour of magnesium and aluminium alloys

Magnesium is the lightest metal used in structural applications, such as aerospace industry, and therefore, it provides the greatest potential for weight or energy reduction. It is particularly suitable for transport technology applications. In order to substitute aluminium alloys in aeronautical engines, wear behaviour of magnesium alloys is considered. A comparison of the unlubricated wear resistance of an aluminium alloy (A 357) and two magnesium alloys (AZ 91 and WE 43) rubbed against 52 100 bearing steel in a pin-on-ring configuration over a range of sliding speed (1-7 m/s) and applied normal loads (20-80 N) is established. In addition to the measurement of the friction force and wear depth, the temperature near the sliding contact is also measured using a thermocouple placed at the back of the pin sample. Thermal effect on friction and worn surfaces are observed and characterized. Wear transitions are found for the AZ 91 and the A 357 alloys. These transitions are controlled by critical temperatures at the contact surfaces. Scanning electron microscopy observations and profilometric analyses are conducted to confirm these transitions and identify the wear mechanisms.