3.2. Wear resistance
In contrast to the microhardness, the fretting wear resistance
of the anodized electrodes exhibited a different relation as a
function of the electrolyte temperature. Fig. 3 illustrates the
evolution of the wear volume of the anodic oxide layer (i.e. the
volume removed by the corundum ball during wear testing) as a
function of the electrolyte temperature. Within the margins of
the error bars, a similar value for the wear volume was measured
for the lower of the considered temperatures up to 25 °C,
whereas from this electrolyte temperature on the wear volume
increased with the electrolyte temperature. Like microhardness
the increase in wear volume displays a linear trend in the
temperature range [25 °C to 45 °C], though it is followed by a
pronounced increase between 45 °C and 55 °C. Hence the wear
resistance of the anodic oxide layers (which is inversely
proportional to the wear volume) remained constant from 5 °C
to 25 °C, then subsequently decreased with increasing
electrolyte temperature, first linearly from 25 °C to 45 °C and
finally significantly from 45 °C to 55 °C.