CAVITATION EROSION OF COPPER AND ALUMINUM IN WATER AT ELEVATED-TEMPERATURE

Cavitation erosion tests were carried out in tap water on aluminium and copper samples in a rotating disk cavitation test apparatus, to study the effect of water temperature on cavitation dynamics and cavitation erosion. A shift in the position of the erosion zone with changing temperature was observed. This was explained in terms of the effect of temperature on the pressure gradient giving rise to cavitation. As had been found for vibratory cavitation, the erosion rate in this case (flow cavitation) increased with increasing water temperature and reached a maximum at approximately 65-degrees-C. However, in contrast to copper, which exhibited the usual behaviour, the erosion rate of aluminium did not decrease with further temperature increase. This apparent anomaly was investigated by employing specially developed cells for corrosion rate and temperature measurements on a cavitating aluminium sample. It was found that an increase in corrosion rate was mainly responsible for the high cavitation erosion rate at temperatures above 50-degrees-C.