EFFECT OF ANODIC AND CATHODIC CURRENT DENSITIES ON THE CAVITATION DAMAGE CHARACTERISTICS OF ALUMINUM ALLOY IN SEAWATER

In this study, the influences of electrolytic gas generation on the surface of aluminum as a cushioning media against cavitation bubbles were experimentally investigated. The electrolytic gas evolution was controlled by applying electric current to the metal with different polarity and current densities. The surface of the metal specimen was either polarized anodically or cathodically while simultaneously being subject to vibratory cavitation. It was revealed that the surface damage behavior was mainly dependent on the current densities applied to the metal. It was apparent that a moderate current density range of between -1 x 10(-3) and -7.5 x 10(-3) A/cm(2) applied cathodically can produce electrolytic gas evolution to cushion the cavitation bubbles sufficiently. However, application of a too a high current density (greater than -1 x 10(-3) A/cm(2)) may lead to cathodic corrosion of Al alloys.