Some New Studies of Sacrificial Anodes

Abstract

Aluminium and its alloys play an important role as anodic materials in sacrificial protection. Many well-known zinc sacrificial anodes are prone to passivation, which reduces their protective activity. For that reason it was necessary to find an anodic material in which the passive state of the protector has been disrupted. Such capabilities have been found with aluminium when a small quantity of an alloying element is added to it, making the ever-present protective oxide film porous and providing small resistance to anodic dissolution of aluminium. The contents of the alloying element in the total alloy mass prepared out of technical purity aluminium (99, 8%) and the alloying element must be as small as possible so as not to affect the basic properties of pure aluminium. Aluminium is the anode of choice for saltwater environments. The purpose of this study is to examine the effect of addition of small quantities of alloying element, which will not affect the basic advantages of aluminium, electrochemical properties and homogeneity of the alloy with the commercial name Akalpro. Due to high output current densities, the Akalpro electrodes are designed so that the outer surface is as small as possible. This is an advantage when protecting parts of objects (e.g. ships) where it is important to ensure protection with small masses of protector. Akalpro does not sparkle when hit, and does not release significant quantities of hydrogen, so that it can be used without danger as sacrificial anode in ballast tanks, for transportation of oil and inflammable liquids.