Zinc Anodes for Cathodic Protection

Abstract

Historically, zinc was first used to provide cathodic protection to the copper‐sheathed hulls of warships a century and a quarter ago. The practice continued with steel‐hulled ships and ‘zincs’ were fitted to most naval vessels. The sacrificial action was not great and electrical contact to the hull was often poor. Reports that zincs were lasting well became common and this was occasionally regarded as synonymous with good practice. The benefit that properly engineered cathodic protection might bring to ships and other metal structures became apparent just prior to, and during, the last war. Two developments seemed necessary to achieve this protection from zinc. Firstly, some modification to the metal was necessary so that the anode remained electrochemically active and, secondly, engineering of the anode itself, in shape, size and disposition, was equally essential.