ABSTRACT
A material can be considered to have failed when its ability to completely satisfy the original design function ceases. Failure can occur as a result of a number of causes, for example, the material may fracture or perhaps degrade as a result of corrosion. This chapter considers the causes of such failures and the methods that can be adopted to prevent, or at least, delay failure. It describes the sacrificial protection of a ship's hull from electrolytic corrosion, which would be accelerated by the presence of a 'manganese bronze' propeller. In a similar way, underground steel pipelines can be protected from corrosion by burying slabs of zinc near to the pipe at suitable intervals. Many plastics materials are relatively inert and resist chemical attack by those reagents which would lead to the severe corrosion of most engineering metals. Metals are subject to corrosion by fairly simple chemical attack in the presence of moisture.
