INFLUENCE OF WATER MOVEMENT ON CORROSION: Ferrous Materials

The influence of water movement on corrosion is of interest in most of the problems concerned with aqueous attack on metals ranging from ships' hulls to metal pipes. Even in cases where no relative motion is imposed, convection currents arise due to temperature variations in the solution. The rate of many reactions between solids and solutions is controlled by the transport of reactants to the surface and of products from it. The main concentration change takes place in a very thin layer next to the solid surface, the boundary diffusion layer. Here transport takes place slowly by diffusion while in the bulk of the solution the concentration is kept the same at all points by convection currents. This article discusses the influence of the boundary layer on corrosion rate of ferrous materials in water.