Cathodic protection with sacrificial anodes.

On the basis of the theory of bimetallic and multimetallic corrosion, the fundamentals of cathodic protection with sacrificial anodes were discussed. The exact reaction kinetic treatment of the process of this kind of cathodic protection is described. The -0.85 V and the 100 mV polarization criteria are analysed on the basis of the reaction kinetic theory described in this paper. The basic concept of sizing sacrificial anodes, including an experimental method is described. Concepts of the choice of anode materials and the role of anode beds are outlined. The chemical and physical effects (effects of oxidizing agents, organic materials, complex forming agents, catalysts, dry backfill, hydrogen embrittlement, alternating and stray current) disturbing the operation of a cathodic protection system are analysed. The most important technological applications are also reviewed. The application of galvanic anode cathodic protection for protection of pipelines and tanks is briefly summarized. Because of the great attention devoted recently to the corrosion of reinforced concrete structures, a more detailed summary is given. Owing to its importance, a separate summary of the protection of reinforced concrete bridges has been made. Finally, a brief description of microbiologically induced corrosion in cathodic protection is given.