Chapter 3 - Materials for Hostile Corrosive Environments

Abstract

The ever-increasing temperature, pressure, stresses, and aggressive environments of the industrial processes demand efficient materials and advanced manufacturing technologies for good performance and prolonged service of the component. Corrosion is one of the major degradation mechanisms by which materials used in the industries fail prematurely and result in significant economic losses. The science of corrosion prevention and control is highly complex in hostile environments, influenced by the fact that corrosion manifests in many forms and is affected by numerous factors, including microstructure, composition, environment, temperature, radiation, pressure, etc. Selecting appropriate material for the hostile environment is the first step in avoiding corrosion at an early stage of service. Fabrication of components from the chosen material without any deviation from design, distortion, defects, and heterogeneous microstructures is the next step in saving the components from undergoing corrosion issues during operation. During service and operation maneuvers, impurities and contamination or malfunctioning of components can lead to initiation and propagation of corrosion processes, shortening the useful service life of the components. Finally, the aging and limitation of the material due to environmental conditions of the operating plant limit the performance. In this chapter issues of material selection, fabrication, testing and evaluation, corrosion protection methodologies, including coatings, surface modification, corrosion monitoring of major components employed for liquid sodium, steam water, seawater, nitric acid, and molten chloride environments employed in nuclear industry will be briefly addressed in a coherent manner. The mechanism and type of corrosion will be briefly explained followed by protection method adopted for the various environments, and the critical issues and insight into the material-environment combination will be addressed. The choice of various materials like Cr-Mo steels, stainless steels, nickel alloys, titanium and zirconium and their alloys, as well as various types of coatings like thermal barrier coatings, double oxide coatings and mixed oxide coatings, superhydrophobic coatings, self-healing repair coatings, and antifouling coatings, will be explained based on their application for various hostile environments.