Various scale analyses to create functioning corrosion products

Abstract

In this chapter, various scale analyses of pitting and atmospheric corrosion were implemented by (A) in situ observation of reactions near the solution/metal interface using synchrotron radiation, and (B) Mössbauer spectroscopy. Polymerization of M(O, OH)6 (M=metal) octahedra [4], which may be expressed as evolution of the Fe(O, OH)6 network as elsewhere [9, 10], is a quite important and useful concept to understand corrosion mechanisms. The combination of this concept with recent advances in the fields of analytical methods provides the opportunity to "see" corrosion reactions under real environments on various scales. Applying presently proposed various scale analytical techniques, authors have been trying to develop further anti-corrosion steels by controlling corrosion products with functions with an eye to M(O, OH)6-octahedra continuum. At this moment two major strategies have been posted: i.e. (1) controlling the interfacial pH: "pH-strategy" and (2) shielding the interface against environments: "shielding-strategy". In the former arguments, various scale observation of ion states in a solution near the interface gave a lot of information on the effects of alloying elements on controlling the function of poly-M(O, OH)6. In the latter, various scale analyses of structure and morphology of rust during wet and dry cycles elucidated the process of nucleation, growth, and aging in terms of poly-M(O, OH)6 octahedra. Designing corrosion products having an eye to M(O, OH) 6 octahedra in terms of their structure and functions is one of the recently established fields of study. Further investigations by various scale analyses will give us useful guidelines to innovate more functioning materials and technologies.