ABSTRACT
Electrochemically Controlled in Solutions ................................................. 346
10.5.1 (100) and (110) Single Crystal Iron Surfaces
Electrochemically Polarized in the Passive State ........................... 347
10.5.2 Effect of Dichromate Treatment on Hardness of
Passive Iron Surfaces..................................................................... 349
10.5.3 Polycrystalline Titanium Surfaces Electrochemically
Controlled in the Passive State...................................................... 352
10.6 In Situ Nanoscratching on Passive Metal Surfaces in Solution ................. 354
10.7 Summary .................................................................................................... 358
References ............................................................................................................ 359
10.1 INTRODUCTION
Corrosion of metals depends on the corrosion products. If very thin and compact
oxide films, i.e., passive films, are formed on the metals, the corrosion rate rapidly
drops to almost zero, i.e., the metals are subjected to the passive state. Many studies
on physicochemical properties of passive films such as composition, structure, thick-
ness have been performed in relation to the corrosion resistances (1,2). The passive
film is locally broken by attacks of aggressive ions such as chloride ions or stresses
generated in the film. If the breakdown sites are not repaired the metals are eventu-
ally subjected to localized corrosion such as pitting corrosion. In spite of that, the
breakdown of passive film is directly related to the mechanical properties of the film,
and there are few studies on mechanical properties of passive films or passive metal
surfaces (3).
