A Novel Model for the Crevice Corrosion of Zirconium in Water-Deficient Organics

Zirconium possesses excellent corrosion properties in a wide range of organic environments. One of the critical requirements for maintaining zirconium’s passivity is that there must be sufficient amounts of water in these environments. When the water content is below the required amount, corrosion problems, such as stress-corrosion cracking, pitting, intergranular attack, high corrosion rate and hydriding, may occur. Still, there is no report in the public domain on the crevice corrosion of zirconium in organic environments.Zirconium’s vulnerability results from zirconium's need for water to re-passivate any damaged sites occurring in the passive film. When there is not sufficient water to repair damaged sites, corrosion problems may occur. Consequently, zirconium should be susceptible to crevice corrosion since the water content is low within a crevice too. However, crevice corrosion is a very slow process. When the conditions favor for the occurrence of corrosion problems outside the crevices, there won’t be sufficient time required for the development of crevice corrosion. When process conditions are not severe enough to readily attack zirconium, then, there is the needed time for crevice corrosion to initiate and propagate. In this presentation, a model is established to implicate the capability of water-deficient organics to induce crevice corrosion in zirconium. The factors affecting the crevice corrosion will be discussed.