Abstract
Zirconium exhibits excellent resistance to most organic environments. To maintain this resistance, it is necessary to have sufficient amounts of water in certain environments. When the water content is insufficient, corrosion problems, such as stress-corrosion cracking, pitting, intergranular attack, high corrosion rate and hydriding, may occur. Yet, there is no report in the public domain on the crevice corrosion of zirconium or any passive alloys in water-deficient organic environments.
Zirconium’s vulnerability in water-deficient organics results from its need for water to repair any damaged sites occurring in the passive film. When there is not sufficient water for maintaining the passivity, corrosion problems may occur.
Accordingly, corrosion problems for zirconium should also include crevice corrosion since the water content is low within a crevice too. Only, crevice corrosion is a very slow process. When the conditions favor the occurrence of corrosion problems outside the crevices, there won’t be sufficient time 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. Incubation time for the initiation of crevice corrosion may be long because of zirconium’s potent capability to passivate. Though, propagation rate is expected to be fast when zirconium’s underlined reactivity is exposed.
A model is established to implicate the capability of water-deficient organics to induce crevice corrosion in zirconium. Stainless steels and titanium are included in discussing the applicability of this model to other passive alloys. The factors affecting the crevice corrosion are discussed. Preventive measures are suggested.
