A method to avoid crevice corrosion in electrochemical determination of pitting potentials

A test arrangement is described, where the electrolyte is brought into contact with the test surface along a multilayered textile tape. This method brings several advantages when compared to the common specimen holders, where part of the specimen surface is masked off by some insulating material. In the absence of crevices, there is no crevice corrosion. No special pretreatment of the test surface is required. Thus, various surface conditions can be tested, including as-received surfaces. The test surface need not be planar. Specimens like bars or weld beads can easily be tested. The desired surface can be selected for the test. The spatial orientation of the test surface can be chosen deliberately. The shape and size of the specimen can vary greatly, which makes the specimen preparation in most cases extremely easy.

The possible uses of the method are demonstrated by room temperature testing of stainless steel sheets and welds in sodium chloride solutions, as well as testing of prestressing steel wire in a saturated calcium hydroxide solution with various concentrations of sodium chloride. Both pit nucleation and repassivation potentials are determined using potentiokinetic techniques. The effects of some experimental variables are studied and discussed.