An experimental comparison of three wire beam electrode based methods for determining corrosion rates and patterns

Laboratory experiments have been carried out to examine the advantages and limitations of three wire beam electrode (WBE) based techniques, including the noise resistance Rn-WBE method, the overpotential-galvanic current method, and the galvanic current method, in determining corrosion rates and patterns. These techniques have been applied simultaneously to several selected corrosion systems of different characteristics. It has been found that the Rn-WBE method has advantages over other WBE based methods when applying to WBE surfaces under uniform corrosion. However, the Rn-WBE method has been found to be unsuitable for low noise level corrosion systems. It has also been found that both Rn-WBE and overpotential-galvanic current methods are similarly applicable to WBE surfaces under nonuniform corrosion. However, the galvanic current method has been found to be suitable only for WBE surfaces under highly localised corrosion. Some related issues regarding Rn calculation such as trend removal and its effects on corrosion mapping have also been discussed.